Optical glass and optical element

Abstract

Provided is a fluorophosphate glass having a low coefficient of thermal expansion. The optical glass contains O ions, F ions, Al ions, P ions, Mg ions, Ca ions, Sr ions and Ba ions as essential components, and in the glass composition expressed in atom%, the content ratio (O / P) of the O ions to the P ions is 3.30-4.50, the content ratio (Al / P) of the Al ions to the P ions is 1.50 or less, the content ratio (F / Al) of the F ions to the Al ions is 6.00 or less, and the content ratio of the Mg ions to the P ions is 1.00 or less. In the glass composition represented by cation%, the total content (Mg + Ca + Sr + Ba) is 40.00 cation% or more, and the cation ratio ((Mg + Ca) / (Mg + Ca + Sr + Ba)) of the total content of Mg ions and Ca ions to the total content of Mg ions, Ca ions, Sr ions, and Ba ions is 0.40 or more.

Description

Technical Field

[0001] The present invention relates to optical glass and optical elements. Background Art

[0002] Fluorophosphate glass is generally an optical glass with low dispersibility and has been used as a material for various optical elements (for example, see Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent No. 6062713 Specification Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] As one of the physical properties desired for optical glass, a property of having a low coefficient of thermal expansion can be cited. For example, by using an optical glass with a small coefficient of thermal expansion, breakage and crack generation of the glass during press molding can be suppressed.

[0008] An object of one embodiment of the present invention is to provide a fluorophosphate glass having a low coefficient of thermal expansion.

[0009] Means for Solving the Problems

[0010] The present inventors repeatedly conducted in-depth studies and as a result newly found that: a fluorophosphate glass having the following glass composition can exhibit a low coefficient of thermal expansion.

[0011] One embodiment of the present invention is as follows.

[0012] [1] An optical glass (hereinafter, also simply referred to as "glass") containing O ions, F ions, Al ions, P ions, Mg ions, Ca ions, Sr ions, and Ba ions as essential components,

[0013] In the glass composition expressed in atomic %,

[0014] The ratio (O / P) of the content of O ions to the content of P ions (hereinafter, also referred to as "O / P ratio" or "O / P") is 3.30 or more and 4.50 or less,

[0015] The ratio (Al / P) of the content of Al ions to the content of P ions (hereinafter, also referred to as "Al / P ratio" or "Al / P") is 1.50 or less,

[0016] The ratio (F / Al) of the content of F ions to the content of Al ions (hereinafter, also referred to as "F / Al ratio" or "F / Al") is 6.00 or less,

[0017] In the glass composition expressed in terms of cation %,

[0018] the total content of Mg ions, Ca ions, Sr ions and Ba ions (Mg + Ca + Sr + Ba) is 40.00 cation % or more,

[0019] and the cation ratio of the total content of Mg ions and Ca ions to the total content of Mg ions, Ca ions, Sr ions and Ba ions ((Mg + Ca) / (Mg + Ca + Sr + Ba)) is 0.40 or more.

[0020] [2] The optical glass according to [1], wherein,

[0021] the total content of Li ions, Na ions and K ions (Li + Na + K) is 20.00 cation % or less.

[0022] [3] The optical glass according to [1] or [2], wherein,

[0023] the cation ratio of the content of Mg ions to the content of Ba ions (Mg / Ba) is 0.05 or more and 5.00 or less.

[0024] [4] The optical glass according to any one of [1] to [3], wherein,

[0025] the total content of Mg ions and Ca ions (Mg + Ca) is 1.00 cation % or more and 50.00 cation % or less.

[0026] [5] The optical glass according to any one of [1] to [4], wherein,

[0027] the total content of Y ions, La ions, Gd ions and Yb ions (Y + La + Gd + Yb) is 0.10 cation % or more and 5.00 cation % or less.

[0028] [6] The optical glass according to any one of [1] to [5], wherein,

[0029] the total content of Si ions and B ions (Si + B) is 10.00 cation % or less.

[0030] [7] The optical glass according to any one of [1] to [6], having an average coefficient of linear expansion α of less than 155×10 -7 / K at 100 °C to 300 °C.

[0031] [8] The optical glass according to any one of [1] to [7], wherein,

[0032] The total content of Li ions, Na ions, and K ions (Li + Na + K) is 20.00 cation % or less, and the cation ratio of the content of Mg ions to the content of Ba ions (Mg / Ba) is 0.05 or more and 5.00 or less.

[0033] The total content of Mg ions and Ca ions (Mg + Ca) is 1.00 cation % or more and 50.00 cation % or less.

[0034] The total content of Y ions, La ions, Gd ions, and Yb ions (Y + La + Gd + Yb) is 0.10 cation % or more and 5.00 cation % or less.

[0035] The total content of Si ions and B ions (Si + B) is 10.00 cation % or less.

[0036] Furthermore, the average coefficient of linear expansion α of the above optical glass at 100°C to 300°C is less than 155×10 -7 / K.

[0037] [9] An optical element made of the optical glass according to any one of [1] to [8].

[0038] Effects of the Invention

[0039] According to an embodiment of the present invention, an optical glass having a low coefficient of thermal expansion as a fluoro-phosphate glass and an optical element made of the optical glass can be provided. Detailed Embodiments

[0040] [Optical Glass]

[0041] <Glass Composition>

[0042] (Analysis Method)

[0043] For various components constituting the glass, the content (mass % of the element) of the elements contained in the glass can be quantified by known methods, such as inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), etc.

[0044] For the anion components, the anion components contained in the glass can be identified and quantified by known analysis methods, such as ion chromatography, non-dispersive infrared absorption method (ND-IR), etc.

[0045] It should be noted that in the present invention and this specification, the content of a constituent being 0%, 0.0%, 0.00%, or not containing or not introducing means that the constituent is substantially not contained, and it is allowed to contain the constituent at an inevitable impurity level.

