Optical glass and optical element

Abstract

[Problem] To provide an optical glass and optical element that have desired optical constants, for which reductions in chemical durability and mechanical properties are suppressed, and for which the glass transition temperature is not high. [Solution] An optical glass for which: the Si4+ content is greater than 0 cation% and is not more than 30 cation%; the B3+ content is greater than 0 cation% and less than 50.00 cation%; the F- content is at least 10 anion%; the Ca2+ content is not more than 25 cation%; the Zn2+ content is not more than 13 cation%; the Ge4+ content is not more than 5 cation%; the total content of La3+, Gd3+, and Y3+ [La3++Gd3++Y3+] is at least 30 cation%; the total content of Mg2+, Ca2+, Sr2+, and Ba2+ [Mg2++Ca2++Sr2++Ba2+] is at least 3.5 cation%; the total content of Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, and Ba2+ [Li++Na++K++Rb++Cs++Mg2++Ca2++Sr2++Ba2+] is at least 3.5 cation%; the cation ratio of the total content of Si4+ and B3+ divided into the Si4+ content [Si4+ / (Si4++B3+)] is at least 0.020; and the cation ratio of the total content of Si4+, B3+, P5+, Ti4+, Nb5+, W6+, Bi3+, Zr4+, and Ta5+ divided into the total content of La3+, Gd3+, Y3+, Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, and Ba2+ [(La3++Gd3++Y3++Li++Na++K++Rb++Cs++Mg2++Ca2++Sr2++Ba2+) / (Si4++B3++P5++Ti4++Nb5++W6++Bi3++Zr4++Ta5+)] is at least 0.83.

Description

Optical Glass and Optical Elements

[0001] The present invention relates to optical glasses and optical elements having desirable optical properties.

[0002] Lenses with high refractive indices and anomalous partial dispersion in each Abbe region are widely used in applications such as in-vehicle cameras, digital cameras such as single-lens reflex cameras, and personal digital assistant devices such as smartphones. For these applications, glass with high chemical durability and mechanical properties is desirable to improve the yield during lens production. Furthermore, for example, when processing glass into aspherical lenses, glass with a high glass transition temperature can be difficult to process. Therefore, glass with a lower glass transition temperature is desired.

[0003] Patent Document 1 discloses an optical glass having a high refractive index and anomalous partial dispersion in the visible to near-ultraviolet region. Patent Document 2 discloses an optical glass having a high refractive index and high transmittance in the near-infrared region. However, neither Patent Document 1 nor Patent Document 2 pays any attention to improving mechanical properties.

[0004] Therefore, there is a need for glasses that have high refractive index and anomalous partial dispersion, combined with chemical durability, reduced glass transition temperature, and mechanical properties.

[0005] JP 2016-155745 A JP 2017-19670 A

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical glass and an optical element that have desired optical constants, are inhibited from decreasing in chemical durability and mechanical properties, and do not have a high glass transition temperature.

[0007] The gist of the present invention is as follows.

[0008] (1) Si ４＋ The content of is more than 0 cation % and 30 cation % or less, ３＋ The content of is more than 0 cation % and less than 50.00 cation %, and F － The content of Ca is 10% or more of anion, ２＋The content of Zn is 25 cation % or less, ２＋ The content of Ge is 13 cation % or less, ４＋ The content of La is 5 cation % or less, ３＋ , Gd ３＋ , and Y ３＋ The total content [La ３＋ +Gd ３＋ +Y ３＋ ] is 30 cation % or more, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ] is 3.5 cation % or more, Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ] is 3.5 cation % or more, Si ４＋ and B ３＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ ) )] is 0.020 or more, Si ４＋ , B ３＋ , P ５＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ , and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , Y３＋ , Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ +Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +P ５＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋ ) ] is 0.83 or more.

[0009] (2) Si ４＋ The content of is more than 0 cation % and 30 cation % or less, ３＋ The content of is more than 0 cation % and less than 50.00 cation %, and F － The content of Ca is 10% or more of anion, ２＋ The content of Zn is 25 cation % or less, ２＋ The content of Ge is 13 cation % or less, ４＋ The content of La is 5 cation % or less, ３＋ , Gd ３＋ , and Y ３＋ The total content [La ３＋ +Gd ３＋ +Y ３＋ ] is 27 cation % or more, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Mg ２＋ + Ca２＋ + Sr ２＋ +Ba ２＋ ] is 3.5 cation % or more, Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ] is 3.5 cation % or more, Si ４＋ and B ３＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ ) )] is 0.070 or more, Si ４＋ , B ３＋ , P ５＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ , and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , Y ３＋ , Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ +Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +P ５＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋ ) )] is 0.83 or more, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ The total content [Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ] is greater than 0 cation %.

[0010] (3) Si ４＋ The content of is more than 0 cation % and 30 cation % or less, ３＋ The content of Al is more than 0 cation % and less than 50.00 cation %; ３＋ The content of Ca is 13 cation % or less, ２＋ The content of Zn is 25 cation % or less, ２＋ The content of Ge is 6 cation % or less, ４＋ The content of F is 5 cation % or less, － The content of La is 10% or more of anion, ３＋ , Gd ３＋ , and Y ３＋ The total content [La ３＋ +Gd ３＋ +Y ３＋ ] is 30 cation % or more, Si ４＋ and B ３＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ ) )] is 0.070 or more, Si ４＋ , B ３＋ , P ５＋ , Ti ４＋ , Nb ５＋ , W６＋ , Bi ３＋ , Zr ４＋ , and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , Y ３＋ , Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ +Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +P ５＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋ ) ] is 0.84 or more.

[0011] (4) B ３＋ The content of La is more than 0 cation % and less than 50.00 cation %; ３＋ The content of Zn is more than 0 cation % and not more than 70 cation %. ２＋ The content of F is 6.5 cation % or less, － The content of La is 10% or more of anion, ３＋ , Gd ３＋ , and Y ３＋ The total content [La ３＋ +Gd ３＋ +Y ３＋ ] is 30 cation % or more, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi３＋ The total content [Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ] is less than 2.0 cation %, and Si ４＋ and B ３＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ ) )] is 0.77 or less, and Si ４＋ , B ３＋ , P ５＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ , and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , Y ３＋ , Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ +Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +P ５＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋) )] is 0.84 or more, the content of Sb ions is 1.0 mass ppm or more in terms of an external percentage, and when the thickness is 10.0 mm ± 0.1 mm, the difference between the external transmittance at a wavelength of 700 nm and the external transmittance at a wavelength of 360 nm is 10% or less.

[0012] (5) B ３＋ The content of La is more than 0 cation % and less than 50.00 cation %; ３＋ The content of Zn is more than 0 cation % and not more than 70 cation %. ２＋ The content of F is 6.5 cation % or less, － The content of La is 10% or more of anion, ３＋ , Gd ３＋ , and Y ３＋ The total content [La ３＋ +Gd ３＋ +Y ３＋ ] is 30 cation % or more, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ The total content [Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ] is 2.0 cation % or more, Si ４＋ and B ３＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ ) )] is 0.77 or less, and Si ４＋ , B ３＋ , P ５＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ , and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , Y ３＋ , Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ +Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +P ５＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋ ) )] is 0.84 or more, the content of Sb ions is 1.0 mass ppm or more in terms of an external proportion, and when the thickness is 10.0 mm ± 0.1 mm, the difference between the external transmittance at a wavelength of 700 nm and the external transmittance at a wavelength of 375 nm is 7.5% or less.

[0013] (6) A glass material for press molding, comprising the optical glass according to any one of (1) to (5) above.

[0014] (7) An optical element made of the optical glass according to any one of (1) to (5) above.

[0015] According to the present invention, it is possible to provide an optical glass and an optical element that have desired optical constants, are inhibited from decreasing in chemical durability and mechanical properties, and do not have a high glass transition temperature.

[0016] In the embodiments of the present invention, the glass composition of the optical glass is expressed in cation % unless otherwise specified. Cation % is the molar percentage when the total content of all cationic components is 100%. The contents and total content of glass components are based on cation % unless otherwise specified, and "%" means "cation %." Furthermore, the cation ratio refers to the ratio (ratio) of the contents of cationic components to each other (including the total content of multiple cationic components) in cation %.

[0017] The anion % is a molar percentage when the total content of all anion components is taken as 100%.

[0018] The valence of the cationic component (e.g., B ３＋ The valence of is +3, Si ４＋ The valence of is +4, La ３＋ The valence of +3) is a value established by convention, and when expressing B, Si, and La as glass components on an oxide basis, B ２ O ３ , SiO ２ , La ２ O ３ Therefore, when analyzing the glass composition, it is not necessary to analyze the valence of the cation component. ２- The valence of -2) is also a value determined by convention, and as described above, the glass component on an oxide basis is, for example, B ２ O ３ , SiO ２ , La ２ O ３ Therefore, when analyzing the glass composition, it is not necessary to analyze the valence of the anion component.

[0019] The content of glass components can be quantified by known methods, such as inductively coupled plasma atomic emission spectroscopy (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), ion chromatography (IC), non-dispersive infrared spectroscopy (ND-IR), etc. In this specification and the present invention, a content of 0% of a component means that the component is substantially not contained, and it is acceptable for the component to be present at an unavoidable impurity level.

[0020] In this specification, chemical durability refers to excellent water resistance Da and / or excellent water resistance Dw. Furthermore, mechanical properties refer to excellent hardness of the glass as measured by the Knoop hardness Hk. The Knoop hardness Hk is an index of the indentation hardness of glass. The Knoop hardness Hk is measured in units of "MPa." However, since it is customary to omit the unit of the Knoop hardness Hk in the technical field to which the present invention pertains, the unit of the Knoop hardness Hk will also be omitted in this specification. Furthermore, the thermal stability and reheating stability of glass both refer to the resistance to crystal precipitation in the glass. Thermal stability refers to the resistance to crystal precipitation when molten glass solidifies, and reheating stability refers to the resistance to crystal precipitation when solidified glass is reheated, such as during reheat pressing.

[0021] As used herein, "reduced or suppressed volatilization of glass components" means that the loss of glass components due to volatilization during melting is small or suppressed. Small loss of glass components due to volatilization during melting suppresses fluctuations in various properties, including refractive index, and also suppresses the occurrence of internal defects such as striae within the glass, thereby stabilizing quality. Furthermore, low loss of glass components directly increases the product yield relative to the input raw materials. Meanwhile, glass components that are prone to volatilization during melting contribute to a decrease in dispersibility, an increase in anomalous partial dispersion, and a decrease in the glass transition temperature Tg. Therefore, suppressing the volatilization of these components can provide optical glasses and optical elements that have the desired optical constants and a moderate glass transition temperature Tg.

[0022] Unless otherwise specified, the refractive index refers to the refractive index nd at the d line of helium (wavelength 587.56 nm).

[0023] The optical glass of the present invention will be described below as a first embodiment and a second embodiment.

[0024] First Embodiment The optical glass according to the first embodiment is made of Si ４＋ The content of is more than 0 cation % and 30 cation % or less, ３＋The content of is more than 0 cation % and less than 50.00 cation %, and F － The content of Ca is 10% or more of anion, ２＋ The content of Zn is 25 cation % or less, ２＋ The content of Ge is 13 cation % or less, ４＋ The content of La is 5 cation % or less, ３＋ , Gd ３＋ , and Y ３＋ The total content [La ３＋ +Gd ３＋ +Y ３＋ ] is 30 cation % or more, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ] is 3.5 cation % or more, Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ] is 3.5 cation % or more, Si ４＋ and B ３＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ ) )] is 0.020 or more, Si ４＋ , B ３＋ , P ５＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr４＋ , and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , Y ３＋ , Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ +Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +P ５＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋ ) )] is 0.83 or more.

[0025] In the optical glass according to the first embodiment, Si ４＋ The content of Si is more than 0% and not more than 30%. ４＋ The lower limit of the content of Si is preferably 1%, and more preferably 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10% in that order. ４＋ The upper limit of the content is preferably 25%, and more preferably 23%, 21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, and 13% in that order.

[0026] Si ４＋ is a glass network forming component. ４＋ By setting the content of Si in the above range, an optical glass having anomalous partial dispersion and improved chemical durability, mechanical properties, and thermal stability can be obtained. ４＋If the content of Si is too low, the chemical durability, mechanical properties, and thermal stability of the glass may be reduced. ４＋ If the content is too high, the meltability of the glass may decrease, the refractive index nd may decrease, and the thermal stability of the glass may decrease, resulting in an increase in the glass transition temperature Tg.

[0027] In the optical glass according to the first embodiment, B ３＋ The content of is more than 0% and less than 50.00%. ３＋ The lower limit of the content of B is preferably 5%, and more preferably 10%, 15%, 17%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, and 26% in that order. ３＋ The upper limit of the content is preferably 45.00%, and more preferably 40.00%, 39.00%, 38.00%, 37.00%, 36.00%, 35.00%, 34.00%, 33.00%, 32.00%, 31.00%, 30.00%, and 29.00% in that order.

[0028] B ３＋ is a glass network forming component. ３＋ By setting the content of B in the above range, chemical durability can be improved. ３＋ If the content of B is too low, the thermal stability and mechanical properties of the glass may be reduced. ３＋ If the content is too high, the volatilization of glass components may increase, and the thermal stability and chemical durability of the glass may decrease.

[0029] The optical glass according to the first embodiment contains F as an anion component. － Includes: F － The content of F is 10% or more. －The lower limit of the content of is preferably 15 anion%, and more preferably 20 anion%, 25 anion%, 27 anion%, 29 anion%, 30 anion%, 31 anion%, 32 anion%, 33 anion%, 34 anion%, 35 anion%, 36 anion%, 37 anion%, 38 anion%, 39 anion%, 40 anion%, 41 anion%, 42 anion%, 43 anion%, and 44 anion%, in that order. － The upper limit of the content of is preferably 80 anion%, and more preferably 75 anion%, 70 anion%, 65 anion%, 63 anion%, 61 anion%, 60 anion%, 59 anion%, 58 anion%, 57 anion%, 56 anion%, 55 anion%, 54 anion%, 53 anion%, 52 anion%, 51 anion%, 50 anion%, 49 anion%, 48 anion%, and 47 anion% in that order. － By setting the content of F within the above range, an optical glass can be obtained which has a high refractive index despite its low dispersion, high thermal stability, anomalous partial dispersion, a low glass transition temperature Tg, and is suitable for precision press molding. － If the content of F is too small, the thermal stability of the glass may decrease, and anomalous partial dispersion may not be obtained. － If the content is too large, the volatilization of glass components may increase.

[0030] In the optical glass according to the first embodiment, Ca ２＋ The content of Ca is 25% or less. ２＋ The upper limit of the content of Ca is preferably 20%, and more preferably 15%, 10%, 9%, 8%, 7%, 6%, and 5% in that order. ２＋ The lower limit of the Ca content is preferably 0%, and more preferably 0.5%, 1%, and 2% in that order. ２＋ The content may be 0%.

[0031] Ca ２＋ By setting the content of Ca in the above range, an optical glass having desired optical constants can be obtained. ２＋If the content is too large, the thermal stability of the glass may be impaired, and the glass transition temperature Tg and liquidus temperature TL may increase.

[0032] In the optical glass according to the first embodiment, Zn ２＋ The content of Zn is 13% or less. ２＋ The upper limit of the content of Zn is preferably 10%, and more preferably 8%, 6%, and 5% in that order. ２＋ The lower limit of the content of Zn is preferably 0%, and more preferably 0.5%, 1%, and 2% in that order. ２＋ The content may be 0%.

[0033] Zn ２＋ is a glass component that, when incorporated, serves to lower the glass transition temperature Tg. ２＋ By setting the content of Zn in the above range, an optical glass with an improved glass transition temperature Tg can be obtained. ２＋ If the content is too high, the specific gravity may increase, the thermal stability and chemical durability of the glass may decrease, and the Abbe number may increase, making it impossible to obtain the desired high refractive index characteristics.

[0034] In the optical glass according to the first embodiment, Ge ４＋ The content of Ge is 5% or less. ４＋ The upper limit of the content of Ge is preferably 4.5%, and more preferably 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, 1%, and 0.5% in that order. ４＋ The lower limit of the content is preferably 0%. ４＋ The content may be 0%.

[0035] Ge ４＋ Although Ge has the function of increasing the dispersibility of glass, it is an extremely expensive component among commonly used glass components. ４＋ By setting the content within the above range, the manufacturing cost of the glass can be reduced.

[0036] In the optical glass according to the first embodiment, La ３＋ , Gd ３＋ , and Y３＋ The total content [La ３＋ +Gd ３＋ +Y ３＋ ] is 30% or more. The lower limit of the total content is preferably 31%, and more preferably 32%, 33%, 34%, 35%, 36%, 37%, and 38% in that order. The upper limit of the total content is preferably 60%, and more preferably 55%, 50%, 48%, 46%, 45%, 44%, 43%, 42%, and 41% in that order. By setting the total content within the above range, an optical glass with a high refractive index nd can be obtained. On the other hand, if the total content is too low, the desired optical constants may not be obtained. If the total content is too high, the thermal stability of the glass may be reduced.

[0037] In the optical glass according to the first embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ] is 3.5% or more. The lower limit of the total content is preferably 5%, and more preferably 7%, 9%, 10%, 11%, 12%, and 13% in that order. The upper limit of the total content is preferably 30%, and more preferably 29%, 28%, 27%, 26%, 25%, 24%, 23%, 22%, 21%, 20%, 19%, 18%, 17%, and 16% in that order. By setting the total content within the above range, an optical glass having desired optical constants, reduced volatilization of glass components, and high thermal stability can be obtained. On the other hand, if the total content is too low, volatilization of glass components may increase, and the thermal stability and devitrification resistance of the glass may be reduced. If the total content is too high, the high refractive index may be impaired, and the thermal stability of the glass may be impaired.

[0038] In the optical glass according to the first embodiment, Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca２＋ , Sr ２＋ , and Ba ２＋ The total content [Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ] is 3.5% or more. The lower limit of the total content is preferably 5%, and more preferably 7%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20% in that order. The upper limit of the total content is preferably 40%, and more preferably 39%, 38%, 37%, 36%, 35%, 34%, 33%, 32%, 31%, 30%, 29%, 28%, 27%, 26%, 25%, 24%, and 23% in that order. By setting the total content within the above range, an optical glass having desired optical constants, a lower glass transition temperature Tg, reduced volatilization of glass components, and high thermal stability can be obtained.

[0039] In the optical glass according to the first embodiment, Si ４＋ and B ３＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ ) is 0.020 or more. The lower limit of the cation ratio is preferably 0.05, and more preferably 0.09, 0.13, 0.15, 0.17, 0.19, 0.21, 0.22, 0.23, 0.24, and 0.25 in that order. The upper limit of the cation ratio is preferably 0.80, and more preferably 0.70, 0.60, 0.50, 0.40, 0.35, 0.34, 0.33, and 0.32 in that order. By setting the cation ratio within the above range, an optical glass with improved chemical durability, mechanical properties, and thermal stability can be obtained.

[0040] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , P ５＋ , Ti ４＋ , Nb ５＋ , W６＋ , Bi ３＋ , Zr ４＋ , and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , Y ３＋ , Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ +Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +P ５＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋ ) is 0.83 or more. The lower limit of the cation ratio is preferably 0.90, and more preferably 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, and 1.50 in that order. The upper limit of the cation ratio is preferably 5.00, and more preferably 4.00, 3.00, 2.50, 2.30, 2.10, 2.00, 1.90, 1.85, 1.80, 1.75, 1.70, and 1.65 in that order. By setting the cation ratio within the above range, volatilization of glass components can be suppressed. On the other hand, if the cation ratio is too small, volatilization of glass components may increase. If the cation ratio is too large, the thermal stability of the glass may be reduced.

[0041] Non-limiting examples of the contents and ratios of glass components other than those described above in the optical glass according to the first embodiment are shown below.

[0042] In the optical glass according to the first embodiment, Si ４＋ and B ３＋ The total content [Si ４＋ +B ３＋ The lower limit of the total content is preferably 10%, and more preferably 15%, 20%, 22%, 24%, 26%, 28%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, and 37% in that order. The upper limit of the total content is preferably 70%, and more preferably 65%, 60%, 58%, 56%, 54%, 52%, 50%, 48%, 47%, 46%, 45%, 44%, 43%, 42%, 41%, and 40% in that order. From the viewpoint of obtaining an optical glass having desired optical constants and anomalous partial dispersion, improved chemical durability, mechanical properties, and thermal stability, and suppressed volatilization of glass components during melting, it is preferable that the total content be within the above range.

[0043] In the optical glass according to the first embodiment, Li ＋ , Na ＋ , and K ＋ The total content [Li ＋ +Na ＋ +K ＋ The lower limit of

[0012] is preferably 0%, and more preferably 1%, 2%, 3%, 4%, 5%, and 6% in that order. The upper limit of the total content is preferably 50%, and more preferably 45%, 40%, 35%, 30%, 25%, 20%, 18%, 16%, 14%, 13%, 12%, 11%, 10%, and 9% in that order. The total content may be 0%. From the viewpoint of lowering the liquidus temperature of the glass and lowering the glass transition temperature Tg, it is preferable that the total content be within the above range.

[0044] In the optical glass according to the first embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ and Zn ２＋ The total content [Mg ２＋ + Ca ２＋ + Sr２＋ +Ba ２＋ +Zn ２＋ The upper limit of the total content is preferably 50%, and more preferably 45%, 40%, 35%, 30%, 25%, 24%, 23%, 22%, 21%, 20%, 19%, 18%, 17%, and 16% in that order. The lower limit of the total content is preferably 3.5%, and more preferably 7%, 9%, 10%, 11%, 12%, and 13% in that order. If the total content is too high, the high refractive index may be impaired and the thermal stability of the glass may be impaired. On the other hand, if the total content is too low, the volatilization of the glass components may increase, and the thermal stability and devitrification resistance of the glass may be reduced. Therefore, the total content is preferably within the above range.

[0045] In the optical glass according to the first embodiment, Li ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ The lower limit of the total content is preferably 3.5%, and more preferably 7%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20% in that order. The upper limit of the total content is preferably 50%, and more preferably 45%, 40%, 35%, 32%, 30%, 29%, 28%, 27%, 26%, 25%, 24%, and 23% in that order. From the viewpoint of obtaining an optical glass having desired optical constants, reduced glass transition temperature Tg and glass liquidus temperature, and reduced volatilization of glass components during melting, it is preferable that the total content be within the above range.

[0046] In the optical glass according to the first embodiment, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ The total content [Ti ４＋+Nb ５＋ +W ６＋ +Bi ３＋ The lower limit of [0.01% by mass] is preferably 0%, and more preferably 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, and 1.6%, in that order. The upper limit of the total content is preferably 20%, and more preferably 15%, 10%, 5%, 4%, 3.5%, 3%, and 2.5%, in that order. From the viewpoint of maintaining high refractive index and low dispersion, the total content may be 0%. From the viewpoint of maintaining a desired Abbe number νd and improving anomalous partial dispersion in the visible to near-ultraviolet region, it is preferable that the total content be within the above range.

[0047] In the optical glass according to the first embodiment, Zr ４＋ and Ta ５＋ The total content [Zr ４＋ +Ta ５＋ The upper limit of the total content is preferably 20%, and more preferably 15%, 10%, 5%, 4%, 3%, 2%, and 1% in that order. The lower limit of the total content is preferably 0%, and more preferably 0.1%, 0.2%, and 0.3% in that order. From the viewpoint of maintaining high refraction and low dispersion, the total content may be 0%. From the viewpoint of maintaining the thermal stability of the glass, it is preferable that the total content be within the above range. If the total content is too high, the thermal stability of the glass may be reduced and the raw material costs may increase.

[0048] In the optical glass according to the first embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ The total content [Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋The upper limit of [0.01% by mass] is preferably 20%, and more preferably 15%, 10%, 5%, 4%, 3.5%, 3%, and 2.5% in that order. The lower limit of the total content is preferably 0%, and more preferably 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, and 1.6% in that order. From the viewpoint of maintaining high refractive index and low dispersion, the total content may be 0%. From the viewpoint of maintaining a desired Abbe number νd and improving anomalous partial dispersion in the visible to near-ultraviolet region, it is preferable that the total content be within the above range.

[0049] In the optical glass according to the first embodiment, Si ４＋ and B ３＋ B relative to the total content of ３＋ The cation ratio of the content [B ３＋ / (Si ４＋ +B ３＋ ) is preferably 0.980, and more preferably 0.95, 0.91, 0.87, 0.85, 0.83, 0.81, 0.79, 0.78, 0.77, 0.76, and 0.75 in that order. The lower limit of the cation ratio is preferably 0.20, and more preferably 0.30, 0.40, 0.50, 0.60, 0.65, 0.66, 0.67, and 0.68 in that order. From the viewpoint of obtaining an optical glass having improved chemical durability, mechanical properties, and thermal stability, it is preferable that the cation ratio be within the above range.

[0050] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , and P ５＋ The total content [Si ４＋ +B ３＋ +P ５＋The lower limit of the total content is preferably 10%, and more preferably 15%, 20%, 22%, 24%, 26%, 28%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, and 37% in that order. The upper limit of the total content is preferably 70%, and more preferably 65%, 60%, 58%, 56%, 54%, 52%, 50%, 48%, 47%, 46%, 45%, 44%, 43%, 42%, 41%, and 40% in that order. From the viewpoint of obtaining an optical glass having desired optical constants and anomalous partial dispersion, improved chemical durability, mechanical properties, and thermal stability, and suppressed volatilization of glass components during melting, it is preferable that the total content be within the above range.

[0051] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , and P ５＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ +P ５＋ ) is preferably 0.80, and more preferably 0.70, 0.60, 0.50, 0.40, 0.35, 0.34, 0.33, and 0.32 in that order. The lower limit of the cation ratio is preferably 0.020, and more preferably 0.05, 0.09, 0.13, 0.15, 0.17, 0.19, 0.21, 0.22, 0.23, 0.24, and 0.25 in that order. From the viewpoint of obtaining an optical glass having improved chemical durability, mechanical properties, and thermal stability, it is preferable that the cation ratio be within the above range.

[0052] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , and P ５＋ B relative to the total content of ３＋ The cation ratio of the content [B ３＋ / (Si ４＋ +B ３＋ +P ５＋) is preferably 0.980, and more preferably 0.95, 0.91, 0.87, 0.85, 0.83, 0.81, 0.79, 0.78, 0.77, 0.76, and 0.75 in that order. The lower limit of the cation ratio is preferably 0.20, and more preferably 0.30, 0.40, 0.50, 0.60, 0.65, 0.66, 0.67, and 0.68 in that order. From the viewpoint of obtaining an optical glass having improved chemical durability, mechanical properties, and thermal stability, it is preferable that the cation ratio be within the above range.

[0053] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , and P ５＋ P relative to the total content of ５＋ The cation ratio of the content [P ５＋ / (Si ４＋ +B ３＋ +P ５＋ ) is preferably 0.50, and more preferably 0.40, 0.30, 0.20, 0.10, 0.08, 0.06, 0.04, and 0.02 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.005, 0.01, and 0.015 in that order. The cation ratio may even be 0. From the viewpoint of obtaining an optical glass with improved chemical durability, mechanical properties, and thermal stability, it is preferable that the cation ratio be within the above range.

[0054] In the optical glass according to the first embodiment, Li ＋ , Na ＋ , and K ＋ Li relative to the total content of ＋ The cation ratio of the content [Li ＋ / (Li ＋ +Na ＋ +K ＋) )] is preferably 1, and more preferably 0.95, 0.90, and 0.85 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 in that order. The cation ratio may be 1. From the viewpoint of suppressing a decrease in stability upon reheating and from the viewpoint of lowering the glass transition temperature Tg, it is preferable that the cation ratio be in the above range.

[0055] In the optical glass according to the first embodiment, Li ＋ , Na ＋ , and K ＋ Na relative to the total content ＋ The cation ratio of the content [Na ＋ / (Li ＋ +Na ＋ +K ＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, and 0.3 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, and 0.15 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in stability upon reheating and from the viewpoint of lowering the glass transition temperature Tg, it is preferable that the cation ratio be in the above range.

[0056] In the optical glass according to the first embodiment, Li ＋ , Na ＋ , and K ＋ K relative to the total content of ＋ The cation ratio of the content [K ＋ / (Li ＋ +Na ＋ +K ＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, and 0.3 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, and 0.15 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in stability upon reheating and from the viewpoint of lowering the glass transition temperature Tg, it is preferable that the cation ratio be in the above range.

[0057] In the optical glass according to the first embodiment, Mg２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Mg relative to the total content ２＋ The cation ratio of the content [Mg ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.55, 0.5, 0.45, and 0.4 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.15, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, and 0.3 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0058] In the optical glass according to the first embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Ca relative to the total content of ２＋ The cation ratio of the content [Ca ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0059] In the optical glass according to the first embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Sr relative to the total content ２＋ The cation ratio of the content [Sr ２＋ / (Mg ２＋ + Ca ２＋ + Sr２＋ +Ba ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0060] In the optical glass according to the first embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Ba relative to the total content of ２＋ The cation ratio of the content [Ba ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) is preferably 0, and more preferably 0.1, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, and 0.60 in this order. The upper limit of the cation ratio is preferably 1, and more preferably 0.90, 0.80, 0.75, 0.74, 0.73, 0.72, 0.71, and 0.70 in this order. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0061] In the optical glass according to the first embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Mg relative to the total content ２＋ The cation ratio of the content [Mg ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.55, 0.5, 0.45, and 0.4 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.15, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, and 0.3 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0062] In the optical glass according to the first embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Ca relative to the total content of ２＋ The cation ratio of the content [Ca ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0063] In the optical glass according to the first embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Sr relative to the total content ２＋ The cation ratio of the content [Sr ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0064] In the optical glass according to the first embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Ba relative to the total content of ２＋ The cation ratio of the content [Ba ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋ ) is preferably 0, and more preferably 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, and 0.60 in this order. The upper limit of the cation ratio is preferably 1, and more preferably 0.90, 0.80, 0.75, 0.74, 0.73, 0.72, 0.71, and 0.70 in this order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0065] In the optical glass according to the first embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Zn relative to the total content of ２＋ The cation ratio of the content [Zn ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, and from the viewpoint of maintaining the high refractive index of the glass, the cation ratio is preferably within the above range.

[0066] In the optical glass according to the first embodiment, La ３＋ , Gd ３＋ , and Y ３＋ La relative to the total content ３＋ The cation ratio of the content [La ３＋ / (La ３＋ +Gd ３＋ +Y ３＋ ) is preferably 0, and more preferably 0.05, 0.10, 0.15, 0.20, 0.25, 0.27, 0.29, 0.31, 0.33, 0.35, 0.37, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, and 0.45 in that order. The upper limit of the cation ratio is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.59, 0.58, 0.57, 0.56, 0.55, 0.54, and 0.53 in that order. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0067] In the optical glass according to the first embodiment, La ３＋ , Gd ３＋ , and Y ３＋ Gd relative to the total content ３＋ The cation ratio of the content [Gd ３＋ / (La ３＋ +Gd ３＋ +Y ３＋) is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, and 0.10 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01 and 0.05 in that order. The cation ratio may be 0. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, the heavy rare earth element Gd ３＋ From the viewpoint of reducing the content and suppressing an increase in raw material costs, it is preferable that the cation ratio be within the above range.

