Optical glass and optical elements

Abstract

To provide optical glass and optical elements. [Solution] The present invention provides an optical glass with a high refractive index and low specific gravity, and an optical element containing this optical glass, while reducing costs. In the glass composition of this optical glass, expressed in mass%, the SiO2 content is 0-20%, the B2O3 content is 5-30%, the BaO content is 0-6.5%, the La2O3 content is 29-55%, the TiO2 content is 5-50%, the Nb2O5 content is 0-5%, the WO3 content is 0-0.6%, the CaO content is 15% or less, the ZnO content is 0-20%, the ZrO2 content is 0-20%, and the mass ratio of the total TiO2 and ZrO2 content to the CaO content ((TiO2+ZrO2) / CaO) is greater than 3.3.

Description

[Technical Field]

[0001] This invention relates to optical glass that reduces costs while having a high refractive index and low specific gravity, and to optical elements containing this optical glass. [Background technology]

[0002] Patent Document 1 discloses an optical glass containing a large amount of Nb2O5. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Chinese Patent Application Publication No. 111320384 Specification [Overview of the project] [Problems that the invention aims to solve]

[0004] Among the components of optical glass, niobium oxide (Nb2O5) can increase the refractive index and decrease the Abbe number. However, if the content is too high, the transmittance of visible light decreases, and the specific gravity and cost of the glass increase.

[0005] Therefore, the present invention was developed in view of the above problems, and its objective is to provide optical glass with a high refractive index and low specific gravity, and optical elements containing this optical glass, while simultaneously reducing costs. [Means for solving the problem]

[0006] The purpose of this invention is as follows.

[0007] (1) In optical glass, the glass composition of this optical glass, expressed in mass%, The SiO2 content is 0-20%. The B2O3 content is 5-30%. The BaO content is 0-6.5%. The La2O3 content is 29-55%. The TiO2 content is 5-50%. The Nb2O5 content is 0-5%. The WO3 content is 0-0.6%. The CaO content is 15% or less. The ZnO content is 0-20%, The ZrO2 content is 0-20%. Optical glass in which the mass ratio of the total TiO2 and ZrO2 content to the CaO content ((TiO2+ZrO2) / CaO) is greater than 3.3.

[0008] (2) In terms of mass percentage, The Y2O3 content is 4.31% or less. The Na2O content is 1.16% or less. The Gd2O3 content is 3% or less. The Ta2O5 content is 3% or less. The optical glass described in (1), which satisfies at least one of the following conditions.

[0009] (3) The optical glass according to (1) or (2), wherein the mass ratio of the CaO content to the total content of CaO, BaO, SrO, and ZnO (CaO / (CaO+BaO+SrO+ZnO)) is greater than 0.

[0010] (4) An optical glass according to any one of the following (1) to (3), wherein the mass ratio of TiO2 content to ZnO content (TiO2 / ZnO) is greater than 0.85.

[0011] (5) An optical glass according to any one of items (1) to (4), wherein the mass ratio of B2O3 content to SiO2 content (B2O3 / SiO2) is 1.5 to 5.87.

[0012] (6) The optical glass according to any one of (1) to (5), wherein the total content of La2O3, Gd2O3 and Y2O3 (La2O3 + Gd2O3 + Y2O3) is 29 to 55%.

[0013] (7) The optical glass according to any one of (1) to (6), wherein the mass ratio of the B2O3 content to the ZrO2 content (B2O3 / ZrO2) is greater than 0 and 6.1 or less.

[0014] (8) The optical glass according to any one of (1) to (7), wherein the mass ratio of the Nb2O5 content to the total content of Nb2O5, TiO2, WO3 and Ta2O5 (Nb2O5 / (Nb2O5 + TiO2 + WO3 + Ta2O5)) is 0 to 0.24.

[0015] (9) The optical glass according to any one of (1) to (8), wherein the mass ratio of the Y2O3 content to the B2O3 content (Y2O3 / B2O3) is 0 to 0.35.