[0046] (Description of Glass Composition Based on Oxides)

[0047] Based on the results obtained from the above analysis, the content of each component in the glass composition based on oxides (unit: mol%) can be calculated, and the specific method is as described below.

[0048] The content of element i (mass% P of the element) obtained by the above analysis method i is divided by the atomic weight M of element i i , and thus the number of moles n of each element is obtained i = P i / M i .

[0049] When the above element i is the cation component A i , the number of moles n of the element obtained above i is replaced with the number of moles n' of the corresponding oxide i . Specifically, when the composition formula of the oxide corresponding to the cation component A i is represented by A i xOy, n' i = n i / x.

[0050] When the above element i is the anion component B i other than the O ion, the number of moles n of the above element i is hereinafter denoted as m i .

[0051] The content of the cation component A i in the glass composition based on oxides, in terms of the oxide A i xOy, PA i (mol%) is represented by PA i = n' i / (Σn' i + Σm i ) × 100.

[0052] The content in the glass composition based on oxides can also refer to the oxide-based fraction.

[0053] In the glass composition based on oxides, the oxide-based fraction PB i of the anion component B i other than the O ion (mol%) is represented by PB i = m i / (Σn' i + Σm i ) × 100.

[0054] Here, Σn' i It is the oxide of the cationic component contained in the glass. i The total number of moles of xOy. The effective figures of the content are used so that even if trace amounts of components are ignored, the calculation results will not be affected.

[0055] (cation %, anion %)

[0056] In the present invention and this specification, unless otherwise specified, the content and total content of cationic components are expressed as cation %, and unless otherwise specified, the content and total content of anionic components are expressed as anion %.

[0057] Here, "cation %" refers to the content in the oxide-based glass composition (expressed in mol %), and is the value calculated by "(number of cations of concern / total number of cations in the glass component) × 100", which is the molar percentage of the cation amount of concern relative to the total amount of cationic components.

[0058] The molar ratio of the contents of the cationic components to each other (cation ratio) is equal to the ratio of the content of the cationic component of interest expressed in cation %.

[0059] "Anion %" refers to the content in the oxide-based glass composition (expressed in mole %), and is the value calculated by "(number of anions of interest / total number of anions in the glass component) × 100", which is the molar percentage of the anion amount of interest relative to the total amount of anion components.

[0060] Based on the description of the above oxide-based glass composition, regarding the anion % of O ions, in the case of A i xOy represents the cationic component A corresponding to element i i The composition formula of the oxide is as follows, and the cationic component A is used i Oxide base fraction PA i (mol%) The cationic component A i The number of O contained in the oxide is expressed as O i =PA i ×y, the anion component B k The valence number is expressed as N k When the anion percentage of O ions is i -Σ(N k / 2)B k ) / (ΣO i -Σ(N k / 2)B k +ΣB k )×100 to calculate.

[0061] Here, ΣOi is the total number of moles of O ions in the glass composition based on oxides, Σ(N k / 2)B k represents the number of moles of O ions replaced by the anion component B k . The numerator in the formula (ΣO i -Σ(N k / 2)B k ) is the number of moles of O ions contained in the glass.

[0062] On the other hand, in the present invention and this specification, regarding the oxygen content, when anion components other than oxygen cannot be detected by analysis based on known methods, all of the anion components (i.e., 100 anion %) are O ions.

[0063] (Cation components, anion components)

[0064] Regarding the valence of cation components, the formal valence of each cation is used. The formal valence refers to the valence necessary to maintain the electrical neutrality of the oxide when the valence of the O ions constituting the oxide is set to -2 for the oxide of the cation of interest, and can be clearly obtained from the chemical formula of the oxide.

[0065] For example, for P ions, in order to maintain the electrical neutrality of O 2- and P contained in the chemical formula of the oxide P2O5, the valence of P is +2×5 / 2 = +5. Generalizing this, the formal valence of the cation Ai contained in the oxide AixOy is "+2y / x". Therefore, when analyzing the glass composition, it is not necessary to analyze up to the valence of the cations.

[0066] In addition, regarding the valence of anions (for example, the valence of O ions is -2), it is also the formal valence based on the idea that O ions accept 2 electrons to adopt a closed-shell structure. Therefore, when analyzing the glass composition, it is not necessary to analyze up to the valence of the anions. In addition, a part of Cu 2+ may become Cu + during melting, but usually the amount is small. Therefore, the valence of Cu can all be regarded as +2.

[0067] (Various ratios in the glass composition expressed in atomic %)

[0068] In the glass composition expressed in atomic %, the ratio of the content of cation components to the content of anion components is the ratio of the contents (expressed in atomic %) of the components of interest when the total amount of all cation components and all anion components is set to 100 atomic %.

[0069] Therefore, the ratio of the content of O ions to the content of P ions (O / P) is the ratio of the content of O ions (expressed in atomic %) to the content of P ions (expressed in atomic %) when the total amount of all cation components and all anion components is set to 100 atomic %.

[0070] The ratio of the content of Al ions to the content of P ions (Al / P) is the ratio of the content of Al ions (expressed in atomic %) to the content of P ions (expressed in atomic %) when the total amount of all cation components and all anion components is set to 100 atomic %.

[0071] The ratio of the content of F ions to the content of Al ions (F / Al) is the ratio of the content of F ions (expressed in atomic %) to the content of Al ions (expressed in atomic %) when the total amount of all cation components and all anion components is set to 100 atomic %.

[0072] Hereinafter, the glass composition of the above optical glass will be described.

[0073] The above optical glass contains O ions, F ions, Al ions, P ions, Mg ions, Ca ions, Sr ions and Ba ions as essential components. The content of each of the above ions as essential components exceeds 0.00 atomic % when expressed in atomic %, exceeds 0.00 anion % in terms of anion components, and exceeds 0.00 cation % in terms of cation components.