[0068] In the optical glass according to the first embodiment, La ３＋ , Gd ３＋ , and Y ３＋ Y relative to the total content of ３＋ The cation ratio of the content [Y ３＋ / (La ３＋ +Gd ３＋ +Y ３＋ ) is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.63, 0.61, 0.60, 0.59, 0.58, 0.57, 0.56, and 0.55 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, 0.15, 0.20, 0.25, 0.27, 0.29, 0.31, 0.33, 0.35, 0.37, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, and 0.48 in that order. The cation ratio may be 0. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0069] In the optical glass according to the first embodiment, Si ４＋ and B ３＋ Al content relative to the total content ３＋ The cation ratio of the content [Al ３＋ / (Si ４＋ +B ３＋) )] is preferably 0.5, and more preferably 0.45, 0.40, 0.35, 0.30, 0.25, and 0.20 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.05, 0.1, and 0.15 in that order. The cation ratio may be 0. Increasing the cation ratio can improve the mechanical properties and chemical durability of the glass. On the other hand, if the cation ratio is too high, the liquidus temperature rises and the thermal stability of the glass is impaired. From the viewpoint of maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0070] In the optical glass according to the first embodiment, Li ＋ , Na ＋ , and K ＋ Al content relative to the total content ３＋ The cation ratio of the content [Al ３＋ / (Li ＋ +Na ＋ +K ＋ ) )] is preferably 2, and more preferably 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6, 0.4, and 0.2 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.1, and 0.15 in that order. The cation ratio may be 0. Increasing the cation ratio can improve the mechanical properties and chemical durability of the glass. On the other hand, if the cation ratio is too high, the liquidus temperature rises, and the thermal stability of the glass is impaired. From the viewpoint of maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0071] In the optical glass according to the first embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Al content relative to the total content ３＋ The cation ratio of the content [Al ３＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋) )] is preferably 2, and more preferably 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6, 0.4, 0.3, and 0.2 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.1, and 0.15 in that order. The cation ratio may be 0. Increasing the cation ratio can improve the mechanical properties and chemical durability of the glass. On the other hand, if the cation ratio is too high, the liquidus temperature rises, and the thermal stability of the glass is impaired. From the viewpoint of maintaining the thermal stability and devitrification resistance of the glass, it is preferable that the cation ratio be within the above range.

[0072] In the optical glass according to the first embodiment, Li ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Al content relative to the total content ３＋ The cation ratio of the content [Al ３＋ / (Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) )] is preferably 5, and more preferably 4, 3, 2, 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6, 0.4, 0.3, and 0.2 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.1, and 0.15 in that order. The cation ratio may be 0. Increasing the cation ratio can improve the mechanical properties and chemical durability of the glass. On the other hand, if the cation ratio is too high, the liquidus temperature rises, and the thermal stability of the glass is impaired. From the viewpoint of maintaining the thermal stability and devitrification resistance of the glass, it is preferable that the cation ratio be within the above range.

[0073] In the optical glass according to the first embodiment, La ３＋ , Gd ３＋ , and Y ３＋ Al content relative to the total content ３＋The cation ratio of the content [Al ３＋ / (La ３＋ +Gd ３＋ +Y ３＋ ) is preferably 2, and more preferably 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6, 0.4, 0.3, and 0.2 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.1, and 0.15 in that order. The cation ratio may be 0. From the viewpoints of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be in the above range.

[0074] In the optical glass according to the first embodiment, Si ４＋ and B ３＋ Li relative to the total content of ＋ , Na ＋ , and K ＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ ) / (Si ４＋ +B ３＋ ) )] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.3, 0.25, 0.24, 0.23, 0.22, and 0.21 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.07, 0.09, 0.10, 0.11, 0.12, 0.13, and 0.14 in that order. The cation ratio may even be 0. From the viewpoints of improving the chemical durability, mechanical properties, and thermal stability of the glass and suppressing a decrease in stability upon reheating, and from the viewpoint of obtaining an optical glass with a reduced glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0075] In the optical glass according to the first embodiment, Si ４＋ and B ３＋ Mg relative to the total content ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba２＋ ) / (Si ４＋ +B ３＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.48, 0.46, 0.45, 0.44, 0.43, 0.42, 0.41, 0.40, and 0.39, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.15, 0.17, 0.19, 0.21, 0.23, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, and 0.35, in that order. From the viewpoint of suppressing deterioration in the chemical durability, mechanical properties, and thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0076] In the optical glass according to the first embodiment, Si ４＋ and B ３＋ Li relative to the total content of ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ ))] is preferably 0.01, and more preferably 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, and 0.52 in that order. The upper limit of the cation ratio is preferably 2, and more preferably 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.9, 0.8, 0.7, 0.68, 0.66, 0.64, 0.62, 0.61, and 0.6 in that order. From the viewpoint of obtaining an optical glass having desired optical constants, suppressing volatilization of glass components during melting, and reducing the glass transition temperature Tg, it is preferred that the cation ratio be within the above range.

[0077] In the optical glass according to the first embodiment, Si ４＋ and B ３＋ La relative to the total content ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ The lower limit of the cation ratio is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.55, 0.60, 0.65, 0.70, 0.72, 0.74, 0.76, 0.78, 0.80, 0.82, 0.84, 0.86, 0.88, 0.90, 0.92, 0.93, 0.94, and 0.95 in that order. The upper limit of the cation ratio is preferably 3, and more preferably 2.5, 2, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.35, 1.3, 1.25, 1.2, 1.15, 1.13, 1.11, 1.10, and 1.09 in that order. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0078] In the optical glass according to the first embodiment, Si ４＋ and B ３＋ Li relative to the total content of ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , La ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋The lower limit of the cation ratio is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, and 1.55 in that order. The upper limit of the cation ratio is preferably 4, and more preferably 3, 2.5, 2.2, 2.0, 1.95, 1.90, 1.85, 1.80, 1.78, 1.76, 1.74, 1.72, 1.70, 1.68, 1.66, 1.64, and 1.62 in that order. From the viewpoint of obtaining an optical glass that is excellent in chemical durability, mechanical properties, and thermal stability while suppressing volatilization of glass components during melting, it is preferable that the cation ratio be within the above range.

[0079] In the optical glass according to the first embodiment, Si ４＋ and B ３＋ Ti relative to the total content of ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ The cation ratio of the total content [(Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ) / (Si ４＋ +B ３＋ ) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, and 0.04 in this order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the refractive index nd at a desired Abbe number νd, it is preferable that the cation ratio be within the above range.

[0080] In the optical glass according to the first embodiment, Si ４＋ and B ３＋ Zr relative to the total content ４＋ and Ta ５＋ The cation ratio of the total content [(Zr ４＋ +Ta ５＋ ) / (Si ４＋ +B ３＋) )] is preferably 0.5, and more preferably 0.4, 0.3, 0.2, and 0.1 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, and 0.04 in that order. The cation ratio may be 0. From the viewpoint of maintaining the thermal stability of the glass and from the viewpoint of suppressing a decrease in the refractive index nd at a desired Abbe number νd, it is preferable that the cation ratio be within the above range.

[0081] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Li relative to the total content ＋ , Na ＋ , and K ＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ) )] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.3, 0.25, 0.24, 0.23, 0.22, and 0.21 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.07, 0.09, 0.10, 0.11, 0.12, 0.13, and 0.14 in that order. The cation ratio may even be 0. From the viewpoints of improving the chemical durability, mechanical properties, and thermal stability of the glass and suppressing a decrease in stability upon reheating, and from the viewpoint of obtaining an optical glass with a reduced glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0082] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Mg relative to the total content ２＋, Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.48, 0.46, 0.45, 0.44, 0.43, 0.42, 0.41, 0.40, and 0.39, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.15, 0.17, 0.19, 0.21, 0.23, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, and 0.35, in that order. From the viewpoint of suppressing deterioration in the chemical durability, mechanical properties, and thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0083] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Li relative to the total content ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋))] is preferably 0.01, and more preferably 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, and 0.52 in that order. The upper limit of the cation ratio is preferably 2, and more preferably 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.9, 0.8, 0.7, 0.68, 0.66, 0.64, 0.62, 0.61, and 0.6 in that order. From the viewpoint of obtaining an optical glass having desired optical constants, suppressing volatilization of glass components during melting, and reducing the glass transition temperature Tg, it is preferred that the cation ratio be within the above range.

[0084] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ La relative to the total content ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ The lower limit of the cation ratio is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.55, 0.60, 0.65, 0.70, 0.72, 0.74, 0.76, 0.78, 0.80, 0.82, 0.84, 0.86, 0.88, 0.90, 0.92, 0.93, 0.94, and 0.95 in that order. The upper limit of the cation ratio is preferably 3, and more preferably 2.5, 2, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.35, 1.3, 1.25, 1.2, 1.15, 1.13, 1.11, 1.10, and 1.09 in that order. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0085] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Li relative to the total content ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , La ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ The lower limit of the cation ratio is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, and 1.55 in that order. The upper limit of the cation ratio is preferably 4, and more preferably 3, 2.5, 2.2, 2.0, 1.95, 1.90, 1.85, 1.80, 1.78, 1.76, 1.74, 1.72, 1.70, 1.68, 1.66, 1.64, and 1.62 in that order. From the viewpoint of obtaining an optical glass that is excellent in chemical durability, mechanical properties, and thermal stability while suppressing volatilization of glass components during melting, it is preferable that the cation ratio be within the above range.

[0086] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ Li relative to the total content ＋ , Na ＋ , and K ＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋ ) )] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.3, 0.25, 0.24, 0.23, 0.22, and 0.21 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.07, 0.09, 0.10, 0.11, 0.12, 0.13, and 0.14 in that order. The cation ratio may even be 0. From the viewpoints of improving the chemical durability, mechanical properties, and thermal stability of the glass and suppressing a decrease in stability upon reheating, and from the viewpoint of obtaining an optical glass with a reduced glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0087] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ Mg relative to the total content ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.48, 0.46, 0.45, 0.44, 0.43, 0.42, 0.41, 0.40, and 0.39, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, 0.15, 0.17, 0.19, 0.21, 0.23, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, and 0.35, in that order. From the viewpoint of suppressing deterioration in the chemical durability, mechanical properties, and thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0088] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ Li relative to the total content ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋))] is preferably 0.01, and more preferably 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, and 0.52 in that order. The upper limit of the cation ratio is preferably 2, and more preferably 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.9, 0.8, 0.7, 0.68, 0.66, 0.64, 0.62, 0.61, and 0.6 in that order. From the viewpoint of obtaining an optical glass having desired optical constants, suppressing volatilization of glass components during melting, and reducing the glass transition temperature Tg, it is preferred that the cation ratio be within the above range.

[0089] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋The lower limit of the cation ratio is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.55, 0.60, 0.65, 0.70, 0.72, 0.74, 0.76, 0.78, 0.80, 0.82, 0.84, 0.86, 0.88, 0.90, 0.92, 0.93, 0.94, and 0.95 in that order. The upper limit of the cation ratio is preferably 3, and more preferably 2.5, 2, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.35, 1.3, 1.25, 1.2, 1.15, 1.13, 1.11, 1.10, and 1.09 in that order. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0090] In the optical glass according to the first embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ Li relative to the total content ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , La ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋The lower limit of the cation ratio is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, and 1.55 in that order. The upper limit of the cation ratio is preferably 4, and more preferably 3, 2.5, 2.2, 2.0, 1.95, 1.90, 1.85, 1.80, 1.78, 1.76, 1.74, 1.72, 1.70, 1.68, 1.66, 1.64, and 1.62 in that order. From the viewpoint of obtaining an optical glass that is excellent in chemical durability, mechanical properties, and thermal stability while suppressing volatilization of glass components during melting, it is preferable that the cation ratio be within the above range.

[0091] In the optical glass according to the first embodiment, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Ti relative to the total content of ４＋ The cation ratio of the content [Ti ４＋ / (Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ) )] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.23, 0.21, 0.2, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, and 0.11 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, and 0.08 in that order. The cation ratio may be 0. From the viewpoints of increasing the refractive index nd and maintaining a desired Abbe number νd and thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0092] In the optical glass according to the first embodiment, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Nb content relative to the total content ５＋ The cation ratio of the content [Nb５＋ / (Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ) )] is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.74, 0.73, 0.72, 0.71, 0.70, 0.69, 0.68, and 0.67 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, and 0.62 in that order. The cation ratio may be 0. From the viewpoints of increasing the refractive index nd, maintaining a desired Abbe number νd, and maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0093] In the optical glass according to the first embodiment, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ W relative to the total content of ６＋ The cation ratio of the content [W ６＋ / (Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.44, 0.43, 0.42, 0.41, 0.40, 0.39, 0.38, 0.37, 0.36, 0.35, 0.34, 0.33, 0.32, 0.31, 0.3, 0.29, 0.28, and 0.27, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.1, 0.12, 0.14, 0.16, 0.18, 0.20, 0.21, 0.22, 0.23, and 0.24, in that order. The cation ratio may be 0. From the viewpoints of increasing the partial dispersion ratio Pg, F, maintaining a desired Abbe number νd, and maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0094] In the optical glass according to the first embodiment, Ti ４＋ , Nb５＋ , W ６＋ , and Bi ３＋ Bi relative to the total content ３＋ The cation ratio of the content [Bi ３＋ / (Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.44, 0.43, 0.42, 0.41, 0.40, 0.39, 0.38, 0.37, 0.36, 0.35, 0.34, 0.33, 0.32, 0.31, 0.3, 0.29, 0.28, and 0.27 in that order. The lower limit of the cation ratio is preferably 0, and may be 0.05, 0.1, 0.12, 0.14, 0.16, 0.18, 0.20, 0.21, 0.22, 0.23, or 0.24. The cation ratio may be 0. It is preferable that the cation ratio be within the above range from the viewpoints of increasing the refractive index nd and the partial dispersion ratio Pg,F, maintaining a desired Abbe number νd, maintaining the thermal stability of the glass, and reducing damage to platinum production melting equipment.

[0095] In the optical glass according to the first embodiment, Zr ４＋ and Ta ５＋ Zr relative to the total content ４＋ The cation ratio of the content [Zr ４＋ / (Zr ４＋ +Ta ５＋ ) )] is preferably 1, and more preferably 0.95, 0.90, and 0.85 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.5, 0.6, 0.7, and 0.8 in that order. The cation ratio may be 0. From the viewpoints of maintaining desired optical constants and reducing raw material costs, it is preferable that the cation ratio be within the above range.

[0096] In the optical glass according to the first embodiment, Zr ４＋ and Ta ５＋ Ta relative to the total content ５＋ The cation ratio of the content [Ta ５＋ / (Zr ４＋ +Ta ５＋) is preferably 1, and more preferably 0.5, 0.4, 0.3, and 0.2 in that order. The lower limit of the cation ratio is preferably 0, and may be 0.05, 0.10, or 0.15. The cation ratio may be 0. From the viewpoints of maintaining desired optical constants and reducing raw material costs, it is preferable that the cation ratio be in the above range.

[0097] In the optical glass according to the first embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Ti relative to the total content of ４＋ The cation ratio of the content [Ti ４＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.23, 0.21, 0.2, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, 0.11, 0.10, 0.09, 0.08, 0.07, and 0.06 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, and 0.04 in that order. The cation ratio may be 0. From the viewpoint of increasing the refractive index nd and maintaining a desired Abbe number νd, it is preferable that the cation ratio be within the above range.

[0098] In the optical glass according to the first embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Nb content relative to the total content ５＋ The cation ratio of the content [Nb ５＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋+Ta ５＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.34, 0.33, 0.32, 0.31, 0.30, 0.29, 0.28, and 0.27 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, and 0.24 in that order. The cation ratio may be 0. From the viewpoint of increasing the refractive index nd and maintaining a desired Abbe number vd, it is preferable that the cation ratio be within the above range.

[0099] In the optical glass according to the first embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Bi relative to the total content ３＋ The cation ratio of the content [Bi ３＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.30, 0.29, 0.28, 0.27, 0.26, 0.25, 0.24, 0.23, 0.22, 0.21, 0.20, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, and 0.11, in that order. The lower limit of the cation ratio is preferably 0, and may be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, or 0.09. The cation ratio may be 0. It is preferable that the cation ratio be within the above range from the viewpoints of increasing the refractive index nd and the partial dispersion ratio Pg,F, maintaining a desired Abbe number νd, maintaining the thermal stability of the glass, and reducing damage to platinum production melting equipment.

[0100] In the optical glass according to the first embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ W relative to the total content of ６＋ The cation ratio of the content [W ６＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.30, 0.29, 0.28, 0.27, 0.26, 0.25, 0.24, 0.23, 0.22, 0.21, 0.20, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, and 0.11, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, and 0.09, in that order. The cation ratio may be 0. From the viewpoints of increasing the partial dispersion ratio Pg, F, maintaining a desired Abbe number νd, and maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0101] In the optical glass according to the first embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Zr relative to the total content ４＋ The cation ratio of the content [Zr ４＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋) )] is preferably 1, and more preferably 0.95, 0.9, 0.85, 0.80, 0.75, 0.70, 0.69, 0.68, 0.67, 0.66, 0.65, 0.64, 0.63, and 0.62 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.1, 0.2, 0.3, 0.4, 0.45, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, and 0.58 in that order. The cation ratio may be 0. From the viewpoints of increasing the refractive index nd, maintaining a desired Abbe number νd, and improving the mechanical properties and chemical durability of the glass, it is preferable that the cation ratio be within the above range.

[0102] In the optical glass according to the first embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Ta relative to the total content ５＋ The cation ratio of the content [Ta ５＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ ) is preferably 1, and more preferably 0.5, 0.4, 0.3, 0.25, 0.2, 0.15, 0.1, 0.08, 0.06, and 0.04 in that order. The lower limit of the cation ratio is preferably 0, and may be 0.01, 0.02, or 0.03. The cation ratio may be 0. From the viewpoints of maintaining desired constants and reducing raw material costs, it is preferable that the cation ratio be within the above range.

[0103] In the optical glass according to the first embodiment, P ５＋ The upper limit of the content of P is preferably 30%, and more preferably 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, and 1% in that order. ５＋ The lower limit of the content of P is preferably 0%, and more preferably 0.05%, 0.1%, and 0.5% in that order. ５＋ The content of P may be 0%.５＋ By setting the content within the above range, it is possible to obtain glass having relatively high mechanical properties and chemical durability.

[0104] In the optical glass according to the first embodiment, Al ３＋ The upper limit of the content of Al is preferably 30%, and more preferably 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, and 1% in that order. ３＋ The lower limit of the Al content is preferably 0%, and more preferably 0.05%, 0.1%, and 0.5% in that order. ３＋ The content of Al may be 0%. ３＋ When contained in an appropriate amount, Al has the effect of suppressing phase separation of glass. ３＋ By increasing the content of Al, the mechanical properties and chemical durability of the glass can be improved. ３＋ If the content of Al is too high, the liquidus temperature rises and the thermal stability of the glass is impaired. If the liquidus temperature rises, the volatilization of glass components increases when the glass is poured and molded, causing striae. From the viewpoint of maintaining the thermal stability of the glass, Al is ３＋ It is preferable that the content of is within the above range.

[0105] In the glass according to the first embodiment, Li ＋ The upper limit of the content of Li is preferably 40%, and more preferably 30%, 20%, 17%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, and 8% in that order. ＋ The lower limit of the content of Li is preferably 0%, and more preferably 1%, 2%, 3%, 4%, 4.5%, 5%, 5.5%, 6%, and 6.5% in that order. ＋ The content of Li may be 0%. ＋ is a component that contributes to lowering the viscosity of the glass. ＋ If the content of Li is too high, the thermal stability of the glass and the stability during reheating may decrease. ＋ If the content of Li is too small, the glass transition temperature Tg may increase. ＋ The content is preferably in the above range.

[0106] In the glass according to the first embodiment, Na ＋ The upper limit of the content of Na is preferably 40%, and more preferably 30%, 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, 1%, and 0.5% in that order. ＋ The lower limit of the content of Na is preferably 0%, and more preferably 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, and 0.35% in that order. ＋ The content of Na may be 0%. ＋ Li ＋ It is a component that contributes to lowering the viscosity of glass, just like Na. ＋ If the content of Na is too high, the thermal stability of the glass and the stability during reheating may decrease. ＋ The content is preferably in the above range.

[0107] In the optical glass according to the first embodiment, K ＋ The upper limit of the content of is preferably 40%, and more preferably 30%, 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, 1%, and 0.5% in that order. ＋ The lower limit of the content of K is preferably 0%, and more preferably 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, and 0.35% in that order. ＋ The content of K may be 0%. ＋ has the function of lowering the liquidus temperature and improving the thermal stability of the glass. ＋ If the content of K is too high, the chemical durability, weather resistance, and stability during reheating will decrease. ＋ The content is preferably in the above range.

[0108] In the optical glass according to the first embodiment, Rb ＋ The upper limit of the content of Rb is preferably 40%, and more preferably 30%, 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, 1%, and 0.5% in that order. ＋ The lower limit of the content of Rb is preferably 0%. ＋ The content of Rb may be 0%. ＋If the content of Rb is too high, the volatilization of glass components during melting increases, making it impossible to obtain the desired glass. ＋ The content is preferably in the above range.

[0109] In the optical glass according to the first embodiment, Cs ＋ The upper limit of the content of Cs is preferably 40%, and more preferably 30%, 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, 1%, and 0.5% in that order. ＋ The lower limit of the content of Cs is preferably 0%. ＋ The content of Cs may be 0%. ＋ If the content of Cs is too high, the volatilization of glass components during melting increases, making it impossible to obtain the desired glass. In addition, there is a risk that the chemical durability and weather resistance may decrease. ＋ The content is preferably in the above range.

[0110] In the optical glass according to the first embodiment, Mg ２＋ The upper limit of the content of Mg is preferably 40%, and more preferably 30%, 20%, 15%, 13%, 11%, 10%, 9%, 8%, 7%, 6.5%, and 6% in that order. ２＋ The lower limit of the content of Mg is preferably 0%, and more preferably 1%, 2%, 3%, and 4% in that order. ２＋ The content of Mg may be 0%. ２＋ If the content of Mg is too high, the thermal stability and devitrification resistance of the glass may decrease. ２＋ If the content of Mg is too small, the stability of the glass when reheated may decrease. ２＋ The content is preferably in the above range.

[0111] In the optical glass according to the first embodiment, Sr ２＋ The upper limit of the content of Sr is preferably 40%, and more preferably 30%, 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, 1%, and 0.5% in that order. ２＋ The lower limit of the Sr content is preferably 0%. ２＋ The content of Sr may be 0%.２＋ is a component that increases the refractive index nd among alkaline earth metals. ２＋ If the content of Sr is too high, the thermal stability and devitrification resistance of the glass may be reduced. ２＋ The content is preferably in the above range.

[0112] In the optical glass according to the first embodiment, Ba ２＋ The upper limit of the content of Ba is preferably 40%, and more preferably 30%, 25%, 20%, 18%, 16%, 15%, 14%, 13%, 12%, and 11% in that order. ２＋ The lower limit of the content of Ba is preferably 0%, and more preferably 1%, 2%, 3%, 4%, 5%, 6%, 7%, and 8% in that order. ２＋ Among alkaline earth metals, Ba is a component that increases the refractive index nd, and at the same time, when contained in an appropriate amount, it lowers the liquidus temperature and improves the stability of the glass. ２＋ If the content of Ba is too high, the thermal stability and stability during reheating of the glass may be reduced. ２＋ If the content of Ba is too small, the thermal stability of the glass may decrease, and the volatilization of glass components during melting may increase. ２＋ The content is preferably in the above range.

[0113] In the optical glass according to the first embodiment, La ３＋ The lower limit of the content of La is preferably 5%, and more preferably 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, and 17.5% in that order. ３＋ The upper limit of the content of La is preferably 50%, and more preferably 48%, 46%, 44%, 42%, 40%, 38%, 36%, 34%, 32%, 30%, 28%, 26%, 24%, 23%, 22%, 21.5%, 21%, 20.5%, and 20% in that order. ３＋ By introducing a certain amount of La, it is possible to suppress the volatilization of glass components and increase the refractive index nd. ３＋If the content of La is too high, the thermal stability of the glass may decrease, and the glass may be prone to devitrification during production. ３＋ The content is preferably in the above range.

[0114] In the glass according to the first embodiment, Gd ３＋ The upper limit of the content of is preferably 50%, and more preferably 40%, 30%, 20%, 15%, 10%, 8%, 6%, 4%, 3%, 2%, and 1% in that order. ３＋ The lower limit of the content of Gd is preferably 0%. ３＋ The content of Gd may be 0%. ３＋ Is La ３＋ Similarly, by introducing a certain amount of Gd, it is possible to suppress the volatilization of glass components and increase the refractive index nd. ３＋ If the content of Gd is too high, the thermal stability of the glass decreases. ３＋ If the content of Gd is too high, the specific gravity of the glass increases, which is undesirable. In addition, there is a risk of an increase in raw material costs. Therefore, from the viewpoint of suppressing the increase in specific gravity while maintaining good thermal stability of the glass, and from the viewpoint of suppressing the increase in specific gravity, and from the viewpoint of suppressing the increase in the content of Gd, which is a heavy rare earth, it is preferable to use a glass containing Gd as the glass having a high thermal stability. ３＋ From the viewpoint of reducing the content of Gd ３＋ The content is preferably in the above range.

[0115] In the glass according to the first embodiment, Y ３＋ The upper limit of the content of is preferably 50%, and more preferably 48%, 46%, 44%, 42%, 40%, 38%, 36%, 34%, 32%, 30%, 28%, 26%, 25%, 24%, 23%, 22.5%, 22%, and 21.5% in that order. ３＋ The lower limit of the content of Y is preferably 0%, and more preferably 1%, 5%, 8%, 10%, 12%, 14%, 16%, and 18% in that order. ３＋ The content may be 0%.

[0116] Y ３＋ By introducing a certain amount of Y, it is possible to suppress the volatilization of glass components and increase the refractive index nd. ３＋If the content of Y is too high, the thermal stability of the glass decreases, and the glass becomes more susceptible to devitrification during manufacturing. ３＋ If the content of Y is too small, the thermal stability of the glass may be reduced. ３＋ The content is preferably in the above range.

[0117] In the glass according to the first embodiment, Yb ３＋ The upper limit of the content of Yb is preferably 50%, and more preferably 40%, 30%, 20%, 15%, 10%, 8%, 6%, 4%, 3%, 2%, and 1% in that order. ３＋ The lower limit of the content of Yb is preferably 0%. ３＋ The content of Yb may be 0%. ３＋ Is, La ３＋ , Gd ３＋ , Y ３＋ Since the molecular weight is larger than that of Yb, it increases the specific gravity of the glass. ３＋ If the content of Yb is too high, the thermal stability of the glass will decrease. ３＋ The content is preferably in the above range.

[0118] In the optical glass according to the first embodiment, Ti ４＋ The upper limit of the content of Ti is preferably 20%, and more preferably 15%, 10%, 5%, 4%, 3.5%, 3%, and 2.5% in that order. ４＋ The lower limit of the content of Ti is preferably 0%, and may further be 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, or 1.6%. ４＋ The content of Ti may be 0%. From the viewpoint of maintaining a desired Abbe number νd and improving anomalous partial dispersion in the visible to near ultraviolet region, ４＋ It is preferable that the content of is within the above range.

[0119] In the optical glass according to the first embodiment, Nb ５＋The upper limit of the content of Nb is preferably 20%, and more preferably 15%, 10%, 5%, 4%, 3.5%, 3%, and 2.5% in that order. ５＋ The lower limit of the Nb content is preferably 0%, and more preferably 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, and 1.6% in that order. ５＋ The content of Nb may be 0%. From the viewpoint of maintaining a desired Abbe number νd and improving anomalous partial dispersion in the visible to near ultraviolet region, ５＋ It is preferable that the content of is within the above range.

[0120] In the optical glass according to the first embodiment, W ６＋ The upper limit of the content of W is preferably 20%, and more preferably 15%, 10%, 5%, 4%, 3.5%, 3%, and 2.5% in that order. ６＋ The lower limit of the content of W is preferably 0%, and more preferably 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, and 1.6% in that order. ６＋ The content of W may be 0%. From the viewpoints of increasing the transmittance, reducing the specific gravity, maintaining a desired Abbe number νd, and improving the anomalous partial dispersion in the visible to near ultraviolet region, ６＋ It is preferable that the content of is within the above range.

[0121] In the optical glass according to the first embodiment, Bi ３＋ The upper limit of the content of Bi is preferably 20%, and more preferably 15%, 10%, 5%, 4%, 3.5%, 3%, and 2.5% in that order. ３＋ The lower limit of the content of Bi is preferably 0%, and may further be 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, or 1.6%. ３＋ The content of Bi may be 0%. From the viewpoints of increasing transmittance and reducing specific gravity, reducing damage to platinum manufacturing equipment, and improving anomalous partial dispersion in the visible to near ultraviolet region, Bi is ３＋ It is preferable that the content of is within the above range.

[0122] In the optical glass according to the first embodiment, Ta ５＋ The upper limit of the content of Ta is preferably 10%, and more preferably 8%, 6%, 4%, 3%, 2%, and 1% in that order. ５＋ The lower limit of the Ta content is preferably 0%, and more preferably 0.05%, 0.1%, and 0.5% in that order. ５＋ The content of Ta may be 0%. ５＋ is a component that contributes to the high refractive index and low dispersion of the glass. ５＋ If the content of Ta is too high, the raw material cost may increase, and the melting property of the glass may decrease. Furthermore, the specific gravity may increase. ５＋ The content is preferably in the above range.

[0123] In the optical glass according to the first embodiment, Zr ４＋ The upper limit of the content of Zr is preferably 10%, and more preferably 8%, 6%, 4%, 3%, 2%, and 1% in that order. ４＋ The lower limit of the Zr content is preferably 0%, and more preferably 0.05%, 0.1%, and 0.5% in that order. ４＋ The content of Zr may be 0%. ４＋ When contained in an appropriate amount, Zr has the effect of improving chemical durability. ４＋ If the content of Zr is too large, the liquidus temperature LT may increase and the meltability of the glass may decrease. ４＋ It is preferable that the content of is within the above range.

[0124] In the glass according to the first embodiment, Sc ３＋ The content of Sc is preferably 2% or less. ３＋ The lower limit of the content is preferably 0%.

[0125] In the glass according to the first embodiment, Hf ４＋ The content of Hf is preferably 2% or less. ４＋ The lower limit of the content is preferably 0%.

[0126] Sc ３＋ , Hf４＋ Although Sc has the function of increasing the dispersibility of glass, it is an expensive component. ３＋ , Hf ４＋ The content of each of the above is preferably within the above range.

[0127] In the glass according to the first embodiment, Lu ３＋ The content of Lu is preferably 2% or less. ３＋ The lower limit of the content is preferably 0%.

[0128] Lu ３＋ Although Lu has the function of increasing the dispersibility of glass, it is also a glass component that increases the specific gravity of glass due to its large molecular weight. ３＋ The content is preferably in the above range.

[0129] The glass according to the first embodiment contains Si as an essential component. ４＋ and B ３＋ , and optionally Ca ２＋ , Zn ２＋ , P ５＋ , Al ３＋ , Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Sr ２＋ , Ba ２＋ , La ３＋ , Gd ３＋ , Y ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Ta ５＋ , and Zr ４＋ The total content of these glass components is preferably 95% or more, more preferably 98% or more, even more preferably 99% or more, and particularly preferably 99.5% or more.

[0130] The optical glass according to the first embodiment contains O as an anion component. ２－ Includes. ２－The upper limit of the content of is preferably 90 anion%, and more preferably 80 anion%, 75 anion%, 73 anion%, 71 anion%, 69 anion%, 67 anion%, 65 anion%, 63 anion%, 61 anion%, 60 anion%, 59 anion%, 58 anion%, 57 anion%, 56 anion%, and 55 anion%, in that order. ２－ The lower limit of the content is preferably 10 anion%, and more preferably 15 anion%, 20 anion%, 25 anion%, 30 anion%, 32 anion%, 34 anion%, 36 anion%, 38 anion%, 40 anion%, 42 anion%, 44 anion%, 45 anion%, 46 anion%, 47 anion%, 48 anion%, 49 anion%, 50 anion%, and 51 anion%, in that order.

