Optical glass and optical element
A tailored glass composition with controlled oxide contents achieves a low thermal expansion coefficient, addressing the durability issues of phosphate-based optical glasses during molding.
Patent Information
- Application Number
- JP2024057298
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-03-29
- Publication Date
- 2025-10-10
AI Technical Summary
Existing phosphate-based optical glasses do not adequately address the need for low thermal expansion coefficients, which are crucial for preventing breakage or cracks during press molding.
A specific glass composition is formulated with controlled contents of B2O3, P2O5, Al2O3, Li2O, Na2O, CaO, ZnO, and other oxides to achieve a low thermal expansion coefficient, refractive index, and Abbe number, with a linear expansion coefficient of 130×10^-7/K or less between 100℃ and 300℃.
The glass composition provides a phosphate-based optical glass with a low thermal expansion coefficient, enhancing its durability and reducing the risk of breakage during molding processes.
Smart Images
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Abstract
Description
[Technical Field]
[0001] The present invention relates to an optical glass and an optical element. [Background technology]
[0002] Phosphate-based glass is generally an optical glass having low dispersion and is used as a material for various optical elements (see, for example, Patent Document 1). [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-269980 Summary of the Invention [Problem to be solved by the invention]
[0004] One of the desirable physical properties of optical glass is a low thermal expansion coefficient, because optical glass with a low thermal expansion coefficient can suppress the occurrence of breakage or cracks in the glass during press molding, for example.
[0005] An object of one aspect of the present invention is to provide a phosphate-based glass having a low thermal expansion coefficient. [Means for solving the problem]
[0006] As a result of extensive research, the present inventors have newly discovered that a phosphate glass having the following glass composition can exhibit a low thermal expansion coefficient.
[0007] One aspect of the present invention is as follows. [1] By mass, B2O3 content is 3.00% or more and 70.00% or less, P2O5 content is 47.00% or more and 80.00% or less, Al2O3 content is 13.00% or less, Li2O content is 0.01% or more, Na2O content is 5.00% or less, CaO content is 18.00% or less, ZnO content is 23.00% or less, The total content of P2O5, B2O3 and SiO2 (P2O5+B2O3+SiO2) is 66.00% or more and 84.00% or less, The total content of MgO, CaO, SrO and BaO (MgO + CaO + SrO + BaO) is 26.00% or less, provided that when the total content of MgO, CaO, SrO and BaO (MgO + CaO + SrO + BaO) is 15.00% or more and 26.00% or less, the total content of P2O5, B2O3 and SiO2 (P2O5 + B2O3 + SiO2) is 69.00% or more and 84.00% or less, The total content of Li2O, Na2O and K2O (Li2O + Na2O + K2O) is 15.00% or less, The mass ratio of P2O5 content to B2O3 content (P2O5 / B2O3) is 18.00 or less, the mass ratio of the NaO content to the total content of LiO, NaO, and KO (NaO / (LiO + NaO + KO)) is 0.50 or less; The total content of MgO and CaO (MgO + CaO) is 2.00% or more, The mass ratio of the total content of Li2O and BaO to the content of B2O3 ((Li2O + BaO) / B2O3) is 0.59 or less, The mass ratio of the total content of Al2O3 and BaO to the content of Li2O ((Al2O3 + BaO) / Li2O) is 2.77 or less, the mass ratio ((MgO + CaO) / (LiO + NaO + KO)) of the total content of MgO and CaO to the total content of LiO, NaO, and KO is 6.10 or less; the mass ratio of the total content of MgO, CaO, SrO, BaO, and ZnO to the total content of P2O5, B2O3, and SiO2 ((MgO + CaO + SrO + BaO + ZnO) / (P2O5 + B2O3 + SiO2)) is 0.36 or less; Refractive index nd is 1.70000 or less, Abbe number νd is 60.00 or more, and Average linear expansion coefficient α between 100℃ and 300℃ is 130×10 -7 / K or less (hereinafter also referred to as "optical glass" or simply "glass"). [2] The optical glass according to [1], wherein the total content of La2O3, Gd2O3 and Y2O3 (La2O3 + Gd2O3 + Y2O3) is 7.00% or less. [3] The optical glass according to [1] or [2], having an Nb2O5 content of 5.00% or less. [4] The optical glass according to any one of [1] to [3], wherein the total content of MgO, CaO, SrO and BaO (MgO+CaO+SrO+BaO) is 4.90% or more and 26.00% or less. [5] The optical glass according to any one of [1] to [4], wherein the mass ratio of the Na2O content to the total content of Li2O, Na2O, and K2O (Na2O / (Li2O+Na2O+K2O)) is 0.19 or less. [6] The optical glass according to any one of [1] to [5], wherein the total content of ZnO and BaO (ZnO+BaO) is 20.50% or less. [7] The optical glass according to any one of [1] to [6], having an SiO2 content of 5.00% or less. [8] The CaO content is less than 9.00%, or The optical glass according to any one of [1] to [7], wherein the CaO content is 9.00% or more and 18.00% or less, and the total content of SrO and BaO (SrO+BaO) is less than 3.00%. [9] The optical glass according to any one of [1] to [8], wherein the total content of SrO and BaO (SrO+BaO) is 13.00% or less.
[10] The optical glass according to any one of [1] to [9], wherein the total content of SrO, BaO and K2O (SrO+BaO+K2O) is 13.00% or less.
[11] The optical glass according to any one of [1] to
[10] , wherein the mass ratio of the total content of SrO and BaO to the content of Li2O ((SrO+BaO) / Li2O) is 5.00 or less.
[12] The P2O5 content is 47.00% or more but less than 58.00%, or The optical glass according to any one of [1] to
[11] , having a P2O5 content of 58.00% or more and 80.00% or less, and a mass ratio of the total content of MgO, CaO, SrO, BaO, and ZnO to the total content of Li2O, Na2O, and K2O ((MgO + CaO + SrO + BaO + ZnO) / (Li2O + Na2O + K2O)) of less than 6.00.
[13] The optical glass according to any one of [1] to
[12] , which has a specific gravity of 3.00 g / cc or less.
[14] The optical glass according to any one of [1] to
[13] , which has an external transmittance of 60% or more at wavelengths of 400 nm to 700 nm when converted to a thickness of 10.0 mm.
