Optical glass, optical element blank and optical element

Abstract

The invention provides optical glass with excellent devitrification resistance, high refractive index and high chromatic dispersion. An optical glass in which, in a glass composition based on oxides, the total content [P2O5 + B2O3 + SiO2 + Al2O3] is 26 mass% or more, the mass ratio [B2O3 / (P2O5 + B2O3 + SiO2 + Al2O3)] is 0.11 to 0.24, the mass ratio [(Li2O + Na2O + K2O) / (P2O5 + B2O3 + SiO2 + Al2O3)] is 0.35 to 0.56, the mass ratio [TiO2 / (TiO2 + Nb2O5 + WO3 + Bi2O3)] is 0.12 to 0.32, the refractive index (nd) exceeds 1.85 and less than 1.90, and the Abbe number (vd) is 15 to 25; in the optical glass, in a glass composition based on oxides, the mass ratio [B2O3 / (P2O5 + B2O3 + SiO2 + Al2O3)] is 0.10 to 0.22, the mass ratio [(Li2O + Na2O + K2O) / (P2O5 + B2O3 + SiO2 + Al2O3)] is 0.30 to 0.38, the mass ratio [(TiO2 + WO3 + Bi2O3) / Nb2O5] is less than 0.15, the refractive index nd is 1.87 to 1.92, and the Abbe number vd is 15 to 25.

Description

[0001] This application is a divisional application of the invention patent application with Chinese application number 201710498839.6. The invention name of the original application is “Optical Glass, Optical Element Blanks and Optical Element”, and the application date is June 27, 2017. Technical Field

[0002] The invention relates to optical glass, an optical element blank and an optical element. Background Art

[0003] In the design of optical systems, high-refractive-index, high-dispersion optical glass with a high refractive index nd and a low Abbe number νd has high utilization value in terms of correcting chromatic aberration and making optical systems more functional and compact.

[0004] As high refractive index and high dispersion optical glass, for example, P 2 O 5 Phosphate-based glass as a main component (see Patent Documents 1 to 12).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2010-260746;

[0008] Patent document 2: Japanese Patent Application Publication No. 6-345481;

[0009] Patent document 3: Japanese Patent Application Publication No. 8-104537;

[0010] Patent document 4: Japanese Patent Application Publication No. 9-188540;

[0011] Patent Document 5: Japanese Patent Application Publication No. 2003-300751;

[0012] Patent Document 6: Japanese Patent Application Publication No. 2010-222236;

[0013] Patent Document 7: Japanese Patent Application Publication No. 2010-260740;

[0014] Patent Document 8: Japanese Patent Application Publication No. 2010-260742;

[0015] Patent Document 9: Japanese Patent Application Publication No. 2011-195369;

[0016] Patent Document 10: Japanese Patent Application Publication No. 2012-17261;

[0017] Patent Document 11: Japanese Patent Application Publication No. 2015-063460;

[0018] Patent Document 12: Japanese Patent Application Publication No. 2015-096468.

[0019] Problem that the invention aims to solve

[0020] In the manufacture of optical elements, a method of reheating optical glass and molding such as reheating pressing is sometimes used. In this case, phosphate-based high-refractive-index and high-dispersion glass may precipitate crystals and tend to lack resistance to devitrification. Summary of the invention

[0021] The present invention has been made in view of such actual circumstances, and an object of the present invention is to provide a high-refractive-index and high-dispersion optical glass having excellent resistance to devitrification.

[0022] Solutions for solving problems

[0023] The present inventors have conducted intensive studies to achieve the above-mentioned object and have found that the object can be achieved by adjusting the content ratio of various components constituting glass (hereinafter referred to as glass components). Based on this finding, the present invention has been completed.

[0024] That is, the gist of the present invention is as follows.

[0025] The optical glass of the first embodiment has, in the glass composition based on oxides,

[0026] P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The total content [P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 ] is 26 mass % or more,

[0027] B 2 O 3 The content of P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The mass ratio of the total content [B 2 O 3 / (P 2 O 5 +B 2 O3 +SiO 2 +Al 2 O 3 )] is 0.11 or more and 0.24 or less,

[0028] Li 2 O、Na 2 O and K 2 Total content of O and P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The mass ratio of the total content [(Li 2 O+Na 2 O+K 2 O) / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is 0.35 or more and 0.56 or less,

[0029] TiO 2 The content of TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 The mass ratio of the total content [TiO 2 / (TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 )] is 0.12 or more and 0.32 or less,

[0030] The refractive index nd is greater than 1.85 and less than 1.90, and the Abbe number νd is greater than or equal to 15 and less than or equal to 25.

[0031] The optical glass of the second embodiment has, in the glass composition based on oxides,

[0032] B 2 O 3 The content of P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3The mass ratio of the total content [B 2 O 3 / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is 0.10 or more and 0.22 or less,

[0033] Li 2 O、Na 2 O and K 2 Total content of O and P 2 O 5 , B 2 O 3 、SiO 2 、Al 2 O 3 The mass ratio of the total content [(Li 2 O+Na 2 O+K 2 O) / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is 0.30 or more and 0.38 or less,

[0034] TiO 2 , WO 3 and Bi 2 O 3 The total content of Nb 2 O 5 The mass ratio of the content [(TiO 2 +WO 3 +Bi 2 O 3 ) / Nb 2 O 5 ] is less than 0.15,

[0035] The refractive index nd is greater than or equal to 1.87 and less than or equal to 1.92, and the Abbe number νd is greater than or equal to 15 and less than or equal to 25.

[0036] Effects of the Invention

[0037] According to the present invention, a high refractive index and high dispersion optical glass having excellent devitrification resistance can be provided. In addition, according to the present invention, an optical element blank and an optical element composed of such an optical glass can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 1 is a graph showing the relationship between the refractive index nd and the crystal melting peak temperature T1 of the glass obtained in the first embodiment of the present invention.

[0039] Figure 2 is an example of a DSC graph. DETAILED DESCRIPTION

[0040] Hereinafter, the mode for implementing the present invention (hereinafter referred to as "embodiment mode") is described in detail. The following embodiment mode is an illustration for illustrating the present invention, and is not intended to limit the present invention to the following content. The present invention can be implemented with appropriate deformation within the scope of its main purpose. Furthermore, for places where the description is repeated, the description may be omitted as appropriate, but the purpose of the invention is not limited. In addition, in this specification, "optical glass" is a glass composition containing a variety of glass constituent components (glass components). Unless otherwise specified, the "optical glass" is used as a general term that is not limited by form (block, plate, spherical, etc.), use (optical element blank, optical element, etc.), and size. That is, there is no restriction on the form, use, and size of optical glass. Optical glass of any form, optical glass of any use, and optical glass of any size are all included in the optical glass of the present invention. In addition, in this specification, optical glass is sometimes referred to as "glass".

[0041] In this specification, unless otherwise specified, the refractive index refers to the refractive index nd of the d-line (wavelength 587.56 nm) of helium.

[0042] The Abbe number νd is used as a value indicating a property related to dispersion and is expressed by the following equation: nF is the refractive index of the hydrogen blue line F (wavelength 486.13 nm), and nC is the refractive index of the hydrogen red line C (wavelength 656.27 nm).

[0043] νd=(nd-1) / nF-nC…(1)

[0044] In this specification, the glass composition is expressed based on the content of each glass component expressed in mass %. Unless otherwise specified, the expression of % of each content means mass %.

[0045] In the present specification, the expression of glass composition in mass % means that, for each glass component represented by oxides and fluorides, the content of each glass component is expressed in mass % when the total content of all glass components is 100 mass %.

[0046] In the present embodiment, the glass composition can be quantified by ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). The analysis value obtained by ICP-AES may sometimes include a measurement error of, for example, about ±5% of the analysis value. In addition, in this specification and the present embodiment, the content of a constituent component of the glass is 0% or does not contain it, which means that the constituent component is substantially not contained, and also means that the content of the constituent component is below the impurity level.

[0047] As described later, Sb 2 O 3 、CeO 2 Sometimes it is added to glass in small amounts as a clarifier. However, in the mass % expression in this specification, the total content of all glass components does not include Sb. 2 O 3 and CeO 2 That is, the content of Sb in the glass component 2 O 3 、CeO 2 The contents expressed in mass % are expressed as follows: 2 O 3 and CeO 2 When the total content of all glass components other than Sb is 100 mass %, 2 O 3 、CeO 2 In this specification, such an expression is referred to as external addition.

[0048] The total content refers to the total amount of the contents of the plurality of glass components (including the case where the content is 0%). In addition, the mass ratio refers to the ratio (ratio) of the contents of the glass components (including the total contents of the plurality of components) expressed in mass %.

[0049] The formability of molten glass used in this specification is sometimes referred to as "formability". In addition, in this specification, the thermal stability and devitrification resistance of glass both refer to the difficulty of crystal precipitation in glass. In particular, thermal stability refers to the difficulty of crystal precipitation when molten glass solidifies, and devitrification resistance refers to the difficulty of crystal precipitation when solidified glass is reheated, such as during reheat pressing.