[0131] The optical glass according to the first embodiment contains O as an anion component. ２－ and F － It may contain components other than O. ２－ and F － As an anion component other than Cl － ,Br － , I － However, Cl － ,Br － , I － All of these components are likely to volatilize during glass melting. The volatilization of these components causes problems such as variations in the glass properties, a decrease in the homogeneity of the glass, and significant wear on the melting equipment. － The content of Br is preferably less than 5 anion %, more preferably less than 3 anion %, even more preferably less than 1 anion %, particularly preferably less than 0.5 anion %, and even more preferably less than 0.25 anion %. － and I － The total content of is preferably less than 5 anion %, more preferably less than 3 anion %, even more preferably less than 1 anion %, particularly preferably less than 0.5 anion %, even more preferably less than 0.1 anion %, and even more preferably 0 anion %.

[0132] The glass according to the first embodiment is preferably composed essentially of the above glass components, but may contain other components as long as the effects of the present invention are not impaired. Furthermore, the present invention does not exclude the inclusion of unavoidable impurities.

[0133] In the optical glass according to the first embodiment, Sb ions can be added from the viewpoint of suppressing a decrease in transmittance at wavelengths around 360 nm and 375 nm. The upper limit of the Sb ion content is preferably 1.0000 mass%, and more preferably 0.5000 mass%, 0.1000 mass%, 0.0900 mass%, 0.0800 mass%, 0.0700 mass%, 0.0600 mass%, 0.0500 mass%, 0.0400 mass%, 0.0300 mass%, 0.0250 mass%, 0.0200 mass%, 0.0150 mass%, 0.0100 mass%, 0.0090 mass%, 0.0080 mass%, 0.0070 mass%, 0.0060 mass%, and 0.0050 mass%, in that order. The lower limit of the Sb ion content is preferably 0.0001 mass%, in terms of exclusive proportion, and is more preferably 0.0005 mass%, 0.0008 mass%, 0.0010 mass%, 0.0012 mass%, 0.0014 mass%, 0.0016 mass%, 0.0018 mass%, 0.0020 mass%, 0.0022 mass%, 0.0024 mass%, 0.0026 mass%, 0.0028 mass%, 0.0030 mass%, 0.0032 mass%, 0.0034 mass%, 0.0036 mass%, and 0.0038 mass%, in that order.

[0134] The Sb ions are, for example, Sb ２ O ３ and Sb ２ S ３Sb ions can be added to glass by the method described above. Sb ions include trivalent, pentavalent, and all other valence Sb ions. The content of Sb ions is an exclusive percentage. That is, the content of Sb ions is expressed in mass % when the total content of all glass components other than Sb ions is 100 mass %. From the viewpoint of suppressing a decrease in transmittance at wavelengths around 360 nm and 375 nm, it is preferable to set the content of Sb ions within the above range. If the content of Sb ions is too high, Pt from the crucible is easily introduced into the glass, forming Pt colloids and causing Tyndall-shaped clouding in the glass, which may result in a decrease in light transmittance regardless of the wavelength band. Furthermore, the light absorption of Sb ions themselves may decrease the light transmittance at specific wavelengths. If Sb ions are not contained or the content of Sb ions is too low, the absorption of Pt ions at wavelengths around 360 nm becomes apparent, which may result in a decrease in light transmittance at specific wavelengths in the wavelength range extending to visible light.

[0135] Furthermore, the optical glass described above provides high transmittance over a wide range of the visible light region. To make the most of these features, it is preferable that the glass does not contain any coloring elements. Examples of coloring elements include Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, and V. The content of each element is preferably less than 100 ppm by mass, more preferably 0 to 80 ppm by mass, and even more preferably 0 to 50 ppm by mass, and it is particularly preferable that the glass is substantially free of these elements.

[0136] Ga, Te, Tb, etc. are components that do not need to be incorporated and are also expensive components. ２ O ３ , TeO ２ , TbO ２ The range of the content of each of these is preferably 0 to 0.1%, more preferably 0 to 0.05%, even more preferably 0 to 0.01%, still more preferably 0 to 0.005%, even more preferably 0 to 0.001%, and it is particularly preferable that they are not substantially contained.

[0137] (Glass Properties) <Abbe Number νd> In the optical glass according to the first embodiment, the Abbe number νd is preferably 37.5 to 78, and can also be 40 to 75, 50 to 70, 55 to 67, 57 to 65, 58 to 64, 59 to 63, or 56 to 60.

[0138] The Abbe number νd can be adjusted to a desired value by appropriately adjusting the content of each glass component. The component that relatively lowers the Abbe number νd, i.e., the high dispersion component, is Nb ５＋ , Ti ４＋ , Zr ４＋ , W ６＋ , Bi ３＋ , Ta ５＋ On the other hand, the component that relatively increases the Abbe number νd, that is, the low dispersion component, is F － , Si ４＋ , B ３＋ , Li ＋ , Na ＋ , K. ＋ , La ３＋ , Ba ２＋ , Ca ２＋ , Sr ２＋ etc.

[0139] In the present invention, the Abbe number νd and the partial dispersion ratios Pg and F, which will be described later, are calculated as follows. That is, the refractive index at the 12 wavelengths shown in Table A is measured according to Japanese Industrial Standards (JIS) JIS B 7071-1, Method for measuring the refractive index of optical glass - Part 1: Minimum deviation angle method. Next, the refractive index of each line obtained by measurement is applied to the Schott dispersion formula defined in Annex B of Japanese Industrial Standards (JIS) JIS B 7071-1, Method for measuring the refractive index of optical glass - Part 1: Minimum deviation angle method, and the constants of the Schott dispersion formula are determined by the least squares method. Then, the Abbe number νd and the partial dispersion ratios Pg and F, which will be described later, are calculated from the values ​​of each linear refractive index obtained using the Schott dispersion formula with the determined constants.

[0140] Shot dispersion formula: n ２ = a ０ +a １ λ ２ +a ２ λ －２ +a ３ λ －４+a ４ λ －６ +a ５ λ －８ where n is the refractive index, λ is the wavelength (μm), and a ０ , a １ , a ２ , a ３ , a ４ , a ５ is a constant. The Abbe number νd is expressed as follows using the refractive indices nd, nF, and nC for the d-line, F-line, and C-line: νd=(nd-1) / (nF-nC)

[0141] <Refractive Index nd> In the optical glass according to the first embodiment, the refractive index nd is preferably 1.58 to 1.78, and can also be 1.59 to 1.75, 1.60 to 1.72, 1.61 to 1.69, 1.62 to 1.68, 1.63 to 1.67, 1.64 to 1.66, or 1.67 to 1.69.

[0142] The refractive index nd can be adjusted to a desired value by appropriately adjusting the content of each glass component. The component that functions to relatively increase the refractive index nd (the component that increases the refractive index) is Nb. ５＋ , Ti ４＋ , W ６＋ , Bi ３＋ , Zr ４＋ , Ta ５＋ , La ３＋ , Gd ３＋ , Y ３＋ On the other hand, the component that acts to relatively lower the refractive index nd (refractive index lowering component) is Si ４＋ , B ３＋ , Li ＋ , Na ＋ , K. ＋ etc.

[0143] In the optical glass according to the first embodiment, the refractive index nd and the Abbe number vd preferably satisfy the following formula [1-1]: nd ≧ (-0.0081 × vd + 2.1181) ... [1-1] The refractive index nd and the Abbe number vd more preferably satisfy the following formula [1-2], and even more preferably satisfy the following formulas in the order [1-3], [1-4], and [1-5]: nd ≧ (-0.0081 × vd + 2.1231) ... [1-2] nd ≧ (-0.0081 × vd + 2.1281) ... [1-3] nd ≧ (-0.0081 × vd + 2.1331) ... [1-4] nd ≧ (-0.0081 × vd + 2.1381) ... [1-5]

[0144] <Partial Dispersion Ratio Pg,F> In the optical glass according to the first embodiment, the lower limit of the partial dispersion ratio Pg,F in the visible short wavelength region is preferably 0.5200, and more preferably 0.5250, 0.5300, 0.5350, 0.5400, 0.5410, 0.5420, 0.5430, 0.5440, and 0.5450 in that order. By setting the partial dispersion ratio Pg,F within the above range, an optical glass suitable for correcting high-order chromatic aberrations can be obtained. On the other hand, the upper limit of the partial dispersion ratio Pg,F is not particularly limited, but is usually 0.5700, and preferably 0.5650.

[0145] Furthermore, in the optical glass according to the first embodiment, it is preferable that the partial dispersion ratio Pg,F satisfy the following formula [2-1]: Pg,F≧0.6200−0.0014×νd ...[2-1] It is more preferable that the partial dispersion ratio Pg,F satisfy the following formula [2-2], and further more preferable that the following formulas [2-3], [2-4], [2-5], and [2-6] be satisfied in this order. Pg,F≧0.6220-0.0014×νd…[2-2] Pg,F≧0.6240-0.0014×νd…[2-3] Pg,F≧0.6260-0.0014×νd…[2-4] Pg,F≧0.6270-0.0014×νd…[2-5] Pg,F≧0.6280-0.0014×νd…[2-6]

[0146] In the optical element made of the optical glass according to the first embodiment, from the viewpoint of correcting chromatic aberration well over a wide wavelength range, it is preferable that the partial dispersion ratio Pg,F satisfy the above formula.

[0147] In the optical glass according to the first embodiment, the upper limit of ΔPg,F is not particularly limited, but is preferably 0.0500, and further preferably 0.0400, 0.0300, 0.0200, 0.0150, 0.0140, 0.0130, 0.0120, 0.0110, or 0.0100. On the other hand, the lower limit of ΔPg,F is preferably -0.0100, and more preferably -0.0090, -0.0080, -0.0070, -0.0060, -0.0050, -0.0040, -0.0030, -0.0020, -0.0010, 0.0000, 0.0010, 0.0020, 0.0030, 0.0040, 0.0050, 0.0060, 0.0070, and 0.0080, in that order. By setting ΔPg,F within the above range, an optical glass suitable for correcting high-order chromatic aberrations can be obtained.

[0148] The partial dispersion ratio Pg,F is calculated using the above-mentioned Schott dispersion formula. In the present invention, the partial dispersion ratio Pg,F is calculated by using the refractive index values ​​measured at the 12 different wavelengths (spectral lines) shown in Table A above, fitting the coefficients of the wavelength term in the formula relating the refractive index to the wavelength, called the Schott dispersion formula, and then using the dispersion formula after determining these coefficients. By using the refractive index values ​​measured at the 12 different wavelengths, the partial dispersion ratio Pg,F can be calculated with high accuracy. On the other hand, it is also possible to calculate the partial dispersion ratio Pg,F using a simplified method by reducing the number of wavelengths at which the refractive index is measured, but the accuracy is insufficient.

[0149] The partial dispersion ratio Pg,F is expressed as follows using the refractive indices ng, nF, and nC for the g-line, F-line, and C-line: Pg,F=(ng-nF) / (nF-nC) Furthermore, in a plane with the Abbe number vd on the horizontal axis and the partial dispersion ratio Pg,F on the vertical axis, the normal line is expressed by the following formula: Pg,F(0)=0.6483-(0.001802×vd) Furthermore, the deviation ΔPg,F of the partial dispersion ratio Pg,F from the normal line is expressed as follows: ΔPg,F=Pg,F-Pg,F(0)

[0150] <Specific Gravity of Glass> The specific gravity of the optical glass according to the first embodiment is preferably 6.0 or less, and more preferably 5.5 or less, 5.0 or less, 4.8 or less, and 4.6 or less in that order. Components that relatively increase the specific gravity include Ba, ２＋ , La ３＋ , Zr ４＋ , Nb ５＋ , Ta ５＋ On the other hand, the components that relatively lower the specific gravity are Si ４＋ , B ３＋ , Li ＋ , Na ＋ , Mg ２＋ The specific gravity can be controlled by appropriately adjusting the contents of these components.

[0151] <Liquidus Temperature LT> The upper limit of the liquidus temperature LT of the optical glass according to the first embodiment is preferably 1200°C, and more preferably 1150°C, 1100°C, 1050°C, 1000°C, 980°C, 970°C, 960°C, 950°C, 940°C, 930°C, 920°C, 910°C, 900°C, and 890°C, in that order. By setting the liquidus temperature within the above range, the glass melting and forming temperatures can be lowered, thereby reducing corrosion of glass melting equipment (e.g., crucibles, molten glass stirring equipment, etc.) during the melting process and the occurrence of striae due to volatilization of the glass components themselves. The lower limit of the liquidus temperature LT is not particularly limited. The liquidus temperature LT is determined by the balance of the contents of all the glass components. Among these, the liquidus temperature LT is affected by the Si content. ４＋ , B ３＋ , Li ＋ , Na ＋ , K. ＋The influence of the content of Zr is large. ４＋ , Al ３＋ When the content of these elements is high, the liquidus temperature rises.

[0152] The liquidus temperature is determined as follows: 10 cc (10 ml) of glass is placed in a platinum crucible and melted at a temperature of 1200°C or higher for 15 to 30 minutes, then cooled to below the glass transition temperature Tg. The glass, together with the platinum crucible, is placed in a melting furnace at a specified temperature and held there for two hours. The holding temperature is set at any temperature in 10°C increments, and after holding for two hours, the glass is cooled and the presence or absence of crystals inside the glass is observed under a 100x optical microscope. This procedure is repeated for each temperature, and the lowest temperature at which no crystals precipitate is taken as the liquidus temperature.

[0153] <Glass Transition Temperature Tg> The upper limit of the glass transition temperature Tg of the optical glass according to the first embodiment is preferably 625°C, and more preferably 620°C, 610°C, 600°C, 590°C, 580°C, 570°C, 560°C, 550°C, 540°C, 530°C, 520°C, 510°C, 500°C, 490°C, and 480°C, in that order. The lower limit of the glass transition temperature Tg is preferably 350°C, and more preferably 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, and 470°C, in that order. From the viewpoint of improving the yield during precision press molding, it is preferable to set the glass transition temperature Tg within the above range. On the other hand, if the glass transition temperature Tg is too high, precision press molding may not be possible. The component that relatively lowers the glass transition temperature Tg is Li ＋ , Na ＋ , K. ＋ , F － The component that relatively increases the glass transition temperature Tg is La ３＋ , Zr ４＋ , Nb ５＋ The glass transition temperature Tg can be controlled by appropriately adjusting the contents of these components.

[0154] <Light Transmittance of Glass> The light transmittance of the optical glass according to the first embodiment can be evaluated by the coloring degrees λ80, λ70, and λ5. The spectral transmittance of a glass sample having a thickness of 10.0 mm±0.1 mm was measured in the wavelength range of 200 to 700 nm, and the wavelength at which the external transmittance was 80% was defined as λ80, the wavelength at which the external transmittance was 70%, and the wavelength at which the external transmittance was 5% was defined as λ70, the wavelength at which the external transmittance was 70%, and the wavelength at which the external transmittance was 5%.

[0155] The λ80 of the optical glass according to the first embodiment is preferably 450 nm or less, more preferably 400 nm or less, and even more preferably 350 nm or less. The λ70 is preferably 430 nm or less, more preferably 380 nm or less, and even more preferably 330 nm or less. The λ5 is preferably 380 nm or less, more preferably 330 nm or less, and even more preferably 280 nm or less.

[0156] <Chemical Durability Acid Resistance Da> In the optical glass according to the first embodiment, the acid resistance Da is preferably grade 5 or higher, more preferably grade 4 or higher, and even more preferably grade 3 or higher.

[0157] Acid resistance Da is evaluated by placing powdered glass (particle size 425 to 600 μm) of a mass equivalent to the specific gravity in a platinum cage, immersing it in a quartz glass round-bottom flask containing 80 mL of 0.01 mol / L nitric acid aqueous solution for 60 minutes, and classifying the glass into the grades in Table B according to the weight loss rate (%).

[0158] <Chemical Durability, Water Resistance Dw> In the optical glass according to the first embodiment, the water resistance Dw is preferably grade 5 or higher, more preferably grade 4 or higher, and even more preferably grade 3 or higher.

[0159] Water resistance Dw is evaluated by placing a mass of powdered glass (particle size 425 to 600 μm) equivalent to the specific gravity in a platinum cage, immersing it in a quartz glass round-bottom flask containing 80 mL of pure water (pH = 6.5 to 7.5), and treating it in a boiling water bath for 60 minutes. The weight loss rate (%) is then classified into the grades shown in Table C and evaluated.

[0160] <Mechanical Properties: Knoop Hardness Hk> The lower limit of the Knoop hardness Hk of the optical glass according to the first embodiment is preferably 400, and more preferably 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, and 520, in that order. It is preferable to keep the Knoop hardness Hk within the above range from the viewpoint of preventing damage when handling the glass and when manufacturing lenses and the like by machining the glass, such as grinding, polishing, and cutting. The upper limit of the Knoop hardness Hk is not particularly limited, but is usually 750, and preferably 600.

[0161] The Knoop hardness Hk is ３＋ , Gd ３＋ , Y ３＋ , Si ４＋ , Zr ４＋ , Al ３＋ The content can be increased by adjusting the content.

[0162] <ΔT360> In the optical glass according to the first embodiment, when the thickness is 10.0 mm±0.1 mm, the upper limit of the difference (ΔT360) between the external transmittance at a wavelength of 700 nm and the external transmittance at a wavelength of 360 nm is preferably 31.0%, and more preferably 30.0%, 28.0%, 26.0%, 24.0%, 22.0%, 20.0%, 18.0%, 16.0%, 15.0%, 14.0%, 13.0%, 12.0%, 11.0%, 10.0%, 9.0%, 8.0%, 7.0%, and 6.0%, in that order. The lower limit of ΔT360 is not particularly limited, but is generally 2 to 30%. ΔT360 can be adjusted by introducing Sb ions. Furthermore, from the viewpoint of maintaining low dispersion, it is not preferable to use high-dispersion components such as Ti, Nb, W, and Bi, but when these are introduced for the purpose of increasing refraction or anomalous dispersion, ΔT360 may increase. By keeping ΔT360 within the above range, it is possible to suppress a decrease in transmittance at a wavelength in the vicinity of 360 nm.

[0163] <ΔT375> In the optical glass according to the first embodiment, when the thickness is 10.0 mm±0.1 mm, the upper limit of the difference (ΔT375) between the external transmittance at a wavelength of 700 nm and the external transmittance at a wavelength of 375 nm is preferably 15.0%, and more preferably 13.0%, 11.0%, 10.0%, 9.0%, 8.0%, 7.5%, 7.0%, 6.8%, 6.7%, 6.6%, 6.5%, 6.4%, 6.3%, 6.2%, 6.1%, and 6.0%, in that order. The lower limit of ΔT375 is not particularly limited, but is generally 2 to 15%. ΔT375 can be adjusted by introducing Sb ions. Furthermore, from the viewpoint of maintaining low dispersion, it is not preferable to use high-dispersion components such as Ti, Nb, W, and Bi, but when these are introduced for the purpose of increasing refraction or anomalous dispersion, ΔT375 may increase. By keeping ΔT375 within the above range, it is possible to suppress a decrease in transmittance at a wavelength in the vicinity of 375 nm.

[0164] The external transmittance is defined as the percentage of the transmitted light intensity relative to the incident light intensity when light is incident in the thickness direction of a glass sample [transmitted light intensity / incident light intensity × 100]. The external transmittance also includes the reflection loss of light rays on the sample surface.

[0165] (Production of Optical Glass) The glass according to the first embodiment may be produced by blending glass raw materials to obtain the above-described predetermined composition, and then using the blended glass raw materials in accordance with a known glass production method. For example, a plurality of compounds may be blended and thoroughly mixed to form batch raw materials, which may then be placed in a platinum crucible or the like to be roughly melted (roughly melted). The molten material obtained by the rough melting is then quenched and pulverized to produce cullet. The cullet is then placed in a platinum crucible, heated, and remelted (remelted) to produce a glass melt, which is then clarified and homogenized, and the glass melt is then shaped and slowly cooled to obtain optical glass. Known methods may be used to shape and slowly cool the glass melt.

[0166] The compounds used when preparing the batch raw materials are not particularly limited as long as they can introduce desired glass components into the glass in desired contents. Examples of such compounds include oxides, carbonates, nitrates, hydroxides, fluorides, composite oxides, fluorosilicates, and fluoroborates.

[0167] (Production of Press-Molding Glass Material) According to one aspect of the present invention, it is possible to provide a press-molding glass material made of the optical glass according to the first embodiment, and a method for producing the same.

[0168] Press molding of glass materials for press molding can be carried out by pressing the glass material, which has been heated and softened, into a press mold. Both heating and press molding can be carried out in the atmosphere. By uniformly applying a powdered mold release agent such as boron nitride to the surface of the glass material for press molding and then heating and press molding, it is possible to reliably prevent the glass from fusing with the mold and also to smoothly spread the glass along the molding surface of the mold. Annealing the glass after press molding to reduce internal strain in the glass allows for the production of homogeneous optical element blanks.

[0169] Examples of glass materials for press molding include precision press molding preforms and glass materials for press molding optical element blanks (glass gobs for press molding), and include glass chunks having a mass corresponding to the mass of the desired press-molded product.

[0170] Glass materials for press molding, also known as preforms, include those used for press molding as is, as well as those that are subjected to mechanical processing such as cutting, grinding, and polishing before being used for press molding. Cutting methods include forming a groove on the surface of the glass sheet at the desired cutting location using a method called scribing, applying local pressure to the grooved area from the backside of the surface where the groove was formed, thereby breaking the glass sheet at the grooved area, and cutting the glass sheet with a cutting blade. Grinding methods include spherical processing and smoothing using a curve generator. Polishing methods include polishing using abrasive grains such as cerium oxide or zirconium oxide.

[0171] The press-molding glass material according to this embodiment is made of optical glass with excellent mechanical properties, and is therefore resistant to damage during handling and processing. A problem with conventional precision press-molding glass materials is that scratches on the glass material surface tend to remain on the surface of optical elements, particularly optically functional surfaces, after press molding. The press-molding glass material according to this embodiment has excellent mechanical properties and is resistant to scratches on the glass material surface, making it suitable for use as a precision press-molding glass material. Furthermore, even when the press-molded product is machined, i.e., ground and polished, after press molding to produce an optical element, a press-molded product that is resistant to damage by machining can be produced.

[0172] (Manufacturing of Optical Element Blank) According to one aspect of the present invention, it is possible to provide an optical element blank made of the optical glass according to the first embodiment. The optical element blank is a glass molded body having a shape similar to the shape of the optical element to be manufactured. The optical element blank can be manufactured by a method of molding glass into a shape that includes a processing allowance to be removed when processing into the shape of the optical element to be manufactured. For example, the optical element blank can be manufactured by a method of heating and softening a glass material for press molding and press-molding it (reheat press method), or a method of supplying a molten glass gob to a press mold by a known method and press-molding it (direct press method).

[0173] (Manufacturing of Optical Elements) To manufacture an optical element using the optical glass according to the first embodiment, known methods may be applied. For example, the optical element blank described above may be used. Furthermore, for example, in the manufacture of the optical glass, molten glass is poured into a mold and formed into a plate to produce a glass material made of the optical glass according to the present invention. The obtained glass material is appropriately cut, ground, and polished to produce cut pieces of a size and shape suitable for press molding. The cut pieces are heated and softened, and then press-molded (reheat pressed) using a known method to produce an optical element blank that approximates the shape of the optical element. The optical element can be manufactured by a method including a step of processing the optical element blank. Examples of processing include cutting, cutting, rough grinding, fine grinding, and polishing. Using the above glass during such processing can reduce breakage and ensure a stable supply of high-quality optical elements.

[0174] Examples of types of optical elements include lenses such as spherical lenses and aspherical lenses, prisms, diffraction gratings, etc. Examples of lens shapes include biconvex lenses, plano-convex lenses, biconcave lenses, plano-concave lenses, convex meniscus lenses, concave meniscus lenses, etc. The optically functional surfaces of the optical elements may be coated with an anti-reflection film, a total reflection film, etc. depending on the intended use.

[0175] The optical element according to this embodiment is made of optical glass with excellent mechanical properties, and therefore is resistant to damage during handling and processing. In particular, the optical element is resistant to damage when fixed. For example, during lens centering, the lens surface is resistant to damage even when clamped from both sides.

[0176] Second Embodiment The optical glass according to the second embodiment is made of Si ４＋ The content of is more than 0 cation % and 30 cation % or less, ３＋ The content of is more than 0 cation % and less than 50.00 cation %, and F － The content of Ca is 10% or more of anion, ２＋ The content of Zn is 25 cation % or less, ２＋ The content of Ge is 13 cation % or less,４＋ The content of La is 5 cation % or less, ３＋ , Gd ３＋ , and Y ３＋ The total content [La ３＋ +Gd ３＋ +Y ３＋ ] is 27 cation % or more, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ] is 3.5 cation % or more, Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ] is 3.5 cation % or more, Si ４＋ and B ３＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ ) )] is 0.070 or more, Si ４＋ , B ３＋ , P ５＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ , and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , Y ３＋ , Li ＋ , Na ＋ , K. ＋ , Rb＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ +Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +P ５＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋ ) )] is 0.83 or more, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ The total content [Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ] exceeds 0 cation %.

[0177] In the optical glass according to the second embodiment, Si ４＋ The content of Si is more than 0% and not more than 30%. ４＋ The lower limit of the content of Si is preferably 1%, and more preferably 1.5%, 2%, 2.5%, 3%, 3.5%, and 4% in that order. ４＋ The upper limit of the content is preferably 25%, and more preferably 23%, 21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, and 7%, in that order.

[0178] Si ４＋ is a glass network forming component. ４＋By setting the content of Si in the above range, an optical glass having anomalous partial dispersion and improved chemical durability, mechanical properties, and thermal stability can be obtained. ４＋ If the content of Si is too low, the chemical durability, mechanical properties, and thermal stability of the glass may be reduced. ４＋ If the content is too high, the meltability of the glass may decrease, the refractive index nd may decrease, and the thermal stability of the glass may decrease, resulting in an increase in the glass transition temperature Tg.

[0179] In the optical glass according to the second embodiment, B ３＋ The content of is more than 0% and less than 50.00%. ３＋ The lower limit of the content of B is preferably 5%, and more preferably 10%, 15%, 17%, 19%, 21%, 23%, 25%, 27%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, and 36% in that order. ３＋ The upper limit of the content is preferably 45.00%, and more preferably 44.00%, 43.00%, 42.50%, 42.00%, 41.50%, 41.00%, 40.50%, and 40.00% in that order.

[0180] B ３＋ is a glass network forming component. ３＋ By setting the content of B in the above range, chemical durability can be improved. ３＋ If the content of B is too low, the thermal stability and mechanical properties of the glass may be reduced. ３＋ If the content is too high, the volatilization of glass components may increase, and the thermal stability and chemical durability of the glass may decrease.

[0181] The optical glass according to the second embodiment contains F as an anion component. － Includes: F － The content of F is 10% or more. －The lower limit of the content of F is preferably 15 anion%, and more preferably 17 anion%, 19 anion%, 21 anion%, 23 anion%, 24 anion%, 25 anion%, 26 anion%, 27 anion%, 28 anion%, 29 anion%, 30 anion%, and 31 anion% in that order. － The upper limit of the content of is preferably 80 anion%, and more preferably 75 anion%, 70 anion%, 65 anion%, 63 anion%, 61 anion%, 59 anion%, 57 anion%, 55 anion%, 53 anion%, 51 anion%, 49 anion%, 47 anion%, 45 anion%, 43 anion%, 41 anion%, 40 anion%, 39 anion%, 38 anion%, 37 anion%, 36 anion%, and 35 anion% in that order. － By setting the content of F within the above range, an optical glass can be obtained which has a high refractive index despite its low dispersion, high thermal stability, anomalous partial dispersion, a low glass transition temperature Tg, and is suitable for precision press molding. － If the content of F is too small, the thermal stability of the glass may decrease, and anomalous partial dispersion may not be obtained. － If the content is too large, the volatilization of glass components may increase.

[0182] In the optical glass according to the second embodiment, Ca ２＋ The content of Ca is 25% or less. ２＋ The upper limit of the content of Ca is preferably 20%, and more preferably 15%, 10%, 9%, 8%, 7%, 6%, and 5% in that order. ２＋ The lower limit of the Ca content is preferably 0%, and more preferably 0.5%, 1%, and 2% in that order. ２＋ The content may be 0%.

[0183] Ca ２＋ By setting the content of Ca in the above range, an optical glass having desired optical constants can be obtained. ２＋ If the content is too large, the thermal stability of the glass may be impaired, and the glass transition temperature Tg and liquidus temperature TL may increase.

[0184] In the optical glass according to the second embodiment, Zn ２＋ The content of Zn is 13% or less. ２＋ The upper limit of the content of Zn is preferably 10%, and more preferably 8%, 6%, and 5% in that order. ２＋ The lower limit of the content of Zn is preferably 0%, and more preferably 0.5%, 1%, and 2% in that order. ２＋ The content may be 0%.

[0185] Zn ２＋ is a glass component that, when incorporated, serves to lower the glass transition temperature Tg. ２＋ By setting the content of Zn in the above range, an optical glass with an improved glass transition temperature Tg can be obtained. ２＋ If the content is too high, the specific gravity may increase, the thermal stability and chemical durability of the glass may decrease, and the Abbe number may increase, making it impossible to obtain the desired high refractive index characteristics.

[0186] In the optical glass according to the second embodiment, Ge ４＋ The content of Ge is 5% or less. ４＋ The upper limit of the content of Ge is preferably 4.5%, and more preferably 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, 1%, and 0.5% in that order. ４＋ The lower limit of the content is preferably 0%. ４＋ The content may be 0%.

[0187] Ge ４＋ Although Ge has the function of increasing the dispersibility of glass, it is an extremely expensive component among commonly used glass components. ４＋ By setting the content within the above range, the manufacturing cost of the glass can be reduced.

[0188] In the optical glass according to the second embodiment, La ３＋ , Gd ３＋ , and Y ３＋ The total content [La ３＋ +Gd ３＋ +Y ３＋] is 27% or more. The lower limit of the total content is preferably 31%, and more preferably 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, and 44% in that order. The upper limit of the total content is preferably 60%, and more preferably 58%, 56%, 55%, 54%, 53%, 52%, 51%, 50%, 49%, and 48% in that order. By setting the total content within the above range, an optical glass with a high refractive index nd can be obtained. On the other hand, if the total content is too low, the desired optical constants may not be obtained. If the total content is too high, the thermal stability of the glass may be reduced.

[0189] In the optical glass according to the second embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ] is 3.5% or more. The lower limit of the total content is preferably 3.6%, and more preferably 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, and 4.5% in that order. The upper limit of the total content is preferably 30%, and more preferably 29%, 28%, 27%, 26%, 25%, 24%, 23%, 22%, 21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, and 8% in that order. By setting the total content within the above range, an optical glass having desired optical constants, reduced volatilization of glass components, and high thermal stability can be obtained. On the other hand, if the total content is too low, the volatilization of the glass components increases, which may reduce the thermal stability and devitrification resistance of the glass, whereas if the total content is too high, the high refractive index may be impaired, and the thermal stability of the glass may be impaired.