[0016] (10)[[ID=P23]] The Nb2O5 content is 0 to 4%; The SiO2 content is 1 to 18%; The B2O3 content is 7 to 28%; The BaO content is 0 to 5.5%; The ZnO content is 1 to 18%; [[ID=P34]]The La2O3 content is 31 to 53%; The Y2O3 content is 3% or less; The TiO2 content is 7 to 45%; The WO3 content is 0 to 0.5%; The ZrO2 content is 1 to 19%; The CaO content is 1 to 13%; The Na2O content is 0.8% or less; The Gd2O3 content is 2% or less; The Ta2O5 content is 2% or less; The mass ratio of the total TiO2 and ZrO2 content to the CaO content ((TiO2 + ZrO2) / CaO) is 3.35 or higher; The mass ratio of CaO content to the total content of CaO, BaO, SrO, and ZnO (CaO / (CaO+BaO+SrO+ZnO)) is between 0.05 and 1.0. The mass ratio of B2O3 content to SiO2 content (B2O3 / SiO2) is between 1.6 and 5.5. The total content of La2O3, Gd2O3, and Y2O3 (La2O3 + Gd2O3 + Y2O3) is 33-55%. The mass ratio of B2O3 content to ZrO2 content (B2O3 / ZrO2) is between 0.4 and 5.7. The mass ratio of the Nb2O5 content to the total content of Nb2O5, TiO2, WO3, and Ta2O5 (Nb2O5 / (Nb2O5+TiO2+WO3+Ta2O5)) is between 0 and 0.2. The mass ratio of TiO2 content to ZnO content (TiO2 / ZnO) is 0.9 or higher; The mass ratio of Y2O3 content to B2O3 content (Y2O3 / B2O3) is between 0 and 0.3. The refractive index nd is between 1.8800 and 1.9200; The Abbe number vd is between 28 and 33; The specific gravity is 4.00 to 5.00; The glass transition temperature (Tg) is 600-670°C; λ 70 The wavelength is 375-440 nm; λ5 is 350-370 nm. An optical glass according to any one of items (1) to (9), satisfying at least one of the following conditions.

[0017] (11) The Nb2O5 content is 0-3%; The SiO2 content is 2-16%; The B2O3 content is 9-26%; The BaO content is 0.1-4.5%; The ZnO content is 2-16%; The La2O3 content is 33-51%; The Y2O3 content is 2% or less; The TiO2 content is 9-40%; The WO3 content is 0-0.4%; The ZrO2 content is 2-18%; The CaO content is 2-12%; The Na2O content is 0.4% or less; The Gd2O3 content is 1% or less; The Ta2O5 content is 1% or less; The mass ratio of the total TiO2 and ZrO2 content to the CaO content ((TiO2 + ZrO2) / CaO) is 3.40 or higher; The mass ratio of CaO content to the total content of CaO, BaO, SrO, and ZnO (CaO / (CaO+BaO+SrO+ZnO)) is between 0.10 and 0.8. The mass ratio of B2O3 content to SiO2 content (B2O3 / SiO2) is between 1.7 and 5.0. The total content of La2O3, Gd2O3, and Y2O3 (La2O3 + Gd2O3 + Y2O3) is between 36.4% and 55%. The mass ratio of B2O3 content to ZrO2 content (B2O3 / ZrO2) is between 0.8 and 4.9. The mass ratio of Nb2O5 content to the total content of Nb2O5, TiO2, WO3, and Ta2O5 (Nb2O5 / (Nb2O5+TiO2+WO3+Ta2O5)) is between 0 and 0.15. The mass ratio of TiO2 content to ZnO content (TiO2 / ZnO) is 0.95 or higher; The mass ratio of Y2O3 content to B2O3 content (Y2O3 / B2O3) is between 0 and 0.2. The refractive index nd is between 1.8850 and 1.9180; The Abbe number vd is between 28.5 and 32.6; Its specific gravity is 4.05 to 4.90; The glass transition temperature (Tg) is 604–668°C; λ 70 The wavelength is 376-439 nm; λ5 is 352-368 nm. An optical glass according to any one of items (1) to (9), satisfying at least one of the following conditions.