[0050] Hereinafter, as a first embodiment, the glass composition on the low refractive index side (refractive index nd exceeds 1.85 and is less than 1.90) is described; as a second embodiment, the glass composition on the high refractive index side (refractive index nd is greater than 1.87 and less than 1.92) is described.

[0051] First Embodiment

[0052] Phosphate-based high-refractive and high-dispersion optical glass requires that the temperature when melting the glass raw materials be maintained high, so that the viscosity of the molten glass tends to decrease excessively, resulting in poor formability of the molten glass.

[0053] Therefore, there is a demand for a phosphate-based high-refractive-index, high-dispersion optical glass that is excellent in molten glass formability and resistance to devitrification.

[0054] The first embodiment is made in view of such actual conditions, and an object of the present invention is to provide a high-refractive-index and high-dispersion optical glass having excellent moldability and resistance to devitrification.

[0055] In the optical glass according to the first embodiment of the present invention, the refractive index nd exceeds 1.85 and is less than 1.90, and the Abbe number νd is greater than or equal to 15 and less than or equal to 25. Hereinafter, the optical glass according to the first embodiment will be described in detail.

[0056] In the optical glass of the first embodiment, P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The total content [P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 ] is more than 26%. Total content [P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 ] is preferably 26.5% or more, and more preferably 27% or more, 27.5% or more, and 28% or more. 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 ] is preferably less than 45%, and more preferably less than 40%, less than 37% and less than 35%, respectively.

[0057] As a network-forming component of glass, P is known to 2 O 5 , B 2 O 3 、SiO 2and Al 2 O 3 These glass network forming components improve the resistance to devitrification. In addition, they have the function of suppressing excessive decrease in the viscosity of the molten glass and making the molten glass easy to shape. Therefore, in the first embodiment, by making P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 When the total content of is within the above range, an optical glass having excellent formability and resistance to devitrification can be obtained.

[0058] In the optical glass of the first embodiment, B 2 O 3 The content of P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The mass ratio of the total content [B 2 O 3 / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is 0.11 or more and 0.24 or less. 2 O 3 / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is preferably 0.13 or more, and more preferably 0.15 or more, 0.16 or more, and 0.17 or more. 2 O 3 / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is preferably 0.22 or less, and more preferably 0.21 or less, 0.20 or less, and 0.19 or less, respectively.

[0059] B 2 O 3In the network-forming component of glass, it has the function of improving the moldability. 2 O 3 When the content of B is high, the devitrification resistance may decrease. In the first embodiment, by making B in the network forming component 2 O 3 When the content ratio of is within the above range, an optical glass having excellent formability and resistance to devitrification can be obtained.

[0060] In the optical glass of the first embodiment, Li 2 O、Na 2 O and K 2 Total O content [Li 2 O+Na 2 O+K 2 O] and P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The mass ratio of the total content [(Li 2 O+Na 2 O+K 2 O) / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is 0.35 or more and 0.56 or less. 2 O+Na 2 O+K 2 O) / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is preferably 0.40 or more, and more preferably 0.45 or more, 0.48 or more, and 0.50 or more. 2 O+Na 2 O+K 2 O) / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is preferably 0.55 or less, more preferably 0.54 or less, and further preferably 0.53 or less.

[0061] Li 2 O、Na 2 O and K 2 O has the function of improving the melting property, but when the content of these increases, the devitrification resistance decreases. 2 O、Na 2 O and K 2 When the content ratio of O to the network-forming component is within the above range, an optical glass having excellent moldability and resistance to devitrification can be obtained.

[0062] In the optical glass of the first embodiment, TiO 2 The content of TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 The mass ratio of the total content [TiO 2 / (TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 )] is 0.12 or more and 0.32 or less. 2 / (TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 )] is preferably 0.15 or more, and more preferably 0.18 or more, 0.20 or more, and 0.21 or more. 2 / (TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 )] is preferably 0.30 or less, and more preferably 0.28 or less, 0.26 or less, and 0.24 or less, respectively.

[0063] TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 All of them are glass components that contribute to high dispersion, but they can also cause coloration. In particular, TiO 2 , which is related to Nb 2 O 5 , WO3 and Bi 2 O 3 It greatly contributes to high dispersion, but it is easy to increase the coloring of the glass. 2 It has the effect of promoting the formation of crystals in the glass during the process of shaping and slowly cooling the molten glass, thereby reducing the transparency of the glass (cloudiness). 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 TiO 2 When the content ratio is within the above range, an optical glass with high dispersion and excellent transmittance can be obtained.

[0064] (Glass composition)

[0065] Hereinafter, the glass components of the optical glass according to the first embodiment will be described in detail.

[0066] In the optical glass of the first embodiment, P 2 O 5 The content of P is preferably 18% or more, and more preferably 20% or more, 21% or more, and 22% or more. 2 O 5 The content of is preferably 32% or less, more preferably 28% or less, 26% or less, and 25% or less, respectively.

[0067] P 2 O 5 It is an essential component for making the glass contain a large amount of high dispersion components. On the other hand, when P is excessively contained 2 O 5 When the thermal stability deteriorates. 2 O 5 The content of is preferably within the above range.

[0068] In the optical glass of the first embodiment, B 2 O 3 The content of B is preferably 0.1% or more, more preferably 2% or more, and more preferably 3% or more. 2 O 3 The content of is preferably 12% or less, more preferably 9% or less, 7% or less, and 6% or less, respectively.

[0069] B 2 O 3 It is a network-forming component of glass and has the function of improving the thermal stability of glass. 2 O 3When the content of B is high, high dispersion is hindered and the devitrification resistance tends to decrease. Therefore, from the perspective of improving the thermal stability and devitrification resistance of the glass, B 2 O 3 The content of is preferably within the above range.

[0070] In the optical glass of the first embodiment, SiO 2 The content of SiO is preferably 3% or less, more preferably 2% or less, and 1.5% or less. 2 The content can also be 0%.

[0071] SiO 2 It is a network-forming component of glass and has the functions of improving the thermal stability, chemical durability, and weather resistance of glass, increasing the viscosity of molten glass, and making molten glass easier to shape. 2 When the content of SiO is high, there is a tendency for the devitrification resistance of the glass to decrease. Therefore, from the perspective of improving the thermal stability and devitrification resistance of the glass, SiO 2 The content of is preferably within the above range.

[0072] In the optical glass of the first embodiment, Al 2 O 3 The content of Al is preferably 3% or less, more preferably 2% or less, and then 1% or less. 2 O 3 The content can also be 0%.

[0073] Al 2 O 3 It is a glass component that has the function of improving the chemical durability and weather resistance of glass and can be considered as a network forming component. 2 O 3 When the content of Al increases, the devitrification resistance of the glass decreases. In addition, problems such as an increase in the glass transition temperature Tg and a decrease in thermal stability are likely to occur. From the perspective of avoiding such problems, Al 2 O 3 The content of is preferably within the above range.

[0074] In the optical glass of the first embodiment, TiO 2 The content of TiO is preferably 3% or more, and more preferably 5%, 8%, and 10% or more. 2 The content of is preferably 20% or less, more preferably 18% or less, 16% or less, and 14% or less, respectively.

[0075] TiO 2 On the other hand, TiO 2It is relatively easy to increase the coloring of glass. In addition, in the process of forming molten glass and slowly cooling it to obtain optical glass, TiO 2 It will promote the formation of crystals in the glass, causing the transparency of the glass to decrease (cloudiness). 2 The content of is preferably within the above range.

[0076] In the optical glass of the first embodiment, Nb 2 O 5 The content of Nb is preferably 35% or more, and more preferably 38% or more, 40% or more, and 42% or more. 2 O 5 The content of is preferably 56% or less, more preferably 50% or less, 48% or less, and 46% or less, respectively.

[0077] Nb 2 O 5 It is a component that contributes to high dispersion. In addition, it is also a glass component that improves the thermal stability and chemical durability of glass. On the other hand, when Nb 2 O 5 When the content of Nb becomes too high, the thermal stability of the glass decreases, and there is a tendency for the coloring of the glass to increase. Therefore, in the optical glass of the first embodiment, Nb 2 O 5 The content of is preferably within the above range.

[0078] In the optical glass of the first embodiment, WO 3 The lower limit of the content of WO is preferably 0%. 3 The content of is preferably 5% or less, more preferably 3% or less, and further preferably 1% or less.

[0079] WO 3 It is easy to cause the coloring of glass and deteriorate the transmittance. 3 The content of is preferably within the above range.

[0080] In the first embodiment, Bi 2 O 3 The content of Bi is preferably 5% or less, more preferably 3% or less, and then 2% or less. 2 O 3 The lower limit of the content is preferably 0%.

[0081] Bi 2 O 3 By containing Bi 2 O 3 To improve the thermal stability of glass. On the other hand, when Bi 2 O 3When the content of Bi increases, the color of the glass will increase. 2 O 3 The content of is preferably within the above range.

[0082] In the optical glass of the first embodiment, TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 The total content [TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 ] is preferably 45% or more, and more preferably 50% or more, 52% or more, and 54% or more. 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 ] is preferably 65% ​​or less, and more preferably 60% or less and 58% or less, respectively.

[0083] TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 It contributes to the high dispersion of glass. In addition, it also has the function of improving the thermal stability of glass by containing these components in appropriate amounts. On the other hand, it is also a component that increases the coloring of glass. Therefore, the total content [TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 ] is preferably within the above range.