[0190] In the optical glass according to the second embodiment, Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ] is 3.5% or more. The lower limit of the total content is preferably 3.6%, and more preferably 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, and 4.5% in that order. The upper limit of the total content is preferably 40%, and more preferably 39%, 38%, 37%, 36%, 35%, 34%, 33%, 32%, 31%, 30%, 29%, 28%, 27%, 26%, 25%, 24%, 23%, 22%, 21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, and 8% in that order. By setting the total content within the above range, an optical glass having desired optical constants, a lower glass transition temperature Tg, reduced volatilization of glass components, and high thermal stability can be obtained.

[0191] In the optical glass according to the second embodiment, Si ４＋ and B ３＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ ) is 0.070 or more. The lower limit of the cation ratio is preferably 0.08, and more preferably 0.09, 0.10, 0.11, and 0.12 in that order. The upper limit of the cation ratio is preferably 0.80, and more preferably 0.70, 0.60, 0.50, 0.40, 0.35, 0.30, 0.29, 0.28, 0.27, 0.26, 0.25, 0.24, 0.23, 0.22, 0.21, and 0.20 in that order. By setting the cation ratio within the above range, an optical glass with improved chemical durability, mechanical properties, and thermal stability can be obtained.

[0192] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , P ５＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ , and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , Y ３＋ , Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ +Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +P ５＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋) is 0.83 or more. The lower limit of the cation ratio is preferably 0.85, and more preferably 0.87, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, and 1.00 in that order. The upper limit of the cation ratio is preferably 5.00, and more preferably 4.00, 3.00, 2.50, 2.30, 2.10, 2.00, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, 1.60, 1.55, 1.50, 1.45, 1.40, 1.35, 1.30, 1.25, 1.20, 1.15, and 1.10 in that order. By setting the cation ratio within the above range, volatilization of glass components can be suppressed. On the other hand, if the cation ratio is too small, volatilization of glass components may increase. On the other hand, if the cation ratio is too large, the thermal stability of the glass may decrease.

[0193] In the optical glass according to the second embodiment, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ The total content [Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ] exceeds 0%. The lower limit of the total content is preferably 0.1%, and more preferably 0.5%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, and 1.5%, in that order. The upper limit of the total content is preferably 20%, and more preferably 18%, 16%, 14%, 12%, 10%, 8%, 6%, 5%, 4%, 3.5%, 3.0%, and 2.5%, in that order. By setting the total content within the above range, it is possible to increase the refractive index, maintain the desired Abbe number νd, and improve the anomalous partial dispersion in the visible to near-ultraviolet region.

[0194] Non-limiting examples of the contents and ratios of glass components other than those described above in the optical glass according to the second embodiment are shown below.

[0195] In the optical glass according to the second embodiment, Si ４＋ and B ３＋ The total content [Si ４＋ +B３＋ The lower limit of the total content is preferably 10%, and more preferably 15%, 20%, 22%, 24%, 26%, 28%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, and 43% in that order. The upper limit of the total content is preferably 70%, and more preferably 65%, 60%, 59%, 58%, 57%, 56%, 55%, 54%, 53%, 52%, 51%, 50%, 49%, 48%, 47%, 46%, and 45% in that order. From the viewpoint of obtaining an optical glass having desired optical constants and anomalous partial dispersion, improved chemical durability, mechanical properties, and thermal stability, and suppressed volatilization of glass components during melting, it is preferable that the total content be within the above range.

[0196] In the optical glass according to the second embodiment, Li ＋ , Na ＋ , and K ＋ The total content [Li ＋ +Na ＋ +K ＋ The lower limit of

[0012] is preferably 0%, and more preferably 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, and 0.6% in that order. The upper limit of the total content is preferably 50%, and more preferably 45%, 40%, 35%, 30%, 25%, 20%, 18%, 16%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, and 2% in that order. The total content may be 0%. From the viewpoints of lowering the liquidus temperature of the glass, lowering the glass transition temperature Tg, and maintaining the thermal stability of the glass, it is preferable that the total content be within the above range.

[0197] In the optical glass according to the second embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ and Zn ２＋ The total content [Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋The upper limit of the total content is preferably 30%, and more preferably 29%, 28%, 27%, 26%, 25%, 24%, 23%, 22%, 21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, and 8% in this order. The lower limit of the total content is preferably 3.5%, and more preferably 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, and 4.5% in this order. If the total content is too high, the high refractive index may be impaired and the thermal stability of the glass may be impaired. On the other hand, if the total content is too low, the volatilization of the glass components increases, which may result in a decrease in the thermal stability, devitrification resistance, and stability during reheating of the glass.Therefore, the total content is preferably within the above range.

[0198] In the optical glass according to the second embodiment, Li ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ The lower limit of the total content is preferably 3.5%, and more preferably 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, and 4.5% in that order. The upper limit of the total content is preferably 50%, and more preferably 45%, 40%, 35%, 32%, 30%, 29%, 28%, 27%, 26%, 25%, 24%, 23%, 22%, 21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, and 6% in that order. From the viewpoint of obtaining an optical glass having desired optical constants, a reduced glass transition temperature Tg and glass liquidus temperature, and reduced volatilization of glass components during melting, it is preferable that the total content be within the above range.

[0199] In the optical glass according to the second embodiment, Zr ４＋ and Ta ５＋ The total content [Zr ４＋ +Ta ５＋ The upper limit of the total content is preferably 20%, and more preferably 15%, 10%, 9%, 8%, 7%, 6%, 5%, and 4% in that order. The lower limit of the total content is preferably 0%, and more preferably 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% in that order. From the viewpoint of maintaining high refraction and low dispersion, the total content may be 0%. From the viewpoint of maintaining the thermal stability of the glass, it is preferable that the total content be within the above range. If the total content is too high, the thermal stability of the glass may be reduced and the raw material costs may increase.

[0200] In the optical glass according to the second embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ The total content [Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ The upper limit of [0.01% by mass] is preferably 20%, and more preferably 18%, 16%, 14%, 12%, 10%, 9%, 8%, 7%, and 6%, in that order. The lower limit of the total content is preferably 0%, and more preferably 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, and 4.0%, in that order. From the viewpoint of maintaining high refractive index and low dispersion, the total content may be 0%. From the viewpoint of maintaining a desired Abbe number νd and improving anomalous partial dispersion in the visible to near-ultraviolet region, it is preferable that the total content be within the above range.

[0201] In the optical glass according to the second embodiment, Si ４＋ and B ３＋ B relative to the total content of ３＋ The cation ratio of the content [B ３＋ / (Si ４＋ +B ３＋) is preferably 0.98, and more preferably 0.97, 0.96, 0.95, 0.94, 0.93, 0.92, 0.91, 0.90, 0.89, and 0.88 in that order. The lower limit of the cation ratio is preferably 0.20, and more preferably 0.30, 0.40, 0.50, 0.60, 0.65, 0.67, 0.69, 0.71, 0.73, 0.75, 0.77, 0.79, and 0.80 in that order. From the viewpoint of obtaining an optical glass having improved chemical durability, mechanical properties, and thermal stability, it is preferable that the cation ratio be within the above range.

[0202] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , and P ５＋ The total content [Si ４＋ +B ３＋ +P ５＋ The lower limit of the total content is preferably 10%, and more preferably 15%, 20%, 22%, 24%, 26%, 28%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, and 43% in that order. The upper limit of the total content is preferably 70%, and more preferably 65%, 60%, 58%, 56%, 54%, 52%, 50%, 48%, 47%, 46%, and 45% in that order. From the viewpoint of obtaining an optical glass having desired optical constants and anomalous partial dispersion, improved chemical durability, mechanical properties, and thermal stability, and suppressed volatilization of glass components during melting, it is preferable that the total content be within the above range.

[0203] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , and P ５＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ +P ５＋) is preferably 0.80, and more preferably 0.70, 0.60, 0.50, 0.40, 0.35, 0.30, 0.29, 0.28, 0.27, 0.26, 0.25, 0.24, 0.23, 0.22, 0.21, and 0.20 in that order. The lower limit of the cation ratio is preferably 0.070, and more preferably 0.08, 0.09, 0.10, 0.11, and 0.12 in that order. From the viewpoint of obtaining an optical glass having improved chemical durability, mechanical properties, and thermal stability, it is preferable that the cation ratio be within the above range.

[0204] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , and P ５＋ B relative to the total content of ３＋ The cation ratio of the content [B ３＋ / (Si ４＋ +B ３＋ +P ５＋ ) is preferably 0.98, and more preferably 0.97, 0.96, 0.95, 0.94, 0.93, 0.92, 0.91, 0.90, 0.89, and 0.88 in that order. The lower limit of the cation ratio is preferably 0.20, and more preferably 0.30, 0.40, 0.50, 0.60, 0.65, 0.67, 0.69, 0.71, 0.73, 0.75, 0.77, 0.79, and 0.80 in that order. From the viewpoint of obtaining an optical glass having improved chemical durability, mechanical properties, and thermal stability, it is preferable that the cation ratio be within the above range.

[0205] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , and P ５＋ P relative to the total content of ５＋ The cation ratio of the content [P ５＋ / (Si ４＋ +B ３＋ +P ５＋) is preferably 0.50, and more preferably 0.40, 0.30, 0.20, 0.10, 0.08, 0.06, 0.04, and 0.02 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.005, 0.01, and 0.015 in that order. The cation ratio may even be 0. From the viewpoint of obtaining an optical glass with improved chemical durability, mechanical properties, and thermal stability, it is preferable that the cation ratio be within the above range.

[0206] In the optical glass according to the second embodiment, Li ＋ , Na ＋ , and K ＋ Li relative to the total content of ＋ The cation ratio of the content [Li ＋ / (Li ＋ +Na ＋ +K ＋ ) )] is preferably 1, and more preferably 0.95, 0.90, and 0.85 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 in that order. The cation ratio may be 1. From the viewpoint of suppressing a decrease in stability upon reheating and from the viewpoint of lowering the glass transition temperature Tg, it is preferable that the cation ratio be in the above range.

[0207] In the optical glass according to the second embodiment, Li ＋ , Na ＋ , and K ＋ Na relative to the total content ＋ The cation ratio of the content [Na ＋ / (Li ＋ +Na ＋ +K ＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, and 0.3 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, and 0.15 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in stability upon reheating and from the viewpoint of lowering the glass transition temperature Tg, it is preferable that the cation ratio be in the above range.

[0208] In the optical glass according to the second embodiment, Li ＋ , Na ＋ , and K ＋ K relative to the total content of ＋ The cation ratio of the content [K ＋ / (Li ＋ +Na ＋ +K ＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, and 0.3 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, and 0.15 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in stability upon reheating and from the viewpoint of lowering the glass transition temperature Tg, it is preferable that the cation ratio be in the above range.

[0209] In the optical glass according to the second embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Mg relative to the total content ２＋ The cation ratio of the content [Mg ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.55, 0.5, 0.45, and 0.4 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.15, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, and 0.3 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0210] In the optical glass according to the second embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Ca relative to the total content of ２＋ The cation ratio of the content [Ca ２＋ / (Mg ２＋ + Ca ２＋ + Sr２＋ +Ba ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0211] In the optical glass according to the second embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Sr relative to the total content ２＋ The cation ratio of the content [Sr ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0212] In the optical glass according to the second embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Ba relative to the total content of ２＋ The cation ratio of the content [Ba ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋) is preferably 0, and more preferably 0.1, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, and 0.60 in this order. The upper limit of the cation ratio is preferably 1, and more preferably 0.90, 0.80, 0.75, 0.74, 0.73, 0.72, 0.71, and 0.70 in this order. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0213] In the optical glass according to the second embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Mg relative to the total content ２＋ The cation ratio of the content [Mg ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.55, 0.5, 0.45, and 0.4 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.15, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, and 0.3 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0214] In the optical glass according to the second embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Ca relative to the total content of ２＋ The cation ratio of the content [Ca ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0215] In the optical glass according to the second embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Sr relative to the total content ２＋ The cation ratio of the content [Sr ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0216] In the optical glass according to the second embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Ba relative to the total content of ２＋ The cation ratio of the content [Ba ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋) is preferably 0, and more preferably 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, and 0.60 in this order. The upper limit of the cation ratio is preferably 1, and more preferably 0.90, 0.80, 0.75, 0.74, 0.73, 0.72, 0.71, and 0.70 in this order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0217] In the optical glass according to the second embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Zn relative to the total content of ２＋ The cation ratio of the content [Zn ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, and from the viewpoint of maintaining the high refractive index of the glass, the cation ratio is preferably within the above range.

[0218] In the optical glass according to the second embodiment, La ３＋ , Gd ３＋ , and Y ３＋ La relative to the total content ３＋ The cation ratio of the content [La ３＋ / (La ３＋ +Gd ３＋ +Y ３＋) is preferably 0, and more preferably 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.62, 0.64, 0.66, and 0.68 in that order. The upper limit of the cation ratio is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.78, 0.76, 0.74, and 0.72 in that order. From the viewpoints of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0219] In the optical glass according to the second embodiment, La ３＋ , Gd ３＋ , and Y ３＋ Gd relative to the total content ３＋ The cation ratio of the content [Gd ３＋ / (La ３＋ +Gd ３＋ +Y ３＋ ) )] is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.48, 0.46, 0.44, 0.42, 0.40, 0.38, 0.36, 0.34, and 0.32 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.05, 0.10, 0.15, 0.20, 0.22, 0.24, 0.26, and 0.28 in that order. The cation ratio may be 0. From the viewpoint of increasing the refractive index nd while suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0220] In the optical glass according to the second embodiment, La ３＋ , Gd ３＋ , and Y ３＋ Y relative to the total content of ３＋ The cation ratio of the content [Y ３＋ / (La ３＋ +Gd ３＋ +Y ３＋) )] is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, 0.10, and 0.05 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, and 0.03 in that order. The cation ratio may be 0. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0221] In the optical glass according to the second embodiment, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Ti relative to the total content of ４＋ The cation ratio of the content [Ti ４＋ / (Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ) )] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.23, 0.21, 0.2, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, and 0.11 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, and 0.08 in that order. The cation ratio may be 0. From the viewpoints of increasing the refractive index nd and maintaining a desired Abbe number νd and thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0222] In the optical glass according to the second embodiment, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Nb content relative to the total content ５＋ The cation ratio of the content [Nb ５＋ / (Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋) )] is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.74, 0.73, 0.72, 0.71, 0.70, 0.69, 0.68, and 0.67 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, and 0.62 in that order. The cation ratio may be 0. From the viewpoints of increasing the refractive index nd, maintaining a desired Abbe number νd, and maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0223] In the optical glass according to the second embodiment, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ W relative to the total content of ６＋ The cation ratio of the content [W ６＋ / (Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.44, 0.43, 0.42, 0.41, 0.40, 0.39, 0.38, 0.37, 0.36, 0.35, 0.34, 0.33, 0.32, 0.31, 0.3, 0.29, 0.28, and 0.27, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.1, 0.12, 0.14, 0.16, 0.18, 0.20, 0.21, 0.22, 0.23, and 0.24, in that order. The cation ratio may be 0. From the viewpoints of increasing the partial dispersion ratio Pg, F, maintaining a desired Abbe number νd, and maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0224] In the optical glass according to the second embodiment, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Bi relative to the total content ３＋The cation ratio of the content [Bi ３＋ / (Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.44, 0.43, 0.42, 0.41, 0.40, 0.39, 0.38, 0.37, 0.36, 0.35, 0.34, 0.33, 0.32, 0.31, 0.3, 0.29, 0.28, and 0.27 in that order. The lower limit of the cation ratio is preferably 0, and may be 0.05, 0.1, 0.12, 0.14, 0.16, 0.18, 0.20, 0.21, 0.22, 0.23, or 0.24. The cation ratio may be 0. It is preferable that the cation ratio be within the above range from the viewpoints of increasing the refractive index nd and the partial dispersion ratio Pg,F, maintaining a desired Abbe number νd, maintaining the thermal stability of the glass, and reducing damage to platinum production melting equipment.

[0225] In the optical glass according to the second embodiment, Zr ４＋ and Ta ５＋ Zr relative to the total content ４＋ The cation ratio of the content [Zr ４＋ / (Zr ４＋ +Ta ５＋ ) )] is preferably 1, and more preferably 0.95, 0.90, and 0.85 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.5, 0.6, 0.7, and 0.8 in that order. The cation ratio may be 0. From the viewpoints of maintaining desired optical constants and reducing raw material costs, it is preferable that the cation ratio be within the above range.

[0226] In the optical glass according to the second embodiment, Zr ４＋ and Ta ５＋ Ta relative to the total content ５＋ The cation ratio of the content [Ta ５＋ / (Zr ４＋ +Ta ５＋) is preferably 1, and more preferably 0.5, 0.4, 0.3, and 0.2 in that order. The lower limit of the cation ratio is preferably 0, and may be 0.05, 0.10, or 0.15. The cation ratio may be 0. From the viewpoints of maintaining desired optical constants and reducing raw material costs, it is preferable that the cation ratio be in the above range.

[0227] In the optical glass according to the second embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Ti relative to the total content of ４＋ The cation ratio of the content [Ti ４＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.23, 0.21, 0.2, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, 0.11, 0.10, 0.09, 0.08, 0.07, and 0.06 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, and 0.04 in that order. The cation ratio may be 0. From the viewpoint of increasing the refractive index nd and maintaining a desired Abbe number νd, it is preferable that the cation ratio be within the above range.

[0228] In the optical glass according to the second embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Nb content relative to the total content ５＋ The cation ratio of the content [Nb ５＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋+Ta ５＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.34, 0.33, 0.32, 0.31, 0.30, 0.29, 0.28, and 0.27 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, and 0.24 in that order. The cation ratio may be 0. From the viewpoint of increasing the refractive index nd and maintaining a desired Abbe number vd, it is preferable that the cation ratio be within the above range.

[0229] In the optical glass according to the second embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Bi relative to the total content ３＋ The cation ratio of the content [Bi ３＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.30, 0.29, 0.28, 0.27, 0.26, 0.25, 0.24, 0.23, 0.22, 0.21, 0.20, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, and 0.11, in that order. The lower limit of the cation ratio is preferably 0, and may be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, or 0.09. The cation ratio may be 0. It is preferable that the cation ratio be within the above range from the viewpoints of increasing the refractive index nd and the partial dispersion ratio Pg,F, maintaining a desired Abbe number νd, maintaining the thermal stability of the glass, and reducing damage to platinum production melting equipment.

[0230] In the optical glass according to the second embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ W relative to the total content of ６＋ The cation ratio of the content [W ６＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.30, 0.29, 0.28, 0.27, 0.26, 0.25, 0.24, 0.23, 0.22, 0.21, 0.20, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, and 0.11, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, and 0.09, in that order. The cation ratio may be 0. From the viewpoints of increasing the partial dispersion ratio Pg, F, maintaining a desired Abbe number νd, and maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0231] In the optical glass according to the second embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Zr relative to the total content ４＋ The cation ratio of the content [Zr ４＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋) )] is preferably 1, and more preferably 0.95, 0.9, 0.85, 0.80, 0.75, 0.70, 0.69, 0.68, 0.67, 0.66, 0.65, 0.64, 0.63, and 0.62 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.1, 0.2, 0.3, 0.4, 0.45, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, and 0.58 in that order. The cation ratio may be 0. From the viewpoints of increasing the refractive index nd, maintaining a desired Abbe number νd, and improving the mechanical properties and chemical durability of the glass, it is preferable that the cation ratio be within the above range.

[0232] In the optical glass according to the second embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Ta relative to the total content ５＋ The cation ratio of the content [Ta ５＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ ) is preferably 1, and more preferably 0.5, 0.4, 0.3, 0.25, 0.2, 0.15, 0.1, 0.08, 0.06, and 0.04 in that order. The lower limit of the cation ratio is preferably 0, and may be 0.01, 0.02, or 0.03. The cation ratio may be 0. From the viewpoints of maintaining desired constants and reducing raw material costs, it is preferable that the cation ratio be within the above range.

[0233] In the optical glass according to the second embodiment, Si ４＋ and B ３＋ Al content relative to the total content ３＋ The cation ratio of the content [Al ３＋ / (Si ４＋ +B ３＋) )] is preferably 0.5, and more preferably 0.45, 0.40, 0.35, 0.30, 0.25, and 0.20 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.05, 0.1, and 0.15 in that order. The cation ratio may be 0. Increasing the cation ratio can improve the mechanical properties and chemical durability of the glass. On the other hand, if the cation ratio is too high, the liquidus temperature rises and the thermal stability of the glass is impaired. From the viewpoint of maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0234] In the optical glass according to the second embodiment, Li ＋ , Na ＋ , and K ＋ Al content relative to the total content ３＋ The cation ratio of the content [Al ３＋ / (Li ＋ +Na ＋ +K ＋ ) )] is preferably 2, and more preferably 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6, 0.4, and 0.2 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.1, and 0.15 in that order. The cation ratio may be 0. Increasing the cation ratio can improve the mechanical properties and chemical durability of the glass. On the other hand, if the cation ratio is too high, the liquidus temperature rises, and the thermal stability of the glass is impaired. From the viewpoint of maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0235] In the optical glass according to the second embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Al content relative to the total content ３＋ The cation ratio of the content [Al ３＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋) )] is preferably 2, and more preferably 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6, 0.4, 0.3, and 0.2 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.1, and 0.15 in that order. The cation ratio may be 0. Increasing the cation ratio can improve the mechanical properties and chemical durability of the glass. On the other hand, if the cation ratio is too high, the liquidus temperature rises, and the thermal stability of the glass is impaired. From the viewpoint of maintaining the thermal stability and devitrification resistance of the glass, it is preferable that the cation ratio be within the above range.

[0236] In the optical glass according to the second embodiment, Li ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Al content relative to the total content ３＋ The cation ratio of the content [Al ３＋ / (Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) )] is preferably 5, and more preferably 4, 3, 2, 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6, 0.4, 0.3, and 0.2 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.1, and 0.15 in that order. The cation ratio may be 0. Increasing the cation ratio can improve the mechanical properties and chemical durability of the glass. On the other hand, if the cation ratio is too high, the liquidus temperature rises, and the thermal stability of the glass is impaired. From the viewpoint of maintaining the thermal stability and devitrification resistance of the glass, it is preferable that the cation ratio be within the above range.

[0237] In the optical glass according to the second embodiment, La ３＋ , Gd ３＋ , and Y ３＋ Al content relative to the total content ３＋The cation ratio of the content [Al ３＋ / (La ３＋ +Gd ３＋ +Y ３＋ ) is preferably 2, and more preferably 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6, 0.4, 0.3, and 0.2 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.1, and 0.15 in that order. The cation ratio may be 0. From the viewpoints of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be in the above range.

[0238] In the optical glass according to the second embodiment, Si ４＋ and B ３＋ Li relative to the total content of ＋ , Na ＋ , and K ＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ ) / (Si ４＋ +B ３＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, 0.09, 0.08, 0.07, and 0.06 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, and 0.05 in that order. The cation ratio may even be 0. From the viewpoints of improving the chemical durability, mechanical properties, and thermal stability of the glass and suppressing a decrease in stability upon reheating, as well as from the viewpoint of obtaining an optical glass with a reduced glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0239] In the optical glass according to the second embodiment, Si ４＋ and B ３＋ Mg relative to the total content ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋) / (Si ４＋ +B ３＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.48, 0.46, 0.44, 0.42, 0.40, 0.38, 0.36, 0.34, 0.32, 0.30, 0.28, 0.26, 0.24, 0.22, 0.20, 0.18, 0.16, 0.14, and 0.12, in that order. The lower limit of the cation ratio is preferably 0.01, and more preferably 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, and 0.10, in that order. From the viewpoint of suppressing deterioration in the chemical durability, mechanical properties, and thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0240] In the optical glass according to the second embodiment, Si ４＋ and B ３＋ Li relative to the total content of ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋) is preferably 0.01, and more preferably 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, and 0.10 in that order. The upper limit of the cation ratio is preferably 2, and more preferably 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.48, 0.46, 0.44, 0.42, 0.40, 0.38, 0.36, 0.34, 0.32, 0.30, 0.28, 0.26, 0.24, 0.22, 0.20, 0.18, 0.16, 0.14, and 0.12 in that order. From the viewpoint of obtaining an optical glass having desired optical constants, suppressing volatilization of glass components during melting, and lowering the glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0241] In the optical glass according to the second embodiment, Si ４＋ and B ３＋ La relative to the total content ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ The lower limit of the cation ratio is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.55, 0.60, 0.65, 0.70, 0.72, 0.74, 0.76, 0.78, 0.80, 0.82, 0.84, 0.86, 0.88, 0.90, 0.92, 0.93, 0.94, and 0.95 in that order. The upper limit of the cation ratio is preferably 3, and more preferably 2.5, 2, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.35, 1.3, 1.25, 1.2, 1.15, 1.13, 1.11, 1.10, and 1.09 in that order. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0242] In the optical glass according to the second embodiment, Si ４＋ and B ３＋ Li relative to the total content of ＋ , Na＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , La ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ ))] is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.05, 1.10, 1.13, and 1.15 in that order. The upper limit of the cation ratio is preferably 4, and more preferably 3, 2.5, 2.2, 2.0, 1.95, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, 1.60, 1.55, 1.50, 1.45, 1.40, 1.35, 1.30, 1.25, and 1.20 in that order. From the viewpoint of obtaining an optical glass that is excellent in chemical durability, mechanical properties, and thermal stability while suppressing volatilization of glass components during melting, it is preferable that the cation ratio be within the above range.

[0243] In the optical glass according to the second embodiment, Si ４＋ and B ３＋ Ti relative to the total content of ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ The cation ratio of the total content [(Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ) / (Si ４＋ +B ３＋) is preferably 0.5, and more preferably 0.4, 0.3, 0.2, and 0.1 in this order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, and 0.04 in this order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the refractive index nd at a desired Abbe number νd, it is preferable that the cation ratio be within the above range.

[0244] In the optical glass according to the second embodiment, Si ４＋ and B ３＋ Zr relative to the total content ４＋ and Ta ５＋ The cation ratio of the total content [(Zr ４＋ +Ta ５＋ ) / (Si ４＋ +B ３＋ ) )] is preferably 0.5, and more preferably 0.4, 0.3, 0.2, and 0.1 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, and 0.04 in that order. The cation ratio may be 0. From the viewpoint of maintaining the thermal stability of the glass and from the viewpoint of suppressing a decrease in the refractive index nd at a desired Abbe number νd, it is preferable that the cation ratio be within the above range.

[0245] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Li relative to the total content ＋ , Na ＋ , and K ＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋) )] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, 0.09, 0.08, 0.07, and 0.06 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, and 0.05 in that order. The cation ratio may even be 0. From the viewpoints of improving the chemical durability, mechanical properties, and thermal stability of the glass and suppressing a decrease in stability upon reheating, and from the viewpoint of obtaining an optical glass with a reduced glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0246] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Mg relative to the total content ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.48, 0.46, 0.44, 0.42, 0.40, 0.38, 0.36, 0.34, 0.32, 0.30, 0.28, 0.26, 0.24, 0.22, 0.20, 0.18, 0.16, 0.14, and 0.12, in that order. The lower limit of the cation ratio is preferably 0.01, and more preferably 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, and 0.10, in that order. From the viewpoint of suppressing deterioration in the chemical durability, mechanical properties, and thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0247] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Li relative to the total content ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ The lower limit of the cation ratio is preferably 0.01, and more preferably 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, and 0.10 in that order. The upper limit of the cation ratio is preferably 2, and more preferably 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.48, 0.46, 0.44, 0.42, 0.40, 0.38, 0.36, 0.34, 0.32, 0.30, 0.28, 0.26, 0.24, 0.22, 0.20, 0.18, 0.16, 0.14, and 0.12 in that order. From the viewpoint of obtaining an optical glass having desired optical constants, suppressing volatilization of glass components during melting, and lowering the glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0248] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ La relative to the total content ３＋ , Gd ３＋ , and Y３＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ The lower limit of the cation ratio is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.55, 0.60, 0.65, 0.70, 0.72, 0.74, 0.76, 0.78, 0.80, 0.82, 0.84, 0.86, 0.88, 0.90, 0.92, 0.93, 0.94, and 0.95, in that order. The upper limit of the cation ratio is preferably 3, and more preferably 2.5, 2, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.35, 1.3, 1.25, 1.2, 1.15, 1.13, 1.11, 1.10, 1.09, 1.08, 1.07, 1.06, and 1.05, in that order. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0249] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Li relative to the total content ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , La ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋+B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ The lower limit of the cation ratio is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.02, 1.04, 1.06, and 1.08 in that order. The upper limit of the cation ratio is preferably 4, and more preferably 3, 2.5, 2.2, 2.0, 1.95, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, 1.60, 1.55, 1.50, 1.45, 1.40, 1.35, 1.30, 1.25, 1.20, and 1.15 in that order. From the viewpoint of obtaining an optical glass that is excellent in chemical durability, mechanical properties, and thermal stability while suppressing volatilization of glass components during melting, it is preferable that the cation ratio be within the above range.

[0250] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ Li relative to the total content ＋ , Na ＋ , and K ＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋) )] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, 0.09, 0.08, 0.07, and 0.06 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, and 0.05 in that order. The cation ratio may even be 0. From the viewpoints of improving the chemical durability, mechanical properties, and thermal stability of the glass and suppressing a decrease in stability upon reheating, and from the viewpoint of obtaining an optical glass with a reduced glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0251] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ Mg relative to the total content ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.48, 0.46, 0.44, 0.42, 0.40, 0.38, 0.36, 0.34, 0.32, 0.30, 0.28, 0.26, 0.24, 0.22, 0.20, 0.18, 0.16, 0.14, and 0.12, in that order. The lower limit of the cation ratio is preferably 0.01, and more preferably 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, and 0.09, in that order. From the viewpoint of suppressing deterioration of the chemical durability, mechanical properties, and thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0252] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ Li relative to the total content ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋The lower limit of the cation ratio is preferably 0.01, and more preferably 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, and 0.09 in that order. The upper limit of the cation ratio is preferably 2, and more preferably 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.48, 0.46, 0.44, 0.42, 0.40, 0.38, 0.36, 0.34, 0.32, 0.30, 0.28, 0.26, 0.24, 0.22, 0.20, 0.18, 0.16, 0.14, and 0.12 in that order. From the viewpoint of obtaining an optical glass having desired optical constants, suppressing volatilization of glass components during melting, and lowering the glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0253] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋) is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.55, 0.60, 0.65, 0.70, 0.72, 0.74, 0.76, 0.78, 0.80, 0.82, 0.84, 0.86, 0.88, 0.90, 0.92, and 0.93 in that order. The upper limit of the cation ratio is preferably 3, and more preferably 2.5, 2, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.35, 1.3, 1.25, 1.2, 1.15, 1.13, 1.11, 1.10, 1.09, 1.08, 1.07, 1.06, 1.05, 1.04, 1.03, 1.02, 1.01, 1.00, 0.99, 0.98, 0.97, 0.96, and 0.95, in that order. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0254] In the optical glass according to the second embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ Li relative to the total content ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , La ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta５＋ The lower limit of the cation ratio is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 0.92, 0.94, 0.96, 0.98, and 1.00 in that order. The upper limit of the cation ratio is preferably 4, and more preferably 3, 2.5, 2.2, 2.0, 1.95, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, 1.60, 1.55, 1.50, 1.45, 1.40, 1.35, 1.30, 1.25, 1.20, 1.15, 1.13, 1.11, 1.10, 1.09, 1.08, 1.07, and 1.06 in that order. From the viewpoint of obtaining an optical glass that is excellent in chemical durability, mechanical properties, and thermal stability while suppressing volatilization of glass components during melting, it is preferable that the cation ratio be within the above range.