[0018] (12) The Nb2O5 content is 0-2%; The SiO2 content is 3-12%; The B2O3 content is 11-24%; The BaO content is 0.1-3.5%; The ZnO content is 3-15%; The La2O3 content is 35-49%; The Y2O3 content is 1% or less; The TiO2 content is 11-30%; The WO3 content is 0-0.3%; The ZrO2 content is 3-17%; The CaO content is 2.5-11%; The Na2O content is 0%; The Gd2O3 content is 0%; The Ta2O5 content is 0%; The mass ratio of the total TiO2 and ZrO2 content to the CaO content ((TiO2 + ZrO2) / CaO) is 3.45 or higher; The mass ratio of CaO content to the total content of CaO, BaO, SrO, and ZnO (CaO / (CaO+BaO+SrO+ZnO)) is between 0.15 and 0.7. The mass ratio of B2O3 content to SiO2 content (B2O3 / SiO2) is between 1.8 and 4.5. The total content of La2O3, Gd2O3, and Y2O3 (La2O3 + Gd2O3 + Y2O3) is 37-51%. The mass ratio of B2O3 content to ZrO2 content (B2O3 / ZrO2) is between 1.2 and 4.1. The mass ratio of the Nb2O5 content to the total content of Nb2O5, TiO2, WO3, and Ta2O5 (Nb2O5 / (Nb2O5+TiO2+WO3+Ta2O5)) is between 0 and 0.1. The mass ratio of TiO2 content to ZnO content (TiO2 / ZnO) is 1.00 or greater; The mass ratio of Y2O3 content to B2O3 content (Y2O3 / B2O3) is between 0 and 0.1. The refractive index nd is between 1.8900 and 1.9160; The Abbe number vd is between 29 and 32.2; Its specific gravity is 4.10 to 4.85; The glass transition temperature (Tg) is 606–666°C; λ 70 The wavelength is 378-438 nm; λ5 is 354-367 nm. An optical glass according to any one of items (1) to (9), satisfying at least one of the following conditions.

[0019] (13) The Nb2O5 content is 0-1%; The SiO2 content is 4-10%; The B2O3 content is 12-22%; The BaO content is 0.2-2.5%; The La2O3 content is 37-47%; The Y2O3 content is 0%; The TiO2 content is 12-20%; The WO3 content is 0-0.2%; The ZrO2 content is 4-16%; The CaO content is 3-10%; The mass ratio of the total TiO2 and ZrO2 content to the CaO content ((TiO2 + ZrO2) / CaO) is 3.50 or higher; The mass ratio of CaO content to the total content of CaO, BaO, SrO, and ZnO (CaO / (CaO+BaO+SrO+ZnO)) is between 0.20 and 0.60. The mass ratio of B2O3 content to SiO2 content (B2O3 / SiO2) is between 1.9 and 4.0. The total content of La2O3, Gd2O3, and Y2O3 (La2O3 + Gd2O3 + Y2O3) is 38-49%. The mass ratio of B2O3 content to ZrO2 content (B2O3 / ZrO2) is between 1.6 and 3.3. The mass ratio of the Nb2O5 content to the total content of Nb2O5, TiO2, WO3, and Ta2O5 (Nb2O5 / (Nb2O5+TiO2+WO3+Ta2O5)) is between 0 and 0.05. The mass ratio of TiO2 content to ZnO content (TiO2 / ZnO) is 1.10 or higher; The mass ratio of Y2O3 content to B2O3 content (Y2O3 / B2O3) is 0; The refractive index nd is between 1.8950 and 1.9120; The Abbe number vd is between 30 and 31.8; Its specific gravity is 4.15 to 4.80; The glass transition temperature (Tg) is 610–664°C; λ 70 The wavelength is 379-437 nm; λ5 is 355-366 nm. An optical glass according to any one of items (1) to (9), satisfying at least one of the following conditions.