[0084] In the optical glass of the first embodiment, P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The total content of TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 The mass ratio of the total content [(P2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 ) / (TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 )] is preferably 0.40 or more and 0.60 or less. 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 ) / (TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 )] is more preferably 0.42 or more, and further preferably 0.44 or more, 0.46 or more, and 0.48 or more. 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 ) / (TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 )] is more preferably 0.58 or less, further preferably 0.56 or less, 0.54 or less, and 0.52 or less, respectively.

[0085] TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 Therefore, the content ratio of these components and the network forming component is preferably within the above range.

[0086] In the optical glass of the first embodiment, Li 2 The content of O is preferably 5% or less, more preferably 3% or less, and then 1% or less. 2 The lower limit of the O content is preferably 0%.

[0087] In the optical glass of the first embodiment, Na 2 The content of O is preferably 12% or less, and more preferably 10% or less, 9% or less, and 8% or less, respectively. 2 The content of O is preferably 0% or more, more preferably 3% or more, 5% or more, and 6% or more, in that order.

[0088] In the optical glass of the first embodiment, K 2 The content of O is preferably 12% or less, more preferably 10% or less, 9% or less, and 8% or less. 2 The content of O is preferably 0% or more, more preferably 3% or more, 5% or more, and 6% or more, in that order.

[0089] Li 2 O、Na 2 O and K 2 O has the function of improving the thermal stability of glass, but when their content increases, thermal stability, chemical durability, and weather resistance will decrease. 2 O、Na 2 O and K 2 The contents of each O are preferably within the above ranges. In order to particularly improve thermal stability and resistance to devitrification, it is preferred to contain Na 2 O.

[0090] In the optical glass of the first embodiment, Li 2 O、Na 2 O and K 2 Total O content [Li 2 O+Na 2 O+K 2 O] is preferably 20% or less, more preferably 18% or less, and 16% or less. 2 O+Na 2 O+K 2 O] is preferably 8% or more, and more preferably 10% or more, 12% or more, and 13% or more, respectively.

[0091] Li 2 O、Na 2 O and K 2 O has the function of improving the thermal stability of glass. However, when these contents increase, chemical durability and weather resistance will decrease. Therefore, Li 2 O、Na 2 O and K 2 Total O content [Li 2 O+Na 2 O+K 2 O] is preferably within the above range.

[0092] In the optical glass of the first embodiment, Cs 2 The upper limit of the content of O is preferably 2%. 2 The lower limit of the O content is preferably 0%.

[0093] Cs 2 O has the function of improving the thermal stability of glass, but when the content increases, the thermal stability, chemical durability and weather resistance of glass will decrease. 2 The O content is preferably within the above range.

[0094] In the optical glass of the first embodiment, the content of MgO is preferably 5% or less, and further preferably 3% or less, and 1% or less. In addition, the lower limit of the content of MgO is preferably 0%. The content of MgO may also be 0%.

[0095] In the optical glass of the first embodiment, the content of CaO is preferably 5% or less, and further preferably 3% or less, and 1% or less in that order. In addition, the lower limit of the content of CaO is preferably 0%. The content of CaO may also be 0%.

[0096] In the optical glass of the first embodiment, the content of SrO is preferably 5% or less, more preferably 3% or less, and 1% or less in that order. In addition, the lower limit of the content of SrO is preferably 0%.

[0097] In the optical glass of the first embodiment, the upper limit of the BaO content is preferably 5%, more preferably 3%, and further preferably 1%. In addition, the lower limit of the BaO content is preferably 0%.

[0098] MgO, CaO, SrO, and BaO are all glass components that have the function of improving the thermal stability and devitrification resistance of glass. However, when the content of these glass components increases, high dispersion will be impaired, and the thermal stability and devitrification resistance of glass will decrease. Therefore, the content of each of these glass components is preferably within the above range.

[0099] In the optical glass of the first embodiment, the total content of MgO, CaO, SrO and BaO [MgO + CaO + SrO + BaO] is preferably 6% or less, and further preferably 4% or less and 2% or less in that order. In addition, the lower limit of the total content [MgO + CaO + SrO + BaO] is preferably 0%. From the viewpoint of maintaining thermal stability and resistance to devitrification without hindering high dispersion, the total content [MgO + CaO + SrO + BaO] is preferably within the above range.

[0100] In the optical glass of the first embodiment, the content of ZnO is preferably 5% or less, more preferably 3% or less, and 1% or less in that order. In addition, the lower limit of the content of ZnO is preferably 0%.

[0101] ZnO is a glass component that has the function of improving the thermal stability of glass. However, when the content of ZnO is too much, the high dispersion of the glass will be damaged. Therefore, from the viewpoint of improving the thermal stability of the glass and maintaining the desired optical properties, the content of ZnO is preferably within the above range.

[0102] In the optical glass of the first embodiment, ZrO 2 The content of ZrO is preferably 5% or less, more preferably 3% or less, and 1% or less. 2 The lower limit of the content is preferably 0%.

[0103] ZrO 2 It is a glass component that has the function of improving the thermal stability and devitrification resistance of glass. 2 When the content of ZrO is too high, the thermal stability tends to decrease. Therefore, from the perspective of maintaining the thermal stability and devitrification resistance of the glass, ZrO 2 The content of is preferably within the above range.

[0104] In the optical glass of the first embodiment, Ta 2 O 5 The content of Ta is preferably 5% or less, more preferably 3% or less, and then 2% or less. 2 O 5 The lower limit of the content is preferably 0%.

[0105] Ta 2 O 5 It is a glass component that has the function of improving the thermal stability and devitrification resistance of glass. 2 O 5 The refractive index is increased, and the dispersion of the glass is reduced. 2 O 5 When the content of Ta increases, the thermal stability of the glass decreases, and when the glass is melted, molten residues of the glass raw materials are easily generated. 2 O 5 The content of Ta is preferably within the above range. 2 O 5 Compared with other glass components, it is an extremely expensive component. 2 O 5 When the content of Ta increases, the production cost of glass will increase. 2 O 5Compared with other glass components, it has a larger molecular weight, which increases the specific gravity of the glass and, as a result, increases the weight of the optical element.

[0106] In the optical glass of the first embodiment, Sc 2 O 3 The upper limit of the content of Sc is preferably 2%. 2 O 3 The lower limit of the content is preferably 0%.

[0107] In the optical glass of the first embodiment, HfO 2 The upper limit of the content of HfO is preferably 2%. 2 The lower limit of the content is preferably 0%.

[0108] Sc 2 O 3 , HfO 2 Both have the function of increasing the refractive index nd and are expensive components. 2 O 3 , HfO 2 Each content of is preferably within the above range.

[0109] In the optical glass of the first embodiment, Lu 2 O 3 The upper limit of the content of Lu is preferably 2%. 2 O 3 The lower limit of the content is preferably 0%.

[0110] Lu 2 O 3 It has the function of increasing the refractive index nd. In addition, due to its large molecular weight, it is also a glass component that increases the specific gravity of the glass. 2 O 3 The content of is preferably within the above range.

[0111] In the optical glass of the first embodiment, GeO 2 The upper limit of the content of GeO is preferably 2%. 2 The lower limit of the content is preferably 0%.

[0112] GeO 2 GeO has the function of increasing the refractive index nd and is an extremely expensive component among the commonly used glass components. Therefore, from the perspective of reducing the manufacturing cost of glass, GeO 2 The content of is preferably within the above range.

[0113] In the optical glass of the first embodiment, La 2 O 3 The upper limit of the content of La is preferably 2%. 2O 3 The lower limit of the content of is preferably 0%. 2 O 3 The content can also be 0%.

[0114] When La 2 O 3 When the content of La increases, the thermal stability and devitrification resistance of the glass decrease, and the glass is prone to devitrification during manufacturing. Therefore, from the perspective of suppressing the decrease in thermal stability and devitrification resistance, La 2 O 3 The content of is preferably within the above range.

[0115] In the optical glass of the first embodiment, Gd 2 O 3 The upper limit of the content of Gd is preferably 2%. 2 O 3 The lower limit of the content is preferably 0%.

[0116] When Gd 2 O 3 When the content of Gd becomes too high, the thermal stability and resistance to devitrification of the glass decrease, and the glass is easily devitrified during manufacturing. 2 O 3 When the content of Gd becomes too much, the specific gravity of the glass increases, which is not preferred. Therefore, from the perspective of maintaining the thermal stability and devitrification resistance of the glass and suppressing the increase in specific gravity, Gd 2 O 3 The content of is preferably within the above range.

[0117] In the optical glass of the first embodiment, Y 2 O 3 The upper limit of the content of Y is preferably 2%. 2 O 3 The lower limit of the content of is preferably 0%. 2 O 3 The content can also be 0%.

[0118] When Y 2 O 3 When the content of Y becomes too much, the thermal stability and devitrification resistance of the glass will decrease. Therefore, from the viewpoint of suppressing the decrease in thermal stability and devitrification resistance, Y 2 O 3 The content of is preferably within the above range.