[0255] In the optical glass according to the second embodiment, P ５＋ The upper limit of the content of P is preferably 30%, and more preferably 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, and 1% in that order. ５＋ The lower limit of the content of P is preferably 0%, and more preferably 0.05%, 0.1%, and 0.5% in that order. ５＋ The content of P may be 0%. ５＋ By setting the content within the above range, it is possible to obtain glass having relatively high mechanical properties and chemical durability.

[0256] In the optical glass according to the second embodiment, Al ３＋ The upper limit of the content of Al is preferably 30%, and more preferably 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, and 1% in that order. ３＋ The lower limit of the Al content is preferably 0%, and more preferably 0.05%, 0.1%, and 0.5% in that order. ３＋ The content of Al may be 0%. ３＋ When contained in an appropriate amount, Al has the effect of suppressing phase separation of glass. ３＋ By increasing the content of Al, the mechanical properties and chemical durability of the glass can be improved. ３＋If the content of Al is too high, the liquidus temperature rises and the thermal stability of the glass is impaired. If the liquidus temperature rises, the volatilization of glass components increases when the glass is poured and molded, causing striae. From the viewpoint of maintaining the thermal stability of the glass, Al is ３＋ It is preferable that the content of is within the above range.

[0257] In the glass according to the second embodiment, Li ＋ The upper limit of the content of Li is preferably 40%, and more preferably 30%, 20%, 17%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, and 2% in that order. ＋ The lower limit of the content of Li is preferably 0%, and more preferably 0.01%, 0.05%, 0.1%, 0.5%, and 1% in that order. ＋ The content of Li may be 0%. ＋ is a component that contributes to lowering the viscosity of the glass. ＋ If the content of Li is too high, the thermal stability of the glass and the stability during reheating may decrease. ＋ If the content of Li is too small, the glass transition temperature Tg may increase. ＋ The content is preferably in the above range.

[0258] In the glass according to the second embodiment, Na ＋ The upper limit of the content of Na is preferably 40%, and more preferably 30%, 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, 1%, and 0.5% in that order. ＋ The lower limit of the content of Na is preferably 0%, and more preferably 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, and 0.35% in that order. ＋ The content of Na may be 0%. ＋ Li ＋ It is a component that contributes to lowering the viscosity of glass, just like Na. ＋ If the content of Na is too high, the thermal stability of the glass and the stability during reheating may decrease. ＋ The content is preferably in the above range.

[0259] In the optical glass according to the second embodiment, K ＋ The upper limit of the content of is preferably 40%, and more preferably 30%, 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, 1%, and 0.5% in that order. ＋ The lower limit of the content of K is preferably 0%, and more preferably 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, and 0.35% in that order. ＋ The content of K may be 0%. ＋ has the function of lowering the liquidus temperature and improving the thermal stability of the glass. ＋ If the content of K is too high, the chemical durability, weather resistance, and stability during reheating will decrease. ＋ The content is preferably in the above range.

[0260] In the optical glass according to the second embodiment, Rb ＋ The upper limit of the content of Rb is preferably 40%, and more preferably 30%, 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, 1%, and 0.5% in that order. ＋ The lower limit of the content of Rb is preferably 0%. ＋ The content of Rb may be 0%. ＋ If the content of Rb is too high, the volatilization of glass components during melting increases, making it impossible to obtain the desired glass. ＋ The content is preferably in the above range.

[0261] In the optical glass according to the second embodiment, Cs ＋ The upper limit of the content of Cs is preferably 40%, and more preferably 30%, 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, 1%, and 0.5% in that order. ＋ The lower limit of the content of Cs is preferably 0%. ＋ The content of Cs may be 0%. ＋ If the content of Cs is too high, the volatilization of glass components during melting increases, making it impossible to obtain the desired glass. In addition, there is a risk that the chemical durability and weather resistance may decrease. ＋The content is preferably in the above range.

[0262] In the optical glass according to the second embodiment, Mg ２＋ The upper limit of the content of Mg is preferably 40%, and more preferably 30%, 20%, 15%, 13%, 11%, 10%, 9%, 8%, 7%, 6.5%, and 6% in that order. ２＋ The lower limit of the content of Mg is preferably 0%, and more preferably 1%, 2%, 3%, and 4% in that order. ２＋ The content of Mg may be 0%. ２＋ If the content of Mg is too high, the thermal stability and devitrification resistance of the glass may decrease. ２＋ If the content of Mg is too small, the stability of the glass when reheated may decrease. ２＋ The content is preferably in the above range.

[0263] In the optical glass according to the second embodiment, Sr ２＋ The upper limit of the content of Sr is preferably 40%, and more preferably 30%, 20%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, 1%, and 0.5% in that order. ２＋ The lower limit of the Sr content is preferably 0%. ２＋ The content of Sr may be 0%. ２＋ is a component that increases the refractive index nd among alkaline earth metals. ２＋ If the content of Sr is too high, the thermal stability and devitrification resistance of the glass may be reduced. ２＋ The content is preferably in the above range.

[0264] In the optical glass according to the second embodiment, Ba ２＋ The upper limit of the content of Ba is preferably 40%, and more preferably 30%, 25%, 20%, 18%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, and 6% in that order. ２＋ The lower limit of the content of Ba is preferably 0%, and more preferably 1%, 2%, 3%, and 4% in that order. ２＋Among alkaline earth metals, Ba is a component that increases the refractive index nd, and at the same time, when contained in an appropriate amount, it lowers the liquidus temperature and improves the stability of the glass. ２＋ If the content of Ba is too high, the thermal stability and stability during reheating of the glass may be reduced. ２＋ If the content of Ba is too small, the thermal stability of the glass may decrease, and the volatilization of glass components during melting may increase. ２＋ The content is preferably in the above range.

[0265] In the optical glass according to the second embodiment, La ３＋ The lower limit of the content of La is preferably 5%, and more preferably 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, and 31% in that order. ３＋ The upper limit of the content of La is preferably 50%, and more preferably 49%, 48%, 47%, 46%, 45%, 44%, 43%, 42%, 41%, 40%, 39%, 38%, 37%, 36%, 35%, and 34% in that order. ３＋ By introducing a certain amount of La, it is possible to suppress the volatilization of glass components and increase the refractive index nd. ３＋ If the content of La is too high, the thermal stability of the glass may decrease, and the glass may be prone to devitrification during production. ３＋ The content is preferably in the above range.

[0266] In the glass according to the second embodiment, Gd ３＋ The upper limit of the content of Gd is preferably 50%, and more preferably 45%, 40%, 35%, 30%, 28%, 26%, 24%, 22%, 20%, 18%, 16%, and 15% in that order. ３＋ The lower limit of the content of Gd is preferably 0%, and more preferably 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, and 12% in that order. ３＋ Is La ３＋Similarly, by introducing a certain amount of Gd, it is possible to suppress the volatilization of glass components and increase the refractive index nd while maintaining the thermal stability of the glass. ３＋ If the content of Gd is too high, the thermal stability of the glass decreases. ３＋ If the content of Gd is too high, the specific gravity of the glass increases, which is undesirable. In addition, there is a risk of an increase in the raw material cost. Therefore, from the viewpoint of suppressing an increase in the specific gravity while maintaining good thermal stability of the glass, it is preferable to use a Gd content of 100% or more. ３＋ The content is preferably in the above range.

[0267] In the glass according to the second embodiment, Y ３＋ The upper limit of the content of is preferably 50%, and more preferably 48%, 46%, 44%, 42%, 40%, 38%, 36%, 34%, 32%, 30%, 28%, 26%, 24%, 22%, 20%, 18%, 16%, 14%, 12%, 10%, 8%, 6%, 5%, 4%, 3%, and 2% in that order. ３＋ The lower limit of the content of Y is preferably 0%, and more preferably 0.01%, 0.05%, 0.1%, 0.5%, and 1% in that order. ３＋ The content may be 0%.

[0268] Y ３＋ By introducing a certain amount of Y, it is possible to suppress the volatilization of glass components and increase the refractive index nd. ３＋ If the content of Y is too high, the thermal stability of the glass decreases, and the glass becomes more susceptible to devitrification during manufacturing. ３＋ is the same rare earth element, La ３＋ and Gd ３＋ The effect of increasing the refractive index nd is small compared to ３＋ If the content of Y is too small, the thermal stability of the glass may be reduced. ３＋ The content is preferably in the above range.

[0269] In the glass according to the second embodiment, Yb ３＋The upper limit of the content of Yb is preferably 50%, and more preferably 40%, 30%, 20%, 15%, 10%, 8%, 6%, 4%, 3%, 2%, and 1% in that order. ３＋ The lower limit of the content of Yb is preferably 0%. ３＋ The content of Yb may be 0%. ３＋ Is, La ３＋ , Gd ３＋ , Y ３＋ Since the molecular weight is larger than that of Yb, it increases the specific gravity of the glass. ３＋ If the content of Yb is too high, the thermal stability of the glass will decrease. ３＋ The content is preferably in the above range.

[0270] In the optical glass according to the second embodiment, Ti ４＋ The upper limit of the content of Ti is preferably 20%, and more preferably 15%, 10%, 5%, 4%, 3.5%, 3%, and 2.5% in that order. ４＋ The lower limit of the content of Ti is preferably 0%, and may further be 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, or 1.6%. From the viewpoint of maintaining a desired Abbe number νd and improving anomalous partial dispersion in the visible to near ultraviolet region, ４＋ It is preferable that the content of is within the above range.

[0271] In the optical glass according to the second embodiment, Nb ５＋ The upper limit of the content of Nb is preferably 20%, and more preferably 15%, 10%, 5%, 4%, 3.5%, 3%, and 2.5% in that order. ５＋ The lower limit of the content of Nb is preferably 0%, and more preferably 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, and 1.6% in that order. ５＋ It is preferable that the content of is within the above range.

[0272] In the optical glass according to the second embodiment, W ６＋The upper limit of the content of W is preferably 20%, and more preferably 15%, 10%, 5%, 4%, 3.5%, 3%, and 2.5% in that order. ６＋ The lower limit of the content of W is preferably 0%, and more preferably 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, and 1.6% in that order. From the viewpoints of increasing the transmittance and reducing the specific gravity, maintaining a desired Abbe number νd, and improving the anomalous partial dispersion in the visible to near ultraviolet region, ６＋ It is preferable that the content of is within the above range.

[0273] In the optical glass according to the second embodiment, Bi ３＋ The upper limit of the content of Bi is preferably 20%, and more preferably 15%, 10%, 5%, 4%, 3.5%, 3%, and 2.5% in that order. ３＋ The lower limit of the content of Bi is preferably 0%, and may further be 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, or 1.6%. ３＋ The content of Bi may be 0%. From the viewpoints of increasing transmittance and reducing specific gravity, reducing damage to platinum manufacturing equipment, and improving anomalous partial dispersion in the visible to near ultraviolet region, Bi is ３＋ It is preferable that the content of is within the above range.

[0274] In the optical glass according to the second embodiment, Ta ５＋ The upper limit of the content of Ta is preferably 10%, and more preferably 8%, 6%, 4%, 3%, 2%, and 1% in that order. ５＋ The lower limit of the Ta content is preferably 0%, and more preferably 0.05%, 0.1%, and 0.5% in that order. ５＋ The content of Ta may be 0%. ５＋ is a component that contributes to the high refractive index and low dispersion of the glass. ５＋ If the content of Ta is too high, the raw material cost may increase, and the melting property of the glass may decrease. Furthermore, the specific gravity may increase. ５＋ The content is preferably in the above range.

[0275] In the optical glass according to the second embodiment, Zr ４＋ The upper limit of the content of Zr is preferably 10%, and more preferably 9%, 8%, 7%, 6%, 5%, and 4% in that order. ４＋ The lower limit of the content of Zr is preferably 0%, and more preferably 0.05%, 0.1%, 0.5%, 1.0%, 1.5%, and 2.0% in that order. ４＋ The content of Zr may be 0%. ４＋ When contained in an appropriate amount, Zr has the effect of improving chemical durability. ４＋ If the content of Zr is too large, the liquidus temperature LT may increase and the meltability of the glass may decrease. ４＋ It is preferable that the content of is within the above range.

[0276] In the glass according to the second embodiment, Sc ３＋ The content of Sc is preferably 2% or less. ３＋ The lower limit of the content is preferably 0%.

[0277] In the glass according to the second embodiment, Hf ４＋ The content of Hf is preferably 2% or less. ４＋ The lower limit of the content is preferably 0%.

[0278] Sc ３＋ , Hf ４＋ Although Sc has the function of increasing the dispersibility of glass, it is an expensive component. ３＋ , Hf ４＋ The content of each of the above is preferably within the above range.

[0279] In the glass according to the second embodiment, Lu ３＋ The content of Lu is preferably 2% or less. ３＋ The lower limit of the content is preferably 0%.

[0280] Lu ３＋ Although Lu has the function of increasing the dispersibility of glass, it is also a glass component that increases the specific gravity of glass due to its large molecular weight. ３＋ The content is preferably in the above range.

[0281] The glass according to the second embodiment contains Si as an essential component. ４＋ and B ３＋ , and optionally Ca ２＋ , Zn ２＋ , P ５＋ , Al ３＋ , Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Sr ２＋ , Ba ２＋ , La ３＋ , Gd ３＋ , Y ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Ta ５＋ , and Zr ４＋ The total content of these glass components is preferably 95% or more, more preferably 98% or more, even more preferably 99% or more, and particularly preferably 99.5% or more.

[0282] The optical glass according to the second embodiment contains O as an anion component. ２－ Includes. ２－ The upper limit of the content of is preferably 90 anion%, and more preferably 88 anion%, 86 anion%, 84 anion%, 82 anion%, 80 anion%, 78 anion%, 76 anion%, 75 anion%, 74 anion%, 73 anion%, 72 anion%, 71 anion%, 70 anion%, 69 anion%, and 68 anion%, in that order. ２－ The lower limit of the content is preferably 10 anion%, and more preferably 15 anion%, 20 anion%, 25 anion%, 30 anion%, 35 anion%, 40 anion%, 45 anion%, 50 anion%, 55 anion%, 60 anion%, 61 anion%, 62 anion%, 63 anion%, 64 anion%, and 65 anion%, in that order.

[0283] The optical glass according to the second embodiment contains O as an anion component.２－ and F － It may contain components other than O. ２－ and F － As an anion component other than Cl － ,Br － , I － However, Cl － ,Br － , I － All of these components are likely to volatilize during glass melting. The volatilization of these components causes problems such as variations in the glass properties, a decrease in the homogeneity of the glass, and significant wear on the melting equipment. － The content of Br is preferably less than 5 anion %, more preferably less than 3 anion %, even more preferably less than 1 anion %, particularly preferably less than 0.5 anion %, and even more preferably less than 0.25 anion %. － and I － The total content of is preferably less than 5 anion %, more preferably less than 3 anion %, even more preferably less than 1 anion %, particularly preferably less than 0.5 anion %, even more preferably less than 0.1 anion %, and even more preferably 0 anion %.

[0284] The glass according to the second embodiment is preferably composed essentially of the above glass components, but may contain other components as long as the effects of the present invention are not impaired. Furthermore, the present invention does not exclude the inclusion of unavoidable impurities.

[0285] In the optical glass according to the second embodiment, Sb ions can be added from the viewpoint of suppressing a decrease in transmittance at wavelengths around 360 nm and 375 nm. The upper limit of the Sb ion content is preferably 1.0000 mass%, and more preferably 0.5000 mass%, 0.1000 mass%, 0.0900 mass%, 0.0800 mass%, 0.0700 mass%, 0.0600 mass%, 0.0500 mass%, 0.0400 mass%, 0.0300 mass%, 0.0250 mass%, 0.0200 mass%, 0.0150 mass%, 0.0100 mass%, 0.0090 mass%, 0.0080 mass%, 0.0070 mass%, 0.0060 mass%, and 0.0050 mass%, in that order. The lower limit of the Sb ion content is preferably 0.0001 mass%, in terms of exclusive proportion, and is more preferably 0.0005 mass%, 0.0008 mass%, 0.0010 mass%, 0.0012 mass%, 0.0014 mass%, 0.0016 mass%, 0.0018 mass%, 0.0020 mass%, 0.0022 mass%, 0.0024 mass%, 0.0026 mass%, 0.0028 mass%, 0.0030 mass%, 0.0032 mass%, 0.0034 mass%, 0.0036 mass%, and 0.0038 mass%, in that order.

[0286] The Sb ions are, for example, Sb ２ O ３ and Sb ２ S ３Sb ions can be added to glass by the method described above. Sb ions include trivalent, pentavalent, and all other valence Sb ions. The content of Sb ions is an exclusive percentage. That is, the content of Sb ions is expressed in mass % when the total content of all glass components other than Sb ions is 100 mass %. From the viewpoint of suppressing a decrease in transmittance at wavelengths around 360 nm and 375 nm, it is preferable to set the content of Sb ions within the above range. If the content of Sb ions is too high, Pt from the crucible is easily introduced into the glass, forming Pt colloids and causing Tyndall-shaped clouding in the glass, which may result in a decrease in light transmittance regardless of the wavelength band. Furthermore, the light absorption of Sb ions themselves may decrease the light transmittance at specific wavelengths. If Sb ions are not contained or the content of Sb ions is too low, the absorption of Pt ions at wavelengths around 360 nm becomes apparent, which may result in a decrease in light transmittance at specific wavelengths in the wavelength range extending to visible light.

[0287] Furthermore, the optical glass described above provides high transmittance over a wide range of the visible light region. To make the most of these features, it is preferable that the glass does not contain any coloring elements. Examples of coloring elements include Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, and V. The content of each element is preferably less than 100 ppm by mass, more preferably 0 to 80 ppm by mass, and even more preferably 0 to 50 ppm by mass, and it is particularly preferable that the glass is substantially free of these elements.

[0288] Ga, Te, Tb, etc. are components that do not need to be incorporated and are also expensive components. ２ O ３ , TeO ２ , TbO ２ The range of the content of each of these is preferably 0 to 0.1%, more preferably 0 to 0.05%, even more preferably 0 to 0.01%, still more preferably 0 to 0.005%, even more preferably 0 to 0.001%, and it is particularly preferable that they are not substantially contained.

[0289] (Glass Properties) <Abbe Number νd> In the optical glass according to the second embodiment, the Abbe number νd is preferably 37.5 to 60, and can also be 40 to 58, 45 to 56, 47 to 54, 48 to 52, 49 to 51, or 55 to 59, or 56 to 58. The Abbe number νd can be calculated and adjusted in the same manner as in the first embodiment.

[0290] <Refractive Index nd> In the optical glass according to the second embodiment, the refractive index nd is preferably 1.60 to 1.92, and can also be 1.65 to 1.87, 1.70 to 1.82, 1.75 to 1.80, 1.76 to 1.79, or 1.65 to 1.68. The refractive index nd can be calculated and adjusted in the same manner as in the first embodiment.

[0291] In the optical glass according to the second embodiment, the refractive index nd and the Abbe number vd preferably satisfy the following formula [3-1]: nd ≧ (-0.0081 × vd + 2.1181) ... [3-1] The refractive index nd and the Abbe number vd more preferably satisfy the following formula [3-2], and even more preferably satisfy the following formulas in the order [3-3], [3-4], and [3-5]: nd ≧ (-0.0081 × vd + 2.1231) ... [3-2] nd ≧ (-0.0081 × vd + 2.1281) ... [3-3] nd ≧ (-0.0081 × vd + 2.1331) ... [3-4] nd ≧ (-0.0081 × vd + 2.1381) ... [3-5]

[0292] <Partial Dispersion Ratio Pg,F> In the optical glass according to the second embodiment, the lower limit of the partial dispersion ratio Pg,F in the visible short wavelength region is preferably 0.5200, and more preferably 0.5250, 0.5300, 0.5350, 0.5400, 0.5450, 0.5500, 0.5510, 0.5520, 0.5530, 0.5540, and 0.5550 in that order. By setting the partial dispersion ratio Pg,F within the above range, an optical glass suitable for correcting high-order chromatic aberrations can be obtained. On the other hand, the upper limit of the partial dispersion ratio Pg,F is not particularly limited, but is usually 0.5700, preferably 0.5650. The partial dispersion ratio Pg,F can be calculated in the same manner as in the first embodiment.

[0293] In the optical glass according to the second embodiment, the partial dispersion ratio Pg,F preferably satisfies the following formula [4-1]: Pg,F≧0.6200−0.0014×νd ...[4-1] The partial dispersion ratio Pg,F more preferably satisfies the following formula [4-2], and even more preferably satisfies the following formulas [4-3], [4-4], [4-5], and [4-6] in this order. Pg,F≧0.6220-0.0014×νd…[4-2] Pg,F≧0.6230-0.0014×νd…[4-3] Pg,F≧0.6240-0.0014×νd…[4-4] Pg,F≧0.6250-0.0014×νd…[4-5] Pg,F≧0.6260-0.0014×νd…[4-6]

[0294] In the optical element made of the optical glass according to the second embodiment, from the viewpoint of correcting chromatic aberration well over a wide wavelength range, it is preferable that the partial dispersion ratio Pg,F satisfy the above formula.

[0295] In the optical glass according to the second embodiment, the upper limit of ΔPg,F is not particularly limited, but is preferably 0.0500, and further preferably 0.0400, 0.0300, 0.0200, 0.0150, 0.0140, 0.0130, 0.0120, 0.0110, or 0.0100. On the other hand, the lower limit of ΔPg,F is preferably -0.0100, and further preferably -0.0090, -0.0080, -0.0070, -0.0060, -0.0050, -0.0040, -0.0030, -0.0020, -0.0010, -0.0005, and 0.0000, in that order. By setting ΔPg,F within the above range, an optical glass suitable for correcting high-order chromatic aberrations can be obtained. ΔPg,F can be calculated in the same manner as in the first embodiment.

[0296] <Specific Gravity of Glass> The specific gravity of the optical glass according to the second embodiment is preferably 6.0 or less, and more preferably 5.9 or less, 5.8 or less, 5.7 or less, 5.6 or less, and 5.5 or less in that order. Components that relatively increase the specific gravity include Ba, ２＋ , La ３＋ , Zr ４＋ , Nb ５＋ , Ta ５＋On the other hand, the components that relatively lower the specific gravity are Si ４＋ , B ３＋ , Li ＋ , Na ＋ , Mg ２＋ The specific gravity can be controlled by appropriately adjusting the contents of these components.

[0297] <Liquidus Temperature LT> The upper limit of the liquidus temperature LT of the optical glass according to the second embodiment is preferably 1200°C, and more preferably 1190°C, 1180°C, 1170°C, 1160°C, 1150°C, 1140°C, 1130°C, and 1120°C in that order. By setting the liquidus temperature within the above range, the glass melting and molding temperatures can be lowered, and as a result, corrosion of glass melting equipment (e.g., crucibles, molten glass stirring equipment, etc.) in the melting process and the occurrence of striae due to volatilization of the glass components themselves can be reduced. The lower limit of the liquidus temperature LT is not particularly limited. The liquidus temperature LT is determined by the balance of the contents of all the glass components. Among these, the liquidus temperature LT is affected by the Si content. ４＋ , B ３＋ , Li ＋ , Na ＋ , K. ＋ The influence of the content of Zr is large. ４＋ , Al ３＋ The liquidus temperature LT is determined in the same manner as in the first embodiment.

[0298] <Glass Transition Temperature Tg> The upper limit of the glass transition temperature Tg of the optical glass according to the second embodiment is preferably 625°C, and more preferably 620°C, 615°C, 610°C, 595°C, 590°C, 585°C, and 580°C in this order. The lower limit of the glass transition temperature Tg is preferably 350°C, and more preferably 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, and 500°C in this order. From the viewpoint of improving the yield during precision press molding, it is preferable to set the glass transition temperature Tg within the above range. On the other hand, if the glass transition temperature Tg is too high, precision press molding may not be possible. Components that relatively lower the glass transition temperature Tg include Li, ＋ , Na＋ , K. ＋ , F － The component that relatively increases the glass transition temperature Tg is La ３＋ , Zr ４＋ , Nb ５＋ The glass transition temperature Tg can be controlled by appropriately adjusting the contents of these components.

[0299] <Light Transmittance of Glass> The light transmittance of the optical glass according to the second embodiment can be evaluated by the coloring degrees λ80, λ70, and λ5. The spectral transmittance of a glass sample having a thickness of 10.0 mm±0.1 mm was measured in the wavelength range of 200 to 700 nm, and the wavelength at which the external transmittance was 80% was defined as λ80, the wavelength at which the external transmittance was 70%, and the wavelength at which the external transmittance was 5% was defined as λ70, the wavelength at which the external transmittance was 70%, and the wavelength at which the external transmittance was 5%.

[0300] The λ80 of the optical glass according to the second embodiment is preferably 450 nm or less, more preferably 400 nm or less, and even more preferably 380 nm or less. The λ70 is preferably 430 nm or less, more preferably 380 nm or less, and even more preferably 360 nm or less. The λ5 is preferably 380 nm or less, more preferably 330 nm or less, and even more preferably 320 nm or less.

[0301] <Chemical Durability Acid Resistance Da> In the optical glass according to the second embodiment, the acid resistance Da is preferably at least grade 5, more preferably at least grade 4, and even more preferably at least grade 3. The acid resistance Da can be evaluated in the same manner as in the first embodiment.

[0302] <Chemical Durability: Water Resistance Dw> In the optical glass according to the second embodiment, the water resistance Dw is preferably at least grade 5, more preferably at least grade 4, and even more preferably at least grade 3. The water resistance Dw can be evaluated in the same manner as in the first embodiment.

[0303] <Mechanical Properties: Knoop Hardness Hk> The lower limit of the Knoop hardness Hk of the optical glass according to the second embodiment is preferably 400, and more preferably 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, and 550, in that order. It is preferable to keep the Knoop hardness Hk within the above range from the viewpoint of preventing damage when handling the glass and when manufacturing lenses and the like by machining the glass, such as grinding, polishing, and cutting. The upper limit of the Knoop hardness Hk is not particularly limited, but is usually 750, and preferably 600.

[0304] The Knoop hardness Hk is ３＋ , Gd ３＋ , Y ３＋ , Si ４＋ , Zr ４＋ , Al ３＋ The content can be increased by adjusting the content.

[0305] <ΔT360> In the optical glass according to the second embodiment, when the thickness is 10.0 mm±0.1 mm, the upper limit of the difference (ΔT360) between the external transmittance at a wavelength of 700 nm and the external transmittance at a wavelength of 360 nm is preferably 30.0%, and more preferably 28.0%, 26.0%, 24.0%, 22.0%, 20.0%, 18.0%, 16.0%, 15.0%, 14.0%, 13.0%, 12.0%, 11.0%, 10.0%, 9.0%, 8.0%, 7.0%, and 6.0%, in that order. The lower limit of ΔT360 is not particularly limited, but is generally 3 to 30%. ΔT360 can be adjusted by introducing Sb ions. Furthermore, from the viewpoint of maintaining low dispersion, it is not preferable to use high-dispersion components such as Ti, Nb, W, and Bi, but when these are introduced for the purpose of increasing refraction or anomalous dispersion, ΔT360 may increase. By keeping ΔT360 within the above range, it is possible to suppress a decrease in transmittance at a wavelength in the vicinity of 360 nm.

[0306] <ΔT375> In the optical glass according to the second embodiment, when the thickness is 10.0 mm±0.1 mm, the upper limit of the difference (ΔT375) between the external transmittance at a wavelength of 700 nm and the external transmittance at a wavelength of 375 nm is preferably 15.0%, and more preferably 13.0%, 11.0%, 10.0%, 9.0%, 8.0%, 7.5%, 7.0%, 6.8%, 6.7%, 6.6%, 6.5%, 6.4%, 6.3%, 6.2%, 6.1%, and 6.0%, in that order. The lower limit of ΔT375 is not particularly limited, but is generally 2 to 15%. ΔT375 can be adjusted by introducing Sb ions. Furthermore, from the viewpoint of maintaining low dispersion, it is not preferable to use high-dispersion components such as Ti, Nb, W, and Bi, but when these are introduced for the purpose of increasing refraction or anomalous dispersion, ΔT375 may increase. By keeping ΔT375 within the above range, it is possible to suppress a decrease in transmittance at a wavelength in the vicinity of 375 nm.

[0307] The external transmittance is defined as the percentage of the transmitted light intensity relative to the incident light intensity when light is incident in the thickness direction of a glass sample [transmitted light intensity / incident light intensity × 100]. The external transmittance also includes the reflection loss of light rays on the sample surface.

[0308] The manufacture of the optical glass, the manufacture of the press-molding glass material, the manufacture of the optical element blank, and the manufacture of the optical element according to the second embodiment can be the same as in the first embodiment.

[0309] Third Embodiment The optical glass according to the third embodiment is made of Si ４＋ The content of is more than 0 cation % and 30 cation % or less, ３＋ The content of Al is more than 0 cation % and less than 50.00 cation %; ３＋ The content of Ca is 13 cation % or less, ２＋ The content of Zn is 25 cation % or less, ２＋ The content of Ge is 6 cation % or less, ４＋ The content of F is 5 cation % or less, － The content of La is 10% or more of anion, ３＋ , Gd ３＋ , and Y３＋ The total content [La ３＋ +Gd ３＋ +Y ３＋ ] is 30 cation % or more, Si ４＋ and B ３＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ ) )] is 0.070 or more, Si ４＋ , B ３＋ , P ５＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ , and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , Y ３＋ , Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ +Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +P ５＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋ ) is 0.84 or more.

[0310] In the optical glass according to the third embodiment, Si ４＋ The content of Si is more than 0% and not more than 30%.４＋ The lower limit of the Si content is preferably 0.60%, and more preferably 1.20%, 1.80%, 2.40%, 3.00%, 3.60%, 4.20%, 4.80%, 5.40%, 6.00%, 6.60%, 7.20%, 7.80%, 8.40%, 9.00%, 9.60%, 10.20%, 10.80%, 11.40%, and 12.00% in that order. ４＋ The upper limit of the content is preferably 29.4%, and more preferably 28.7%, 28.1%, 27.4%, 26.8%, 26.1%, 25.5%, 24.8%, 24.2%, 23.5%, 22.9%, 22.2%, 21.6%, 20.9%, 20.3%, 19.6%, 19.0%, 18.3%, 17.7%, and 17.0% in that order.

[0311] Si ４＋ is a glass network forming component. ４＋ By setting the content of Si in the above range, an optical glass having anomalous partial dispersion and improved chemical durability, mechanical properties, and thermal stability can be obtained. ４＋ If the content of Si is too low, the chemical durability, mechanical properties, and thermal stability of the glass may be reduced. ４＋ If the content is too high, the meltability of the glass may decrease, the refractive index nd may decrease, and the thermal stability of the glass may decrease, resulting in an increase in the glass transition temperature Tg.

[0312] In the optical glass according to the third embodiment, B ３＋ The content of is more than 0% and less than 50.00%. ３＋ The lower limit of the content of B is preferably 1.10%, and more preferably 2.20%, 3.30%, 4.40%, 5.50%, 6.60%, 7.70%, 8.80%, 9.90%, 11.00%, 12.10%, 13.20%, 14.30%, 15.40%, 16.50%, 17.60%, 18.70%, 19.80%, 20.90%, and 22.00% in that order. ３＋The upper limit of the content is preferably 49.3%, and more preferably 48.5%, 47.8%, 47.0%, 46.3%, 45.5%, 44.8%, 44.0%, 43.3%, 42.5%, 41.8%, 41.0%, 40.3%, 39.5%, 38.8%, 38.0%, 37.3%, 36.5%, 35.8%, and 35.0% in that order.

[0313] B ３＋ is a glass network forming component. ３＋ By setting the content of B in the above range, chemical durability can be improved. ３＋ If the content of B is too low, the thermal stability and mechanical properties of the glass may be reduced. ３＋ If the content is too high, the volatilization of glass components may increase, and the thermal stability and chemical durability of the glass may decrease.