[0020] (14) The Nb2O5 content is 0%; The B2O3 content is 13-20%; The BaO content is 0.2-1.5%; The La2O3 content is 39-45%; The WO3 content is 0-0.1%; The ZrO2 content is 5-15%; The mass ratio of the total TiO2 and ZrO2 content to the CaO content ((TiO2 + ZrO2) / CaO) is 3.55 or higher; The mass ratio of CaO content to the total content of CaO, BaO, SrO, and ZnO (CaO / (CaO+BaO+SrO+ZnO)) is between 0.20 and 0.50. The mass ratio of B2O3 content to SiO2 content (B2O3 / SiO2) is between 2.0 and 3.5. The total content of La2O3, Gd2O3, and Y2O3 (La2O3 + Gd2O3 + Y2O3) is 39-45%. The mass ratio of the Nb2O5 content to the total content of Nb2O5, TiO2, WO3, and Ta2O5 (Nb2O5 / (Nb2O5+TiO2+WO3+Ta2O5)) is 0; The refractive index nd is between 1.9000 and 1.9100; The Abbe number vd is between 31 and 31.6; Its specific gravity is 4.20 to 4.70; λ 70 The wavelength is 380-436 nm; λ5 is 356-365 nm. An optical glass according to any one of items (1) to (9), satisfying at least one of the following conditions.

[0021] (15) The BaO content is 0.3-0.5%; The WO3 content is 0%. An optical glass according to any one of items (1) to (9), satisfying at least one of the following conditions.

[0022] (16) An optical element containing optical glass as described in any one of items (1) to (15). [Effects of the Invention]

[0023] According to the present invention, it is possible to reduce costs while simultaneously providing optical glass with a high refractive index and low specific gravity, and optical elements containing this optical glass. [Modes for carrying out the invention]

[0024] Embodiments of the present invention will now be described. It is important to note that, unless otherwise specified, the glass composition of optical glass is expressed on an oxide basis in the present invention and this specification. Here, "glass composition on an oxide basis" refers to the glass composition obtained by converting it based on the substances that are completely decomposed when the glass raw materials melt and exist in the optical glass in the form of oxides, and each glass component is written as SiO2, TiO2, etc., according to convention. Unless otherwise specified, the content and total content of glass components are on a mass basis, and "%" refers to "mass%".

[0025] The content of glass components can be quantified by known methods such as inductively coupled plasma atomic emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). Furthermore, in this specification and the present invention, a component content of 0% means that the component is substantially absent, but is acceptable to contain the component at an unavoidable impurity level.

[0026] Furthermore, unless otherwise specified, the refractive index in this specification refers to the refractive index nd under the helium d line (wavelength 587.56 nm).

[0027] The glass composition of the optical glass of the present invention will be described in more detail below. The "lower limit" below means greater than or equal to the value stated, and the "upper limit" below means less than or equal to the value stated.

[0028] (Glass composition) In the optical glass of the present invention, the SiO2 content is 0 to 20%. The lower limit of the SiO2 content is preferably 1%, and more preferably 2%, 3%, and 4%, in that order. The upper limit of the SiO2 content is preferably 18%, and more preferably 17%, 16%, 15%, 14%, 13%, 12%, 11%, and 10%, in that order. SiO2 is a network-forming component of glass, and the addition of SiO2 can increase the viscosity of the molten glass, improve the devitrification resistance of the glass, suppress the rise in the glass transition temperature, and decrease the specific gravity of the glass. However, if the SiO2 content is too high, it will lead to a decrease in the refractive index.