[0119] In the optical glass of the first embodiment, Yb 2 O 3 The upper limit of the content of Yb is preferably 2%. 2 O 3 The lower limit of the content is preferably 0%.

[0120] Yb 2 O 3 Because of La 2 O 3 , Gd 2 O 3 , Y 2 O 3 The molecular weight is larger than that of the glass, so the specific gravity of the glass increases. When the specific gravity of the glass increases, the mass of the optical element increases. For example, when a heavy lens is assembled in an autofocus camera lens, the power required to drive the lens during autofocusing increases, and the battery consumption becomes more severe. Therefore, it is desirable to reduce Yb 2 O 3 The content of glass can suppress the increase of specific gravity of glass.

[0121] In addition, when Yb 2 O 3 If the content of Yb is too high, the thermal stability and devitrification resistance of the glass will decrease. From the perspective of preventing the decrease in the thermal stability of the glass and suppressing the increase in specific gravity, Yb 2 O 3 The content of is preferably within the above range.

[0122] The optical glass of the first embodiment preferably mainly consists of the above-mentioned glass components, namely, P 2 O 5 , B 2 O 3 、SiO 2 、Al 2 O 3 、TiO 2 , Nb 2 O 5 , WO 3 、Bi 2 O 3 , Li 2 O、Na 2 O.K 2 O、Cs 2 O, MgO, CaO, SrO, BaO, ZnO, ZrO 2 、 2 O 5 Sc 2 O 3 , HfO 2 、Lu 2 O 3 ,GeO 2 ,La 2 O 3 , Gd 2 O 3 , Y 2 O 3Yb 2 O 3 In the structure, the total content of the above-mentioned glass components is preferably more than 95%, more preferably more than 98%, further preferably more than 99%, and further preferably more than 99.5%.

[0123] In the optical glass of the first embodiment, TeO 2 The upper limit of the content of TeO is preferably 2%. 2 The lower limit of the content is preferably 0%.

[0124] Due to TeO 2 It is toxic, so it is preferred to reduce TeO 2 Therefore, TeO 2 The content of is preferably within the above range.

[0125] The optical glass of the first embodiment is preferably basically composed of the above-mentioned glass components, but may contain other components within a range that does not hinder the effects of the present invention. In the present invention, the inclusion of inevitable impurities is not excluded.

[0126] <Other ingredients>

[0127] Pb, As, Cd, Tl, Be, and Se are all toxic. Therefore, it is preferable that the optical glass of the first embodiment does not contain these elements as glass components.

[0128] U, Th, and Ra are all radioactive elements. Therefore, it is preferable that the optical glass of the first embodiment does not contain these elements as glass components.

[0129] V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, and Tm increase the coloring of the glass and may become a source of fluorescence. Therefore, it is preferred that the optical glass of the first embodiment does not contain these elements as glass components.

[0130] Sb(Sb 2 O 3 )、Ce(CeO 2 ) is an element that can be added arbitrarily to function as a clarifier. Among them, Sb (Sb 2 O 3 ) is a clarifier with a great clarification effect. However, Sb (Sb 2 O 3 ) has strong oxidizing property. When Sb(Sb 2 O 3When the addition amount of 2 increases, due to the light absorption of Sb ions, the coloring of the glass will increase, so it is not preferred. In addition, when melting the glass, when Sb exists in the melt, it will promote the dissolution of platinum constituting the glass melting crucible into the melt, and the platinum concentration in the glass will become high. When platinum exists in the glass in the form of ions, the coloring of the glass will increase due to light absorption. In addition, when platinum exists in the glass in the form of solid substances, it will become a light scattering source, and the quality of the glass will deteriorate. Ce (CeO 2 ) has a smaller clarification effect compared with Sb (Sb 2 O 3 ). When a large amount of Ce (CeO 2 ) is added, the coloring of the glass will become stronger. Therefore, when adding a clarifying agent, it is preferable to add Sb (Sb 2 O 3 ) while paying attention to the addition amount.

[0131] The content of Sb 2 O 3 is expressed in terms of the external addition amount. That is, when the total content of all glass components except Sb 2 O 3 and CeO 2 is set to 100% by mass, the content of Sb 2 O 3 is preferably less than 1% by mass, more preferably less than 0.5% by mass. Further preferably less than 0.1% by mass, less than 0.05% by mass, and less than 0.03% by mass in sequence. The content of Sb 2 O 3 can also be 0% by mass.

[0132] The content of CeO 2 is also expressed in terms of the external ratio. That is, when the total content of all glass components except CeO 2 , Sb 2 O 3 is set to 100% by mass, the content range of CeO 2 is preferably less than 2% by mass, more preferably less than 1% by mass, further preferably less than 0.5% by mass, and even more preferably less than 0.1% by mass. The content of CeO 2 can also be 0% by mass. By making the content of CeO 2 within the above range, the clarification of the glass can be improved.

[0133] (Glass properties)

[0134] In the optical glass of the first embodiment, the refractive index nd exceeds 1.85 and is less than 1.90. The refractive index nd is preferably 1.855 or more, and more preferably 1.860 or more, and 1.865 or more. In addition, the refractive index nd is preferably 1.890 or less, and more preferably 1.885 or less, 1.880 or less, and 1.875 or less.

[0135] In the optical glass of the first embodiment, the Abbe number νd is greater than or equal to 15 and less than or equal to 25. The Abbe number νd is preferably greater than or equal to 16, and more preferably greater than or equal to 17, greater than or equal to 18, and greater than or equal to 19. In addition, the Abbe number νd is preferably less than or equal to 24, and more preferably less than or equal to 23, less than or equal to 22, and less than or equal to 21.

[0136] <Crystal melting peak temperature Tl>

[0137] Crystal melting peak temperature T1 is the temperature at which all pseudocrystals in the glass disappear, and is related to the liquidus temperature. For example, when crystal melting peak temperature T1 becomes high, it is necessary to maintain the glass temperature during molding high, so the viscosity of the molten glass decreases excessively, and the moldability deteriorates.

[0138] The crystal melting peak temperature T1 varies according to the components contained in the glass. In the first embodiment, in order to increase the refractive index nd of the glass, it is necessary to contain a large amount of Nb. 2 O 5 、TiO 2 However, these high refractive index components are also components that increase the crystal melting peak temperature T1. Furthermore, in order to stably contain these components in the glass, it is necessary to simultaneously 2 O 5 , B 2 O 3 The content of network forming components is increased. Here, the network forming component has the effect of suppressing the viscosity decrease of the molten glass. That is, sometimes, although the crystal melting peak temperature T1 will rise in appearance with the increase of the refractive index nd of the glass, the viscosity of the molten glass will be reduced, that is, the deterioration of the formability will be suppressed.

[0139] Figure 1 : is a graph showing the relationship between the refractive index nd and the crystal melting peak temperature Tl (°C) of the glass obtained in the first embodiment. Figure 1 In the figure, the glass with good formability is shown as an example (diamond mark), and the glass other than the example is shown as a comparative example (square mark). It can be seen that as the refractive index nd of the glass increases, the preferred crystal melting peak temperature Tl tends to increase. Figure 1 The preferred crystal melting peak temperature Tl corresponding to the refractive index nd of the glass is expressed by the following formula (2).

[0140] Tl<1000nd-790…(2)

[0141] A more preferred crystal melting peak temperature T1 is represented by the following formula (3).

[0142] Tl<1300nd-1364…(3)

[0143] The crystal melting peak temperature T1 can be determined by differential scanning calorimetry (DSC (Differential Scanning Calorimetry)). Figure 2 is an example of a DSC graph. The vertical axis is differential scanning calorimetry (DSC), and the horizontal axis is the temperature (T) of the sample. The DSC graph has regions representing glass transition, crystallization, and crystal melting. The crystal melting peak Tl is at Figure 2 The temperature at which DSC shows a peak in the crystal melting region. Figure 2 The crystal melting start temperature in the crystal melting region is the temperature at which DSC starts to rise. According to DSC, the crystal melting peak temperature T1, which is an index of the liquidus temperature, can be obtained with high accuracy and relatively simple.

[0144] <Glass transition temperature Tg>

[0145] The glass transition temperature Tg of the optical glass of the first embodiment is preferably 750°C or lower, more preferably 730°C or lower, and 710°C or lower. The glass transition temperature Tg is preferably 520°C or higher, more preferably 560°C or higher, and 600°C or higher.

[0146] By making the glass transition temperature Tg satisfy the above range, the increase in the annealing temperature of the glass can be suppressed, and thermal damage to annealing equipment, for example, a continuous annealing furnace called RARE or a batch annealing furnace can be reduced.

[0147] By making the glass transition temperature Tg satisfy the above range, it is easy to maintain a desired Abbe number and refractive index and to maintain good thermal stability of the glass.

[0148] <Light Transmittance of Glass>

[0149] In the first embodiment, light transmittance can be evaluated based on the coloring degree λ5.

[0150] A glass (thickness 10.0 mm ± 0.1 mm) having two parallel optically polished planes is used, and light is incident perpendicularly to one of the two planes. Then, the ratio of the intensity Iout of the transmitted light emitted from the other plane to the intensity Iin of the incident light (Iout / Iin) is calculated, that is, the external transmittance is calculated. Using a spectrometer, the wavelength of the incident light is scanned in the range of, for example, 280 to 700 nm, and the external transmittance is measured, thereby obtaining a spectral transmittance curve.