[0314] In the optical glass according to the third embodiment, Al ３＋ The content of Al is 13% or less. ３＋ The upper limit of the content of Al is preferably 12.4%, and more preferably 11.8%, 11.2%, 10.6%, 10.0%, 9.4%, 8.8%, 8.2%, 7.6%, 7.0%, 6.4%, 5.8%, 5.2%, 4.6%, 4.0%, 3.4%, 2.8%, 2.2%, 1.6%, and 1.0% in that order. ３＋ The lower limit of the Al content is preferably 0%, and more preferably 0.03%, 0.05%, 0.08%, 0.10%, 0.13%, 0.15%, 0.18%, 0.20%, 0.23%, 0.25%, 0.28%, 0.30%, 0.33%, 0.35%, 0.38%, 0.40%, 0.43%, 0.45%, 0.48%, and 0.50% in that order. ３＋ The content may be 0%.

[0315] Al ３＋ When contained in an appropriate amount, Al has the effect of suppressing phase separation of glass. ３＋ By increasing the content of Al, the mechanical properties and chemical durability of the glass can be improved. ３＋If the Al content is too high, the liquidus temperature rises and the thermal stability of the glass is impaired. When the liquidus temperature rises, the volatilization of glass components increases during the flow and molding of the glass, causing striae. ３＋ By setting the content within the above range, the thermal stability of the glass can be maintained.

[0316] In the optical glass according to the third embodiment, Ca ２＋ The content of Ca is 25% or less. ２＋ The upper limit of the Ca content is preferably 23.8%, and more preferably 22.6%, 21.4%, 20.2%, 19.0%, 17.8%, 16.6%, 15.4%, 14.2%, 13.0%, 11.8%, 10.6%, 9.4%, 8.2%, 7.0%, 5.8%, 4.6%, 3.4%, 2.2%, and 1.0% in that order. ２＋ The lower limit of the Ca content is preferably 0%, and more preferably 0.03%, 0.05%, 0.08%, 0.10%, 0.13%, 0.15%, 0.18%, 0.20%, 0.23%, 0.25%, 0.28%, 0.30%, 0.33%, 0.35%, 0.38%, 0.40%, 0.43%, 0.45%, 0.48%, and 0.50% in that order. ２＋ The content may be 0%.

[0317] Ca ２＋ By setting the content of Ca in the above range, an optical glass having desired optical constants can be obtained. ２＋ If the content is too large, the thermal stability of the glass may be impaired, and the glass transition temperature Tg and liquidus temperature TL may increase.

[0318] In the optical glass according to the third embodiment, Zn ２＋ The content of Zn is 6% or less. ２＋ The upper limit of the content of is preferably 5.8%, and more preferably 5.5%, 5.3%, 5.0%, 4.8%, 4.5%, 4.3%, 4.0%, 3.8%, 3.5%, 3.3%, 3.0%, 2.8%, 2.5%, 2.3%, 2.0%, 1.8%, 1.5%, 1.3%, and 1.0% in that order. ２＋The lower limit of the content of Zn is preferably 0%, and more preferably 0.03%, 0.05%, 0.08%, 0.10%, 0.13%, 0.15%, 0.18%, 0.20%, 0.23%, 0.25%, 0.28%, 0.30%, 0.33%, 0.35%, 0.38%, 0.40%, 0.43%, 0.45%, 0.48%, and 0.50% in that order. ２＋ The content may be 0%.

[0319] Zn ２＋ is a glass component that, when incorporated, serves to lower the glass transition temperature Tg. ２＋ By setting the content of Zn in the above range, an optical glass with an improved glass transition temperature Tg can be obtained. ２＋ If the content is too high, the specific gravity may increase, the thermal stability and chemical durability of the glass may decrease, and the Abbe number may increase, making it impossible to obtain the desired high refractive index characteristics.

[0320] In the optical glass according to the third embodiment, Ge ４＋ The content of Ge is 5% or less. ４＋ The upper limit of the content of Ge is preferably 4.5%, and more preferably 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, 1%, and 0.5% in that order. ４＋ The lower limit of the content is preferably 0%. ４＋ The content may be 0%.

[0321] Ge ４＋ Although Ge has the function of increasing the dispersibility of glass, it is an extremely expensive component among commonly used glass components. ４＋ By setting the content within the above range, the manufacturing cost of the glass can be reduced.

[0322] The optical glass according to the third embodiment contains F as an anion component. － Includes: F － The content of F is 10% or more. －The lower limit of the content of is preferably 11 anion%, and more preferably 12 anion%, 13 anion%, 14 anion%, 15 anion%, 16 anion%, 17 anion%, 18 anion%, 19 anion%, 20 anion%, 21 anion%, 22 anion%, 23 anion%, 24 anion%, 25 anion%, 26 anion%, 27 anion%, 28 anion%, 29 anion%, 30 anion%, 31 anion%, 32 anion%, 33 anion%, and 34 anion% in that order. － The upper limit of the content of is preferably 90 anion%, and more preferably in the order of 85 anion%, 80 anion%, 75 anion%, 70 anion%, 68 anion%, 66 anion%, 64 anion%, 62 anion%, 60 anion%, 59 anion%, 58 anion%, 57 anion%, 56 anion%, 55 anion%, 54 anion%, 53 anion%, 52 anion%, 51 anion%, 50 anion%, 49 anion%, 48 anion%, and 47 anion%. － By setting the content of F within the above range, an optical glass can be obtained which has a high refractive index despite its low dispersion, high thermal stability, anomalous partial dispersion, a low glass transition temperature Tg, and is suitable for precision press molding. － If the content of F is too small, the thermal stability of the glass may decrease, and anomalous partial dispersion may not be obtained. － If the content is too large, the volatilization of glass components may increase.

[0323] In the optical glass according to the third embodiment, La ３＋ , Gd ３＋ , and Y ３＋ The total content [La ３＋ +Gd ３＋ +Y ３＋] is 30% or more. The lower limit of the total content is preferably 32%, and more preferably 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, and 60% in that order. The upper limit of the total content is preferably 80%, and more preferably 79%, 78%, 77%, 76%, 75%, 74%, 73%, 72%, 71%, 70%, 69%, 68%, 67%, 66%, 65%, 64%, 63%, and 62% in that order. By keeping the total content within the above range, an optical glass with a high refractive index nd can be obtained. On the other hand, if the total content is too low, the desired optical constants may not be obtained. If the total content is too high, the thermal stability of the glass may be reduced.

[0324] In the optical glass according to the third embodiment, Si ４＋ and B ３＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ ) is 0.070 or more. The lower limit of the cation ratio is preferably 0.10, and more preferably 0.12, 0.14, 0.16, 0.18, 0.20, 0.22, 0.24, 0.26, 0.28, 0.30, 0.32, 0.34, 0.36, 0.38, and 0.40, in that order. The upper limit of the cation ratio is preferably 0.99, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.53, 0.51, 0.49, 0.47, 0.45, 0.43, and 0.42, in that order. By setting the cation ratio within the above range, an optical glass having improved chemical durability, mechanical properties, and thermal stability can be obtained.

[0325] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , P ５＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ , and Ta ５＋ La relative to the total content ３＋, Gd ３＋ , Y ３＋ , Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ +Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +P ５＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋ The lower limit of the cation ratio is preferably 0.87, and more preferably 0.90, 0.93, 0.96, 0.99, 1.02, 1.05, 1.08, 1.11, 1.14, 1.17, 1.20, 1.23, 1.26, 1.29, 1.32, 1.35, 1.38, 1.41, 1.44, 1.47, 1.50, 1.53, and 1.56 in that order. The upper limit of the cation ratio is preferably 4.00, and more preferably 3.00, 2.95, 2.90, 2.85, 2.80, 2.75, 2.70, 2.65, 2.60, 2.55, 2.50, 2.45, 2.40, 2.35, 2.30, 2.25, 2.20, 2.15, 2.10, 2.05, 2.00, 1.95, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, and 1.60, in that order. By setting the cation ratio within the above range, volatilization of glass components can be suppressed. On the other hand, if the cation ratio is too small, volatilization of glass components may increase. If the cation ratio is too large, the thermal stability of the glass may decrease.

[0326] Non-limiting examples of the contents and ratios of glass components other than those described above in the optical glass according to the third embodiment are shown below.

[0327] In the optical glass according to the third embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ The lower limit of [0.01% by weight] is preferably 0%, and more preferably 0.50%, 1.00%, 1.05%, 1.10%, 1.15%, 1.20%, 1.25%, 1.30%, 1.35%, 1.40%, 1.45%, 1.50%, 1.55%, 1.60%, 1.65%, 1.70%, 1.75%, and 1.80% in that order. The total content may be 0%. The upper limit of the total content is preferably 30%, and more preferably 25%, 20%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, and 3% in that order. From the viewpoint of obtaining an optical glass having desired optical constants, reduced volatilization of glass components, and high thermal stability, it is preferable that the total content be within the above range. On the other hand, if the total content is too low, the volatilization of the glass components increases, which may reduce the thermal stability and devitrification resistance of the glass, whereas if the total content is too high, the high refractive index may be impaired, and the thermal stability of the glass may be impaired.

[0328] In the optical glass according to the third embodiment, Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The total content [Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr２＋ +Ba ２＋ The lower limit of the total content is preferably 0%, and more preferably 0.50%, 1.00%, 1.05%, 1.10%, 1.15%, 1.20%, 1.25%, 1.30%, 1.35%, 1.40%, 1.45%, 1.50%, 1.55%, 1.60%, 1.65%, 1.70%, 1.75%, and 1.80% in that order. The upper limit of the total content is preferably 50%, and more preferably 45%, 40%, 35%, 30%, 25%, 20%, 18%, 16%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, and 2% in that order. From the viewpoint of obtaining an optical glass having desired optical constants, a lowered glass transition temperature Tg, reduced volatilization of glass components, and high thermal stability, it is preferable that the total content be within the above range.

[0329] In the optical glass according to the third embodiment, Si ４＋ and B ３＋ The total content [Si ４＋ +B ３＋ The lower limit of the total content is preferably 10%, and more preferably 15%, 20%, 22%, 24%, 26%, 28%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, and 38% in that order. The upper limit of the total content is preferably 70%, and more preferably 65%, 60%, 59%, 58%, 57%, 56%, 55%, 54%, 53%, 52%, 51%, 50%, 49%, 48%, 47%, 46%, 45%, 44%, 43%, 42%, 41%, 40%, and 39% in that order. From the viewpoint of obtaining an optical glass having desired optical constants and anomalous partial dispersion, improved chemical durability, mechanical properties, and thermal stability, and suppressed volatilization of glass components during melting, it is preferable that the total content be within the above range.

[0330] In the optical glass according to the third embodiment, Li ＋ , Na ＋ , and K ＋ The total content [Li ＋ +Na ＋ +K ＋The lower limit of

[0012] is preferably 0%, and more preferably 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, and 0.6% in that order. The upper limit of the total content is preferably 50%, and more preferably 45%, 40%, 35%, 30%, 25%, 20%, 18%, 16%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, and 2% in that order. The total content may be 0%. From the viewpoint of lowering the liquidus temperature of the glass and lowering the glass transition temperature Tg, it is preferable that the total content be within the above range.

[0331] In the optical glass according to the third embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ and Zn ２＋ The total content [Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋ The upper limit of

[0013] is preferably 30%, and more preferably 25%, 20%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, and 3% in that order. The lower limit of the total content is preferably 0%, and more preferably 0.5%, 1.00%, 1.05%, 1.10%, 1.15%, 1.20%, 1.25%, 1.30%, 1.35%, 1.40%, 1.45%, 1.50%, 1.55%, 1.60%, 1.65%, 1.70%, 1.75%, and 1.80% in that order. The total content may be 0%. If the total content is too high, the high refractive index may be impaired and the thermal stability of the glass may be impaired. If the total content is too low, the volatilization of glass components increases, which may result in a decrease in the thermal stability and devitrification resistance of the glass. Therefore, the total content is preferably within the above range.

[0332] In the optical glass according to the third embodiment, Li ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋The total content [Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ The lower limit of the total content is preferably 0%, and more preferably 0.50%, 1.00%, 1.05%, 1.10%, 1.15%, 1.20%, 1.25%, 1.30%, 1.35%, 1.40%, 1.45%, 1.50%, 1.55%, 1.60%, 1.65%, 1.70%, 1.75%, and 1.80% in that order. The upper limit of the total content is preferably 50%, and more preferably 45%, 40%, 35%, 30%, 25%, 20%, 18%, 16%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, and 2% in that order. From the viewpoint of obtaining an optical glass having desired optical constants, a reduced glass transition temperature Tg and glass liquidus temperature, and reduced volatilization of glass components during melting, it is preferable that the total content be within the above range.

[0333] In the optical glass according to the third embodiment, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ The total content [Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ The lower limit of [0.01% by weight] is preferably 0%, and more preferably 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, and 1.8%, in that order. The upper limit of the total content is preferably 20%, and more preferably 18%, 16%, 14%, 12%, 10%, 9%, 8%, 7%, 6%, 5.0%, 4.5%, 4.0%, 3.5%, 3.0%, and 2.5%, in that order. From the viewpoint of maintaining high refractive index and low dispersion, the total content may be 0%. From the viewpoint of maintaining a desired Abbe number νd and improving anomalous partial dispersion in the visible to near-ultraviolet region, it is preferable that the total content be within the above range.

[0334] In the optical glass according to the third embodiment, Zr ４＋ and Ta ５＋ The total content [Zr ４＋ +Ta ５＋ The upper limit of the total content is preferably 20%, and more preferably 15%, 10%, 9%, 8%, 7%, 6%, 5%, and 4% in that order. The lower limit of the total content is preferably 0%, and more preferably 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% in that order. From the viewpoint of maintaining high refraction and low dispersion, the total content may be 0%. From the viewpoint of maintaining the thermal stability of the glass, it is preferable that the total content be within the above range. If the total content is too high, the thermal stability of the glass may be reduced and the raw material costs may increase.

[0335] In the optical glass according to the third embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ The total content [Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ The upper limit of [0.01% by mass] is preferably 20%, and more preferably 18%, 16%, 14%, 12%, 10%, 9%, 8%, 7%, and 6% in that order. The lower limit of the total content is preferably 0%, and more preferably 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, and 4.5% in that order. From the viewpoint of maintaining high refractive index and low dispersion, the total content may be 0%. From the viewpoint of maintaining a desired Abbe number νd and improving anomalous partial dispersion in the visible to near-ultraviolet region, it is preferable that the total content be within the above range.

[0336] In the optical glass according to the third embodiment, Si ４＋ and B ３＋ B relative to the total content of ３＋ The cation ratio of the content [B ３＋ / (Si ４＋ +B ３＋) is preferably 0.93, and more preferably 0.90, 0.88, 0.86, 0.84, 0.82, 0.80, 0.78, 0.76, 0.74, 0.72, 0.70, 0.68, 0.66, 0.64, 0.62, and 0.60 in that order. The lower limit of the cation ratio is preferably 0.10, and more preferably 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.47, 0.49, 0.51, 0.53, 0.55, 0.57, and 0.58 in that order. From the viewpoint of obtaining an optical glass having improved chemical durability, mechanical properties, and thermal stability, it is preferable that the cation ratio be within the above range.

[0337] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , and P ５＋ The total content [Si ４＋ +B ３＋ +P ５＋ The lower limit of the total content is preferably 10%, and more preferably 15%, 20%, 22%, 24%, 26%, 28%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, and 38% in that order. The upper limit of the total content is preferably 70%, and more preferably 65%, 60%, 59%, 58%, 57%, 56%, 55%, 54%, 53%, 52%, 51%, 50%, 49%, 48%, 47%, 46%, 45%, 44%, 43%, 42%, 41%, 40%, and 39% in that order. From the viewpoint of obtaining an optical glass having desired optical constants and anomalous partial dispersion, improved chemical durability, mechanical properties, and thermal stability, and suppressed volatilization of glass components during melting, it is preferable that the total content be within the above range.

[0338] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , and P ５＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ +P ５＋) is preferably 0.99, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.53, 0.51, 0.49, 0.47, 0.45, 0.43, and 0.42 in that order. The lower limit of the cation ratio is preferably 0.07, and more preferably 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, 0.22, 0.24, 0.26, 0.28, 0.30, 0.32, 0.34, 0.36, 0.38, and 0.40 in that order. From the viewpoint of obtaining an optical glass having improved chemical durability, mechanical properties, and thermal stability, it is preferable that the cation ratio be within the above range.

[0339] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , and P ５＋ B relative to the total content of ３＋ The cation ratio of the content [B ３＋ / (Si ４＋ +B ３＋ +P ５＋ ) is preferably 0.93, and more preferably 0.90, 0.88, 0.86, 0.84, 0.82, 0.80, 0.78, 0.76, 0.74, 0.72, 0.70, 0.68, 0.66, 0.64, 0.62, and 0.60 in that order. The lower limit of the cation ratio is preferably 0.01, and more preferably 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.47, 0.49, 0.51, 0.53, 0.55, 0.57, and 0.58 in that order. From the viewpoint of obtaining an optical glass having improved chemical durability, mechanical properties, and thermal stability, it is preferable that the cation ratio be within the above range.

[0340] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , and P ５＋ P relative to the total content of ５＋ The cation ratio of the content [P ５＋ / (Si ４＋ +B ３＋ +P ５＋) is preferably 0.50, and more preferably 0.40, 0.30, 0.20, 0.10, 0.08, 0.06, 0.04, and 0.02 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.005, 0.01, and 0.015 in that order. The cation ratio may even be 0. From the viewpoint of obtaining an optical glass with improved chemical durability, mechanical properties, and thermal stability, it is preferable that the cation ratio be within the above range.

[0341] In the optical glass according to the third embodiment, Li ＋ , Na ＋ , and K ＋ Li relative to the total content of ＋ The cation ratio of the content [Li ＋ / (Li ＋ +Na ＋ +K ＋ ) )] is preferably 1, and more preferably 0.95, 0.90, and 0.85 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 in that order. The cation ratio may be 1. From the viewpoint of suppressing a decrease in stability upon reheating and from the viewpoint of lowering the glass transition temperature Tg, it is preferable that the cation ratio be in the above range.

[0342] In the optical glass according to the third embodiment, Li ＋ , Na ＋ , and K ＋ Na relative to the total content ＋ The cation ratio of the content [Na ＋ / (Li ＋ +Na ＋ +K ＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, and 0.3 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, and 0.15 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in stability upon reheating and from the viewpoint of lowering the glass transition temperature Tg, it is preferable that the cation ratio be in the above range.

[0343] In the optical glass according to the third embodiment, Li ＋ , Na ＋ , and K ＋ K relative to the total content of ＋ The cation ratio of the content [K ＋ / (Li ＋ +Na ＋ +K ＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, and 0.3 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, and 0.15 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in stability upon reheating and from the viewpoint of lowering the glass transition temperature Tg, it is preferable that the cation ratio be in the above range.

[0344] In the optical glass according to the third embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Mg relative to the total content ２＋ The cation ratio of the content [Mg ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.55, 0.5, 0.45, and 0.4 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.15, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, and 0.3 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0345] In the optical glass according to the third embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Ca relative to the total content of ２＋ The cation ratio of the content [Ca ２＋ / (Mg ２＋ + Ca ２＋ + Sr２＋ +Ba ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0346] In the optical glass according to the third embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Sr relative to the total content ２＋ The cation ratio of the content [Sr ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0347] In the optical glass according to the third embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Ba relative to the total content of ２＋ The cation ratio of the content [Ba ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋) is preferably 0, and more preferably 0.1, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, and 0.60 in this order. The upper limit of the cation ratio is preferably 1, and more preferably 0.90, 0.80, 0.75, 0.74, 0.73, 0.72, 0.71, and 0.70 in this order. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0348] In the optical glass according to the third embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Mg relative to the total content ２＋ The cation ratio of the content [Mg ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.55, 0.5, 0.45, and 0.4 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.15, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, and 0.3 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0349] In the optical glass according to the third embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Ca relative to the total content of ２＋ The cation ratio of the content [Ca ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0350] In the optical glass according to the third embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Sr relative to the total content ２＋ The cation ratio of the content [Sr ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0351] In the optical glass according to the third embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Ba relative to the total content of ２＋ The cation ratio of the content [Ba ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋) is preferably 0, and more preferably 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, and 0.60 in this order. The upper limit of the cation ratio is preferably 1, and more preferably 0.90, 0.80, 0.75, 0.74, 0.73, 0.72, 0.71, and 0.70 in this order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, the cation ratio is preferably within the above range.

[0352] In the optical glass according to the third embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , and Zn ２＋ Zn relative to the total content of ２＋ The cation ratio of the content [Zn ２＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +Zn ２＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, and 0.15 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.1 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the stability and thermal stability of the glass during reheating, and from the viewpoint of maintaining the high refractive index of the glass, the cation ratio is preferably within the above range.

[0353] In the optical glass according to the third embodiment, La ３＋ , Gd ３＋ , and Y ３＋ La relative to the total content ３＋ The cation ratio of the content [La ３＋ / (La ３＋ +Gd ３＋ +Y ３＋) is preferably 0, and more preferably 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.62, 0.64, 0.66, and 0.68 in that order. The upper limit of the cation ratio is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.78, 0.76, 0.74, and 0.72 in that order. From the viewpoints of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0354] In the optical glass according to the third embodiment, La ３＋ , Gd ３＋ , and Y ３＋ Gd relative to the total content ３＋ The cation ratio of the content [Gd ３＋ / (La ３＋ +Gd ３＋ +Y ３＋ ) is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.48, 0.46, 0.44, 0.42, 0.40, 0.38, 0.36, 0.34, and 0.32 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.05, 0.10, 0.15, 0.20, 0.22, 0.24, 0.26, and 0.28 in that order. The cation ratio may be 0. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, the heavy rare earth element Gd ３＋ From the viewpoint of reducing the content and suppressing an increase in raw material costs, it is preferable that the cation ratio be within the above range.

[0355] In the optical glass according to the third embodiment, La ３＋ , Gd ３＋ , and Y ３＋ Y relative to the total content of ３＋ The cation ratio of the content [Y ３＋ / (La ３＋ +Gd ３＋ +Y ３＋The upper limit of the cation ratio is preferably 1, and more preferably 0.95, 0.93, 0.91, 0.89, 0.87, 0.85, 0.84, 0.83, 0.82, 0.81, 0.80, 0.79, 0.78, 0.77, 0.76, 0.75, 0.74, 0.73, 0.72, 0.71, and 0.70, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, and 0.67, in that order. The cation ratio may be 0. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0356] In the optical glass according to the third embodiment, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Ti relative to the total content of ４＋ The cation ratio of the content [Ti ４＋ / (Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ) )] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.23, 0.21, 0.2, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, and 0.11 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, and 0.08 in that order. The cation ratio may be 0. From the viewpoints of increasing the refractive index nd and maintaining a desired Abbe number νd and thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0357] In the optical glass according to the third embodiment, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Nb content relative to the total content ５＋ The cation ratio of the content [Nb５＋ / (Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ) )] is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.74, 0.73, 0.72, 0.71, 0.70, 0.69, 0.68, and 0.67 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, and 0.62 in that order. The cation ratio may be 0. From the viewpoints of increasing the refractive index nd, maintaining a desired Abbe number νd, and maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0358] In the optical glass according to the third embodiment, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ W relative to the total content of ６＋ The cation ratio of the content [W ６＋ / (Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.44, 0.43, 0.42, 0.41, 0.40, 0.39, 0.38, 0.37, 0.36, 0.35, 0.34, 0.33, 0.32, 0.31, 0.3, 0.29, 0.28, and 0.27, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.1, 0.12, 0.14, 0.16, 0.18, 0.20, 0.21, 0.22, 0.23, and 0.24, in that order. The cation ratio may be 0. From the viewpoints of increasing the partial dispersion ratio Pg, F, maintaining a desired Abbe number νd, and maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0359] In the optical glass according to the third embodiment, Ti ４＋ , Nb５＋ , W ６＋ , and Bi ３＋ Bi relative to the total content ３＋ The cation ratio of the content [Bi ３＋ / (Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.44, 0.43, 0.42, 0.41, 0.40, 0.39, 0.38, 0.37, 0.36, 0.35, 0.34, 0.33, 0.32, 0.31, 0.3, 0.29, 0.28, and 0.27 in that order. The lower limit of the cation ratio is preferably 0, and may be 0.05, 0.1, 0.12, 0.14, 0.16, 0.18, 0.20, 0.21, 0.22, 0.23, or 0.24. The cation ratio may be 0. It is preferable that the cation ratio be within the above range from the viewpoints of increasing the refractive index nd and the partial dispersion ratio Pg,F, maintaining a desired Abbe number νd, maintaining the thermal stability of the glass, and reducing damage to platinum production melting equipment.

[0360] In the optical glass according to the third embodiment, Zr ４＋ and Ta ５＋ Zr relative to the total content ４＋ The cation ratio of the content [Zr ４＋ / (Zr ４＋ +Ta ５＋ ) )] is preferably 1, and more preferably 0.95, 0.90, and 0.85 in that order. The cation ratio may be 1. The lower limit of the cation ratio is preferably 0, and more preferably 0.5, 0.6, 0.7, and 0.8 in that order. From the viewpoints of maintaining desired optical constants and reducing raw material costs, it is preferable that the cation ratio be within the above range.

[0361] In the optical glass according to the third embodiment, Zr ４＋ and Ta ５＋ Ta relative to the total content ５＋ The cation ratio of the content [Ta ５＋ / (Zr ４＋ +Ta ５＋) is preferably 1, and more preferably 0.5, 0.4, 0.3, and 0.2 in that order. The lower limit of the cation ratio is preferably 0, and may be 0.05, 0.10, or 0.15. The cation ratio may be 0. From the viewpoints of maintaining desired optical constants and reducing raw material costs, it is preferable that the cation ratio be in the above range.

[0362] In the optical glass according to the third embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Ti relative to the total content of ４＋ The cation ratio of the content [Ti ４＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.23, 0.21, 0.2, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, 0.11, 0.10, 0.09, 0.08, 0.07, and 0.06 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, and 0.04 in that order. The cation ratio may be 0. From the viewpoint of increasing the refractive index nd and maintaining a desired Abbe number νd, it is preferable that the cation ratio be within the above range.

[0363] In the optical glass according to the third embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Nb content relative to the total content ５＋ The cation ratio of the content [Nb ５＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋+Ta ５＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.34, 0.33, 0.32, 0.31, 0.30, 0.29, 0.28, and 0.27 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, and 0.24 in that order. The cation ratio may be 0. From the viewpoint of increasing the refractive index nd and maintaining a desired Abbe number vd, it is preferable that the cation ratio be within the above range.

[0364] In the optical glass according to the third embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Bi relative to the total content ３＋ The cation ratio of the content [Bi ３＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.30, 0.29, 0.28, 0.27, 0.26, 0.25, 0.24, 0.23, 0.22, 0.21, 0.20, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, and 0.11, in that order. The lower limit of the cation ratio is preferably 0, and may be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, or 0.09. The cation ratio may be 0. It is preferable that the cation ratio be within the above range from the viewpoints of increasing the refractive index nd and the partial dispersion ratio Pg,F, maintaining a desired Abbe number νd, maintaining the thermal stability of the glass, and reducing damage to platinum production melting equipment.

[0365] In the optical glass according to the third embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ W relative to the total content of ６＋ The cation ratio of the content [W ６＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ The upper limit of the cation ratio is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.30, 0.29, 0.28, 0.27, 0.26, 0.25, 0.24, 0.23, 0.22, 0.21, 0.20, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, and 0.11, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, and 0.09, in that order. The cation ratio may be 0. From the viewpoints of increasing the partial dispersion ratio Pg, F, maintaining a desired Abbe number νd, and maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0366] In the optical glass according to the third embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Zr relative to the total content ４＋ The cation ratio of the content [Zr ４＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋) )] is preferably 1, and more preferably 0.95, 0.9, 0.85, 0.80, 0.75, 0.70, 0.69, 0.68, 0.67, 0.66, 0.65, 0.64, 0.63, and 0.62 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.1, 0.2, 0.3, 0.4, 0.45, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, and 0.58 in that order. The cation ratio may be 0. From the viewpoints of increasing the refractive index nd, maintaining a desired Abbe number νd, and improving the mechanical properties and chemical durability of the glass, it is preferable that the cation ratio be within the above range.

[0367] In the optical glass according to the third embodiment, Ti ４＋ , Nb ５＋ , Bi ３＋ , W ６＋ , Zr ４＋ , and Ta ５＋ Ta relative to the total content ５＋ The cation ratio of the content [Ta ５＋ / (Ti ４＋ +Nb ５＋ +Bi ３＋ +W ６＋ + Zr ４＋ +Ta ５＋ ) is preferably 1, and more preferably 0.5, 0.4, 0.3, 0.25, 0.2, 0.15, 0.1, 0.08, 0.06, and 0.04 in that order. The lower limit of the cation ratio is preferably 0, and may be 0.01, 0.02, or 0.03. The cation ratio may be 0. From the viewpoints of maintaining desired constants and reducing raw material costs, it is preferable that the cation ratio be within the above range.

[0368] In the optical glass according to the third embodiment, Si ４＋ and B ３＋ Al content relative to the total content ３＋ The cation ratio of the content [Al ３＋ / (Si ４＋ +B ３＋) is preferably 0.5, and more preferably 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.18, 0.16, 0.14, 0.12, and 0.10 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.05, and 0.10 in that order. The cation ratio may be 0. Increasing the cation ratio can improve the mechanical properties and chemical durability of the glass. On the other hand, if the cation ratio is too high, the liquidus temperature rises and the thermal stability of the glass is impaired. From the viewpoint of maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0369] In the optical glass according to the third embodiment, Li ＋ , Na ＋ , and K ＋ Al content relative to the total content ３＋ The cation ratio of the content [Al ３＋ / (Li ＋ +Na ＋ +K ＋ ) )] is preferably 2, and more preferably 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6, 0.4, 0.2, 0.18, 0.16, 0.14, 0.12, and 0.10 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.10 in that order. The cation ratio may be 0. Increasing the cation ratio can improve the mechanical properties and chemical durability of the glass. On the other hand, if the cation ratio is too high, the liquidus temperature rises, and the thermal stability of the glass is impaired. From the viewpoint of maintaining the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0370] In the optical glass according to the third embodiment, Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Al content relative to the total content ３＋ The cation ratio of the content [Al ３＋ / (Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋) )] is preferably 5, and more preferably 4, 3.5, 3.0, 2.5, 2, 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6, 0.4, 0.3, 0.2, 0.18, 0.16, 0.14, 0.12, and 0.10, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.10, in that order. The cation ratio may be 0. Increasing the cation ratio can improve the mechanical properties and chemical durability of the glass. On the other hand, if the cation ratio is too high, the liquidus temperature rises, and the thermal stability of the glass is impaired. From the viewpoint of maintaining the thermal stability and devitrification resistance of the glass, it is preferable that the cation ratio be within the above range.

[0371] In the optical glass according to the third embodiment, Li ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ Al content relative to the total content ３＋ The cation ratio of the content [Al ３＋ / (Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) )] is preferably 5, and more preferably 4, 3, 2, 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6, 0.4, 0.3, 0.2, 0.18, 0.16, 0.14, 0.12, and 0.10, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.10, in that order. The cation ratio may be 0. Increasing the cation ratio can improve the mechanical properties and chemical durability of the glass. On the other hand, if the cation ratio is too high, the liquidus temperature rises, and the thermal stability of the glass is impaired. From the viewpoint of maintaining the thermal stability and devitrification resistance of the glass, it is preferable that the cation ratio be within the above range.