[0029] In the optical glass of the present invention, the B2O3 content is 5 to 30%. The lower limit of the B2O3 content is preferably 6%, and more preferably 7%, 8%, 9%, 10%, 11%, 12%, and 13%, in that order. The upper limit of the B2O3 content is preferably 29%, and more preferably 28%, 27%, 26%, 25%, 24%, 23%, 22%, 21%, and 20%, in that order. B2O3 is a network-forming component of glass and an essential component indispensable as a glass-forming oxide. The B2O3 component can improve the devitrification resistance of glass and reduce the specific gravity of glass. However, if the B2O3 content is too high, the refractive index of the glass will decrease, the Abbe number will increase, and moreover, the chemical durability will decrease.

[0030] In the optical glass of the present invention, the Nb2O5 content is 0 to 5%. The Nb2O5 content is preferably 4% or less, more preferably 3% or less, 2% or less, 1% or less, 0.5% or less, and most preferably 0%. The Nb2O5 component can increase the refractive index, decrease the Abbe number, and improve the devitrification of the glass. However, if the Nb2O5 content is too high, it leads to a decrease in the devitrification resistance of the glass and a decrease in the transmittance of visible light, and also increases the specific gravity of the glass, raising the cost of the glass material.

[0031] In the optical glass of the present invention, the BaO content is 0 to 6.5%. The lower limit of the BaO content is preferably 0.1%, and more preferably 0.2% and 0.3%, respectively. The upper limit of the BaO content is preferably 6%, and more preferably 5.5%, 5.0%, 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, and 0.5%, respectively. The BaO component can increase the refractive index of the glass, improve the meltability and devitrification resistance of the glass raw material, and lower the glass transition temperature. However, if the BaO content is too high, it will cause devitrification and an increase in specific gravity of the glass.

[0032] In the optical glass of the present invention, the La2O3 content is 29-55%. The lower limit of the La2O3 content is preferably 30%, and more preferably 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, and 39%, in that order. The upper limit of the La2O3 content is preferably 54%, and more preferably 53%, 52%, 51%, 50%, 49%, 48%, 47%, 46%, and 45%, in that order. The La2O3 component can increase the refractive index as a rare earth oxide and can also suppress an increase in the Abbe number. However, if the La2O3 content is too high, it may reduce the stability of the glass and increase the devitrification of the glass.

[0033] In the optical glass of the present invention, the TiO2 content is 5 to 50%. The lower limit of the TiO2 content is preferably 6%, and more preferably 7%, 8%, 9%, 10%, 11%, and 12%, in that order. The upper limit of the TiO2 content is preferably 50%, and more preferably 45%, 40%, 35%, 30%, 25%, and 20%, in that order. The TiO2 component can increase the refractive index of the glass, decrease the Abbe number, and improve the devitrification of the glass. However, if the TiO2 content is too high, it increases the coloration of the glass, decreases the visible light transmittance of the glass, decreases the Abbe number of the glass, and increases the risk of devitrification of the glass.

[0034] In the optical glass of the present invention, the WO3 content is 0 to 0.6%. The WO3 content is preferably 0.5% or less, more preferably 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, and most preferably 0%. WO3 is a component that increases the refractive index of the glass and enhances the color dispersion of the glass, and the addition of the WO3 component also tends to reduce the crystallization of the glass. However, if the WO3 content is too high, it increases the coloration of the glass, decreases the transmittance of the glass to light, and also increases the specific gravity of the glass.

[0035] In the optical glass of the present invention, the CaO content is 15% or less. The lower limit of the CaO content can be 0.00%, preferably 0.5%, and more preferably 1%, 1.5%, 2%, 2.5%, and 3%, respectively. The upper limit of the CaO content is preferably 14%, and more preferably 13%, 12%, 11%, and 10%, respectively. CaO is a component that increases the meltability of the glass raw material and lowers the specific gravity of the glass. However, if the CaO content is too high, it will cause a decrease in the refractive index of the glass and increase the risk of devitrification of the glass.