[0074] In the glass composition expressed in atomic %, from the viewpoint of reducing the thermal expansion coefficient of the glass, the O / P ratio (O / P) is 3.30 or more, preferably 3.33 or more, and more preferably in the order of 3.35 or more, 3.38 or more, 3.40 or more, 3.42 or more, 3.44 or more, 3.46 or more, 3.48 or more, 3.50 or more.

[0075] From the viewpoint of maintaining the thermal stability of the glass, the O / P ratio is 4.50 or less, preferably 4.40 or less, and more preferably in the order of 4.30 or less, 4.20 or less, 4.10 or less, 4.00 or less.

[0076] From the viewpoint of maintaining the thermal stability of the glass, the Al / P ratio (Al / P) is 1.50 or less, preferably 1.40 or less, and more preferably in the order of 1.30 or less, 1.20 or less, 1.15 or less, 1.13 or less, 1.10 or less.

[0077] From the viewpoint of maintaining the high refractive index of the glass, the Al / P ratio (Al / P) is preferably 0.20 or more, and more preferably in the order of 0.30 or more, 0.40 or more, 0.50 or more, 0.60 or more, 0.70 or more, 0.80 or more.

[0078] From the viewpoint of reducing the thermal expansion coefficient of the glass, the F / Al ratio (F / Al) is 6.00 or less, preferably 5.95 or less, and more preferably in the order of 5.90 or less, 5.85 or less, 5.80 or less, 5.75 or less, 5.70 or less, 5.65 or less, 5.60 or less, 5.55 or less, 5.50 or less.

[0079] From the viewpoint of maintaining the low dispersibility of the glass, the F / Al ratio (F / Al) is preferably 3.00 or more, and more preferably in the order of 3.20 or more, 3.40 or more, 3.60 or more, 3.80 or more, 4.00 or more, 4.10 or more, 4.20 or more, 4.30 or more, 4.40 or more, 4.50 or more.

[0080] Regarding the O ion content, from the viewpoints of maintaining the thermal stability and high refractive index of the glass, it is preferably 20.00 anion % or more, and more preferably in the order of 22.00 anion % or more, 24.00 anion % or more, 26.00 anion % or more, 28.00 anion % or more, 30.00 anion % or more.

[0081] From the viewpoint of maintaining the low dispersibility of the glass, the O ion content is preferably 80.00 anion % or less, and more preferably in the order of 75.00 anion % or less, 70.00 anion % or less, 65.00 anion % or less, 60.00 anion % or less, 58.00 anion % or less, 56.00 anion % or less, 54.00 anion % or less, 52.00 anion % or less, 50.00 anion % or less.

[0082] Regarding the F ion content, from the viewpoint of maintaining the low dispersibility of the glass, it is preferably 20.00 anion % or more, and more preferably in the order of 25.00 anion % or more, 30.00 anion % or more, 35.00 anion % or more, 40.00 anion % or more, 42.00 anion % or more, 44.00 anion % or more, 46.00 anion % or more, 48.00 anion % or more, 50.00 anion % or more.

[0083] From the viewpoint of maintaining the high refractive index of the glass, the F ion content is preferably 80.00 anion % or less, and more preferably in the order of 78.00 anion % or less, 76.00 anion % or less, 74.00 anion % or less, 72.00 anion % or less, 70.00 anion % or less.

[0084] Regarding the Al ion content, from the viewpoints of maintaining the thermal stability, chemical stability, and high refractive index of the glass, it is preferably 5.00 cation % or more, and more preferably in the order of 8.00 cation % or more, 10.00 cation % or more, 12.00 cation % or more, 14.00 cation % or more, 15.00 cation % or more, 16.00 cation % or more, 17.00 cation % or more, 18.00 cation % or more, 19.00 cation % or more, 20.00 cation % or more.

[0085] From the viewpoint of suppressing the rise in the liquidus temperature, the Al ion content is preferably 40.00 cation % or less, and more preferably in the order of 38.00 cation % or less, 36.00 cation % or less, 35.00 cation % or less, 34.00 cation % or less, 33.00 cation % or less, 32.00 cation % or less, 31.00 cation % or less, 30.00 cation % or less.

[0086] Regarding the P ion content, from the viewpoints of maintaining the thermal stability and low dispersibility of the glass, it is preferably 1.00 cation % or more, and more preferably in the order of 3.00 cation % or more, 5.00 cation % or more, 7.00 cation % or more, 10.00 cation % or more, 12.00 cation % or more, 14.00 cation % or more, 16.00 cation % or more, 18.00 cation % or more, 20.00 cation % or more.

[0087] From the viewpoint of maintaining the chemical durability of the glass, the P ion content is preferably 50.00 cation % or less, and more preferably in the order of 48.00 cation % or less, 46.00 cation % or less, 44.00 cation % or less, 42.00 cation % or less, 40.00 cation % or less, 38.00 cation % or less, 36.00 cation % or less, 35.00 cation % or less, 34.00 cation % or less, 33.00 cation % or less, 32.00 cation % or less, 31.00 cation % or less, 30.00 cation % or less.

[0088] Regarding the Mg ion content, from the viewpoints of maintaining the thermal stability of the glass and reducing the thermal expansion coefficient, it is preferably 0.10 cation % or more, and more preferably in the order of 0.50 cation % or more, 0.70 cation % or more, 1.00 cation % or more, 2.00 cation % or more, 3.00 cation % or more, 4.00 cation % or more, 5.00 cation % or more.

[0089] From the viewpoint of suppressing the decrease in the thermal stability of the glass, the Mg ion content is preferably 30.00 cation % or less, more preferably in the order of 25.00 cation % or less, 20.00 cation % or less, 18.00 cation % or less, 16.00 cation % or less, 15.00 cation % or less, 14.00 cation % or less, 13.00 cation % or less, 12.00 cation % or less, 11.00 cation % or less, 10.00 cation % or less.