[0372] In the optical glass according to the third embodiment, La ３＋ , Gd３＋ , and Y ３＋ Al content relative to the total content ３＋ The cation ratio of the content [Al ３＋ / (La ３＋ +Gd ３＋ +Y ３＋ ) )] is preferably 2, and more preferably 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6, 0.4, 0.3, 0.2, 0.18, 0.16, 0.14, 0.12, and 0.10 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.05 and 0.10 in that order. The cation ratio may be 0. From the viewpoints of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0373] In the optical glass according to the third embodiment, Si ４＋ and B ３＋ Li relative to the total content of ＋ , Na ＋ , and K ＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ ) / (Si ４＋ +B ３＋ ) )] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.3, 0.25, 0.20, 0.15, 0.1, 0.09, 0.08, 0.07, and 0.06 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, and 0.05 in that order. The cation ratio may even be 0. From the viewpoints of improving the chemical durability, mechanical properties, and thermal stability of the glass and suppressing a decrease in stability upon reheating, and from the viewpoint of obtaining an optical glass with a reduced glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0374] In the optical glass according to the third embodiment, Si ４＋ and B ３＋ Mg relative to the total content ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋The cation ratio of the total content [(Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.40, 0.35, 0.30, 0.28, 0.26, 0.24, 0.22, 0.20, 0.18, 0.16, 0.14, 0.12, 0.10, 0.09, 0.08, 0.07, and 0.06, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.005, 0.010, 0.015, 0.020, 0.025, 0.030, and 0.035, in that order. From the viewpoint of suppressing deterioration in the chemical durability, mechanical properties, and thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0375] In the optical glass according to the third embodiment, Si ４＋ and B ３＋ Li relative to the total content of ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋))] is preferably 0, and more preferably 0.005, 0.010, 0.015, 0.020, 0.025, 0.030, and 0.035 in that order. The upper limit of the cation ratio is preferably 2, and more preferably 1.5, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.40, 0.35, 0.30, 0.28, 0.26, 0.24, 0.22, 0.20, 0.18, 0.16, 0.14, 0.12, 0.10, 0.09, 0.08, 0.07, and 0.06 in that order. From the viewpoint of obtaining an optical glass having desired optical constants, suppressing volatilization of glass components during melting, and reducing the glass transition temperature Tg, it is preferred that the cation ratio be within the above range.

[0376] In the optical glass according to the third embodiment, Si ４＋ and B ３＋ La relative to the total content ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ ) is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, and 1.55 in that order. The upper limit of the cation ratio is preferably 3.00, and more preferably 2.95, 2.90, 2.85, 2.80, 2.75, 2.70, 2.65, 2.60, 2.55, 2.50, 2.45, 2.40, 2.35, 2.30, 2.25, 2.20, 2.15, 2.10, 2.05, 2.00, 1.95, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, and 1.60, in that order. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0377] In the optical glass according to the third embodiment, Si ４＋ and B ３＋Li relative to the total content of ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , La ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ ) is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, and 1.55 in that order. The upper limit of the cation ratio is preferably 4, and more preferably 3.00, 2.95, 2.90, 2.85, 2.80, 2.75, 2.70, 2.65, 2.60, 2.55, 2.50, 2.45, 2.40, 2.35, 2.30, 2.25, 2.20, 2.15, 2.10, 2.05, 2.00, 1.95, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, and 1.60, in that order. From the viewpoint of obtaining an optical glass that is excellent in chemical durability, mechanical properties, and thermal stability while suppressing volatilization of glass components during melting, it is preferable to set the cation ratio within the above range.

[0378] In the optical glass according to the third embodiment, Si ４＋ and B ３＋ Ti relative to the total content of ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ The cation ratio of the total content [(Ti ４＋ +Nb ５＋ +W ６＋ +Bi３＋ ) / (Si ４＋ +B ３＋ The upper limit of the cation ratio is preferably 0.5, and more preferably 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, 0.14, 0.13, 0.12, 0.11, 0.10, 0.09, 0.08, 0.07, 0.06, and 0.05 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.001, 0.002, 0.004, 0.006, 0.008, 0.010, 0.012, 0.014, 0.016, 0.018, 0.020, 0.022, 0.024, 0.026, 0.028, 0.030, 0.032, 0.034, 0.036, and 0.038 in that order. The cation ratio may be 0. From the viewpoint of suppressing a decrease in the refractive index nd at a desired Abbe number vd, it is preferable that the cation ratio be in the above range.

[0379] In the optical glass according to the third embodiment, Si ４＋ and B ３＋ Zr relative to the total content ４＋ and Ta ５＋ The cation ratio of the total content [(Zr ４＋ +Ta ５＋ ) / (Si ４＋ +B ３＋ ) )] is preferably 0.5, and more preferably 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, 0.14, 0.13, 0.12, 0.11, 0.10, 0.09, 0.08, and 0.07 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.002, 0.004, 0.006, 0.008, 0.010, 0.012, 0.014, 0.016, 0.018, 0.020, 0.022, 0.024, 0.026, 0.028, 0.030, 0.032, 0.034, 0.036, 0.038, 0.040, 0.042, 0.044, 0.046, 0.048, 0.050, 0.052, and 0.054, in that order. The cation ratio may be 0. From the viewpoint of maintaining the thermal stability of the glass and from the viewpoint of suppressing a decrease in the refractive index nd at a desired Abbe number νd, it is preferable that the cation ratio be within the above range.

[0380] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Li relative to the total content ＋ , Na ＋ , and K ＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ) )] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, 0.09, 0.08, 0.07, and 0.06 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, and 0.05 in that order. The cation ratio may even be 0. From the viewpoints of improving the chemical durability, mechanical properties, and thermal stability of the glass and suppressing a decrease in stability upon reheating, and from the viewpoint of obtaining an optical glass with a reduced glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0381] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Mg relative to the total content ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋+Bi ３＋ ) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.40, 0.35, 0.30, 0.28, 0.26, 0.24, 0.22, 0.20, 0.18, 0.16, 0.14, 0.12, 0.10, 0.09, 0.08, 0.07, and 0.06 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.005, 0.010, 0.015, 0.020, 0.025, 0.030, and 0.035 in that order. The cation ratio may even be 0. From the viewpoint of suppressing deterioration in the chemical durability, mechanical properties, and thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0382] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Li relative to the total content ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋The lower limit of the cation ratio is preferably 0, and more preferably 0.005, 0.010, 0.015, 0.020, 0.025, 0.030, and 0.035 in that order. The upper limit of the cation ratio is preferably 2, and more preferably 1.5, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.40, 0.35, 0.30, 0.28, 0.26, 0.24, 0.22, 0.20, 0.18, 0.16, 0.14, 0.12, 0.10, 0.09, 0.08, 0.07, and 0.06 in that order. The cation ratio may be 0. From the viewpoint of obtaining an optical glass having desired optical constants, suppressing volatilization of glass components during melting, and lowering the glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0383] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ La relative to the total content ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋) is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, and 1.55 in that order. The upper limit of the cation ratio is preferably 3.00, and more preferably 2.95, 2.90, 2.85, 2.80, 2.75, 2.70, 2.65, 2.60, 2.55, 2.50, 2.45, 2.40, 2.35, 2.30, 2.25, 2.20, 2.15, 2.10, 2.05, 2.00, 1.95, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, and 1.60, in that order. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0384] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ Li relative to the total content ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , Ba ２＋ , La ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ +La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋) is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, and 1.55 in that order. The upper limit of the cation ratio is preferably 4, and more preferably 3.00, 2.95, 2.90, 2.85, 2.80, 2.75, 2.70, 2.65, 2.60, 2.55, 2.50, 2.45, 2.40, 2.35, 2.30, 2.25, 2.20, 2.15, 2.10, 2.05, 2.00, 1.95, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, and 1.60, in that order. From the viewpoint of obtaining an optical glass that is excellent in chemical durability, mechanical properties, and thermal stability while suppressing volatilization of glass components during melting, it is preferable to set the cation ratio within the above range.

[0385] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ Li relative to the total content ＋ , Na ＋ , and K ＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋) )] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, 0.09, 0.08, 0.07, and 0.06 in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, and 0.05 in that order. The cation ratio may even be 0. From the viewpoints of improving the chemical durability, mechanical properties, and thermal stability of the glass and suppressing a decrease in stability upon reheating, and from the viewpoint of obtaining an optical glass with a reduced glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0386] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ Mg relative to the total content ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋) is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.40, 0.35, 0.30, 0.28, 0.26, 0.24, 0.22, 0.20, 0.18, 0.16, 0.14, 0.12, 0.10, 0.09, 0.08, 0.07, and 0.06, in that order. The lower limit of the cation ratio is preferably 0, and more preferably 0.005, 0.010, 0.015, 0.020, 0.025, 0.030, and 0.035, in that order. From the viewpoint of suppressing deterioration in the chemical durability, mechanical properties, and thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0387] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ Li relative to the total content ＋ , Na ＋ , K. ＋ , Mg ２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(Li ＋ +Na ＋ +K ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋))] is preferably 0, and more preferably 0.005, 0.010, 0.015, 0.020, 0.025, 0.030, and 0.035 in that order. The upper limit of the cation ratio is preferably 2, and more preferably 1.5, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.40, 0.35, 0.30, 0.28, 0.26, 0.24, 0.22, 0.20, 0.18, 0.16, 0.14, 0.12, 0.10, 0.09, 0.08, 0.07, and 0.06 in that order. From the viewpoint of obtaining an optical glass having desired optical constants, suppressing volatilization of glass components during melting, and reducing the glass transition temperature Tg, it is preferable that the cation ratio be within the above range.

[0388] In the optical glass according to the third embodiment, Si ４＋ , B ３＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , and Y ３＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ ) / (Si ４＋ +B ３＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋) is preferably 0.01, and more preferably 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, and 1.55 in that order. The upper limit of the cation ratio is preferably 3.00, and more preferably 2.95, 2.90, 2.85, 2.80, 2.75, 2.70, 2.65, 2.60, 2.55, 2.50, 2.45, 2.40, 2.35, 2.30, 2.25, 2.20, 2.15, 2.10, 2.05, 2.00, 1.95, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, and 1.60, in that order. From the viewpoint of increasing the refractive index nd and suppressing a decrease in the thermal stability of the glass, it is preferable that the cation ratio be within the above range.

[0389] In the glass according to the third embodiment, Li ＋ The upper limit of the content of Li is preferably 31.0%, and more preferably 29.5%, 28.0%, 26.5%, 25.0%, 23.5%, 22.0%, 20.5%, 19.0%, 17.5%, 16.0%, 14.5%, 13.0%, 11.5%, 10.0%, 8.5%, 7.0%, 5.5%, 4.0%, 2.5%, and 1.0% in that order. ＋ The lower limit of the content of Li is preferably 0%, and more preferably 0.03%, 0.05%, 0.08%, 0.10%, 0.13%, 0.15%, 0.18%, 0.20%, 0.23%, 0.25%, 0.28%, 0.30%, 0.33%, 0.35%, 0.38%, 0.40%, 0.43%, 0.45%, 0.48%, and 0.50% in that order. ＋ The content of Li may be 0%. ＋ is a component that contributes to lowering the viscosity of the glass. ＋ If the content of Li is too high, the thermal stability of the glass and the stability during reheating may decrease. ＋ If the content of Li is too small, the glass transition temperature Tg may increase. ＋ The content is preferably in the above range.

[0390] In the glass according to the third embodiment, Na ＋ The upper limit of the content of Na is preferably 31.0%, and more preferably 29.5%, 28.0%, 26.5%, 25.0%, 23.5%, 22.0%, 20.5%, 19.0%, 17.5%, 16.0%, 14.5%, 13.0%, 11.5%, 10.0%, 8.5%, 7.0%, 5.5%, 4.0%, 2.5%, and 1.0% in that order. ＋ The lower limit of the content of Na is preferably 0%, and more preferably 0.03%, 0.05%, 0.08%, 0.10%, 0.13%, 0.15%, 0.18%, 0.20%, 0.23%, 0.25%, 0.28%, 0.30%, 0.33%, 0.35%, 0.38%, 0.40%, 0.43%, 0.45%, 0.48%, and 0.50% in that order. ＋ The content of Na may be 0%. ＋ Li ＋ It is a component that contributes to lowering the viscosity of glass, just like Na. ＋ If the content of Na is too high, the thermal stability of the glass and the stability during reheating may decrease. ＋ The content is preferably in the above range.

[0391] In the optical glass according to the third embodiment, K ＋ The upper limit of the content of is preferably 31.0%, and more preferably 29.5%, 28.0%, 26.5%, 25.0%, 23.5%, 22.0%, 20.5%, 19.0%, 17.5%, 16.0%, 14.5%, 13.0%, 11.5%, 10.0%, 8.5%, 7.0%, 5.5%, 4.0%, 2.5%, and 1.0% in that order. ＋ The lower limit of the content of K is preferably 0%, and more preferably 0.03%, 0.05%, 0.08%, 0.10%, 0.13%, 0.15%, 0.18%, 0.20%, 0.23%, 0.25%, 0.28%, 0.30%, 0.33%, 0.35%, 0.38%, 0.40%, 0.43%, 0.45%, 0.48%, and 0.50% in that order. ＋ The content of K may be 0%. ＋ has the function of lowering the liquidus temperature and improving the thermal stability of the glass.＋ If the content of K is too high, the chemical durability, weather resistance, and stability during reheating will decrease. ＋ The content is preferably in the above range.

[0392] In the optical glass according to the third embodiment, Mg ２＋ The upper limit of the content of Mg is preferably 31.0%, and more preferably 29.5%, 28.0%, 26.5%, 25.0%, 23.5%, 22.0%, 20.5%, 19.0%, 17.5%, 16.0%, 14.5%, 13.0%, 11.5%, 10.0%, 8.5%, 7.0%, 5.5%, 4.0%, 2.5%, and 1.0% in that order. ２＋ The lower limit of the Mg content is preferably 0%, and more preferably 0.03%, 0.05%, 0.08%, 0.10%, 0.13%, 0.15%, 0.18%, 0.20%, 0.23%, 0.25%, 0.28%, 0.30%, 0.33%, 0.35%, 0.38%, 0.40%, 0.43%, 0.45%, 0.48%, and 0.50% in that order. ２＋ The content of Mg may be 0%. ２＋ If the content of Mg is too high, the thermal stability and devitrification resistance of the glass may decrease. ２＋ If the content of Mg is too small, the stability of the glass when reheated may decrease. ２＋ The content is preferably in the above range.

[0393] In the optical glass according to the third embodiment, Sr ２＋ The upper limit of the Sr content is preferably 31.0%, and more preferably 29.5%, 28.0%, 26.5%, 25.0%, 23.5%, 22.0%, 20.5%, 19.0%, 17.5%, 16.0%, 14.5%, 13.0%, 11.5%, 10.0%, 8.5%, 7.0%, 5.5%, 4.0%, 2.5%, and 1.0% in that order. ２＋The lower limit of the Sr content is preferably 0%, and more preferably 0.03%, 0.05%, 0.08%, 0.10%, 0.13%, 0.15%, 0.18%, 0.20%, 0.23%, 0.25%, 0.28%, 0.30%, 0.33%, 0.35%, 0.38%, 0.40%, 0.43%, 0.45%, 0.48%, and 0.50% in that order. ２＋ The content of Sr may be 0%. ２＋ is a component that increases the refractive index nd among alkaline earth metals. ２＋ If the content of Sr is too high, the thermal stability and devitrification resistance of the glass may be reduced. ２＋ The content is preferably in the above range.

[0394] In the optical glass according to the third embodiment, Ba ２＋ The upper limit of the content of Ba is preferably 31.0%, and more preferably 29.5%, 28.0%, 26.5%, 25.0%, 23.5%, 22.0%, 20.5%, 19.0%, 17.5%, 16.0%, 14.5%, 13.0%, 11.5%, 10.0%, 8.5%, 7.0%, 5.5%, 4.0%, 2.5%, and 1.0% in that order. ２＋ The lower limit of the content of Ba is preferably 0%, and more preferably 0.03%, 0.05%, 0.08%, 0.10%, 0.13%, 0.15%, 0.18%, 0.20%, 0.23%, 0.25%, 0.28%, 0.30%, 0.33%, 0.35%, 0.38%, 0.40%, 0.43%, 0.45%, 0.48%, and 0.50% in that order. ２＋ The content of Ba may be 0%. ２＋ Among alkaline earth metals, Ba is a component that increases the refractive index nd, and at the same time, when contained in an appropriate amount, it lowers the liquidus temperature and improves the stability of the glass. ２＋ If the content of Ba is too high, the thermal stability and stability during reheating of the glass may be reduced. ２＋ If the content of Ba is too small, the thermal stability of the glass may decrease, and the volatilization of glass components during melting may increase. ２＋ The content is preferably in the above range.

[0395] In the optical glass according to the third embodiment, La ３＋ The lower limit of the content of La is preferably 0%, and more preferably 0.90%, 1.80%, 2.70%, 3.60%, 4.50%, 5.40%, 6.30%, 7.20%, 8.10%, 9.00%, 9.90%, 10.80%, 11.70%, 12.60%, 13.50%, 14.40%, 15.30%, 16.20%, 17.10%, and 18.00% in that order. ３＋ The upper limit of the content of La is preferably 70.0%, and more preferably 68.2%, 66.3%, 64.5%, 62.6%, 60.8%, 58.9%, 57.1%, 55.2%, 53.4%, 51.5%, 49.7%, 47.8%, 46.0%, 44.1%, 42.3%, 40.4%, 38.6%, 36.7%, 34.9%, and 33.0% in that order. ３＋ By introducing a certain amount of La, it is possible to suppress the volatilization of glass components and increase the refractive index nd. ３＋ If the content of La is too high, the thermal stability of the glass may decrease, and the glass may be prone to devitrification during production. ３＋ The content is preferably in the above range.

[0396] In the glass according to the third embodiment, Gd ３＋ The upper limit of the content of Gd is preferably 70.0%, and more preferably 67.2%, 64.4%, 61.6%, 58.8%, 56.0%, 53.2%, 50.4%, 47.6%, 44.8%, 42.0%, 39.2%, 36.4%, 33.6%, 30.8%, 28.0%, 25.2%, 22.4%, 19.6%, 16.8%, and 14.0% in that order. ３＋ The lower limit of the content of Gd is preferably 0%, and more preferably 0.60%, 1.20%, 1.80%, 2.40%, 3.00%, 3.60%, 4.20%, 4.80%, 5.40%, 6.00%, 6.60%, 7.20%, 7.80%, 8.40%, 9.00%, 9.60%, 10.20%, 10.80%, 11.40%, and 12.00% in that order. ３＋ The content of Gd may be 0%. ３＋Is La ３＋ Similarly, by introducing a certain amount of Gd, it is possible to suppress the volatilization of glass components and increase the refractive index nd. ３＋ If the content of Gd is too high, the thermal stability of the glass decreases. ３＋ If the content of Gd is too high, the specific gravity of the glass increases, which is undesirable. In addition, there is a risk of an increase in raw material costs. Therefore, from the viewpoint of suppressing the increase in specific gravity while maintaining good thermal stability of the glass, and from the viewpoint of suppressing the increase in specific gravity, and from the viewpoint of suppressing the increase in the content of Gd, which is a heavy rare earth, it is preferable to use a glass containing Gd as the glass having a high thermal stability. ３＋ From the viewpoint of reducing the content of Gd ３＋ The content is preferably in the above range.

[0397] In the glass according to the third embodiment, Y ３＋ The upper limit of the content of Y is preferably 70.0%, and more preferably 68.7%, 67.3%, 66.0%, 64.6%, 63.3%, 61.9%, 60.6%, 59.2%, 57.9%, 56.5%, 55.2%, 53.8%, 52.5%, 51.1%, 49.8%, 48.4%, 47.1%, 45.7%, 44.4%, and 43.0% in that order. ３＋ The lower limit of the content of Y is preferably 0%, and more preferably 2.05%, 4.10%, 6.15%, 8.20%, 10.25%, 12.30%, 14.35%, 16.40%, 18.45%, 20.50%, 22.55%, 24.60%, 26.65%, 28.70%, 30.75%, 32.80%, 34.85%, 36.90%, 38.95%, and 41.00% in that order. ３＋ The content may be 0%.

[0398] Y ３＋ By introducing a certain amount of Y, it is possible to suppress the volatilization of glass components and increase the refractive index nd. ３＋ If the content of Y is too high, the thermal stability of the glass decreases, and the glass becomes more susceptible to devitrification during manufacturing. ３＋ If the content of Y is too small, the thermal stability of the glass may be reduced. ３＋ The content is preferably in the above range.

[0399] In the optical glass according to the third embodiment, Ti ４＋ The upper limit of the content of Ti is preferably 10.0%, and more preferably 9.0%, 8.0%, 7.0%, 6.0%, 5.0%, 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.3%, 2.0%, 1.7%, 1.4%, 1.1%, 0.9%, 0.7%, 0.5%, 0.4%, and 0.3% in that order. ４＋ The lower limit of the content of Ti is preferably 0%, and may further be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, or 0.15%. ４＋ The content of Ti may be 0%. From the viewpoint of maintaining a desired Abbe number νd and improving anomalous partial dispersion in the visible to near ultraviolet region, ４＋ It is preferable that the content of is within the above range.

[0400] In the optical glass according to the third embodiment, Nb ５＋ The upper limit of the Nb content is preferably 10.0%, and more preferably 9.0%, 8.0%, 7.0%, 6.0%, 5.0%, 4.5%, 4.0%, 3.7%, 3.5%, 3.3%, 3.1%, 2.9%, 2.7%, 2.5%, 2.3%, 2.1%, 1.9%, 1.7%, 1.6%, and 1.5% in that order. ５＋ The lower limit of the Nb content is preferably 0%, and more preferably 0.06%, 0.11%, 0.17%, 0.22%, 0.28%, 0.33%, 0.39%, 0.44%, 0.50%, 0.55%, 0.61%, 0.66%, 0.72%, 0.77%, 0.83%, 0.88%, 0.94%, 0.99%, 1.05%, and 1.10% in that order. ５＋ The content of Nb may be 0%. From the viewpoint of maintaining a desired Abbe number νd and improving anomalous partial dispersion in the visible to near ultraviolet region, ５＋ It is preferable that the content of is within the above range.

[0401] In the optical glass according to the third embodiment, W ６＋The upper limit of the content of W is preferably 10.0%, and more preferably 9.0%, 8.0%, 7.0%, 6.0%, 5.0%, 4.5%, 4.0%, 3.5%, 3.0%, 2.8%, 2.6%, 2.4%, 2.2%, 2.0%, 1.8%, 1.6%, 1.4%, 1.2%, 1.0%, and 0.8% in that order. ６＋ The lower limit of the content of W is preferably 0%, and more preferably 0.02%, 0.04%, 0.06%, 0.08%, 0.10%, 0.12%, 0.14%, 0.16%, 0.18%, 0.20%, 0.22%, 0.24%, 0.26%, 0.28%, 0.30%, 0.32%, 0.34%, 0.36%, 0.38%, and 0.40% in that order. ６＋ The content of W may be 0%. From the viewpoints of increasing the transmittance, reducing the specific gravity, maintaining a desired Abbe number νd, and improving the anomalous partial dispersion in the visible to near ultraviolet region, ６＋ It is preferable that the content of is within the above range.

[0402] In the optical glass according to the third embodiment, Zr ４＋ The upper limit of the content of Zr is preferably 10.0%, and more preferably 9.0%, 8.0%, 7.0%, 6.0%, 5.5%, 5.0%, 4.5%, 4.3%, 4.1%, 4.0%, 3.9%, 3.8%, 3.7%, 3.6%, 3.5%, 3.4%, 3.3%, 3.2%, 3.1%, and 3.0% in that order. ４＋ The lower limit of the content of Zr is preferably 0%, and more preferably 0.13%, 0.25%, 0.38%, 0.50%, 0.63%, 0.75%, 0.88%, 1.00%, 1.13%, 1.25%, 1.38%, 1.50%, 1.63%, 1.75%, 1.88%, 2.00%, 2.13%, 2.25%, 2.38%, and 2.50% in that order. ４＋ The content of Zr may be 0%. ４＋ When contained in an appropriate amount, Zr has the effect of improving chemical durability. ４＋ If the content of Zr is too large, the liquidus temperature LT may increase and the meltability of the glass may decrease. ４＋ It is preferable that the content of is within the above range.

[0403] In the optical glass according to the third embodiment, Sb ions can be added from the viewpoint of suppressing a decrease in transmittance at wavelengths around 360 nm and 375 nm. The upper limit of the Sb ion content is preferably 1.0000 mass%, and more preferably 0.5000 mass%, 0.1000 mass%, 0.0900 mass%, 0.0800 mass%, 0.0700 mass%, 0.0600 mass%, 0.0500 mass%, 0.0400 mass%, 0.0300 mass%, 0.0250 mass%, 0.0200 mass%, 0.0150 mass%, 0.0100 mass%, 0.0090 mass%, 0.0080 mass%, 0.0070 mass%, 0.0060 mass%, and 0.0050 mass%, in that order. The lower limit of the Sb ion content is preferably 0.0001 mass%, in terms of exclusive proportion, and is more preferably 0.0005 mass%, 0.0008 mass%, 0.0010 mass%, 0.0012 mass%, 0.0014 mass%, 0.0016 mass%, 0.0018 mass%, 0.0020 mass%, 0.0022 mass%, 0.0024 mass%, 0.0026 mass%, 0.0028 mass%, 0.0030 mass%, 0.0032 mass%, 0.0034 mass%, 0.0036 mass%, and 0.0038 mass%, in that order.

[0404] The Sb ions are, for example, Sb ２ O ３ and Sb ２ S ３Sb ions can be added to glass by the method described above. Sb ions include trivalent, pentavalent, and all other valence Sb ions. The content of Sb ions is an exclusive percentage. That is, the content of Sb ions is expressed in mass % when the total content of all glass components other than Sb ions is 100 mass %. From the viewpoint of suppressing a decrease in transmittance at wavelengths around 360 nm and 375 nm, it is preferable to set the content of Sb ions within the above range. If the content of Sb ions is too high, Pt from the crucible is easily introduced into the glass, forming Pt colloids and causing Tyndall-shaped clouding in the glass, which may result in a decrease in light transmittance regardless of the wavelength band. Furthermore, the light absorption of Sb ions themselves may decrease the light transmittance at specific wavelengths. If Sb ions are not contained or the content of Sb ions is too low, the absorption of Pt ions at wavelengths around 360 nm becomes apparent, which may result in a decrease in light transmittance at specific wavelengths in the wavelength range extending to visible light.

[0405] The optical glass according to the third embodiment contains O as an anion component. ２－ Includes. ２－ The upper limit of the content of is preferably 90 anion%, and more preferably 89 anion%, 88 anion%, 87 anion%, 86 anion%, 85 anion%, 84 anion%, 83 anion%, 82 anion%, 81 anion%, 80 anion%, 79 anion%, 78 anion%, 77 anion%, 76 anion%, 75 anion%, 74 anion%, and 73 anion% in that order. ２－ The lower limit of the content is preferably 10 anion%, and more preferably 12 anion%, 14 anion%, 16 anion%, 18 anion%, 20 anion%, 22 anion%, 24 anion%, 26 anion%, 28 anion%, 30 anion%, 32 anion%, 34 anion%, 36 anion%, 38 anion%, 40 anion%, 42 anion%, 44 anion%, 46 anion%, 48 anion%, 50 anion%, and 52 anion%, in that order.

[0406] In the optical glass according to the third embodiment, the contents and ratios of glass components other than those mentioned above can be the same as those in the first embodiment.

[0407] (Glass Properties) <Abbe Number vd> In the optical glass according to the third embodiment, the upper limit of the Abbe number vd is preferably 70, and can also be 68, 66, 64, 62, 60, 58, 56, 54, 52, or 50. The lower limit of the Abbe number vd is preferably 37.5, and can also be 39, 40, 41, 42, 43, 44, 45, 46, 47, or 48.

[0408] The Abbe number νd is calculated in the same manner as in the first embodiment. The Abbe number νd can be set to a desired value by appropriately adjusting the content of each glass component. The component that relatively lowers the Abbe number νd, i.e., the high dispersion component, is Nb ５＋ , Ti ４＋ , Zr ４＋ , W ６＋ , Bi ３＋ , Ta ５＋ On the other hand, the component that relatively increases the Abbe number νd, that is, the low dispersion component, is F － , Si ４＋ , B ３＋ , Li ＋ , Na ＋ , K. ＋ , La ３＋ , Ba ２＋ , Ca ２＋ , Sr ２＋ etc.

[0409] <Refractive Index nd> In the optical glass according to the third embodiment, the upper limit of the refractive index nd is preferably 1.92, and can be 1.87, 1.82, 1.80, 1.79, or 1.78. The lower limit of the refractive index nd is preferably 1.60, and can be 1.65, 1.70, 1.75, 1.76, or 1.77.

[0410] The refractive index nd can be adjusted to a desired value by appropriately adjusting the content of each glass component. The component that functions to relatively increase the refractive index nd (the component that increases the refractive index) is Nb. ５＋ , Ti ４＋ , W ６＋ , Bi ３＋ , Zr ４＋ , Ta ５＋ , La ３＋ , Gd３＋ , Y ３＋ On the other hand, the component that acts to relatively lower the refractive index nd (refractive index lowering component) is Si ４＋ , B ３＋ , Li ＋ , Na ＋ , K. ＋ etc.

[0411] In the optical glass according to the third embodiment, the refractive index nd and the Abbe number vd preferably satisfy the following formula [1-1]: nd ≧ (-0.0081 × vd + 2.1181) ... [1-1] The refractive index nd and the Abbe number vd more preferably satisfy the following formula [1-2], and even more preferably satisfy the following formulas in the order [1-3], [1-4], and [1-5]: nd ≧ (-0.0081 × vd + 2.1231) ... [1-2] nd ≧ (-0.0081 × vd + 2.1281) ... [1-3] nd ≧ (-0.0081 × vd + 2.1331) ... [1-4] nd ≧ (-0.0081 × vd + 2.1381) ... [1-5]

[0412] <Partial Dispersion Ratio Pg,F> In the optical glass according to the third embodiment, the lower limit of the partial dispersion ratio Pg,F in the visible short wavelength region is preferably 0.5200, and more preferably 0.5250, 0.5300, 0.5350, 0.5400, 0.5450, 0.5460, 0.5470, 0.5480, 0.5490, 0.5500, 0.5510, 0.5520, 0.5530, 0.5540, 0.5550, 0.5560, and 0.5570 in that order. By setting the partial dispersion ratio Pg,F within the above range, an optical glass suitable for correcting high-order chromatic aberrations can be obtained. On the other hand, the upper limit of the partial dispersion ratio Pg,F is not particularly limited, but is usually 0.5700, and preferably 0.5650.

[0413] In the optical glass according to the third embodiment, the partial dispersion ratio Pg,F preferably satisfies the following formula [2-1]: Pg,F≧0.6200−0.0014×νd ...[2-1] It is more preferable that the partial dispersion ratio Pg,F satisfies the following formula [2-2], and even more preferable that the following formulas [2-3], [2-4], [2-5], and [2-6] be satisfied in this order. Pg,F≧0.6220-0.0014×νd…[2-2] Pg,F≧0.6240-0.0014×νd…[2-3] Pg,F≧0.6260-0.0014×νd…[2-4] Pg,F≧0.6270-0.0014×νd…[2-5] Pg,F≧0.6280-0.0014×νd…[2-6]

[0414] In the optical element made of the optical glass according to the third embodiment, from the viewpoint of correcting chromatic aberration well over a wide wavelength range, it is preferable that the partial dispersion ratio Pg,F satisfy the above formula.