[0036] In the optical glass of the present invention, the ZnO content is 0 to 20%. The lower limit of the ZnO content is preferably 0.5%, and more preferably 1%, 1.5%, 2%, 2.5%, and 3%, respectively. The upper limit of the ZnO content is preferably 19%, and more preferably 18%, 17%, 16%, and 15%, respectively. ZnO is a component that lowers the glass transition temperature of the glass, reduces its specific gravity, and enhances the chemical stability of the glass. However, if the ZnO content is too high, it can cause a decrease in the refractive index of the glass and a decrease in the melt viscosity of the glass, and the risk of devitrification of the glass increases.

[0037] In the optical glass of the present invention, the ZrO2 content is 0 to 20%. The lower limit of the ZrO2 content is preferably 0.5%, and more preferably 1%, 1.5%, 2%, 3%, 4%, and 5%, in that order. The upper limit of the ZrO2 content is preferably 19%, and more preferably 18%, 17%, 16%, and 15%, in that order. ZrO2 is a component that increases the refractive index of the glass and improves its weather resistance. However, if the ZrO2 content is too high, it will cause an increase in the Abbe number of the glass and a decrease in the devitrification resistance of the glass.

[0038] In the optical glass of the present invention, the mass ratio of the total content of TiO2 and ZrO2 to the CaO content ((TiO2+ZrO2) / CaO) is greater than 3.3. Preferably, this mass ratio ((TiO2+ZrO2) / CaO) is 3.35 or higher, and more preferably, 3.40 or higher, 3.45 or higher, 3.50 or higher, and 3.55 or higher, respectively. By setting this mass ratio ((TiO2+ZrO2) / CaO) within the above range, the desired glass specific gravity and transmittance to light can be obtained, and the target optical parameters of the present invention can be realized.

[0039] Furthermore, the content of glass components other than those mentioned above in the optical glass of the present invention is shown below as a non-limiting example.

[0040] In one form, the Y2O3 content is 4.31% or less. Preferably, the Y2O3 content is 4% or less, more preferably 3% or less, 2% or less, 1% or less, 0.5% or less, and most preferably 0%. Y2O3 is a component that increases the refractive index of the glass, reduces color dispersion, and improves the weather resistance of the glass. However, if the Y2O3 content is too high, the color dispersion of the glass decreases, making it difficult to meet the requirements for color dispersion of the glass, and the glass becomes prone to devitrification.

[0041] In one form, the Na2O content is 1.16% or less. The Y2O3 content is preferably 1.0% or less, more preferably 0.8% or less, 0.4% or less, 0.2% or less, and most preferably 0%. Na2O is a component that improves the meltability of the glass raw material, but if the Na2O content is too high, it causes devitrification of the glass.

[0042] In one form, the Gd2O3 content is 3% or less. Preferably, the Gd2O3 content is 2.5% or less, more preferably 2.0% or less, 1.5% or less, 1.0% or less, 0.5% or less, and most preferably 0%. Gd2O3 is a component that increases the refractive index of glass and improves its resistance to devitrification, but if the Gd2O3 content is too high, it will cause devitrification of the glass, increase the specific gravity of the glass, and also increase the cost of the glass.

[0043] In one form, the Ta2O5 content is 3% or less. Preferably, the Ta2O5 content is 2.5% or less, more preferably 2.0% or less, 1.5% or less, 1.0% or less, 0.5% or less, and most preferably 0%. Ta2O5 is a component that increases the refractive index of the glass, improves its resistance to devitrification, and increases the viscosity of the molten glass. However, if the Ta2O5 content is too high, it increases the specific gravity of the glass and also increases the cost of the glass.