[15] The total content of La2O3, Gd2O3 and Y2O3 (La2O3 + Gd2O3 + Y2O3) is 7.00% or less; Nb2O5 content is 5.00% or less, The total content of MgO, CaO, SrO and BaO (MgO + CaO + SrO + BaO) is 4.90% or more and 26.00% or less, the mass ratio of the NaO content to the total content of LiO, NaO, and KO (NaO / (LiO + NaO + KO)) is 0.19 or less; The total content of ZnO and BaO (ZnO + BaO) is 20.50% or less, SiO2 content less than 5.00% The CaO content is less than 9.00% and the total content of SrO and BaO (SrO + BaO) is 13.00% or less, or the CaO content is 9.00% or more and 18.00% or less and the total content of SrO and BaO (SrO + BaO) is less than 3.00%; The total content of SrO, BaO and K2O (SrO + BaO + K2O) is 13.00% or less, the mass ratio of the total content of SrO and BaO to the content of LiO ((SrO + BaO) / LiO) is 5.00 or less; the P2O5 content is 47.00% or more and less than 58.00%, or the P2O5 content is 58.00% or more and 80.00% or less and the mass ratio of the total content of MgO, CaO, SrO, BaO and ZnO to the total content of Li2O, Na2O and K2O ((MgO + CaO + SrO + BaO + ZnO) / (Li2O + Na2O + K2O)) is less than 6.00; Specific gravity is 3.00g / cc or less, and The optical glass according to any one of [1] to
[14] , which has an external transmittance of 60% or more in wavelengths of 400 nm to 700 nm when converted into a thickness of 10.0 mm.
[16] An optical element made of the optical glass according to any one of [1] to
[15] . [Effects of the Invention]
[0008] According to one aspect of the present invention, it is possible to provide an optical glass that is a phosphate-based glass having a low thermal expansion coefficient, and an optical element made of this optical glass. DETAILED DESCRIPTION OF THE INVENTION
[0009] [Optical glass] <Glass composition> In the present invention and this specification, the glass composition is expressed as a glass composition based on oxides. Here, "glass composition based on oxides" refers to a glass composition obtained by converting the glass raw materials into oxides that are present in the glass after being completely decomposed during melting. Furthermore, unless otherwise specified, the glass composition is expressed on a mass basis (mass %, mass ratio). The glass composition of the present invention and the present specification can be determined by a method such as ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). Quantitative analysis is performed for each element using ICP-AES. The analytical values are then converted into oxide notation. The analytical values obtained by ICP-AES may contain a measurement error of, for example, about ±5% of the analytical value. Therefore, the oxide notation values converted from the analytical values may also contain an error of about ±5%. In the present invention and this specification, the terms "substantially free of," "free of," "not incorporated," or "0.00% content of a component" mean that the content of the component is at or below the impurity level. At or below the impurity level means, for example, less than 0.01% by mass.
[0010] The glass composition of the optical glass will now be described in more detail.
[0011] B2O3 is a glass structure-forming component. From the viewpoint of maintaining the stability of the glass, the B2O3 content is 3.00% or more, preferably 4.00% or more, and more preferably 5.00% or more, 6.00% or more, 7.00% or more, 8.00% or more, and 9.00% or more in that order. On the other hand, from the viewpoint of low dispersion of the glass, the B2O3 content is 70.00% or less, preferably 60.00% or less, and more preferably 50.00% or less, 40.00% or less, 30.00% or less, 20.00% or less, 18.00% or less, 16.00% or less, 15.00% or less, 14.00% or less, and 13.00% or less in that order.
[0012] The above optical glass is a phosphate-based glass and therefore contains P2O5. P2O5 is also a glass structure-forming component. From the viewpoint of maintaining the stability of the glass, the P2O5 content is 47.00% or more, preferably 50.00% or more, and more preferably 52.00% or more, 54.00% or more, 56.00% or more, 57.00%, 58.00% or more, 59.00%, and 60.00% or more in that order. On the other hand, from the viewpoint of suppressing an increase in the glass transition temperature Tg, the P2O5 content is 80.00% or less, preferably 75.00% or less, and more preferably 70.00% or less, 69.00% or less, 68.00% or less, 67.00% or less, 66.00% or less, 65.00% or less, 64.00% or less, and 63.00% or less in that order. The P2O5 content can be less than 58.00% in one embodiment and greater than or equal to 58.00% in another embodiment.
[0013] From the viewpoint of preventing the refractive index of the glass from decreasing, the mass ratio of the P2O5 content to the B2O3 content (P2O5 / B2O3) is 18.00 or less, preferably 16.00 or less, and more preferably 14.00 or less, 12.00 or less, 11.00 or less, 10.00 or less, 9.00 or less, and 8.00 or less in that order. From the viewpoint of low dispersion of the glass, the mass ratio (P2O5 / B2O3) is preferably more than 0.00, and more preferably 1.00 or more, 2.00 or more, 3.00 or more, 4.00 or more, and 5.00 or more in that order.
[0014] Al2O3 is a component that can increase the stability of the glass. The Al2O3 content can be, for example, 0.00%, 0.00% or more, more than 0.00%, 1.00% or more, 2.00% or more, 3.00% or more, or 4.00% or more. However, the introduction of an excessive amount of Al2O3 tends to reduce the stability of the glass. Therefore, from the viewpoint of maintaining the stability of the glass, the Al2O3 content is 13.00% or less, preferably 12.00% or less, and more preferably 11.00% or less, 10.00% or less, 9.00% or less, 8.00% or less, 7.00% or less, and 6.00% or less in that order.
[0015] SiO2 is also a component that can increase the stability of the glass. The SiO2 content can be, for example, 0.00%, 0.00% or more, more than 0.00%, or 0.10% or more. The SiO content may be, for example, 15.00% or less or 10.00% or less. From the viewpoint of suppressing the occurrence of striae, the SiO content is preferably 5.00% or less, and more preferably 4.50% or less, 4.00% or less, 3.50% or less, 3.00% or less, 2.50% or less, 2.00% or less, 1.50% or less, 1.00% or less, and 0.80% or less in that order.
[0016] From the viewpoint of maintaining the stability of the glass, the total content of P2O5, B2O3 and SiO2 (P2O5+B2O3+SiO2) is 66.00% or more, preferably 68.00% or more, and more preferably 70.00% or more and 72.00% or more in that order. However, when the total content of MgO, CaO, SrO, and BaO (MgO + CaO + SrO + BaO) is 15.00% or more, the total content of P2O5, B2O3, and SiO2 (P2O5 + B2O3 + SiO2) is 69.00% or more, from the viewpoint of maintaining the stability of the glass and reducing the thermal expansion coefficient. On the other hand, from the viewpoint of preventing the refractive index of the glass from decreasing, the total content (P2O5+B2O3+SiO2) is 84.00% or less, preferably 83.00% or less, and more preferably 82.00% or less, 81.00% or less, 80.00% or less, 79.00% or less, 78.00% or less, 77.00% or less, and 76.00% or less, in that order.
[0017] From the viewpoint of preventing the refractive index of the glass from decreasing, the total content of LiO, NaO, and KO (LiO + NaO + KO) is 15.00% or less, preferably 14.00% or less, and more preferably 13.00% or less, 12.00% or less, 11.00% or less, 10.00% or less, 9.00% or less, 8.00% or less, 7.00% or less, 6.00% or less, and 5.00% or less, in that order. The total content (Li2O+Na2O+K2O) can be, for example, 0.01% or more, 0.10% or more, 1.00% or more, 2.00% or more, or 3.00% or more.