[0090] Regarding the Ca ion content, from the viewpoints of maintaining the thermal stability of the glass and reducing the coefficient of thermal expansion, it is preferably 0.10 cation % or more, more preferably in the order of 0.50 cation % or more, 0.70 cation % or more, 1.00 cation % or more, 3.00 cation % or more, 5.00 cation % or more, 7.00 cation % or more, 10.00 cation % or more, 11.00 cation % or more, 12.00 cation % or more, 13.00 cation % or more, 14.00 cation % or more, 15.00 cation % or more.

[0091] From the viewpoint of suppressing the decrease in the thermal stability of the glass, the Ca ion content is preferably 40.00 cation % or less, more preferably in the order of 35.00 cation % or less, 33.00 cation % or less, 30.00 cation % or less, 29.00 cation % or less, 28.00 cation % or less, 27.00 cation % or less, 26.00 cation % or less, 25.00 cation % or less.

[0092] Regarding the Sr ion content, from the viewpoints of maintaining the thermal stability and high refractive index of the glass, it is preferably 0.10 cation % or more, more preferably in the order of 0.50 cation % or more, 0.70 cation % or more, 1.00 cation % or more, 3.00 cation % or more, 5.00 cation % or more, 7.00 cation % or more, 10.00 cation % or more, 11.00 cation % or more, 12.00 cation % or more, 13.00 cation % or more, 14.00 cation % or more, 15.00 cation % or more.

[0093] From the viewpoints of reducing the coefficient of thermal expansion and suppressing the decrease in the thermal stability, the Sr ion content is preferably 40.00 cation % or less, more preferably in the order of 35.00 cation % or less, 33.00 cation % or less, 30.00 cation % or less, 27.00 cation % or less, 25.00 cation % or less, 24.00 cation % or less, 23.00 cation % or less, 22.00 cation % or less, 21.00 cation % or less, 20.00 cation % or less.

[0094] Regarding Ba ions, from the viewpoint of maintaining the thermal stability and high refractive index of the glass, it is preferably 0.10 cation % or more, and more preferably in the order of 0.50 cation % or more, 0.70 cation % or more, 1.00 cation % or more, 2.00 cation % or more, 3.00 cation % or more, 4.00 cation % or more, 5.00 cation % or more.

[0095] From the viewpoints of reducing the thermal expansion coefficient, suppressing the increase in specific gravity, and suppressing the decrease in thermal stability, the content of Ba ions is preferably 30.00 cation % or less, and more preferably in the order of 25.00 cation % or less, 20.00 cation % or less, 18.00 cation % or less, 15.00 cation % or less, 14.00 cation % or less, 13.00 cation % or less, 12.00 cation % or less, 11.00 cation % or less, 10.00 cation % or less.

[0096] From the viewpoint of maintaining the thermal stability of the glass, the total content of Mg ions, Ca ions, Sr ions, and Ba ions (Mg + Ca + Sr + Ba) is 40.00 cation % or more, preferably 41.00 cation % or more, and more preferably in the order of 42.00 cation % or more, 43.00 cation % or more, 44.00 cation % or more, 45.00 cation % or more.

[0097] From the viewpoint of suppressing the decrease in the thermal stability of the glass, the total content of Mg ions, Ca ions, Sr ions, and Ba ions (Mg + Ca + Sr + Ba) is preferably 70.00 cation % or less, and more preferably in the order of 65.00 cation % or less, 63.00 cation % or less, 60.00 cation % or less, 57.00 cation % or less, 55.00 cation % or less.

[0098] From the viewpoints of maintaining the thermal stability of the glass and reducing the thermal expansion coefficient, the cation ratio of the total content of Mg ions and Ca ions to the total content of Mg ions, Ca ions, Sr ions, and Ba ions ((Mg + Ca) / (Mg + Ca + Sr + Ba)) is 0.40 or more, preferably 0.41 or more, and more preferably in the order of 0.42 or more, 0.43 or more, 0.44 or more, 0.45 or more.

[0099] From the viewpoint of maintaining the high refractive index of the glass, the total content of Mg ions and Ca ions relative to the total content of Mg ions, Ca ions, Sr ions and Ba ions, i.e., the cation ratio ((Mg + Ca) / (Mg + Ca + Sr + Ba)), is preferably 0.70 or less, and more preferably in the order of 0.65 or less, 0.63 or less, 0.60 or less, 0.59 or less, 0.58 or less, 0.57 or less, 0.56 or less, 0.55 or less.

[0100] From the viewpoints of maintaining the thermal stability of the glass and reducing the coefficient of thermal expansion, the cation ratio of the content of Mg ions to the content of Ba ions (Mg / Ba) is preferably 0.05 or more, and more preferably in the order of 0.08 or more, 0.10 or more, 0.13 or more, 0.15 or more, 0.18 or more, 0.20 or more, 0.30 or more, 0.40 or more, 0.50 or more, 0.60 or more.

[0101] From the viewpoint of maintaining the high refractive index of the glass, the above cation ratio (Mg / Ba) is preferably 5.00 or less, and more preferably in the order of 4.00 or less, 3.00 or less, 2.80 or less, 2.60 or less, 2.40 or less, 2.20 or less, 2.00 or less, 1.80 or less, 1.50 or less, 1.40 or less, 1.30 or less, 1.20 or less, 1.10 or less, 1.00 or less.

[0102] From the viewpoints of maintaining the thermal stability of the glass and reducing the coefficient of thermal expansion, the total content of Mg ions and Ca ions (Mg + Ca) is preferably 1.00 cation % or more, and more preferably in the order of 3.00 cation % or more, 5.00 cation % or more, 7.00 cation % or more, 10.00 cation % or more, 12.00 cation % or more, 10.00 cation % or more, 12.00 cation % or more, 14.00 cation % or more, 16.00 cation % or more, 18.00 cation % or more, 20.00 cation % or more.