[0044] In one embodiment, the mass ratio of the CaO content to the total content of CaO, BaO, SrO, and ZnO (CaO / (CaO+BaO+SrO+ZnO)) is greater than 0. The lower limit of this mass ratio (CaO / (CaO+BaO+SrO+ZnO)) is preferably 0.05, and more preferably 0.1, 0.15, and 0.20, respectively. The upper limit of this mass ratio (CaO / (CaO+BaO+SrO+ZnO)) is preferably 1.0, and more preferably 0.90, 0.80, 0.70, 0.60, and 0.50, respectively. By setting this mass ratio (CaO / (CaO+BaO+SrO+ZnO)) within the above range, the transmittance of the glass to light can be increased while simultaneously obtaining the desired glass specific gravity.

[0045] In one embodiment, the mass ratio of TiO2 content to ZnO content (TiO2 / ZnO) is greater than 0.85. This mass ratio (TiO2 / ZnO) is preferably 0.90 or higher, and more preferably 0.95 or higher, 1.00 or higher, 1.05 or higher, and 1.10 or higher, in that order. By setting this mass ratio (TiO2 / ZnO) within the above range, the desired glass specific gravity and light transmittance can be obtained, and the target optical parameters of the present invention can be realized. ZnO can lower the liquidus temperature of the glass and improve the devitrification resistance of the glass, and TiO2 / ZnO can reflect the change in the liquidus temperature of the glass. However, if the value of this ratio is too high, the liquidus temperature of the glass will rise, which is unfavorable for achieving the target parameters, and if the value of this ratio is too low, the viscosity of the glass will decrease, which is unfavorable for glass molding.

[0046] In one embodiment, the mass ratio of B2O3 content to SiO2 content (B2O3 / SiO2) is 1.5 to 5.87. The lower limit of this mass ratio (B2O3 / SiO2) is preferably 1.6, and more preferably 1.7, 1.8, 1.9, and 2.0, respectively. The upper limit of this mass ratio (B2O3 / SiO2) is preferably 5.5, and more preferably 5.0, 4.5, 4.0, and 3.5, respectively. If this mass ratio (B2O3 / SiO2) is too high, the viscosity of the glass decreases, which is unfavorable for glass molding. Conversely, if this mass ratio (B2O3 / SiO2) is too low, the viscosity of the glass increases, which is also unfavorable for glass molding.

[0047] In one embodiment, the total content of La2O3, Gd2O3, and Y2O3 (La2O3+Gd2O3+Y2O3) is preferably 29-55%, and more preferably 36.4-55%. The lower limit of this total content (La2O3+Gd2O3+Y2O3) is preferably 31%, and more preferably 32%, 33%, 34%, 35%, 36%, 37%, 38%, and 39%, respectively. The upper limit of this total content (La2O3+Gd2O3+Y2O3) is preferably 55%, and more preferably 54%, 53%, 52%, 51%, 50%, 49%, 48%, 47%, 46%, and 45%, respectively. By keeping the total content (La2O3 + Gd2O3 + Y2O3) within the above range, it is possible to increase the refractive index of the glass and decrease the color dispersion of the glass, while also avoiding an increase in the melting temperature of the glass, a decrease in the stability of the glass, and a decrease in devitrification resistance.

[0048] In one embodiment, the mass ratio of B2O3 content to ZrO2 content (B2O3 / ZrO2) is greater than 0 and 6.1 or less. The lower limit of this mass ratio (B2O3 / ZrO2) is preferably 0.4, and more preferably 0.6, 0.8, 1.0, 1.2, 1.4, and 1.6, respectively. The upper limit of this mass ratio (B2O3 / ZrO2) is preferably 5.7, and more preferably 5.3, 4.9, 4.5, 4.1, 3.7, and 3.3, respectively. By setting this mass ratio (B2O3 / ZrO2) within the above range, the weather resistance and stability of the glass can be improved, the viscosity can be kept within an appropriate range, the network structure of the glass can not be destroyed, and the crystallization temperature of the glass can not be increased.