[0151] As the wavelength of incident light changes from the absorption edge on the short wavelength side of the glass toward the long wavelength side, the external transmittance increases and shows a high value.

[0152] λ5 is a wavelength at which the external transmittance is 5%. In the wavelength region of 280 to 700 nm, the external transmittance of glass on the longer wavelength side than λ5 shows a value greater than 5%.

[0153] By using an optical glass having a shorter wavelength of λ5, it is possible to provide an optical element capable of achieving appropriate color reproduction.

[0154] For this reason, the range of λ5 is preferably 400 nm or less, and more preferably 390 nm or less. The lower limit of λ5 is, for example, 360 nm.

[0155] (Manufacture of optical glass)

[0156] The optical glass of the first embodiment of the present invention is prepared by mixing glass raw materials in a manner to obtain the above-mentioned prescribed composition, and using the prepared glass raw materials to make it according to a known glass manufacturing method. For example, a plurality of compounds are mixed and fully mixed to form a batch material, and the batch material is added to a quartz crucible or a platinum crucible for rough melting. The molten material obtained by the rough melting is quenched and crushed to make cullet. Furthermore, the cullet is added to a platinum crucible, heated, and remelted to form molten glass, and after further clarification and homogenization, the molten glass is molded and slowly cooled to obtain an optical glass. The molding and slow cooling of the molten glass can be carried out by known methods.

[0157] Furthermore, the compound used in preparing the batch material is not particularly limited as long as the desired glass component can be introduced into the glass in a desired content, and examples of such a compound include oxides, carbonates, nitrates, hydroxides, and fluorides.

[0158] (Manufacture of optical components, etc.)

[0159] When the optical glass of the first embodiment of the present invention is used to make an optical element, a known method can be applied. For example, glass raw materials are melted into molten glass, and the molten glass is flowed into a casting mold to be formed into a plate-like shape to make a glass material composed of the optical glass of the present invention. The obtained glass material is appropriately cut, ground, and polished to make slices of a size and shape suitable for press molding. The slices are heated and softened, and press molded (reheated and pressed) by a known method to make an optical element blank that is similar in shape to the optical element. The optical element blank is annealed, and ground and polished by a known method to make an optical element.

[0160] The optical functional surface of the manufactured optical element may be coated with an anti-reflection film, a total reflection film, etc. depending on the intended use.

[0161] Examples of the optical element include various lenses such as a spherical lens, a prism, a diffraction grating, and the like.

[0162] Second Embodiment

[0163] Phosphate-based high-refractive and high-dispersion optical glasses may cause crystal precipitation when molten glass is solidified, and tend to lack thermal stability.

[0164] In addition, as a component that contributes to the high refractive index and high dispersion of optical glass, TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 However, these may cause the coloring of the glass to increase, and deteriorate the transmittance of the glass depending on the content ratio.

[0165] The second embodiment is made in view of such actual conditions, and an object of the present invention is to provide a high-refractive-index and high-dispersion optical glass having excellent transmittance, thermal stability, and resistance to devitrification.

[0166] The optical glass of the second embodiment of the present invention has a refractive index nd of 1.87 to 1.92 and an Abbe number νd of 15 to 25. The optical glass of the second embodiment will be described in detail below.

[0167] In the optical glass of the second embodiment, B 2 O 3 The content of P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The mass ratio of the total content [B2 O 3 / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is 0.10 or more and 0.22 or less. 2 O 3 / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is preferably 0.11 or more, and more preferably 0.12 or more, 0.13 or more, and 0.14 or more. 2 O 3 / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is preferably 0.20 or less, and more preferably 0.18 or less, 0.17 or less, and 0.16 or less, respectively.

[0168] As a network-forming component of glass, P is known to 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 . B 2 O 3 Among the network-forming components of glass, B has the function of lowering the liquidus temperature and improving the thermal stability of glass. 2 O 3 When the content of B is high, the devitrification resistance of the solidified glass may decrease when it is reheated (reheated and pressed). 2 O 3 When the content ratio of is within the above range, an optical glass having excellent thermal stability and resistance to devitrification can be obtained.

[0169] In the optical glass of the second embodiment, Li 2 O、Na 2 O and K 2 Total O content [Li 2 O+Na 2 O+K2 O] and P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The mass ratio of the total content [(Li 2 O+Na 2 O+K 2 O) / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is 0.30 or more and 0.38 or less. 2 O+Na 2 O+K 2 O) / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is preferably 0.31 or more, and more preferably 0.32 or more. 2 O+Na 2 O+K 2 O) / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is preferably 0.37 or less, and more preferably 0.36 or less, 0.35 or less, and 0.34 or less, respectively.

[0170] Li 2 O、Na 2 O and K 2 O has the function of improving the melting property, but when the content of these increases, the devitrification resistance when the solidified glass is reheated (reheating and pressing) will decrease. 2 O、Na 2 O and K 2 When the content ratio of O to the network-forming component is within the above range, an optical glass having excellent thermal stability and resistance to devitrification can be obtained.

[0171] In the optical glass of the second embodiment, TiO 2 , WO 3 and Bi2 O 3 The total content of Nb 2 O 5 The mass ratio of the content [(TiO 2 +WO 3 +Bi 2 O 3 ) / Nb 2 O 5 ] is less than 0.15. Mass ratio [(TiO 2 +WO 3 +Bi 2 O 3 ) / Nb 2 O 5 ] is preferably 0.10 or less, more preferably 0.09 or less, and further preferably 0.08 or less. 2 +WO 3 +Bi 2 O 3 ) / Nb 2 O 5 ] is preferably greater than 0.02, and more preferably greater than 0.03, greater than 0.04, and greater than 0.05, respectively.

[0172] TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 All of them are glass components that contribute to high dispersion, but they can also cause increased coloration. 2 O 5 It is a component that contributes to high dispersion and is less likely to increase coloration. 2 , WO 3 and Bi 2 O 3 The total content of Nb 2 O 5 When the content ratio of is within the above range, an optical glass having high dispersion and excellent transmittance can be obtained.

[0173] (Glass composition)

[0174] Hereinafter, the glass components of the optical glass according to the second embodiment will be described in detail.

[0175] In the optical glass of the second embodiment, P 2 O 5 The content of P is preferably 18% or more, and more preferably 19% or more, 21% or more, and 23% or more. 2 O 5The content of is preferably 32% or less, more preferably 30% or less, 28% or less, and 26% or less, respectively.

[0176] P 2 O 5 It is an essential component for making the glass contain a large amount of high dispersion components. On the other hand, when P is excessively contained 2 O 5 When the thermal stability deteriorates. 2 O 5 The content of is preferably within the above range.

[0177] In the optical glass of the second embodiment, B 2 O 3 The content of B is preferably 0.1% or more, more preferably 2% or more, and more preferably 3% or more. 2 O 3 The content of is preferably 12% or less, more preferably 9% or less, 7% or less, and 6% or less, respectively.

[0178] B 2 O 3 It is a network-forming component of glass and has the function of improving the thermal stability of glass. 2 O 3 When the content of B is high, high dispersion is hindered and the devitrification resistance tends to decrease. Therefore, from the perspective of improving the thermal stability and devitrification resistance of the glass, B 2 O 3 The content of is preferably within the above range.

[0179] In the optical glass of the second embodiment, SiO 2 The content of SiO is preferably 3% or less, more preferably 2% or less, and 1.5% or less. 2 The content can also be 0%.

[0180] SiO 2 It is a network-forming component of glass and has the functions of improving the thermal stability, chemical durability, and weather resistance of glass, increasing the viscosity of molten glass, and making molten glass easier to shape. 2 When the content of SiO is high, the devitrification resistance of the glass tends to decrease. Therefore, from the perspective of improving the thermal stability and devitrification resistance of the glass, SiO 2 The content of is preferably within the above range.

[0181] In the optical glass of the second embodiment, Al 2 O 3 The content of Al is preferably 3% or less, more preferably 2% or less, and then 1% or less. 2 O3 The content can also be 0%.

[0182] Al 2 O 3 It is a glass component that has the function of improving the chemical durability and weather resistance of glass and can be considered as a network forming component. 2 O 3 When the content of Al increases, the devitrification resistance of the glass decreases. In addition, problems such as an increase in the glass transition temperature Tg and a decrease in thermal stability are likely to occur. From the perspective of avoiding such problems, Al 2 O 3 The content of is preferably within the above range.

[0183] In the optical glass of the second embodiment, P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The total content [P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 ] is preferably 25% or more, and more preferably 26% or more, 27% or more, and 28% or more. 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 ] is preferably less than 45%, and more preferably less than 35%, less than 33%, and less than 31%, respectively.

[0184] P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 It is a network-forming component of glass, mainly improving the thermal stability and resistance to devitrification of glass. It has the function of increasing the viscosity of molten glass and making it easier to shape molten glass. 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The total content of is preferably within the above range.

[0185] In the optical glass of the second embodiment, TiO 2 The content of TiO is preferably 0% or more, and more preferably 2% or more, and 3% or more. 2 The content of is preferably 10% or less, more preferably 8% or less, and further preferably 6% or less.