[0103] From the viewpoint of maintaining the high refractive index of the glass, the total content of Mg ions and Ca ions (Mg + Ca) is preferably 50.00 cation % or less, and more preferably in the order of 45.00 cation % or less, 40.00 cation % or less, 38.00 cation % or less, 36.00 cation % or less, 34.00 cation % or less, 32.00 cation % or less, 30.00 cation % or less, 29.00 cation % or less, 28.00 cation % or less, 27.00 cation % or less, 26.00 cation % or less, 25.00 cation % or less.

[0104] The total content of Li ions, Na ions and K ions (Li + Na + K) can be 0.00 cation %, 0.00 cation % or more, more than 0.00 cation % or 0.10 cation % or more.

[0105] From the viewpoint of reducing the thermal expansion coefficient of the glass, the total content of Li ions, Na ions and K ions (Li + Na + K) is preferably 20.00 cation % or less, and more preferably in the order of 18.00 cation % or less, 15.00 cation % or less, 13.00 cation % or less, 10.00 cation % or less, 9.00 cation % or less, 8.00 cation % or less, 7.00 cation % or less, 6.00 cation % or less, 5.00 cation % or less.

[0106] The content of each of Li ions, Na ions and K ions can be 0.00 cation %, 0.00 cation % or more, more than 0.00 cation % or 0.10 cation % or more.

[0107] From the viewpoint of reducing the thermal expansion coefficient of the glass, the content of each of Li ions, Na ions and K ions is preferably 20.00 cation % or less, and more preferably in the order of 18.00 cation % or less, 15.00 cation % or less, 13.00 cation % or less, 10.00 cation % or less, 9.00 cation % or less, 8.00 cation % or less, 7.00 cation % or less, 6.00 cation % or less, 5.00 cation % or less.

[0108] The total content of Y ions, La ions, Gd ions and Yb ions (Y + La + Gd + Yb) can be 0.00 cation %, 0.00 cation % or more, more than 0.00 cation %, and from the viewpoint of maintaining the high refractive index of the glass, it is preferably 0.10 cation % or more, and more preferably in the order of 0.20 cation % or more, 0.30 cation % or more, 0.40 cation % or more, 0.50 cation % or more.

[0109] From the viewpoints of suppressing the increase in the liquidus temperature of the glass and maintaining the thermal stability, the total content of Y ions, La ions, Gd ions and Yb ions (Y + La + Gd + Yb) is preferably 5.00 cation % or less, and more preferably in the order of 4.50 cation % or less, 4.00 cation % or less, 3.80 cation % or less, 3.60 cation % or less, 3.40 cation % or less, 3.20 cation % or less, 3.00 cation % or less.

[0110] The content of each of Y ions, La ions, Gd ions, Yb ions and Lu ions can be 0.00 cation %, 0.00 cation % or more or more than 0.00 cation %.

[0111] From the viewpoints of suppressing the increase in the liquid-phase temperature while maintaining the high refractive index of the glass and maintaining the thermal stability, the content of each of the Y ion, La ion, Gd ion, Yb ion, and Lu ion is preferably 5.00 cation % or less, more preferably in the order of 4.00 cation % or less and 3.00 cation % or less.

[0112] The total content of the Si ion and the B ion (Si + B) may be 0.00 cation %, 0.00 cation % or more, or more than 0.00 cation %.

[0113] From the viewpoints of suppressing the volatilization during the melting of the glass and maintaining the high refractive index of the glass, the total content of the Si ion and the B ion (Si + B) is preferably 10.00 cation % or less, more preferably in the order of 7.00 cation % or less, 5.00 cation % or less, 3.00 cation % or less, 1.00 cation % or less, and 0.50 cation % or less.

[0114] The content of the Si ion may be 0.00 cation %, 0.00 cation % or more, or more than 0.00 cation %.

[0115] From the viewpoints of suppressing the volatilization during the melting of the glass and maintaining the high refractive index of the glass, the content of the Si ion is preferably 10.00 cation % or less, more preferably in the order of 7.00 cation % or less, 5.00 cation % or less, 3.00 cation % or less, 1.00 cation % or less, and 0.50 cation % or less.

[0116] The content of the B ion may be 0.00 cation %, 0.00 cation % or more, or more than 0.00 cation %.

[0117] From the viewpoints of suppressing the volatilization during the melting of the glass and maintaining the high refractive index of the glass, the content of the B ion is preferably 10.00 cation % or less, more preferably in the order of 7.00 cation % or less, 5.00 cation % or less, 3.00 cation % or less, 1.00 cation % or less, and 0.50 cation % or less.

[0118] The content of the Zn ion may be 0.00 cation %, 0.00 cation % or more, or more than 0.00 cation %.

[0119] From the viewpoint of maintaining the low dispersibility of the glass, the content of the Zn ion is preferably 10.00 cation % or less, more preferably in the order of 8.00 cation % or less, 5.00 cation % or less, 3.00 cation % or less, and 1.00 cation % or less.

[0120] The content of Zr ions can be 0.00 cationic %, 0.00 cationic % or more, or more than 0.00 cationic %.

[0121] From the viewpoints of suppressing the increase in the liquidus temperature of the glass and maintaining low dispersibility, the content of Zr ions is preferably 5.00 cationic % or less, and more preferably in the order of 3.00 cationic % or less, 1.00 cationic % or less, and 0.50 cationic % or less.

[0122] The content of each of Ti ions, Nb ions, W ions, and Bi ions can be 0.00 cationic %, 0.00 cationic % or more, or more than 0.00 cationic %.