[0415] In the optical glass according to the third embodiment, the upper limit of ΔPg,F is not particularly limited, but is preferably 0.0500, and further preferably 0.0400, 0.0300, 0.0200, 0.0150, 0.0140, 0.0130, 0.0120, 0.0110, or 0.0100. On the other hand, the lower limit of ΔPg,F is preferably -0.0100, and further preferably -0.0090, -0.0080, -0.0070, -0.0060, -0.0050, -0.0040, -0.0030, -0.0020, -0.0010, or 0.0000, in that order. By setting ΔPg,F within the above range, an optical glass suitable for correcting high-order chromatic aberrations can be obtained.

[0416] The partial dispersion ratios Pg,F and ΔPg,F are calculated in the same manner as in the first embodiment.

[0417] <Specific Gravity of Glass> The specific gravity of the optical glass according to the third embodiment is preferably 6.0 or less, and more preferably 5.9 or less, 5.8 or less, 5.7 or less, 5.6 or less, 5.5 or less, and 5.4 or less in that order. Components that relatively increase the specific gravity include Ba, ２＋ , La ３＋ , Zr ４＋ , Nb ５＋, Ta ５＋ On the other hand, the components that relatively lower the specific gravity are Si ４＋ , B ３＋ , Li ＋ , Na ＋ , Mg ２＋ The specific gravity can be controlled by appropriately adjusting the contents of these components.

[0418] <Liquidus Temperature LT> The upper limit of the liquidus temperature LT of the optical glass according to the third embodiment is preferably 1200°C, and more preferably 1150°C, 1140°C, 1130°C, 1120°C, 1110°C, 1100°C, 1090°C, 1080°C, 1070°C, 1060°C, 1050°C, 1040°C, 1030°C, 1020°C, 1010°C, 1000°C, 990°C, 980°C, 970°C, 960°C, 950°C, 940°C, 930°C, 920°C, 910°C, and 900°C, in that order. By setting the liquidus temperature within the above range, the melting and forming temperatures of the glass can be lowered, and as a result, corrosion of glass melting equipment (e.g., crucibles, molten glass stirring equipment, etc.) during the melting process and the occurrence of striae due to volatilization of the glass components themselves can be reduced. The lower limit of the liquidus temperature LT is not particularly limited. The liquidus temperature LT is determined by the balance of the contents of all the glass components. Among them, the liquidus temperature LT is affected by the content of Si. ４＋ , B ３＋ , Li ＋ , Na ＋ , K. ＋ The influence of the content of Zr is large. ４＋ , Al ３＋ The liquidus temperature increases when the content of the elements such as tungsten, tungsten oxide, and tungsten fluoride is large. The liquidus temperature is measured in the same manner as in the first embodiment.

[0419] <Glass Transition Temperature Tg> The upper limit of the glass transition temperature Tg of the optical glass according to the third embodiment is preferably 625°C, and more preferably 623°C, 621°C, 619°C, 617°C, 615°C, 613°C, 611°C, 609°C, and 607°C in this order. The lower limit of the glass transition temperature Tg is preferably 350°C, and more preferably 370°C, 390°C, 410°C, 430°C, 450°C, 470°C, 490°C, 510°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, and 590°C in this order. From the viewpoint of improving the yield during precision press molding, it is preferable to set the glass transition temperature Tg within the above range. On the other hand, if the glass transition temperature Tg is too high, precision press molding may not be possible. Components that relatively lower the glass transition temperature Tg include Li, ＋ , Na ＋ , K. ＋ , F － The component that relatively increases the glass transition temperature Tg is La ３＋ , Zr ４＋ , Nb ５＋ The glass transition temperature Tg can be controlled by appropriately adjusting the contents of these components.

[0420] <Light Transmittance of Glass> The light transmittance of the optical glass according to the third embodiment can be evaluated by the coloring degrees λ80, λ70, and λ5. The spectral transmittance of a glass sample having a thickness of 10.0 mm±0.1 mm was measured in the wavelength range of 200 to 700 nm, and the wavelength at which the external transmittance was 80% was defined as λ80, the wavelength at which the external transmittance was 70%, and the wavelength at which the external transmittance was 5% was defined as λ70, the wavelength at which the external transmittance was 70%, and the wavelength at which the external transmittance was 5%.

[0421] The λ80 of the optical glass according to the third embodiment is preferably 450 nm or less, more preferably 400 nm or less, and even more preferably 380 nm or less. The λ70 is preferably 430 nm or less, more preferably 380 nm or less, and even more preferably 360 nm or less. The λ5 is preferably 380 nm or less, more preferably 330 nm or less, and even more preferably 320 nm or less.

[0422] <Chemical Durability Acid Resistance Da> In the optical glass according to the third embodiment, the acid resistance Da is preferably at least grade 5, and more preferably at least grade 4, at least grade 3, at least grade 2, and at least grade 1. The acid resistance Da is evaluated in the same manner as in the first embodiment.

[0423] <Chemical Durability: Water Resistance Dw> In the optical glass according to the third embodiment, the water resistance Dw is preferably at least grade 5, and more preferably at least grade 4, at least grade 3, at least grade 2, and at least grade 1. The water resistance Dw is evaluated in the same manner as in the first embodiment.

[0424] <Mechanical Properties: Knoop Hardness Hk> The lower limit of the Knoop hardness Hk of the optical glass according to the third embodiment is preferably 400, and more preferably 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, and 550, in that order. It is preferable to keep the Knoop hardness Hk within the above range from the viewpoint of preventing damage when handling the glass and when manufacturing lenses and the like by machining the glass, such as grinding, polishing, and cutting. The upper limit of the Knoop hardness Hk is not particularly limited, but is usually 750, and preferably 600.

[0425] The Knoop hardness Hk is ３＋ , Gd ３＋ , Y ３＋ , Si ４＋ , Zr ４＋ , Al ３＋ The content can be increased by adjusting the content.

[0426] <ΔT360> In the optical glass according to the third embodiment, when the thickness is 10.0 mm±0.1 mm, the upper limit of the difference (ΔT360) between the external transmittance at a wavelength of 700 nm and the external transmittance at a wavelength of 360 nm is preferably 31.0%, and more preferably 30.0%, 28.0%, 26.0%, 24.0%, 22.0%, 20.0%, 18.0%, 16.0%, 15.0%, 14.0%, 13.0%, 12.0%, 11.0%, 10.0%, 9.0%, 8.0%, 7.0%, and 6.0%, in that order. The lower limit of ΔT360 is not particularly limited, but is generally 2 to 30%. ΔT360 can be adjusted by introducing Sb ions. Furthermore, from the viewpoint of maintaining low dispersion, it is not preferable to use high-dispersion components such as Ti, Nb, W, and Bi, but when these are introduced for the purpose of increasing refraction or anomalous dispersion, ΔT360 may increase. By keeping ΔT360 within the above range, it is possible to suppress a decrease in transmittance at a wavelength in the vicinity of 360 nm.

[0427] <ΔT375> In the optical glass according to the third embodiment, when the thickness is 10.0 mm±0.1 mm, the upper limit of the difference (ΔT375) between the external transmittance at a wavelength of 700 nm and the external transmittance at a wavelength of 375 nm is preferably 15.0%, and more preferably 13.0%, 11.0%, 10.0%, 9.0%, 8.0%, 7.5%, 7.0%, 6.8%, 6.7%, 6.6%, 6.5%, 6.4%, 6.3%, 6.2%, 6.1%, and 6.0%, in that order. The lower limit of ΔT375 is not particularly limited, but is generally 2 to 15%. ΔT375 can be adjusted by introducing Sb ions. Furthermore, from the viewpoint of maintaining low dispersion, it is not preferable to use high-dispersion components such as Ti, Nb, W, and Bi, but when these are introduced for the purpose of increasing refraction or anomalous dispersion, ΔT375 may increase. By keeping ΔT375 within the above range, it is possible to suppress a decrease in transmittance at a wavelength in the vicinity of 375 nm.

[0428] The external transmittance is defined as the percentage of the transmitted light intensity relative to the incident light intensity when light is incident in the thickness direction of a glass sample [transmitted light intensity / incident light intensity × 100]. The external transmittance also includes the reflection loss of light rays on the sample surface.

[0429] The manufacture of the optical glass, the manufacture of the press-molding glass material, the manufacture of the optical element blank, and the manufacture of the optical element according to the third embodiment can be the same as in the first embodiment.

[0430] Fourth Embodiment The optical glass according to the fourth embodiment is ３＋ The content of La is more than 0 cation % and less than 50.00 cation %; ３＋ The content of Zn is more than 0 cation % and not more than 70 cation %. ２＋ The content of F is 6.5 cation % or less, － The content of La is 10% or more of anion, ３＋ , Gd ３＋ , and Y ３＋ The total content [La ３＋ +Gd ３＋ +Y ３＋ ] is 30 cation % or more, Ti ４＋ , Nb ５＋ , W ６＋ , and Bi ３＋ The total content [Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ ] is less than 2.0 cation %, and Si ４＋ and B ３＋ Si content relative to the total content ４＋ The cation ratio of the content [Si ４＋ / (Si ４＋ +B ３＋ ) )] is 0.77 or less, and Si ４＋ , B ３＋ , P ５＋ , Ti ４＋ , Nb ５＋ , W ６＋ , Bi ３＋ , Zr ４＋ , and Ta ５＋ La relative to the total content ３＋ , Gd ３＋ , Y ３＋ , Li ＋ , Na ＋ , K. ＋ , Rb ＋ , Cs ＋ , Mg２＋ , Ca ２＋ , Sr ２＋ , and Ba ２＋ The cation ratio of the total content [(La ３＋ +Gd ３＋ +Y ３＋ +Li ＋ +Na ＋ +K ＋ +Rb ＋ +Cs ＋ + Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ ) / (Si ４＋ +B ３＋ +P ５＋ +Ti ４＋ +Nb ５＋ +W ６＋ +Bi ３＋ + Zr ４＋ +Ta ５＋ ) is 0.84 or more, the content of Sb ions is 1.0 mass ppm or more in terms of external proportion, and when the thickness is 10.0 mm±0.1 mm, the difference between the external transmittance at a wavelength of 700 nm and the external transmittance at a wavelength of 360 nm is 10% or less.

[0431] In the optical glass according to the fourth embodiment, B ３＋ The content of is more than 0% and less than 50.00%. ３＋ The lower limit of the content of B is preferably 1.00%, and more preferably 2.00%, 3.00%, 4.00%, 5.00%, 6.00%, 7.00%, 8.00%, 9.00%, 10.00%, 11.00%, 12.00%, 13.00%, 14.00%, 15.00%, 16.00%, 17.00%, 18.00%, 19.00%, and 20.00% in that order. ３＋ The upper limit of the content is preferably 45.00%, and more preferably 44.00%, 43.00%, 42.00%, 41.00%, 40.00%, 39.00%, 38.00%, 37.00%, 36.00%, 35.00%, 34.00%, 33.00%, 32.00%, 31.00%, 30.00%, 29.00%, 28.00%, 27.00%, 26.00%, 25.00%, and 24.00% in that order.

[0432] B ３＋ is a glass network forming component. ３＋ By setting the content of B in the above range, chemical durability can be improved. ３＋ If the content of B is too low, the thermal stability and mechanical properties of the glass may be reduced. ３＋ If the content is too high, the volatilization of glass components may increase, and the thermal stability and chemical durability of the glass may decrease.

[0433] In the optical glass according to the fourth embodiment, La ３＋ The content of La is more than 0% and not more than 70%. ３＋ The lower limit of the content of La is preferably 0.90%, and more preferably 1.80%, 2.70%, 3.60%, 4.50%, 5.40%, 6.30%, 7.20%, 8.10%, 9.00%, 9.90%, 10.80%, 11.70%, 12.60%, 13.50%, 14.40%, 15.30%, 16.20%, 17.10%, and 18.00% in that order. ３＋ The upper limit of the content of La is preferably 65%, and more preferably 60%, 55%, 50%, 48%, 46%, 44%, 42%, 40%, 38%, 36%, 34%, 32%, 30%, 28%, 26%, and 24% in that order. ３＋ By setting the content of La in the above range, it is possible to suppress the volatilization of glass components and increase the refractive index nd. ３＋ If the content is too high, the thermal stability of the glass may decrease, and the glass may become more susceptible to devitrification during production.

[0434] In the optical glass according to the fourth embodiment, Zn ２＋ The content of Zn is 6.5% or less. ２＋ The upper limit of the content of Zn is preferably 6.0%, and more preferably 5.5%, 5.0%, 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, and 1.5% in that order. ２＋The lower limit of the content of Zn is preferably 0%, and more preferably 0.03%, 0.05%, 0.08%, 0.10%, 0.13%, 0.15%, 0.18%, 0.20%, 0.23%, 0.25%, 0.28%, 0.30%, 0.33%, 0.35%, 0.38%, 0.40%, 0.43%, 0.45%, 0.48%, and 0.50% in that order. ２＋ The content may be 0%.

[0435] Zn ２＋ is a glass component that, when incorporated, serves to lower the glass transition temperature Tg. ２＋ By setting the content of Zn in the above range, an optical glass with an improved glass transition temperature Tg can be obtained. ２＋ If the content is too high, the specific gravity may increase, the thermal stability and chemical durability of the glass may decrease, and the Abbe number may increase, making it impossible to obtain the desired high refractive index characteristics.

[0436] The optical glass according to the fourth embodiment contains F as an anion component. － Includes: F － The content of F is 10% or more. － The lower limit of the content of is preferably 12 anion%, and more preferably 14 anion%, 16 anion%, 18 anion%, 20 anion%, 22 anion%, 24 anion%, 26 anion%, 28 anion%, 30 anion%, 32 anion%, 34 anion%, 35 anion%, 36 anion%, 37 anion%, 38 anion%, 39 anion%, 40 anion%, 41 anion%, 42 anion%, 43 anion%, 44 anion%, 45 anion%, and 46 anion% in that order. － The upper limit of the content of is preferably 90 anion%, and more preferably in the order of 85 anion%, 80 anion%, 75 anion%, 70 anion%, 68 anion%, 66 anion%, 64 anion%, 62 anion%, 60 anion%, 59 anion%, 58 anion%, 57 anion%, 56 anion%, 55 anion%, 54 anion%, 53 anion%, 52 anion%, 51 anion%, 50 anion%, and 49 anion%. －By setting the content of F within the above range, an optical glass can be obt...

Claims

1. Si 4+ The content of which exceeds 0 cation% and is 30 cation% or less, B 3+ The content of which exceeds 0 cation% and is less than 50.00 cation%, F - The content of which is 20 anion % or more, Ca 2+ The content of which is 25 cation% or less, Zn 2+ The content of which is 13 cation% or less, Ge 4+ has a content of 4.5 cation % or less, The content of Mg2+ is 13 cation % or less, The content of Yb3+ is 6 cation % or less, La 3+ , Gd 3+ , and Y 3+ total content [La 3+ + Gd 3+ + Y 3+ is 30 cation % or more, Mg 2+ , Ca 2+ , Sr 2+ , and Ba 2+ is at least 3.5 cation % in total content [[Mg 2+ + Ca 2+ + Sr 2+ + Ba 2+ , and Li + 、Na + 、K + 、Rb + 、Cs + 、Mg 2+ 、Ca 2+ 、Sr 2+ 、and Ba 2+ total content of [Li + + Na + + K + + Rb + + Cs + + Mg 2+ + Ca 2+ + Sr 2+ + Ba 2+ is 3.5 cation % or more, Si 4+ and B 3+ The cation ratio [Si 4+ / (Si 4+ + B 4+ + B 3+ ) of the content of Si with respect to the total content of Si and B is 0.020 or more, S 4+ , B 3+ , P 5+ , Ti 4+ , Nb 5+ , W 6+ , Bi 3+ , Zr 4+ , and Ta 5+ La relative to the total content 3+ , Gd 3+ , Y 3+ , Li + , Na + , K + , Rb + , Cs + , Mg 2+ , Ca 2+ , Sr 2+ , and Ba 2+ The cationic ratio of the total content [(La 3+ +Gd 3+ +Y 3+ + Li + +Na + +K + + Rb + +Cs + + Mg 2+ +Ca 2+ + Sr 2+ +Ba 2+ ) / (Si 4+ +B 3+ +P 5+ + Ti 4+ +Nb 5+ +W 6+ +Bi 3+ + Zr 4+ +Ta 5+ ) is 0.83 or more; Optical glass.

2. Si 4+ The content thereof exceeds 0 cation % and is 30 cation % or less, B 3+ The content of which exceeds 0 cation % and is less than 50.00 cation %. Al 3+ The content of which is 13 cation% or less, Ca 2+ The content of which is 25 cation% or less, The Zn content 2+ is 6 cation % or less, Ge 4+ The content of which is 4.5 cation % or less, F - has a content of 20 anion % or more, The content of Mg2+ is 13.0 cation % or less, The content of Yb3+ is 6 cation % or less, La 3+ , Gd 3+ , and Y 3+ total content [La 3+ + Gd 3+ + Y 3+ is 30 cation% or more, Si 4+ and B 3+ The cation ratio of the content of Si 4+ to the total content of 4+ [Si 4+ / (Si 3+ + B)] is 0.070 or more, S 4+ , B 3+ , P 5+ , Ti 4+ , Nb 5+ , W 6+ , Bi 3+ , Zr 4+ , and Ta 5+ La relative to the total content 3+ , Gd 3+ , Y 3+ , Li + , Na + , K + , Rb + , Cs + , Mg 2+ , Ca 2+ , Sr 2+ , and Ba 2+ The cationic ratio of the total content [(La 3+ +Gd 3+ +Y 3+ + Li + +Na + +K + + Rb + +Cs + + Mg 2+ +Ca 2+ + Sr 2+ +Ba 2+ ) / (Si 4+ +B 3+ +P 5+ + Ti 4+ +Nb 5+ +W 6+ +Bi 3+ + Zr 4+ +Ta 5+ ) is 0.84 or more; Optical glass.

3. The optical glass according to Claim 1, satisfying any one or more of the following. The cation ratio of the content of Ba2+ to the total content of Mg2+, Ca2+, Sr2+, and Ba2+ [Ba2+ / (Mg2+ + Ca2+ + Sr2+ + Ba2+)] is 0.1 to 1. The cation ratio of the content of Ba2+ to the total content of Mg2+, Ca2+, Sr2+, Ba2+, and Zn2+ [Ba2+ / (Mg2+ + Ca2+ + Sr2+ + Ba2+ + Zn2+)] is 0.10 to 1.

4. The optical glass according to Claim 1, satisfying any one or more of the following. The total content of Si4+ and B3+ [Si4+ + B3+] is 10 to 70 cation %. The total content of Si4+, B3+, and P5+ [Si4+ + B3+ + P5+] is 10 to 70 cation %. The cation ratio of the content of Si4+ to the total content of Si4+, B3+, and P5+ [Si4+ / (Si4+ + B3+ + P5+)] is 0.020 to 0.

80. The cation ratio of the content of B3+ to the total content of Si4+, B3+, and P5+ [B3+ / (Si4+ + B3+ + P5+)] is 0.20 to 0.

980. The cation ratio of the content of P5+ to the total content of Si4+, B3+, and P5+ [P5+ / (Si4+ + B3+ + P5+)] is 0 to 0.

50. The cation ratio of the content of Y3+ to the total content of La3+, Gd3+, and Y3+ [Y3+ / (La3+ + Gd3+ + Y3+)] is 0 to 0.

95. The cation ratio of the content of Al3+ to the total content of Si4+ and B3+ [Al3+ / (Si4+ + B3+)] is 0 to 0.

5. The cation ratio of the content of Al3+ to the total content of Li+, Na+, K+, Mg2+, Ca2+, Sr2+, and Ba2+ [Al3+ / (Li+ + Na+ + K+ + Mg2+ + Ca2+ + Sr2+ + Ba2+)] is 0 to 5. The cation ratio of the content of Al3+ to the total content of La3+, Gd3+, and Y3+ [Al3+ / (La3+ + Gd3+ + Y3+)] is 0 to 2. The cation ratio of the total content of La3+, Gd3+, and Y3+ to the total content of Si4+ and B3+ [(La3+ + Gd3+ + Y3+) / (Si4+ + B3+)] is 0.01 to 3. The cation ratio of the total content of Li+, Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+, La3+, Gd3+, and Y3+ to the total content of Si4+ and B3+ [(Li+ + Na+ + K+ + Mg2+ + Ca2+ + Sr2+ + Ba2+ + La3+ + Gd3+ + Y3+) / (Si4+ + B3+)] is 0.01 to 4. The cation ratio of the total content of La3+, Gd3+, and Y3+ to the total content of Si4+, B3+, Ti4+, Nb5+, W6+, and Bi3+ [(La3+ + Gd3+ + Y3+) / (Si4+ + B3+ + Ti4+ + Nb5+ + W6+ + Bi3+)] is 0.01 to 3. The cation ratio of the total content of La3+, Gd3+, and Y3+ to the total content of Si4+, B3+, Ti4+, Nb5+, W6+, Bi3+, Zr4+ and Ta5+ [(La3+ + Gd3+ + Y3+) / (Si4+ + B3+ + Ti4+ + Nb5+ + W6+ + Bi3+ + Zr4+ + Ta5+)] is 0.01 to 3. The cation ratio of the content of Zr4+ to the total content of Ti4+, Nb5+, Bi3+, W6+, Zr4+, and Ta5+ [Zr4+ / (Ti4+ + Nb5+ + Bi3+ + W6+ + Zr4+ + Ta5+)] is 0 to 0.

95.

5. The optical glass according to Claim 1, satisfying any one or more of the following. The content of P5+ is 0 to 30 cation %. The content of Al3+ is 0 to 30 cation %. The content of Li+ is 0 to 40 cation %. The content of Na+ is 0 to 40 cation %. The content of K+ is 0 to 40 cation %. The content of Rb+ is 0 to 40 cation %. The content of Cs+ is 0 to 40 cation %. The content of Mg2+ is 0 to 10 cation %. The content of Sr2+ is 0 to 40 cation %. The content of Ba2+ is 0 to 40 cation %. The content of La3+ is 5 to 50 cation %. The content of Gd3+ is 50 cation % or less. The content of Y3+ is 0 to 50 cation %. The content of Yb3+ is 3 cation % or less. The content of Ti4+ is 0 to 20 cation %. The content of Nb5+ is 0 to 20 cation %. The content of W6+ is 0 to 20 cation %. The content of Bi3+ is 0 to 20 cation %. The content of Ta5+ is 0 to 10 cation %. The content of Zr4+ is 0 to 10 cation %. The content of Sc3+ is 0 to 2 cation %. The content of Hf4+ is 0 to 2 cation %. The content of Lu3+ is 0 to 2 cation %.

6. The optical glass according to Claim 1, wherein the total content of Si4+, B3+, Ca2+, Zn2+, P5+, Al3+, Li+, Na+, K+, Rb+, Cs+, Mg2+, Sr2+, Ba2+, La3+, Gd3+, Y3+, Ti4+, Nb5+, W6+, Bi3+, Ta5+, and Zr4+ is 95 cation % or more.

7. The optical glass according to Claim 1, satisfying any one or more of the following. The content of O2- is 10 to 90 anion %. The content of Cl- is less than 5 anion %. The total content of Br− and I− is less than 5 anion %. The content of each of Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, and V is less than 100 ppm by mass. The content of each of Ga2O3, TeO2, and TbO2 is 0 to 0.1% by mass.

8. The optical glass according to Claim 1, satisfying any one or more of the following. The Abbe number νd is 37.5 to 78. The refractive index nd is 1.58 to 1.

78. The refractive index nd and the Abbe number νd satisfy the following formula [1-1]. nd ≧ (−0.0081 × νd + 2.1181) ··· [1-1] The partial dispersion ratio Pg,F satisfies the following formula [2-1]. Pg,F ≧ 0.6200 − 0.0014 × νd … [2-1] ΔPg,F is −0.0100 to 0.0500. The liquidus temperature LT is 1200°C or lower. The glass transition temperature Tg is 350 to 625°C. The acid resistance Da is Grade 5 or higher. The water resistance Dw is Grade 5 or higher. The Knoop hardness Hk is 400 to 750.

9. The optical glass according to Claim 2, satisfying any one or more of the following. The cation ratio [Ba2+ / (Mg2+ + Ca2+ + Sr2+ + Ba2+)] of the content of Ba2+ to the total content of Mg2+, Ca2+, Sr2+, and Ba2+ is 0.1 to 1. The cation ratio [Ba2+ / (Mg2+ + Ca2+ + Sr2+ + Ba2+ + Zn2+)] of the content of Ba2+ to the total content of Mg2+, Ca2+, Sr2+, Ba2+, and Zn2+ is 0.10 to 1.

10. The optical glass according to Claim 2, satisfying any one or more of the following. The total content of Si4+ and B3+ [Si4+ + B3+] is 10 to 70 cation %. The total content of Si4+, B3+, and P5+ [Si4+ + B3+ + P5+] is 10 to 70 cation %. The cation ratio [Si4+ / (Si4+ + B3+ + P5+)] of the content of Si4+ to the total content of Si4+, B3+, and P5+ is 0.07 to 0.

99. The cation ratio of the content of B3+ to the total content of Si4+, B3+, and P5+ [B3+ / (Si4+ + B3+ + P5+)] is 0.01 to 0.

93. The cation ratio of the content of P5+ to the total content of Si4+, B3+, and P5+ [P5+ / (Si4+ + B3+ + P5+)] is 0 to 0.

50. The cation ratio of the content of Y3+ to the total content of La3+, Gd3+, and Y3+ [Y3+ / (La3+ + Gd3+ + Y3+)] is 0 to 0.

95. The cation ratio of the content of Al3+ to the total content of Si4+ and B3+ [Al3+ / (Si4+ + B3+)] is 0 to 0.

5. The cation ratio of the content of Al3+ to the total content of Li+, Na+, K+, Mg2+, Ca2+, Sr2+, and Ba2+ [Al3+ / (Li+ + Na+ + K+ + Mg2+ + Ca2+ + Sr2+ + Ba2+)] is 0 to 5. The cation ratio of the content of Al3+ to the total content of La3+, Gd3+, and Y3+ [Al3+ / (La3+ + Gd3+ + Y3+)] is 0 to 2. The cation ratio of the total content of La3+, Gd3+, and Y3+ to the total content of Si4+ and B3+ [(La3+ + Gd3+ + Y3+) / (Si4+ + B3+)] is 0.01 to 3.

00. The cation ratio of the total content of Li+, Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+, La3+, Gd3+, and Y3+ to the total content of Si4+ and B3+ [(Li+ + Na+ + K+ + Mg2+ + Ca2+ + Sr2+ + Ba2+ + La3+ + Gd3+ + Y3+) / (Si4+ + B3+)] is 0.01 to 4. The cation ratio [(La³⁺ + Gd³⁺ + Y³⁺) / (Si⁴⁺ + B³⁺ + Ti⁴⁺ + Nb⁵⁺ + W⁶⁺ + Bi³⁺)] of the total content of La³⁺, Gd³⁺, and Y³⁺ to the total content of Si⁴⁺, B³⁺, Ti⁴⁺, Nb⁵⁺, W⁶⁺, and Bi³⁺ is 0.01 to 3.

00. The cation ratio [(La³⁺ + Gd³⁺ + Y³⁺) / (Si⁴⁺ + B³⁺ + Ti⁴⁺ + Nb⁵⁺ + W⁶⁺ + Bi³⁺ + Zr⁴⁺ + Ta⁵⁺)] of the total content of La³⁺, Gd³⁺, and Y³⁺ to the total content of Si⁴⁺, B³⁺, Ti⁴⁺, Nb⁵⁺, W⁶⁺, Bi³⁺, Zr⁴⁺ and Ta⁵⁺ is 0.01 to 3.

00. The cation ratio [Zr⁴⁺ / (Ti⁴⁺ + Nb⁵⁺ + Bi³⁺ + W⁶⁺ + Zr⁴⁺ + Ta⁵⁺)] of the content of Zr⁴⁺ to the total content of Ti⁴⁺, Nb⁵⁺, Bi³⁺, W⁶⁺, Zr⁴⁺, and Ta⁵⁺ is 0 to 0.

95.

11. The optical glass according to Claim 2, satisfying any one or more of the following. The content of P⁵⁺ is 0 to 30 cation %. The content of Li⁺ is 0 to 31.0 cation %. The content of Na⁺ is 0 to 31.0 cation %. The content of K⁺ is 0 to 31.0 cation %. The content of Rb⁺ is 0 to 40 cation %. The content of Cs⁺ is 0 to 40 cation %. The content of Mg²⁺ is 0 to 10.0 cation %. The content of Sr²⁺ is 0 to 31.0 cation %. The content of Ba²⁺ is 0 to 31.0 cation %. The content of La³⁺ is 0 to 70.0 cation %. The content of Gd³⁺ is 0 to 70.0 cation %. The content of Y³⁺ is 0 to 70.0 cation %. The content of Yb³⁺ is 3 cation % or less. The content of Ti⁴⁺ is 0 to 10.0 cation %. The content of Nb⁵⁺ is 0 to 10.0 cation %. The content of W⁶⁺ is 0 to 10.0 cation %. The content of Bi³⁺ is 0 to 20 cation %. The content of Ta⁵⁺ is 0 to 10 cation %. The content of Zr⁴⁺ is 0 to 10.0 cation %. The content of Sc3+ is 0 to 2 cation %. The content of Hf4+ is 0 to 2 cation %. The content of Lu3+ is 0 to 2 cation %.

12. The optical glass according to claim 2, wherein the total content of Si4+, B3+, Ca2+, Zn2+, P5+, Al3+, Li+, Na+, K+, Rb+, Cs+, Mg2+, Sr2+, Ba2+, La3+, Gd3+, Y3+, Ti4+, Nb5+, W6+, Bi3+, Ta5+, and Zr4+ is 95 cation % or more.

13. The optical glass according to claim 2, satisfying any one or more of the following. The content of O2- is 10 to 90 anion %. The content of Cl- is less than 5 anion %. The total content of Br- and I- is less than 5 anion %. The content of each of Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, and V is less than 100 mass ppm. The content of each of Ga2O3, TeO2, and TbO2 is 0 to 0.1 mass %.

14. The optical glass according to claim 2, satisfying any one or more of the following. The Abbe number νd is 37.5 to 70. The refractive index nd is 1.60 to 1.

92. The refractive index nd and the Abbe number νd satisfy the following formula [1-1]. nd ≧ (-0.0081 × νd + 2.1181) ··· [1-1] The partial dispersion ratio Pg,F satisfies the following formula [2-1]. Pg,F ≧ 0.6200 - 0.0014 × νd … [2-1] ΔPg,F is -0.0100 to 0.0500. The liquidus temperature LT is 1200 °C or lower. The glass transition temperature Tg is 350 to 625 °C. The acid resistance Da is grade 5 or higher. The water resistance Dw is grade 5 or higher. The Knoop hardness Hk is 400 to 750.

15. The optical glass according to claim 2, wherein the total content [Mg2+ + Ca2+ + Sr2+ + Ba2+] of Mg2+, Ca2+, Sr2+, and Ba2+ is 0 to 30 cation %.

16. The optical glass according to claim 2, wherein the total content of Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, and Ba2+ [Li+ + Na+ + K+ + Rb+ + Cs+ + Mg2+ + Ca2+ + Sr2+ + Ba2+] is 0 to 45 cation %.

17. A glass material for press molding, comprising the optical glass according to any one of claims 1 to 16.

18. An optical element, comprising the optical glass according to any one of claims 1 to 16.