[0186] TiO 2 It is easy to increase the coloring of glass. In addition, in the process of forming molten glass and slowly cooling it to obtain optical glass, TiO 2 It will promote the formation of crystals in the glass, causing the transparency of the glass to decrease (cloudiness). 2 The content of is preferably within the above range.

[0187] In the optical glass of the second embodiment, Nb 2 O 5 The content of Nb is preferably 50% or more, more preferably 52% or more, and more preferably 54% or more. 2 O 5 The content of is preferably 65% ​​or less, more preferably 60% or less, and further preferably 58% or less.

[0188] Nb 2 O 5 It is a component that contributes to high dispersion. In addition, it is also a glass component that improves the thermal stability and chemical durability of glass. On the other hand, when Nb 2 O 5 When the content of Nb becomes too high, the thermal stability of the glass decreases and the coloring of the glass tends to increase. 2 O 5 The content of is preferably within the above range.

[0189] In the optical glass of the second embodiment, WO 3 The lower limit of the content of WO is preferably 0%. 3 The content of is preferably 5% or less, more preferably 3% or less, and further preferably 1% or less.

[0190] WO 3 It is easy to cause the coloring of glass and deteriorate the transmittance. 3 The content of is preferably within the above range.

[0191] In the second embodiment, Bi 2 O 3 The content of Bi is preferably 5% or less, more preferably 3% or less, and then 2% or less. 2 O 3 The lower limit of the content is preferably 0%.

[0192] Bi 2 O 3 By containing Bi 2 O 3 To improve the thermal stability of glass. On the other hand, when Bi 2 O 3 When the content of Bi increases, the color of the glass will increase. 2 O 3 The content of is preferably within the above range.

[0193] Furthermore, in the optical glass of the second embodiment, TiO 2 The content of TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 The mass ratio of the total content [TiO 2 / (TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 )] is 0.03 or more and less than 0.15. The mass ratio [TiO 2 / (TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 )] is more preferably 0.04 or more, and still more preferably 0.05 or more. 2 / (TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 )] is more preferably 0.10 or less, and even more preferably 0.08 or less.

[0194] TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 All of them are glass components that contribute to high dispersion, but they can also cause coloration. In particular, TiO 2 , which is related to Nb 2 O 5 , WO 3 and Bi 2O 3 It is more conducive to high dispersion, but it is easy to increase the coloring of the glass. 2 It has the effect of promoting the formation of crystals in the glass during the process of shaping and slowly cooling the molten glass, thereby reducing the transparency of the glass (cloudiness). 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 TiO 2 The content ratio is preferably within the above range.

[0195] In the optical glass of the second embodiment, Li 2 The content of O is preferably 5% or less, more preferably 3% or less, and then 1% or less. 2 The lower limit of the O content is preferably 0%.

[0196] In the optical glass of the second embodiment, Na 2 The content of O is preferably 5% or less, and more preferably 3% or less. 2 The lower limit of the O content is preferably 0%.

[0197] In the optical glass of the second embodiment, K 2 The content of O is preferably 10% or less, and more preferably 8% or less. 2 The lower limit of the O content is preferably 0%.

[0198] Li 2 O、Na 2 O and K 2 O has the function of lowering the liquidus temperature and improving the thermal stability of glass, but when these contents increase, chemical durability and weather resistance will decrease. 2 O、Na 2 O and K 2 Each content of O is preferably within the above range.

[0199] In the optical glass of the second embodiment, Li 2 O、Na 2 O and K 2 Total O content [Li 2 O+Na 2 O+K 2 O] is preferably 15% or less, more preferably 12% or less, and 10% or less. 2 O+Na 2 O+K 2O] is preferably 5% or more, more preferably 6% or more, and then 7% or more.

[0200] Li 2 O、Na 2 O and K 2 O has the function of lowering the liquidus temperature and improving the thermal stability of glass. However, when the content of these increases, the chemical durability and weather resistance will decrease. Therefore, Li 2 O、Na 2 O and K 2 Total O content [Li 2 O+Na 2 O+K 2 O] is preferably within the above range.

[0201] In the optical glass of the second embodiment, Cs 2 The content of O is preferably 2% or more.

[0202] Cs 2 O has the function of improving the thermal stability of glass, but when the content increases, the chemical durability and weather resistance will decrease. 2 The O content is preferably within the above range.

[0203] In the optical glass of the second embodiment, the content of MgO is preferably 5% or less, more preferably 3% or less, and 1% or less in that order. In addition, the lower limit of the content of MgO is preferably 0%.

[0204] In the optical glass of the second embodiment, the content of CaO is preferably 5% or less, more preferably 3% or less, and 1% or less in that order. In addition, the lower limit of the content of CaO is preferably 0%.

[0205] In the optical glass of the second embodiment, the content of SrO is preferably 5% or less, more preferably 3% or less, and 1% or less in that order. In addition, the lower limit of the content of SrO is preferably 0%.

[0206] In the optical glass of the second embodiment, the content of BaO is preferably 5% or less, more preferably 3% or less, and 1% or less in that order. In addition, the lower limit of the content of BaO is preferably 0%.

[0207] MgO, CaO, SrO, and BaO are all glass components that have the function of improving the thermal stability and devitrification resistance of glass. However, when the content of these glass components increases, high dispersion will be impaired, and the thermal stability and devitrification resistance of glass will decrease. Therefore, the content of each of these glass components is preferably within the above range.

[0208] In the optical glass of the second embodiment, the total content of MgO, CaO, SrO and BaO [MgO + CaO + SrO + BaO] is preferably 6% or less, and further preferably 4% or less and 2% or less in that order. In addition, the lower limit of the total content [MgO + CaO + SrO + BaO] is preferably 0%. The total content [MgO + CaO + SrO + BaO] may be 0%. From the viewpoint of maintaining thermal stability without hindering high dispersion, the total content [MgO + CaO + SrO + BaO] is preferably within the above range.

[0209] In the optical glass of the second embodiment, the content of ZnO is preferably 5% or less, more preferably 3% or less, and 1% or less in that order. In addition, the lower limit of the content of ZnO is preferably 0%.

[0210] ZnO is a glass component that has the function of improving the thermal stability of glass. However, when the content of ZnO is too much, the high dispersion of the glass will be damaged. Therefore, from the viewpoint of improving the thermal stability of the glass and maintaining the desired optical properties, the content of ZnO is preferably within the above range.

[0211] In the optical glass of the second embodiment, ZrO 2 The content of ZrO is preferably 5% or less, more preferably 3% or less, and 1% or less. 2 The lower limit of the content is preferably 0%.

[0212] ZrO 2 It is a glass component that has the function of improving the thermal stability and resistance to devitrification of glass. 2 When the content of ZrO is too high, the thermal stability of the glass tends to decrease. Therefore, from the perspective of maintaining the thermal stability of the glass, ZrO 2 The content of is preferably within the above range.

[0213] In the optical glass of the second embodiment, Ta 2 O 5 The content of Ta is preferably 5% or less, more preferably 3% or less, and then 2% or less. 2 O 5 The lower limit of the content is preferably 0%.

[0214] Ta 2 O 5 It is a glass component having the function of improving the thermal stability of glass. 2 O 5 The refractive index is increased, and the dispersion of the glass is reduced. 2 O 5When the content of Ta increases, the thermal stability of the glass decreases, and when the glass is melted, molten residues of the glass raw materials are easily generated. 2 O 5 The content of is preferably within the above range.

[0215] In the optical glass of the second embodiment, Sc 2 O 3 The content of Sc is preferably 2% or less. 2 O 3 The lower limit of the content is preferably 0%.

[0216] In the optical glass of the second embodiment, HfO 2 The content of HfO is preferably 2% or less. 2 The lower limit of the content is preferably 0%.

[0217] Sc 2 O 3 , HfO 2 Both have the function of increasing the refractive index nd and are expensive components. 2 O 3 , HfO 2 Each content of is preferably within the above range.

[0218] In the optical glass of the second embodiment, Lu 2 O 3 The content of Lu is preferably 2% or less. 2 O 3 The lower limit of the content is preferably 0%.

[0219] Lu 2 O 3 It has the function of increasing the refractive index nd. In addition, due to its large molecular weight, it is also a glass component that increases the specific gravity of the glass. 2 O 3 The content of is preferably within the above range.

[0220] In the optical glass of the second embodiment, GeO 2 The content of GeO is preferably less than 2%. 2 The lower limit of the content is preferably 0%.

[0221] GeO 2 GeO has the function of increasing the refractive index nd and is an extremely expensive component among the commonly used glass components. Therefore, from the perspective of reducing the manufacturing cost of glass, GeO 2 The content of is preferably within the above range.

[0222] In the optical glass of the second embodiment, La 2 O3 The content of La is preferably 2% or less. 2 O 3 The lower limit of the content is preferably 0%.

[0223] When La 2 O 3 When the content of La increases, the thermal stability of the glass decreases. Therefore, from the perspective of suppressing the decrease in the thermal stability of the glass, La 2 O 3 The content of is preferably within the above range.