[0123] From the viewpoints of maintaining the thermal stability of the glass and maintaining low dispersibility, the content of each of Ti ions, Nb ions, W ions, and Bi ions is preferably 5.00 cationic % or less, and more preferably in the order of 3.00 cationic % or less, 1.00 cationic % or less, and 0.50 cationic % or less.

[0124] The content of Cl ions can be 0.00 anionic %, 0.00 anionic % or more, or more than 0.00 anionic %.

[0125] From the viewpoint of suppressing the devitrification of the glass from the tube to the outer periphery of the tube when the molten glass flows out of the tube and thus suppressing the deterioration of the glass quality caused by devitrification, the content of Cl ions is preferably 1.00 anionic % or less, and more preferably in the order of 0.50 anionic % or less and 0.30 anionic % or less.

[0126] The content of each of Sb ions and Ce ions can be 0.00 cationic %, 0.00 cationic % or more, or more than 0.00 cationic %. By adding Sb and / or Ce, a clarification effect can be obtained.

[0127] The content of each of Sb ions and Ce ions is preferably 1.00 cationic % or less, more preferably 0.50 cationic % or less, and 0.30% or less.

[0128] Pb, Cd, As, and Th pose potential environmental burden risks, so it is preferred that the above optical glass does not contain these elements. That is, the above optical glass is preferably a glass that does not contain Pb, Cd, As, and Th in the glass composition expressed in cationic % and in the glass expressed in atomic %.

[0129] Cu, Co, Ni, Fe, Cr, Eu, Nd, and Er are elements that cause coloration. Therefore, it is preferable that the above optical glass does not contain these elements. The content of each of the above elements in the glass composition expressed in atomic % is preferably 100 ppm or less, more preferably in the order of 80 ppm or less and 50 ppm. The above optical glass is preferably a glass that does not contain Cu, Co, Ni, Fe, Cr, Eu, Nd, and Er in the glass composition expressed in cation % and in the glass expressed in atomic %.

[0130] Hf, Ga, Ge, Te, and Tb are costly components. Therefore, it is preferable that the above optical glass does not contain these elements. That is, the above optical glass is preferably a glass that does not contain Hf, Ga, Ge, Te, and Tb in the glass composition expressed in cation % and in the glass expressed in atomic %.

[0131] <Glass physical properties>

[0132] (Coefficient of thermal expansion)

[0133] The above optical glass can exhibit a low coefficient of thermal expansion by having the glass composition described above. As an index of the coefficient of thermal expansion, the average coefficient of linear expansion α from 100 °C to 300 °C can be cited. Hereinafter, the average coefficient of linear expansion α from 100 °C to 300 °C is also referred to as "α(100 - 300)". The α(100 - 300) of the above optical glass is preferably less than 155×10 -7 / K, more preferably in the order of 154×10 -7 / K or less, 153×10 -7 / K or less, 152×10 -7 / K or less, 151×10 -7 / K or less, 150×10 -7 / K or less, 149×10 -7 / K or less, 148×10 -7 / K or less, 147×10 -7 / K or less, 146×10 -7 / K or less, 145×10 -7 / K or less. α(100 - 300) can be, for example, 130×10 -7 / K or more or 132×10 -7 / K or more, but it can also be lower than the values exemplified here.

[0134] The average coefficient of linear expansion α at 100 °C to 300 °C can be measured by the method specified in the Japan Optical Glass Industry Association Standard JOGIS08-1975 "Method for Measuring Thermal Expansion of Optical Glass". For example, a cylindrical glass specimen with a diameter of 5 mm and a length of 20 mm can be prepared and measured using a thermomechanical analysis device TMA4000s manufactured by Bruker AXS (BRUKER axs) Co., Ltd.

[0135] (Abbe number νd)

[0136] The above optical glass can exhibit low dispersibility by having the above glass composition. For the Abbe number νd, which is an index of dispersibility, it is expressed as νd = (nd - 1) / (nF - nC) using the refractive indices nd, nF, and nC under d-ray, F-ray, and C-ray, respectively. From the viewpoint of the usefulness as a material for optical elements, the Abbe number νd of the above optical glass is preferably more than 76.50, more preferably in the order of 77.00 or more, 77.50 or more, 77.70 or more, and 78.00 or more. In addition, the Abbe number νd of the above optical glass can be, for example, 90.00 or less or 85.00 or less, but it can also be higher than the values exemplified here.

[0137] (Refractive index nd)

[0138] From the viewpoint of the usefulness as a material for optical elements, the refractive index nd of the above optical glass can be, for example, 1.45000 or more, 1.46000 or more, 1.47000 or more, 1.48000 or more, 1.49000 or more, 1.50000 or more. In addition, for example, it can be 1.55000 or less or 1.54000 or less. In the present invention and this specification, "refractive index" means "refractive index nd". The refractive index nd means the refractive index at a wavelength of 587.56 nm.

[0139] (Glass transition temperature Tg)

[0140] The above optical glass can exhibit a glass transition temperature Tg of, for example, 550 °C or less, 540 °C or less, 530 °C or less, 520 °C or less, 510 °C or less, 500 °C or less by having the above glass composition. In addition, the glass transition temperature Tg of the above optical glass can be, for example, 300 °C or more or 400 °C or more, but it can also be lower than the values exemplified here. The glass transition temperature Tg can be obtained by the method described later.

[0141] (Specific gravity)

[0142] From the viewpoint of lightening the weight of optical elements, it is preferable that the specific gravity of the optical glass is low. For example, the specific gravity of the above optical glass may be 4.00 g / cc or less, 3.90 g / cc or less, 3.85 g / cc or less, 3.80 g / cc or less, or 3.75 g / cc or less. In addition, for example, the specific gravity of the above optical glass may be 3.00 g / cc or more. However, since a lower specific gravity is more preferable, the lower limit is not particularly limited. The specific gravity can be determined by the Archimedes method.