[0018] Li2O is a component that contributes to lowering the thermal expansion coefficient of glass, lowering dispersion, and increasing the refractive index, and also lowering the glass transition temperature Tg. The Li2O content is 0.01% or more, preferably 0.10% or more, and more preferably 0.30% or more, 0.50% or more, 0.80% or more, 1.00% or more, 1.30% or more, 1.50% or more, 1.80% or more, 2.00% or more, 2.30% or more, 2.80% or more, and 3.00% or more, in that order. From the viewpoint of maintaining the stability of the glass, the LiO content is preferably 10.00% or less, and more preferably 9.50% or less, 9.00% or less, 8.50% or less, 8.00% or less, 7.50% or less, 7.00% or less, 6.50% or less, 6.00% or less, 5.50% or less, and 5.00% or less, in that order.
[0019] Na2O is a component that contributes to lowering the thermal expansion coefficient of glass and reducing dispersion. The Na2O content can be, for example, 0.00%, 0.00% or more, more than 0.00%, 0.01% or more, or 0.10% or more. From the viewpoint of maintaining the stability of the glass, the NaO content is 5.00% or less, preferably 4.80% or less, and more preferably 4.50% or less, 4.30% or less, 4.00% or less, 3.80% or less, 3.50% or less, 3.30% or less, 3.00% or less, 2.80% or less, 2.50% or less, 2.20% or less, 2.00% or less, 1.80% or less, 1.50% or less, 1.30% or less, 1.00% or less, 0.80% or less, and 0.50% or less in that order.
[0020] The K2O content can be, for example, 0.00% or 0.00% or more, and from the viewpoint of maintaining the stability of the glass, it is preferably more than 0.00%, more preferably 0.01% or more, and further preferably 0.10% or more. From the viewpoint of further lowering the thermal expansion coefficient of the glass, the K2O content is preferably 15.00% or less, and is more preferably 14.00% or less, 13.00% or less, 12.00% or less, 11.00% or less, 10.00% or less, 9.00% or less, 8.00% or less, 7.50% or less, 7.00% or less, 6.50% or less, 6.00% or less, 5.50% or less, 5.00% or less, 4.50% or less, 4.00% or less, 3.50% or less, 3.00% or less, 2.50% or less, 2.00% or less, 1.50% or less, and 1.00% or less in that order.
[0021] The mass ratio of the Na2O content to the total content of Li2O, Na2O, and K2O (Na2O / (Li2O+Na2O+K2O)) can be 0.00, 0.00 or more, more than 0.00, 0.01 or more, 0.50 or more, or 0.10 or more. From the viewpoint of preventing the refractive index of the glass from decreasing, the mass ratio (Na2O / (Li2O+Na2O+K2O)) is 0.50 or less, preferably 0.40 or less, and more preferably 0.30 or less, 0.25 or less, 0.20 or less, 0.19 or less, 0.18 or less, 0.17 or less, 0.16 or less, and 0.15 or less, in that order.
[0022] The total content of MgO and CaO (MgO + CaO) is 2.00% or more, preferably 4.00% or more, and more preferably 6.00% or more, 8.00% or more, 9.00% or more, 10.00% or more, 11.00% or more, 12.00% or more, 13.00% or more, and 14.00% or more in that order, from the viewpoint of suppressing high dispersion of the glass and suppressing an increase in the thermal expansion coefficient. Furthermore, the total content (MgO + CaO) can be, for example, 24.00% or less, 23.00% or less, 22.00% or less, 21.00% or less, 20.00% or less, 19.00% or less, or 18.00% or less.
[0023] From the viewpoint of suppressing high dispersion of the glass, the total content of MgO, CaO, SrO and BaO (MgO + CaO + SrO + BaO) is 26.00% or less, preferably 24.00% or less, and more preferably 22.00% or less, 21.00% or less, 20.00% or less, 19.00% or less, and 18.00% or less in that order. On the other hand, from the viewpoint of preventing the refractive index of the glass from decreasing, the total content (MgO+CaO+SrO+BaO) is preferably 4.90% or more, more preferably 5.00% or more, and more preferably 5.50% or more, 6.00% or more, 7.00% or more, 8.00% or more, 9.00% or more, 10.00% or more, 11.00% or more, 12.00% or more, 13.00% or more, and 14.00% or more in that order. The total content (MgO+CaO+SrO+BaO) can be less than 15.00% in one embodiment, and can be equal to or greater than 15.00% in another embodiment.
[0024] From the viewpoint of suppressing an increase in the thermal expansion coefficient of the glass, the total content of SrO and BaO (SrO + BaO) is preferably 13.00% or less, and is more preferably 12.00% or less, 11.00% or less, 10.00% or less, 9.00% or less, 8.00% or less, 7.00% or less, 6.00% or less, 5.00% or less, 4.00% or less, 3.00% or less, less than 3.00%, 2.00% or less, 1.50% or less, and 1.00% or less in that order. The total content (SrO + BaO) can be, for example, 0.00%, 0.00% or more, more than 0.00%, 0.01% or more, or 0.10% or more.
[0025] CaO is a component that contributes to lowering the thermal expansion coefficient of the glass and reducing dispersion. The CaO content can be, for example, 0.00%, 0.00% or more, more than 0.00%, 0.10% or more, 1.00% or more, 2.00% or more, 3.00% or more, 4.00% or more, 5.00% or more, 6.00% or more, 7.00% or more, 8.00% or more, or 9.00% or more. From the viewpoint of suppressing high dispersion of the glass, the CaO content is 18.00% or less, preferably 16.00% or less, and more preferably 15.00% or less, 14.50% or less, 14.00% or less, 13.50% or less, 13.00% or less, 12.00% or less, 11.00% or less, 10.00% or less, less than 9.00%, and 8.00% or less, in that order.
[0026] In one embodiment, the optical glass has a CaO content of less than 9.00%, and in another embodiment, the CaO content is 9.00% or more. When the CaO content is 9.00% or more, from the viewpoint of low dispersion of the glass, the total content (SrO + BaO) is preferably less than 3.00%, and more preferably 2.80% or less, 2.50% or less, 2.20% or less, 2.00% or less, 1.80% or less, 1.50% or less, 1.30% or less, 1.10% or less, and 1.00% or less, in that order. In this case, the total content (SrO + BaO) can be, for example, 0.00%, 0.00% or more, more than 0.00%, 0.01% or more, or 0.10% or more.
[0027] MgO is also a component that contributes to lowering the thermal expansion coefficient of the glass and reducing dispersion. The MgO content can be, for example, 0.00%, 0.00% or more, more than 0.00%, 0.10% or more, or 1.00% or more. The MgO content can be, for example, 16.00% or less, 15.00% or less, 14.00% or less, 13.00% or less, 12.00% or less, 11.00% or less, 10.00% or less, 9.00% or less, 8.00% or less, 7.00% or less, 6.00% or less, 5.00% or less, or 4.00% or less.