[0224] In the optical glass of the second embodiment, Gd 2 O 3 The content of Gd is preferably 2% or less. 2 O 3 The lower limit of the content is preferably 0%.

[0225] When Gd 2 O 3 When the content of Gd becomes too high, the thermal stability of the glass decreases. 2 O 3 If the content of Gd becomes too much, the specific gravity of the glass increases, which is not preferred. Therefore, from the perspective of maintaining the thermal stability of the glass and suppressing the increase in specific gravity, Gd 2 O 3 The content of is preferably within the above range.

[0226] In the optical glass of the second embodiment, Y 2 O 3 The content of Y is preferably 2% or less. 2 O 3 The lower limit of the content is preferably 0%.

[0227] When Y 2 O 3 When the content of Y becomes too much, the thermal stability of the glass decreases, and the glass is easily devitrified during production. Therefore, from the perspective of suppressing the decrease in the thermal stability of the glass, Y 2 O 3 The content of is preferably within the above range.

[0228] In the optical glass of the second embodiment, Yb 2 O 3 The content of Yb is preferably 2% or less. 2 O 3 The lower limit of the content is preferably 0%.

[0229] Yb 2 O 3 Because of La 2 O3 , Gd 2 O 3 , Y 2 O 3 The molecular weight is larger than that of the glass, so the specific gravity of the glass increases. When the specific gravity of the glass increases, the mass of the optical element increases. For example, when a heavy lens is assembled in an autofocus camera lens, the power required to drive the lens during autofocusing increases, and the battery consumption becomes more severe. Therefore, it is desirable to reduce Yb 2 O 3 The content of glass can suppress the increase of specific gravity of glass.

[0230] In addition, when Yb 2 O 3 If the content of Yb is too high, the thermal stability of the glass will decrease. From the perspective of preventing the decrease in the thermal stability of the glass and suppressing the increase in specific gravity, Yb 2 O 3 The content of is preferably within the above range.

[0231] The optical glass of the second embodiment preferably mainly consists of the above-mentioned glass components, namely, P 2 O 5 , B 2 O 3 、SiO 2 、Al 2 O 3 、TiO 2 , Nb 2 O 5 , WO 3 、Bi 2 O 3 , Li 2 O、Na 2 O.K 2 O、Cs 2 O, MgO, CaO, SrO, BaO, ZnO, ZrO 2 、 2 O 5 Sc 2 O 3 , HfO 2 、Lu 2 O 3 ,GeO 2 ,La 2 O 3 , Gd 2 O 3 , Y 2 O 3 and Yb 2 O 3In the structure, the total content of the above-mentioned glass components is preferably more than 95%, more preferably more than 98%, further preferably more than 99%, and further preferably more than 99.5%.

[0232] In the optical glass of the second embodiment, TeO 2 The content of TeO is preferably 2% or less. 2 The lower limit of the content is preferably 0%.

[0233] Due to TeO 2 It is toxic, so it is preferred to reduce TeO 2 Therefore, TeO 2 The content of is preferably within the above range.

[0234] The optical glass of the second embodiment is preferably basically composed of the above-mentioned glass components, but may contain other components within a range that does not hinder the effects of the present invention. In the present invention, the inclusion of inevitable impurities is not excluded.

[0235] The other component compositions of the second embodiment can be set in the same manner as in the first embodiment.

[0236] (Glass properties)

[0237] In the optical glass of the second embodiment, the refractive index nd is greater than or equal to 1.87 and less than or equal to 1.92. The refractive index nd is preferably greater than or equal to 1.880, and more preferably greater than or equal to 1.885, greater than or equal to 1.890, and greater than or equal to 1.895. In addition, the refractive index nd is preferably less than or equal to 1.915, and more preferably less than or equal to 1.910, less than or equal to 1.905, and less than or equal to 1.900.

[0238] In the optical glass of the second embodiment, the Abbe number νd is greater than or equal to 15 and less than or equal to 25. The Abbe number νd is preferably greater than or equal to 16, and more preferably greater than or equal to 17, greater than or equal to 18, and greater than or equal to 19. In addition, the Abbe number νd is preferably less than or equal to 24, and more preferably less than or equal to 23, less than or equal to 22, and less than or equal to 21.

[0239] <Glass transition temperature Tg>

[0240] The glass transition temperature Tg of the optical glass of the second embodiment is preferably 750°C or lower, more preferably 730°C or lower, and 710°C or lower. The glass transition temperature Tg is preferably 520°C or higher, more preferably 560°C or higher, and 600°C or higher.

[0241] By making the glass transition temperature Tg satisfy the above range, the increase in the annealing temperature of the glass can be suppressed, and thermal damage to annealing equipment, for example, a continuous annealing furnace called RARE or a batch annealing furnace can be reduced.

[0242] By making the glass transition temperature Tg satisfy the above range, it is easy to maintain a desired Abbe number and refractive index and to maintain good thermal stability of the glass.

[0243] <Light Transmittance of Glass>

[0244] In the second embodiment, light transmittance can be evaluated based on the coloring degree λ5.

[0245] A glass (thickness 10.0 mm ± 0.1 mm) having two parallel optically polished planes is used, and light is incident perpendicularly to one of the two planes. Then, the ratio of the intensity Iout of the transmitted light emitted from the other plane to the intensity Iin of the incident light (Iout / Iin) is calculated, that is, the external transmittance is calculated. Using a spectrometer, the wavelength of the incident light is scanned in the range of, for example, 280 to 700 nm, and the external transmittance is measured, thereby obtaining a spectral transmittance curve.

[0246] As the wavelength of incident light changes from the absorption edge on the short wavelength side of the glass toward the long wavelength side, the external transmittance increases and shows a high value.

[0247] λ5 is a wavelength at which the external transmittance is 5%. In the wavelength region of 280 to 700 nm, the external transmittance of glass on the longer wavelength side than λ5 shows a value greater than 5%.

[0248] By using an optical glass having a shorter wavelength of λ5, it is possible to provide an optical element capable of achieving appropriate color reproduction.

[0249] For this reason, the range of λ5 is preferably 400 nm or less, and more preferably 390 nm or less. The standard of the lower limit of λ5 is, for example, 360 nm.

[0250] <Specific gravity of glass>

[0251] The optical glass of the second embodiment is a high-refractive-index, high-dispersion glass with a low specific gravity. Generally, if the specific gravity of the glass can be reduced, the weight of the lens can be reduced. As a result, the power consumption of the autofocus drive of the lens equipped with the lens can be reduced. On the other hand, when the specific gravity is reduced excessively, it will lead to a decrease in thermal stability. Here, since the specific gravity d depends on the refractive index nd, in this embodiment, the specific gravity d is divided by (nd-1) to standardize it. In the second embodiment, the standardized specific gravity [d / (nd-1)] is preferably less than 4.0, and more preferably less than 3.9. In addition, from the viewpoint of improving thermal stability, [d / (nd-1)] is preferably greater than 3.0.

[0252] The production of the optical glass and the production of the optical element and the like according to the second embodiment can be set in the same manner as in the first embodiment.

[0253] Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to the following examples.

[0254] (Example 1)

[0255] [Production of glass samples]

[0256] In order to obtain glass having the composition of No. 1-1 to 1-32 shown in Tables 1-1 and 1-2, compound raw materials corresponding to each component, that is, raw materials such as phosphate, carbonate, oxide, etc., are weighed and fully mixed to prepare a blended raw material. The blended raw material is put into a platinum crucible, heated to 1000 to 1350° C. in an atmospheric environment to melt, and homogenized and clarified by stirring to obtain molten glass. The molten glass is cast into a molding die to be molded, and slowly cooled to obtain a bulk glass sample.

[0257] [Evaluation of glass samples]

[0258] The obtained glass samples were measured for glass composition, specific gravity, refractive index nd, Abbe number νd, λ5, glass transition temperature Tg and crystal melting peak temperature Tl using the methods shown below, and moldability and devitrification resistance were evaluated.

[0259] [1] Glass composition

[0260] Appropriate amounts of the glass samples obtained as described above were selected, subjected to acid and alkali treatments, and the contents of the glass components were measured using ICP-AES. The results are shown in Tables 1-1 and 1-2.

[0261] [2] Specific gravity

[0262] The measurement was performed based on the Japan Optical Glass Industry Association Standard JOGIS-05. The results are shown in Tables 1-4 and 1-5.

[0263] [3] Refractive index nd and Abbe number νd

[0264] The measurement was performed based on the Japan Optical Glass Industry Association Standard JOGIS-01. The results are shown in Tables 1-4 and 1-5.

[0265] [4] Glass transition temperature Tg, crystal melting peak temperature Tl

[0266] The glass transition temperature Tg and the crystal melting peak temperature Tl were determined based on a DSC chart of a solid glass when the temperature was increased using a differential scanning calorimeter DSC3300SA (NETZSCH Japan). The results are shown in Tables 1-4 and 1-5.

[0267] [5]λ5

[0268] The glass sample was processed into a 10 mm thick, parallel and optically polished plane, and the spectral transmittance in the wavelength range from 280 nm to 700 nm was measured. The intensity of the light incident vertically on one optically polished plane was set as intensity A, and the intensity of the light emitted from the other plane was set as intensity B, and the spectral transmittance B / A was calculated. The wavelength at which the spectral transmittance is 5% was set as λ5. In addition, the spectral transmittance also includes the reflection loss of the light at the surface of the sample. The results are shown in Tables 1-4 and 1-5.