[0143] <Manufacturing method of optical glass>

[0144] The above optical glass can be obtained as follows: Weigh and mix phosphates, fluorides, oxides, carbonates, sulfates, nitrates, hydroxides, etc. as raw materials in such a way as to obtain the target glass composition, fully mix them to form a mixed batch, heat and melt them in a melting container, and perform defoaming and stirring to produce a homogeneous and bubble-free molten glass, and then shape it to obtain the optical glass. Specifically, it can be produced by a known melting method.

[0145] [Glass raw materials for press molding, optical element blanks, and their manufacturing methods]

[0146] Another embodiment of the present invention relates to:

[0147] Glass raw materials for press molding made of the above optical glass;

[0148] Optical element blanks made of the above optical glass.

[0149] According to another embodiment of the present invention, there is also provided:

[0150] A manufacturing method of glass raw materials for press molding having a process of shaping the above optical glass into glass raw materials for press molding;

[0151] A manufacturing method of optical element blanks having a process of press molding the glass raw materials for press molding of the above optical glass by using a press molding die to produce optical element blanks; and

[0152] A manufacturing method of optical element blanks having a process of shaping the above optical glass into optical element blanks.

[0153] An optical element blank refers to an optical element base material that is approximately the same shape as the target optical element, with a polishing material (a surface layer that will be removed by polishing) added to the shape of the optical element, and a grinding material (a surface layer that will be removed by grinding) added as needed. The optical element is finely processed by grinding and polishing the surface of the optical element blank. In one method, an optical element blank can be produced by a method of pressure molding (referred to as the direct press method) a molten glass obtained by melting an appropriate amount of the above-mentioned glass. In another method, an optical element blank can also be produced by solidifying a molten glass obtained by melting an appropriate amount of the above-mentioned glass.

[0154] In addition, in another method, an optical element blank can be produced by preparing a glass raw material for pressure molding and subjecting the prepared glass raw material for pressure molding to pressure molding.

[0155] The pressure molding of the glass raw material for pressure molding can be carried out by a known method of applying pressure to the glass raw material for pressure molding that is in a softened state by heating, using a pressure molding die. Both heating and pressure molding can be carried out in the atmosphere. By annealing after pressure molding to reduce the internal strain of the glass, a homogeneous optical element blank can be obtained.

[0156] Regarding the glass raw material for pressure molding, in addition to the raw material called a glass gob for pressure molding that is directly supplied for pressure molding to produce an optical element blank while maintaining its original state, it also includes raw materials that are subjected to machining such as cutting, grinding, and polishing and then supplied for pressure molding after passing through a glass gob for pressure molding. As a cutting method, the following methods are included: a method of forming a groove in the part to be cut on the surface of a glass plate by a method called scribing, applying local pressure from the back side of the surface where the groove is formed to the groove part, and cutting the glass plate at the groove part; a method of cutting the glass plate using a cutting tool, etc. In addition, as grinding and polishing methods, barrel polishing, etc. can be cited.

[0157] An optical element blank can be produced, for example, by casting molten glass into a mold and forming it into a glass plate, and then cutting the glass plate into multiple glass pieces to prepare the glass raw material for pressure molding. Or, it can also be formed into an appropriate amount of molten glass to produce a glass gob for pressure molding. It can also be produced by reheating and softening the glass gob for pressure molding and then performing pressure molding to produce an optical element blank. The method of reheating, softening, and performing pressure molding on the glass to produce an optical element blank is called the reheat press method as opposed to the direct press method.

[0158] [Optical Element and Its Manufacturing Method]

[0159] Another embodiment of the present invention relates to:

[0160] An optical element made of the above optical glass.

[0161] The above optical element is made using the above optical glass. In the above optical element, one or more coatings such as a multilayer film such as an antireflection film can be formed on the glass surface.

[0162] In addition, according to one aspect of the present invention, there can also be provided:

[0163] A method for manufacturing an optical element having a process of manufacturing an optical element by grinding and / or polishing the above optical element blank.

[0164] In the above method for manufacturing an optical element, machining such as grinding and polishing can be performed by a known method. By sufficiently cleaning and drying the surface of the optical element after processing, an optical element with high internal quality and surface quality can be obtained. In this way, an optical element made of the above optical glass can be obtained. Examples of the optical element include various lenses such as a spherical lens, an aspherical lens, and a microlens, and a prism.

[0165] In addition, the optical element made of the above optical glass is also suitable as a lens constituting a joined optical element. Examples of the joined optical element include an element formed by joining lenses to each other (joined lens), an element formed by joining a lens and a prism, etc. For example, a joined optical element can be manufactured by the following method: The joining surfaces of two optical elements to be joined are precisely processed (e.g., spherical polishing) so that their shapes become reverse shapes, a UV-curable adhesive for bonding the lenses is coated, and after they are bonded together, ultraviolet light is irradiated through the lens to cure the adhesive, thereby manufacturing the joined optical element. Multiple elements to be joined can be manufactured using various optical glasses with different Abbe numbers νd respectively, and then joined together to manufacture an element suitable for correcting chromatic aberration.

[0166] Examples

[0167] Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the embodiments shown in the examples.

[0168] [Example 1]

[0169] <Specimen No.1 to 73>

[0170] In such a way as to achieve the glass compositions shown in the following table, corresponding phosphates, fluorides, nitrates, sulfates, carbonates, hydroxides, oxides, boric acid, etc. were respectively used as raw materials for introducing each component, the raw materials were weighed, and thoroughly mixed to prepare a blended raw material.

[0171] The compounding raw materials were placed in a platinum crucible and heated in a furnace set at 700 to 1100 °C for 90 minutes of melting. After homogenization by stirring the molten glass, the molten glass was poured into a preheated mold, naturally cooled to near the glass transition temperature, immediately placed in an annealing furnace, held at a temperature around the glass transition temperature for about 30 minutes, slowly cooled at a slow cooling rate of -30 °C / hour for 4 hours, and then naturally cooled to room temperature in the furnace, whereby each of the optical glasses of Specimen Nos. 1 to 73 shown in the following table was obtained.