[0028] SrO and BaO are components that contribute to lowering the thermal expansion coefficient of the glass. The SrO content can be, for example, 0.00% or 0.00% or more, and from the viewpoint of maintaining the stability of the glass, it is preferably more than 0.00%, more preferably 0.10% or more, and further preferably 1.00% or more. From the viewpoint of suppressing an increase in the thermal expansion coefficient of the glass, the SrO content is preferably 16.00% or less, and more preferably 14.00% or less, 12.00% or less, 10.00% or less, 8.00% or less, 6.00% or less, 4.00% or less, 3.00% or less, 2.00% or less, and 1.00% or less in that order. The BaO content can be, for example, 0.00% or 0.00% or more, and from the viewpoint of maintaining the stability of the glass, it is preferably more than 0.00%, more preferably 0.10% or more, and further preferably 1.00% or more. From the viewpoint of suppressing an increase in the thermal expansion coefficient of the glass, the BaO content is preferably 10.00% or less, and more preferably 8.00% or less, 6.00% or less, 4.00% or less, 3.00% or less, 2.00% or less, and 1.00% or less in that order.
[0029] The mass ratio of the total content of Li2O and BaO to the B2O3 content ((Li2O+BaO) / B2O3) is 0.59 or less, preferably 0.57 or less, and more preferably 0.55 or less, 0.53 or less, 0.51 or less, 0.49 or less, 0.47 or less, 0.45 or less, 0.43 or less, 0.41 or less, 0.39 or less, and 0.37 or less, in that order, from the viewpoint of reducing the dispersion of the glass and the thermal expansion coefficient. The mass ratio ((Li2O+BaO) / B2O3) can be, for example, more than 0.00, and can also be 0.01 or more, 0.05 or more, 0.10 or more, or 0.20 or more.
[0030] The mass ratio of the total content of Al2O3 and BaO to the Li2O content ((Al2O3 + BaO) / Li2O) is 2.77 or less, preferably 2.50 or less, and more preferably 2.30 or less, 2.00 or less, 1.80 or less, and 1.60 or less, in that order, from the viewpoint of maintaining the stability of the glass and reducing the thermal expansion coefficient. The mass ratio ((Al2O3 + BaO) / Li2O) can be, for example, 0.00, 0.00 or more, more than 0.00, 0.10 or more, 0.50 or more, or 1.00 or more.
[0031] From the viewpoint of reducing the dispersion of the glass and the thermal expansion coefficient, the mass ratio of the total content of MgO and CaO to the total content of LiO, NaO, and KO ((MgO+CaO) / (LiO+NaO+KO)) is 6.10 or less, preferably 5.90 or less, and more preferably 5.80 or less, 5.70 or less, 5.60 or less, 5.50 or less, 5.40 or less, 5.30 or less, 5.20 or less, 5.10 or less, 5.50 or less, 4.90 or less, 4.80 or less, 4.70 or less, 4.60 or less, 4.50 or less, 4.40 or less, 4.30 or less, 4.20 or less, 4.10 or less, 4.00 or less, 3.90 or less, 3.80 or less, and 3.70 or less, in that order. The mass ratio ((MgO+CaO) / (Li2O+Na2O+K2O)) can be, for example, 0.00, 0.00 or more, more than 0.00, 0.10 or more, 0.50 or more, 1.00 or more, 2.00 or more, or 3.00 or more.
[0032] The mass ratio of the total content of SrO and BaO to the content of Li2O ((SrO+BaO) / Li2O) can be, for example, 0.00, 0.00 or more, more than 0.00, 0.01 or more, or 0.10 or more. From the viewpoint of suppressing an increase in the thermal expansion coefficient of the glass, the mass ratio ((SrO+BaO) / LiO) is preferably 5.00 or less, and more preferably 4.80 or less, 4.50 or less, 4.30 or less, 4.00 or less, 3.50 or less, 3.00 or less, 2.50 or less, 2.00 or less, 1.50 or less, 1.00 or less, 0.80 or less, and 0.50 or less, in that order.
[0033] The total content of SrO, BaO and KO (SrO + BaO + KO) can be, for example, 0.00% or 0.00% or more, and from the viewpoint of maintaining the stability of the glass, it is preferably more than 0.00%, more preferably 0.10% or more, and further preferably 0.50% or more. From the viewpoint of suppressing an increase in the thermal expansion coefficient of the glass, the total content (SrO+BaO+KO) is preferably 13.00% or less, and more preferably 12.00 or less, 11.00% or less, 10.00 or less, 9.00% or less, 8.00 or less, 7.00% or less, 6.00 or less, 5.00% or less, 4.00 or less, 3.00% or less, 2.00 or less, 1.00% or less, 0.90 or less, and 0.80% or less in that order.
[0034] ZnO is a component that contributes to improving the stability and increasing the refractive index of the glass. The ZnO content can be, for example, 0.00%, 0.00% or more, more than 0.00%, 0.10% or more, or 1.00% or more. From the viewpoint of suppressing high dispersion of the glass, the ZnO content is 23.00% or less, preferably 21.00% or less, and more preferably 19.00% or less, 17.00% or less, 15.00% or less, 13.00% or less, 11.00% or less, 9.00% or less, 7.00% or less, 5.00% or less, 3.00% or less, and 1.00% or less in that order.
[0035] The total content of ZnO and BaO (ZnO+BaO) can be, for example, 0.00%, 0.00% or more, more than 0.00%, 0.10% or more, or 1.00% or more. From the viewpoint of suppressing high dispersion of the glass and suppressing an increase in the thermal expansion coefficient, it is preferably 20.50% or less, and more preferably 20.00% or less, 19.00% or less, 18.00% or less, 17.00% or less, 16.00% or less, 15.00% or less, 14.00% or less, 13.00% or less, 12.00% or less, 11.00% or less, 10.00% or less, 9.00% or less, 8.00% or less, 7.00% or less, 6.00% or less, 5.00% or less, 4.00% or less, 3.00% or less, 2.00% or less, and 1.00% or less in that order.
[0036] The mass ratio of the total content of MgO, CaO, SrO, BaO, and ZnO to the total content of P2O5, B2O3, and SiO2 ((MgO + CaO + SrO + BaO + ZnO) / (P2O5 + B2O3 + SiO2)) is 0.36 or less, preferably 0.35 or less, and more preferably 0.34 or less, 0.33 or less, 0.30 or less, 0.27 or less, 0.25 or less, and 0.24 or less, in that order, from the viewpoint of maintaining the stability of the glass and reducing the thermal expansion coefficient. The mass ratio ((MgO + CaO + SrO + BaO + ZnO) / (P2O5 + B2O3 + SiO2)) can be, for example, more than 0.00, 0.01 or more, 0.10 or more, 0.50 or more, 1.00 or more, 1.50 or more, or 2.00 or more.