[0269] [6] Formability

[0270] In this embodiment, the formability of the molten glass is evaluated based on whether the crystal melting peak temperature T1 satisfies the following formula (2). The case where the crystal melting peak temperature T1 obtained in the above [4] satisfies the formula (2) is judged as "good", and the case where the crystal melting peak temperature T1 does not satisfy the following formula (2) is judged as "bad". The results are shown in Tables 1-4 and 1-5.

[0271] Tl<1000nd-790…(2)

[0272] The evaluation of the glasses No. 1-1 to 1-32 of the examples was all “good.” It was confirmed that the glasses No. 1-1 to 1-32 of the examples were glasses having excellent moldability of molten glass.

[0273] [7] Softening test (devitrification resistance)

[0274] In the present embodiment, the softening test is an evaluation method that serves as an index of resistance to devitrification. A 1 cm square glass sample is heated in a first test furnace for 10 minutes, and then in a second test furnace for 10 minutes, and then the presence or absence of crystals or turbidity is confirmed with an optical microscope, wherein the first test furnace is set to the glass transition temperature Tg of the glass, and the second test furnace is set to a temperature 120 to 200°C higher than the Tg of the glass. The observation magnification of the optical microscope is 10 to 100 times. The case where no crystals or turbidity are confirmed is judged as "good", and the case where at least one of crystals and turbidity is confirmed is judged as "bad". The results are shown in Tables 1-4 and 1-5. The judgments of the glasses No. 1-1 to 1-32 of the examples are all "good". It is confirmed that the glasses No. 1-1 to 1-32 of the examples are glasses with excellent resistance to devitrification.

[0275] (Comparative Example 1)

[0276] (Production and evaluation of glass samples No. 1-33 to 1-41)

[0277] The glasses were prepared and evaluated in the same manner as for Glass No. 1-1 to 1-32. The results are shown in Tables 1-3 and 1-6.

[0278] Glass Nos. 1-33 to 1-41 of the comparative examples were judged as “poor” in the evaluation of formability or softening test. The glasses of the comparative examples were inferior in thermal stability or devitrification resistance to the glasses of the examples.

[0279] [Table 1-1]

[0280]

[0281] [Table 1-2]

[0282]

[0283] [Table 1-3]

[0284]

[0285] [Table 1-4]

[0286]

[0287] [Table 1-5]

[0288]

[0289] [Table 1-6]

[0290]

[0291] (Fabrication of optical component blanks)

[0292] Glass samples having compositions of No. 1-1 to 1-32 shown in Tables 1-1 and 1-2 were annealed, cut, and ground to produce slices.

[0293] The slices are pressed into shape by reheating and pressing to produce optical element blanks.

[0294] The optical element blank is subjected to precision annealing to precisely adjust the refractive index to a desired refractive index, and then ground and polished by a known method to obtain an optical element.

[0295] (Example 2)

[0296] [Production of glass samples No.2-1 to No.2-18]

[0297] In order to obtain a glass having the composition shown in Tables 2-1 and 2-2, compound raw materials corresponding to each component, that is, raw materials such as phosphates, carbonates, and oxides, are weighed and fully mixed to prepare a blended raw material. The blended raw material is put into a platinum crucible, heated to 1000°C to 1350°C in an atmospheric environment to melt, and homogenized and clarified by stirring to obtain molten glass. The molten glass is cast into a molding die to be molded, and slowly cooled to obtain a bulk glass sample.

[0298] [Evaluation of glass samples]

[0299] The glass composition, specific gravity, refractive index nd, Abbe number νd, λ5 and glass transition temperature Tg of the obtained glass samples were measured in the same manner as in Example 1. The results are shown in Tables 2-1, 2-2, 2-3 and 2-4. In addition, thermal stability and devitrification resistance were evaluated using the methods shown below.

[0300] (1) Thermal stability

[0301] The molten glass is cast into a molding die and slowly cooled to obtain a block-shaped glass sample. The obtained glass sample is then observed for crystals in the glass using an optical microscope. The magnification of the optical microscope is 10 to 100 times. The case where no crystals are confirmed is judged as "good", and the case where crystals are confirmed is judged as "bad". The results are shown in Tables 2-3 and 2-4. The judgments for Example Glass No. 2-1 to 2-18 are all "good". It is confirmed that the glasses of Example Glass No. 2-1 to 2-18 are glasses with excellent thermal stability.

[0302] (2) Softening test (devitrification resistance)

[0303] In this specification, the softening test is an evaluation method that serves as an index of resistance to devitrification. A 1 cm square glass sample is heated in the first test furnace for 10 minutes, and then in the second test furnace for 10 minutes, and then the presence or absence of crystals or turbidity is confirmed with an optical microscope, wherein the first test furnace is set to the glass transition temperature Tg of the glass, and the second test furnace is set to a temperature 120 to 200°C higher than the Tg of the glass. The observation magnification of the optical microscope is 10 to 100 times. The case where no crystals or turbidity are confirmed is judged as "good", and the case where at least one of crystals and turbidity is confirmed is judged as "poor". The results are shown in Tables 2-3 and 2-4. The judgments for Example Glass No. 2-1 to 2-18 are all "good". It is confirmed that Example Glass No. 2-1 to 2-18 is a glass with excellent resistance to devitrification.

[0304] (Comparative Example 2)

[0305] (Production and evaluation of glass samples No. 2-19 to 2-24)

[0306] The glasses were prepared and evaluated in the same manner as in Glass No. 2-1 to 2-18 of the examples. The results are shown in Table 2-4.

[0307] Glass Nos. 2-19 to 2-24 of Comparative Examples were judged as “poor” in the thermal stability or softening test, and were inferior in thermal stability or devitrification resistance to the glasses of Examples.

[0308] In addition, although the glass No. 2-24 of the comparative example was excellent in thermal stability and devitrification resistance, its normalized specific gravity [d / (nd-1)] was larger than that of the glass of the example.

[0309] [Table 2-1]

[0310]

[0311] [Table 2-2]

[0312]

[0313] [Table 2-3]

[0314]

[0315] [Table 2-4]

[0316]

[0317] (Fabrication of optical component blanks and optical components)

[0318] Glass samples having compositions of No. 2-1 to 2-18 shown in Tables 2-1 and 2-2 were annealed, cut, and ground to produce slices.

[0319] The slices are pressed into shape by reheating and pressing to produce optical element blanks.

[0320] The optical element blank is subjected to precision annealing to precisely adjust the refractive index to a desired refractive index, and then ground and polished by a known method to obtain an optical element.

Claims

1. An optical glass, in, In the glass composition based on oxides, P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The total content [P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 ] is 26 mass % or more, B 2 O 3 The content of P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The mass ratio of the total content [B 2 O 3 / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is 0.11 or more and 0.24 or less, Li 2 O、Na 2 O and K 2 Total content of O and P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The mass ratio of the total content [(Li 2 O+Na 2 O+K 2 O) / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is 0.35 or more and 0.56 or less, TiO 2 The content of TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 The mass ratio of the total content [TiO 2 / (TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 )] is 0.12 or more and 0.32 or less, The refractive index nd is greater than 1.85 and less than 1.90, and the Abbe number νd is greater than or equal to 15 and less than or equal to 25.

2. The optical glass according to claim 1, in, Bi 2 O 3 The content is less than 5% by mass.

3. The optical glass according to claim 1 or 2, in, P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The total content of TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 The mass ratio of the total content [(P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 ) / (TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 )] is greater than 0.40 and less than 0.

60.

4. An optical glass, in, In the glass composition based on oxides, B 2 O 3 The content of P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The mass ratio of the total content [B 2 O 3 / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is 0.10 or more and 0.22 or less, Li 2 O、Na 2 O and K 2 Total content of O and P 2 O 5 , B 2 O 3 、SiO 2 、Al 2 O 3 The mass ratio of the total content [(Li 2 O+Na 2 O+K 2 O) / (P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 )] is 0.30 or more and 0.38 or less, TiO 2 , WO 3 and Bi 2 O 3 The total content of Nb 2 O 5 The mass ratio of the content [(TiO 2 +WO 3 +Bi 2 O 3 ) / Nb 2 O 5 ] is less than 0.15, The refractive index nd is greater than or equal to 1.87 and less than or equal to 1.92, and the Abbe number νd is greater than or equal to 15 and less than or equal to 25.

5. The optical glass according to claim 4, in, TiO 2 The content of TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 The mass ratio of the total content [TiO 2 / (TiO 2 +Nb 2 O 5 +WO 3 +Bi 2 O 3 )] is greater than 0.03 and less than 0.

15.

6. The optical glass according to claim 4 or 5, in, P 2 O 5 , B 2 O 3 、SiO 2 and Al 2 O 3 The total content [P 2 O 5 +B 2 O 3 +SiO 2 +Al 2 O 3 ] is greater than 25 mass %.

7. An optical element blank, which is composed of the optical glass according to any one of claims 1 to 6.

8. An optical element, comprising the optical glass according to any one of claims 1 to 6.

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