[0172] <Physical Property Evaluation>

[0173] The various physical properties of each of the optical glasses shown in the table described below were measured by the following method.

[0174] (1) Average linear expansion coefficient α at 100 °C to 300 °C

[0175] For each optical glass, the average linear expansion coefficient α at 100 °C to 300 °C was measured by the method specified in the Japan Optical Glass Industry Association Standard JOGIS 08-1975 "Method for Measuring Thermal Expansion of Optical Glass". Specifically, a cylindrical glass specimen with a diameter of 5 mm and a length of 20 mm was prepared and measured using a thermomechanical analysis device TMA4000s manufactured by BRUKER axs.

[0176] (2) Refractive index nd and Abbe number νd

[0177] The refractive index nd and Abbe number νd of each optical glass were measured by the refractive index measurement method of the Japan Optical Glass Industry Association Standard.

[0178] (3) Glass transition temperature Tg

[0179] Using a material obtained by sufficiently pulverizing the glass in a mortar as a specimen and a platinum cell as a specimen container, the glass transition temperature Tg was measured using a differential scanning calorimeter (DSC3300SA) manufactured by NETZSCH JAPAN Co., Ltd. with a heating rate of 10 °C / min.

[0180] (4) Specific gravity

[0181] The specific gravity was measured by the Archimedes method.

[0182] The above results are shown in the following table.

[0183]

[0184]

[0185]

[0186]

[0187]

[0188]

[0189]

[0190]

[0191]

[0192]

[0193]

[0194]

[0195]

[0196]

[0197] (Example 2)

[0198] Glass blocks (glass gobs) for press molding were made using the various glasses obtained in Example 1. The glass gobs were heated and softened in the atmosphere and press-molded using a press-molding die to produce lens blanks (optical element blanks). The produced lens blanks were taken out of the press-molding die, annealed, and subjected to machining including polishing to produce spherical lenses formed from the various glasses made in Example 1. The produced spherical lenses were observed with the naked eye, and no cracks or fissures were confirmed.

[0199] (Example 3)

[0200] A desired amount of the molten glass made in Example 1 was press-molded using a press-molding die to produce lens blanks (optical element blanks). The produced lens blanks were taken out of the press-molding die, annealed, and subjected to machining including polishing to produce spherical lenses formed from the various glasses made in Example 1. The produced spherical lenses were observed with the naked eye, and no cracks or fissures were confirmed.

[0201] (Example 4)

[0202] The glass blocks (optical element blanks) made by solidifying the molten glass made in Example 1 were annealed and subjected to machining including polishing to produce spherical lenses formed from the various glasses made in Example 1.

[0203] It should be understood that the embodiments disclosed herein are exemplary in all respects and not restrictive. The scope of the present invention is defined by the claims, rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0204] For example, for the glass composition of the above example, by making the composition adjustments described in the specification, an optical glass according to an embodiment of the present invention can be obtained.

[0205] In addition, without doubt, any combination of two or more of the features exemplified in the specification or described as the preferred scope can be made.

Claims

1. An optical glass comprising O ions, F ions, Al ions, P ions, Mg ions, Ca ions, Sr ions and Ba ions as essential components, In the glass composition expressed in atomic %, The ratio of the content of O ions to the content of P ions (O / P) is 3.30 or more and 4.50 or less, The ratio of the content of Al ions to the content of P ions (Al / P) is 1.50 or less, The ratio of the content of F ions to the content of Al ions (F / Al) is 6.00 or less, In the glass composition expressed in cation %, The total content of Mg ions, Ca ions, Sr ions and Ba ions (Mg+Ca+Sr+Ba) is 40.00 cation % or more, Furthermore, the cation ratio ((Mg+Ca) / (Mg+Ca+Sr+Ba)) of the total content of Mg ions and Ca ions to the total content of Mg ions, Ca ions, Sr ions, and Ba ions is 0.40 or more.

2. The optical glass according to claim 1, wherein: The total content of Li ions, Na ions, and K ions (Li+Na+K) is 20.00 cation % or less.

3. The optical glass according to claim 1, wherein: The cation ratio (Mg / Ba) of the content of Mg ions to the content of Ba ions is 0.05 or more and 5.00 or less.

4. The optical glass according to claim 1, wherein: The total content of Mg ions and Ca ions (Mg+Ca) is 1.00 cation % or more and 50.00 cation % or less.

5. The optical glass according to claim 1, wherein: The total content of Y ions, La ions, Gd ions, and Yb ions (Y+La+Gd+Yb) is 0.10 cation % or more and 5.00 cation % or less.

6. The optical glass according to claim 1, wherein: The total content of Si ions and B ions (Si+B) is 10.00 cation % or less.

7. The optical glass according to claim 1, wherein the average linear expansion coefficient α at 100°C to 300°C is less than 155×10 -7 / K.

8. The optical glass according to claim 1, wherein: The total content of Li ions, Na ions and K ions (Li+Na+K) is less than 20.00 cation %, The cation ratio (Mg / Ba) of the content of Mg ions to the content of Ba ions is 0.05 or more and 5.00 or less, The total content of Mg ions and Ca ions (Mg+Ca) is 1.00 cation % or more and 50.00 cation % or less, The total content of Y ions, La ions, Gd ions, and Yb ions (Y+La+Gd+Yb) is 0.10 cation % or more and 5.00 cation % or less, The total content of Si ions and B ions (Si+B) is less than 10.00 cation %, Furthermore, the average linear expansion coefficient α of the optical glass at 100°C to 300°C is less than 155×10 -7 / K. 9 . An optical element, comprising the optical glass according to claim 1 .

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