[0037] When the P2O5 content is 58.00% or more, from the viewpoints of maintaining glass stability and achieving low dispersion, the mass ratio of the total content of MgO, CaO, SrO, BaO, and ZnO to the total content of Li2O, Na2O, and K2O ((MgO+CaO+SrO+BaO+ZnO) / (Li2O+Na2O+K2O)) is preferably less than 6.00, and is more preferably 5.80 or less, 5.70 or less, 5.60 or less, 5.50 or less, 5.40 or less, 5.30 or less, 5.20 or less, 5.10 or less, 5.00 or less, 4.90 or less, 4.80 or less, 4.70 or less, 4.60 or less, 4.50 or less, 4.40 or less, 4.30 or less, 4.20 or less, 4.10 or less, 4.00 or less, and 3.90 or less, in that order. When the P2O5 content is less than 58.00%, the mass ratio ((MgO+CaO+SrO+BaO+ZnO) / (Li2O+Na2O+K2O)) may be within the above range or may exceed the above range. In both cases where the P2O5 content is less than 58.00% and where the P2O5 content is 58.00% or greater, the mass ratio ((MgO+CaO+SrO+BaO+ZnO) / (Li2O+Na2O+K2O)) can be, for example, more than 0.00, 0.10 or greater, 0.50 or greater, 1.00 or greater, 1.50 or greater, 2.00 or greater, 2.50 or greater, or 3.00 or greater.
[0038] The total content of La2O3, Gd2O3 and Y2O3 (La2O3 + Gd2O3 + Y2O3) can be 0.00% or greater than or equal to 0.00%. From the viewpoint of suppressing high dispersion of the glass, the total content (La2O3 + Gd2O3 + Y2O3) is preferably 7.00% or less, and is more preferably 6.50% or less, 6.00% or less, 5.00% or less, 4.00% or less, 3.00% or less, 2.00% or less, 1.00% or less, 0.50% or less, and 0.10% or less in that order, and may even be 0.00%.
[0039] The content of each of La2O3, Gd2O3 and Y2O3 can be 0.00% or more. From the viewpoint of suppressing high dispersion of the glass, the content of each of La2O3, Gd2O3 and Y2O3 is preferably 7.00% or less, and is preferably 6.50% or less, 6.00% or less, 5.00% or less, 4.00% or less, 3.00% or less, 2.00% or less, 1.00% or less, 0.50% or less, and 0.10% or less in that order, and may even be 0.00%.
[0040] The Nb2O5 content can be 0.00% or greater than or equal to 0.00%. From the viewpoint of suppressing high dispersion of the glass, the Nb2O5 content is preferably 5.00% or less, and is more preferably 4.50% or less, 4.00% or less, 3.50% or less, 3.00% or less, 2.00% or less, 1.00% or less, 0.50% or less, and 0.10% or less, in that order, and may be 0.00%.
[0041] The ZrO2 content can be 0.00%, 0.00% or more, more than 0.00% or 0.10% or more. From the viewpoint of suppressing high dispersion of the glass, the ZrO2 content is preferably 5.00% or less, and more preferably 4.00% or less, 3.00% or less, 2.00% or less, 1.00% or less, and 0.50% or less in that order.
[0042] Sb2O3 is a component that can be added as a fining agent. Adding a small amount can help prevent a decrease in light transmittance due to the inclusion of impurities such as Fe, but increasing the amount of Sb2O3 tends to increase glass coloration. Therefore, the amount of Sb2O3 added is preferably 0.00% or more and 0.15% or less, more preferably 0.00% or more and 0.12% or less, even more preferably 0.00% or more and 0.10% or less, and even more preferably 0.00% or more and 0.05% or less, based on the total amount of glass components other than Sb2O3, which is taken as 100% by mass. The Sb2O3 content by external percentage refers to the Sb2O3 content expressed in mass % when the total content of glass components other than Sb2O3 is taken as 100% by mass.
[0043] SnO2 can also be added as a fining agent, but if it is added in excess of 1.00% by weight, the glass will become discolored, and when the glass is heated, softened, and reshaped by press molding or other methods, the Sn can act as a starting point for crystal nucleation, leading to a tendency for devitrification. Therefore, the amount of SnO2 added is preferably between 0.00% and 1.00%, more preferably between 0.00% and 0.50%, and particularly preferably none is added. The SnO2 content by weight refers to the SnO2 content expressed in mass% when the total content of glass components other than SnO2 is taken as 100% by weight.
[0044] From the viewpoint of environmental considerations, the above optical glass preferably contains substantially no Pb. In a glass that contains substantially no Pb, the PbO content is preferably 0.00% or more and less than 0.01%.
[0045] From the viewpoint of making the most of the excellent light transmittance of glass, it is preferable that the above optical glass is substantially free of coloring components. In the present invention and this specification, the term "coloring component" refers to one or more elements selected from the group consisting of Ti, Cu, Cr, V, Fe, Ni, and Co. It is preferable that the content of the coloring components as oxides in the above optical glass (the total content when two or more elements are contained) is 0.00% or more and less than 0.01%.
[0046] F is a component that significantly increases the volatility of glass during melting, reducing the stability and uniformity of the glass's optical properties. Therefore, it is preferable that the optical glass be substantially free of F. The F content can be defined as the content (unit: mass%) of F element expressed as an external ratio relative to 100 mass% of the total content of the glass composition based on oxides, as determined above. In the optical glass, the F content defined in this way is preferably less than 0.10%, more preferably less than 0.08%, and even more preferably less than 0.05%. The F content can be 0.00% or more, and may be 0.00%.
[0047] <Glass properties> (coefficient of thermal expansion) The optical glass can exhibit a low thermal expansion coefficient by having the glass composition described above. An index of the thermal expansion coefficient is the average linear expansion coefficient α at 100°C to 300°C. Hereinafter, the average linear expansion coefficient α at 100°C to 300°C will also be referred to as "α(100 / 300)". The α(100 / 300) of the optical glass is 130×10 -7 / K or less, 125×10 -7 / K or less, 120×10 -7 / K or less, 115×10 -7 / K or less, 110×10 -7 / K or less is more preferable. α(100 / 300) is, for example, 70×10 -7 / K or higher, 75×10 -7 / K or more or 80 x 10 -7 / K or more, but can also be less than the values exemplified here. The average coefficient of linear expansion α at 100°C to 300°C is measured by the method specified in Japan Optical Glass Industry Association Standard JOGIS 08-1975 "Method for measuring thermal expansion of optical glass." The measurement can be performed, for example, by preparing a cylindrical glass sample with a diameter of 5 mm and a length of 20 mm and using a thermomechanical analyzer TMA8311 manufactured by Rigaku Corporation.
[0048] (Abbe number νd) The optical glass can exhibit low dispersion due to its glass composition. The Abbe number vd, which is an index of dispersion, is expressed as vd=(nd-1) / (nF-nC) using the refractive indices nd, nF, and nC at the d-line, F-line, and C-line. From the viewpoint of usefulness as a material for optical elements, the Abbe number vd of the optical glass is 60.00 or more, preferably 62.00 or more, and more preferably 64.00 or more. The Abbe number vd of the optical glass can be, for example, 80.00 or less, 75.00 or less, or 70.00 or less, but may exceed the values exemplified here.
[0049] (refractive index nd) From the viewpoint of usefulness as a material for optical elements, the refractive index nd of the optical glass is 1.70000 or less, preferably 1.65000 or less, with 1.60000 or less and 1.55000 or less being more preferred. The refractive index nd can be, for example, 1.45000 or more, 1.46000 or more, 1.47000 or more, 1.48000 or more, 1.49000 or more, or 1.50000 or more. In the present invention and this specification, "refractive index" means "refractive index nd." The refractive index nd is the refractive index at a wavelength of 587.56 nm.
[0050] (specific gravity) A low specific gravity of optical glass is preferable from the viewpoint of reducing the weight of optical elements. The specific gravity of the optical glass can be, for example, 3.00 g / cc or less, 2.90 g / cc or less, or 2.80 g / cc or less. The specific gravity of the optical glass can be, for example, 2.00 g / cc or more, but since a lower specific gravity is more preferable, there is no particular lower limit. The specific gravity is determined by Archimedes' method.
[0051] (glass transition temperature Tg) By having the above glass composition, the optical glass can exhibit a glass transition temperature Tg of, for example, 550°C or lower, 540°C or lower, 530°C or lower, 520°C or lower, 510°C or lower, or 500°C or lower. The glass transition temperature Tg of the optical glass can be, for example, 300°C or higher or 400°C or higher, but can also be lower than the values exemplified here. The glass transition temperature Tg is determined by the method described below.
[0052] (Transmittance characteristics) The optical glass preferably has an external transmittance of 60% or more at wavelengths of 400 nm to 700 nm, calculated as a thickness of 10.0 mm. "An external transmittance of 60% or more at wavelengths of 400 nm to 700 nm, calculated as a thickness of 10.0 mm," refers to an external transmittance of 60% or more at a thickness of 10.0 mm over the entire wavelength range of 400 nm to 700 nm. The optical glass may have an external transmittance of 60% or more and 100% or less at a wavelength of 400 nm to 700 nm, calculated as a thickness of 10.0 mm. Optical glass having such transmittance characteristics is useful as a material for optical elements. For example, the above transmittance characteristics can be achieved by using glass that is substantially free of coloring components.
[0053] The transmittance characteristics of the above glass are determined by the following method. The glass sample is processed to have parallel, optically polished flat surfaces, and the external transmittance at wavelengths of 400 to 700 nm is measured. The external transmittance includes the reflection loss of light rays on the sample surface. If the glass being measured is not 10.0 mm thick, the thickness of the glass being measured is taken as d0, and the transmittance at each wavelength λ is converted using the following formula A to determine the transmittance characteristics converted to a 10.0 mm thickness.
[0054] Formula A: T(λ)=(1-R(λ))2×exp(loge((T0(λ) / 100) / (1-R(λ))2)×d / d0)×100
[0055] In formula A, T(λ): converted transmittance (%) at wavelength λ, T0(λ): measured transmittance (%) at wavelength λ, d: converted thickness (mm), d0: glass thickness (mm), R(λ) = ((n(λ)-1) / (n(λ)+1)) 2 The reflectance at wavelength λ is expressed as n(λ), where n(λ) is the refractive index at wavelength λ. The refractive index at wavelength λ, n(λ), is measured at each wavelength in accordance with the Japanese Industrial Standards (JIS) JIS B 7071-1 "Method for measuring the refractive index of optical glass - Part 1: Minimum deviation angle method."
[0056] <Optical glass manufacturing method> The above optical glass can be obtained, for example, by the following method. Raw materials such as phosphates, fluorides, oxides, carbonates, sulfates, nitrates, and hydroxides are weighed, blended, and thoroughly mixed to prepare a mixed batch (raw material blend). The prepared mixed batch is heated and melted in a melting vessel, and then degassed and stirred to obtain a homogeneous, bubble-free glass melt. The glass melt can be produced using a known melting method. The above optical glass can be obtained by molding the resulting glass melt.
[0057] [Glass materials for press molding, optical element blanks, and their manufacturing methods] Another aspect of the present invention is a glass material for press molding comprising the optical glass; an optical element blank made of the optical glass; Regarding.
[0058] According to another aspect of the present invention, a method for producing a glass material for press molding, comprising a step of molding the optical glass into a glass material for press molding; a method for producing an optical element blank, comprising a step of press-molding the glass material for optical glass press molding using a press mold to produce an optical element blank; a method for manufacturing an optical element blank, comprising a step of molding the optical glass into an optical element blank; is also provided.
[0059] An optical element blank is an optical element base material that approximates the shape of the desired optical element, with polishing allowances (surface layers to be removed by polishing) and, if necessary, grinding allowances (surface layers to be removed by grinding) added to the shape of the optical element. The optical element is finished by grinding and polishing the surface of the optical element blank. In one embodiment, the optical element blank can be produced by a method (called a direct press method) in which a molten glass obtained by melting an appropriate amount of the above glass is press-molded. In another embodiment, the optical element blank can also be produced by solidifying a molten glass obtained by melting an appropriate amount of the above glass.
[0060] In another embodiment, an optical element blank can be produced by preparing a glass material for press molding and press-molding the prepared glass material for press molding.
[0061] Press molding of a glass material for press molding can be carried out by a known method in which a glass material for press molding in a heated and softened state is pressed in a press mold. Both heating and press molding can be carried out in the atmosphere. After press molding, the glass is annealed to reduce internal strain, thereby obtaining a homogeneous optical element blank.
[0062] Glass materials for press molding include not only glass gobs for press molding that are used for press molding as they are to produce optical element blanks, but also glass gobs for press molding that are machined by cutting, grinding, polishing, etc. and then used for press molding. Cutting methods include forming a groove in the area of the surface of the glass plate to be cut by a method called scribing, applying local pressure to the grooved area from the back side of the surface where the groove was formed, thereby breaking the glass plate at the grooved area, and cutting the glass plate with a cutting blade. Grinding and polishing methods include barrel polishing, etc.
[0063] A glass material for press molding can be produced, for example, by casting molten glass into a mold to form a glass plate, and then cutting this glass plate into a plurality of glass pieces. Alternatively, a suitable amount of molten glass can be molded to produce a glass gob for press molding. An optical element blank can also be produced by reheating, softening, and press-molding a glass gob for press molding. The method of producing an optical element blank by reheating, softening, and press-molding glass is called a reheat press method, as opposed to a direct press method.
[0064] [Optical element and its manufacturing method] Another aspect of the present invention is Optical elements made of the above optical glass Regarding. The optical element is manufactured using the optical glass. In the optical element, the glass surface may be coated with one or more layers, such as a multilayer film including an anti-reflection film.
[0065] According to another aspect of the present invention, a method for manufacturing an optical element, comprising a step of manufacturing an optical element by grinding and / or polishing the optical element blank described above; is also provided.
[0066] In the method for manufacturing the optical element, known methods can be used for mechanical processing such as grinding and polishing, and by thoroughly cleaning and drying the surface of the optical element after processing, an optical element with high internal and surface quality can be obtained. In this way, an optical element made of the optical glass can be obtained. Examples of optical elements include various lenses such as spherical lenses, aspherical lenses, and microlenses, as well as prisms.
[0067] Furthermore, optical elements made of the above optical glass are also suitable as lenses constituting cemented optical elements. Examples of cemented optical elements include those in which lenses are cemented together (cemented lenses) and those in which a lens and a prism are cemented together. For example, a cemented optical element can be produced by precisely machining (for example, by spherical polishing) the cementing surfaces of two optical elements to be cemented so that their shapes are inverted, applying an ultraviolet-curing adhesive used for bonding cemented lenses, bonding them together, and then irradiating ultraviolet light through the lenses to cure the adhesive. By producing multiple optical elements to be cemented using multiple types of glass or the like with different Abbe numbers νd and cementing them together, an element suitable for correcting chromatic aberration can be produced. [Example]
[0068] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the embodiments shown in the examples.
[0069] [Example 1] <Sample No. 1-168> To obtain the glass compositions shown in the tables below, the corresponding phosphates, fluorides, nitrates, sulfates, carbonates, hydroxides, oxides, boric acid, etc. were used as raw materials for introducing the respective components, and the raw materials were weighed and thoroughly mixed to obtain blended raw materials. This blended raw material was placed in a platinum crucible and heated and melted for 120 minutes in a furnace set at 1100 to 1350°C. After stirring to homogenize the molten glass, the molten glass was poured into a preheated mold and allowed to cool to near the glass transition temperature. It was then immediately placed in an annealing furnace and held at a temperature near the glass transition temperature for about 30 minutes, after which it was slowly cooled at a rate of -30°C / hour for 4 hours, and then allowed to cool to room temperature in the furnace to obtain the optical glasses of Samples 1 to 168 shown in the table below.
[0070] <Physical property evaluation> The physical properties of each optical glass shown in the table below were measured by the following methods.
[0071] (1) Average coefficient of linear expansion α between 100°C and 300°C For each optical glass, the average coefficient of linear expansion α was measured at 100°C to 300°C according to 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 sample with a diameter of 5 mm and a length of 20 mm was prepared, and the measurement was carried out using a thermomechanical analyzer TMA8311 manufactured by Rigaku Corporation.
[0072] (2) Refractive index nd Abbe number νd The refractive index nd and Abbe number νd of each optical glass were measured by the refractive index measurement method specified by the Japan Optical Glass Industry Association.
[0073] (3) Specific gravity Specific gravity was measured by Archimedes' method.
[0074] (4) Glass transition temperature Tg The glass was thoroughly crushed in a mortar and used as a sample. A platinum cell was used as the sample container, and the glass transition temperature Tg was measured at a heating rate of 10°C / min using a differential scanning calorimeter (DSC8271) manufactured by Rigaku Corporation.
[0075] (5) Transmittance characteristics A test piece was cut out from the obtained glass, and both surfaces were mirror-polished to have parallel, optically polished flat surfaces to a thickness of 10.0 mm. The external transmittance at wavelengths of 400 to 700 nm was then measured using a spectrophotometer. It was confirmed that for all of Samples Nos. 1 to 168, the external transmittance at wavelengths of 400 nm to 700 nm was 60% or more and 100% or less at a thickness of 10.0 mm.
[0076] The results are shown in the table below. In the table, the content of the glass component is expressed in mass%. A "○" in the table indicates that the item described in the title of the column in which the "○" is written is met.
[0077] [Table 1-1]
[0078]
Table 1-2
[0079]
Table 1-3
[0080]
Table 1-4
[0081]
Table 1-5
[0082]
Table 1-6
[0083]
Table 1-7
[0084]
Table 1-8
[0085]
Table 1-9
[0086]
Table 2-1
[0087]
Table 2-2
[0088]
Table 2-3
[0089]
Table 2-4
[0090]
Table 2-5
[0091]
Table 2-6
[0092]
Table 2-7
[0093]
Table 2-8
[0094]
Table 2-9
[0095]
Table 3-1
[0096]
Table 3-2
[0097]
Table 3-3
[0098]
Table 3-4
[0099]
Table 3-5
[0100]
Table 3-6
[0101]
Table 3-7
[0102]
Table 3-8
[0103]
Table 3-9
[0104]
Table 4-1
[0105]
Table 4-2
[0106]
Table 4-3
[0107]
Table 4-4
[0108]
Table 4-5
[0109]
Table 4-6
[0110]
Table 4-7
[0111]
Table 4-8
[0112]
Table 4-9
[0113]
Table 5-1
[0114]
Table 5-2
[0115]
Table 5-3
[0116]
Table 5-4
[0117]
Table 5-5
[0118]
Table 5-6
[0119]
Table 5-7
[0120]
Table 5-8
[0121]
Table 5-9
[0122]
Table 6-1
[0123]
Table 6-2
[0124]
Table 6-3
[0125]
Table 6-4
[0126]
Table 6-5
[0127]
Table 6-6
[0128]
Table 6-7
[0129]
Table 6-8
[0130]
Table 6-9
[0131]
Table 7-1
[0132]
Table 7-2
[0133]
Table 7-3
[0134]
Table 7-4
[0135]
Table 7-5
[0136]
Table 7-6
[0137]
Table 7-7
[0138]
Table 7-8
[0139]
Table 7-9
[0140] Example 2 Glass gobs for press molding (glass gobs) were prepared using the various glasses obtained in Example 1. These glass gobs were heated and softened in the atmosphere and press-molded in a press mold to produce lens blanks (optical element blanks). The produced lens blanks were removed from the press mold, annealed, and subjected to machining including polishing to produce spherical lenses made from the various glasses produced in Example 1. The produced spherical lenses were visually inspected, and no breaks or cracks were found.
[0141] Example 3 A desired amount of the molten glass produced in Example 1 was press-molded in a press mold to produce a lens blank (optical element blank). The produced lens blank was removed from the press mold, annealed, and subjected to machining including polishing to produce a spherical lens made from the various glasses produced in Example 1. The produced spherical lens was visually inspected, and no breakage or cracks were found.
[0142] Example 4 The glass molten glass produced in Example 1 was solidified to produce a glass lump (optical element blank), which was then annealed and subjected to machining including polishing to produce spherical lenses made of the various glasses produced in Example 1.
[0143] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. For example, by adjusting the composition as described in the specification for the glass compositions exemplified above, an optical glass according to one aspect of the present invention can be obtained. Furthermore, it is of course possible to arbitrarily combine two or more of the items described in the specification as examples or preferred ranges.
Claims
1. By mass, B ２ O ３ The content is 3.00% or more and 70.00% or less, P ２ O ５ The content is 47.00% or more and 80.00% or less, Al ２ O ３ The content is 13.00% or less, Li ２ O content is 0.01% or more, Na ２ O content is 5.00% or less, CaO content is 18.00% or less, ZnO content is 23.00% or less, P ２ O ５ , B ２ O ３ and SiO ２ The total content (P ２ O ５ +B ２ O ３ +SiO ２ ) is 66.00% or more and 84.00% or less, The total content of MgO, CaO, SrO and BaO (MgO + CaO + SrO + BaO) is 26.00% or less, provided that when the total content of MgO, CaO, SrO and BaO (MgO + CaO + SrO + BaO) is 15.00% or more and 26.00% or less, P ２ O ５ , B ２ O ３ and SiO ２ The total content (P ２ O ５ +B ２ O ３ +SiO ２ ) is 69.00% or more and 84.00% or less, Li ２ O, Na ２ O and K ２ The total content of O (Li ２ O + Na ２ O+K ２ O) is 15.00% or less, B ２ O ３ P content ２ O ５ Mass ratio of content (P ２ O ５ / B ２ O ３ ) is 18.00 or less, Li ２ O, Na ２ O and K ２ Na content relative to total O content ２ Mass ratio of O content (Na ２ O / (Li ２ O + Na ２ O+K ２ O)) is 0.50 or less, The total content of MgO and CaO (MgO + CaO) is 2.00% or more, B ２ O ３ Li content ２ The mass ratio of the total content of O and BaO ((Li ２ O+BaO) / B ２ O ３ ) is 0.59 or less, Li ２ Al relative to O content ２ O ３ and BaO total content mass ratio ((Al ２ O ３ + BaO) / Li ２ O) is 2.77 or less, Li ２ O, Na ２ O and K ２ The mass ratio of the total content of MgO and CaO to the total content of O ((MgO + CaO) / (Li ２ O + Na ２ O+K ２ O)) is 6.10 or less, P ２ O ５ , B ２ O ３ and SiO ２ The mass ratio of the total content of MgO, CaO, SrO, BaO, and ZnO to the total content of MgO, CaO, SrO, BaO, and ZnO ((MgO + CaO + SrO + BaO + ZnO) / (P ２ O ５ +B ２ O ３ +SiO ２ )) is 0.36 or less, A refractive index nd of 1.70000 or less, Abbe number νd is 60.00 or more, and Average linear expansion coefficient α at 100°C to 300°C is 130 x 10 －７ Optical glass having a refractive index of 1 / K or less.
2. La ２ O ３ , Gd ２ O ３ and Y ２ O ３ The total content (La ２ O ３ +Gd ２ O ３ +Y ２ O ３ 2. The optical glass according to claim 1, wherein the content of C is 7.00% or less.
3. Nb ２ O ５ 2. The optical glass according to claim 1, wherein the content is 5.00% or less.
4. 2. The optical glass according to claim 1, wherein the total content of MgO, CaO, SrO, and BaO (MgO + CaO + SrO + BaO) is 4.90% or more and 26.00% or less.
5. Li ２ O, Na ２ O and K ２ Na content relative to total O content ２ Mass ratio of O content (Na ２ O / (Li ２ O + Na ２ O+K ２ 2. The optical glass according to claim 1, wherein .DELTA.O) is 0.19 or less.
6. 2. The optical glass according to claim 1, wherein the total content of ZnO and BaO (ZnO + BaO) is 20.50% or less.
7. SiO ２ 2. The optical glass according to claim 1, wherein the content is 5.00% or less.
8. The CaO content is less than 9.00%, or 2. The optical glass according to claim 1, wherein the CaO content is 9.00% or more and 18.00% or less, and the total content of SrO and BaO (SrO + BaO) is less than 3.00%.
9. 2. The optical glass according to claim 1, wherein the total content of SrO and BaO (SrO+BaO) is 13.00% or less.
10. SrO, BaO and K ２ The total content of O (SrO + BaO + K ２ 2. The optical glass of claim 1, wherein O is 13.00% or less.
11. Li ２ The mass ratio of the total content of SrO and BaO to the O content ((SrO + BaO) / Li ２ 2. The optical glass according to claim 1, wherein .DELTA..O) is 5.00 or less.
12. P ２ O ５ The content is 47.00% or more and less than 58.00%, or P ２ O ５ The content is 58.00% or more and 80.00% or less and Li ２ O, Na ２ O and K ２ The mass ratio of the total content of MgO, CaO, SrO, BaO, and ZnO to the total content of O ((MgO + CaO + SrO + BaO + ZnO) / (Li ２ O + Na ２ O+K ２ 2. The optical glass of claim 1 , wherein σ is less than 6.
00.
13. 2. The optical glass according to claim 1, which has a specific gravity of 3.00 g / cc or less.
14. 2. The optical glass according to claim 1, which has an external transmittance of 60% or more in wavelengths of 400 nm to 700 nm when converted into a thickness of 10.0 mm.
15. La ２ O ３ , Gd ２ O ３ and Y ２ O ３ The total content (La ２ O ３ +Gd ２ O ３ +Y ２ O ３ ) is 7.00% or less, Nb ２ O ５ The content is 5.00% or less, The total content of MgO, CaO, SrO, and BaO (MgO + CaO + SrO + BaO) is 4.90% or more and 26.00% or less, Li ２ O, Na ２ O and K ２ Na content relative to total O content ２ Mass ratio of O content (Na ２ O / (Li ２ O + Na ２ O+K ２ O)) is 0.19 or less, The total content of ZnO and BaO (ZnO + BaO) is 20.50% or less, SiO ２ The content is 5.00% or less, The CaO content is less than 9.00% and the total content of SrO and BaO (SrO + BaO) is 13.00% or less, or the CaO content is 9.00% or more and 18.00% or less and the total content of SrO and BaO (SrO + BaO) is less than 3.00%; SrO, BaO and K ２ The total content of O (SrO + BaO + K ２ O) is 13.00% or less, Li ２ The mass ratio of the total content of SrO and BaO to the O content ((SrO + BaO) / Li ２ O) is 5.00 or less, P ２ O ５ The content is 47.00% or more and less than 58.00%, or P ２ O ５ The content is 58.00% or more and 80.00% or less and Li ２ O, Na ２ O and K ２ The mass ratio of the total content of MgO, CaO, SrO, BaO, and ZnO to the total content of O ((MgO + CaO + SrO + BaO + ZnO) / (Li ２ O + Na ２ O+K ２ O)) is less than 6.00, A specific gravity of 3.00 g / cc or less; and 2. The optical glass according to claim 1, which has an external transmittance of 60% or more in wavelengths of 400 nm to 700 nm, calculated as a thickness of 10.0 mm.
16. An optical element made of the optical glass according to any one of claims 1 to 15.
Citation Information
Patent Citations
Optical glass
JP2010269980A