[0049] In one embodiment, the mass ratio of Nb2O5 content to the total content of Nb2O5, TiO2, WO3, and Ta2O5 (Nb2O5 / (Nb2O5+TiO2+WO3+Ta2O5)) is 0 to 0.24. This mass ratio (Nb2O5 / (Nb2O5+TiO2+WO3+Ta2O5)) is preferably 0.20 or less, more preferably 0.15 or less, 0.10 or less, 0.05 or less, and most preferably 0. By setting this mass ratio (Nb2O5 / (Nb2O5+TiO2+WO3+Ta2O5)) within the above range, a high refractive index and a reduced Abbe number can be obtained, while simultaneously obtaining the desired glass specific gravity.

[0050] In one embodiment, the mass ratio of Y2O3 content to B2O3 content (Y2O3 / B2O3) is 0 to 0.35. This mass ratio (Y2O3 / B2O3) is preferably 0.30 or less, more preferably 0.25 or less, 0.20 or less, 0.15 or less, 0.10 or less, 0.05 or less, and most preferably 0. Y2O3 is a high refractive index component, and B2O3 is a low refractive index component. The value of this ratio can reflect the change in the refractive index and stability of the glass, but if the value of this ratio is too high, the stability of the glass decreases.

[0051] Furthermore, the glass of the present invention may contain Sb2O3 and ZnS components as needed. The Sb2O3 component has an antifoaming effect when the glass is melted, and the ZnS component is added to the glass raw material as a reducing agent to suppress the mixing of platinum into the glass and increase the transmittance of the glass. The content of the ZnS component as a reducing agent relative to the total mass of the glass may be 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less, and the content of the Sb2O3 component as an antifoaming agent relative to the total mass of the glass may be 3% or less or 2% or less.

[0052] (Properties of glass) <refractive index nd> The refractive index nd of the optical glass of the present invention can be 1.87955 or higher, and is preferably between 1.8800 and 1.9200. The lower limit of the refractive index nd is preferably 1.8850, and more preferably 1.8900, 1.8950, and 1.9000, in that order. The upper limit of the refractive index nd is preferably 1.9180, and more preferably 1.9160, 1.9140, 1.9120, and 1.9100, in that order.

[0053] The refractive index nd can be set to a desired value by appropriately adjusting the content of each glass component. Components that relatively increase the refractive index nd (high refractive index components) include TiO2, ZrO2, La2O3, Y2O3, and Gd2O3. On the other hand, components that relatively decrease the refractive index nd (low refractive index components) include SiO2, B2O3, and Na2O. Furthermore, for example, the refractive index nd can be set to a desired value by appropriately adjusting the ratio of the above-mentioned content.

[0054] <Abbe number vd> The Abbe number vd is a value that represents the property related to chromatic dispersion, and is expressed as vd = (nd-1) / (nF-nC) using the refractive indices nd, nF, and nC for the d-line, F-line, and C-line, respectively. In the optical glass of the present invention, the Abbe number vd is preferably 28 to 33. The lower limit of the Abbe number vd is preferably 28.5, and more preferably 29.0, 29.5, 30.0, 30.5, and 31.0, respectively. The upper limit of the Abbe number vd is preferably 32.6, and more preferably 32.2, 32.0, 31.8, and 31.6, respectively.

[0055] The Abbe number vd can be set to a desired value by appropriately adjusting the content of each glass component. Components that relatively decrease the Abbe number vd include La2O3 and Nb2O5. On the other hand, components that relatively increase the Abbe number vd include B2O3. Furthermore, for example, the Abbe number vd can be set to a desired value by appropriately adjusting the ratio of the above-mentioned content.

[0056] <Specific gravity of glass> The specific gravity of the optical glass of the present invention is preferably 4.00 to 5.00. The lower limit of the specific gravity of the optical glass is preferably 4.05, and more preferably 4.10, 4.15, and 4.20, respectively. The upper limit of the specific gravity is preferably 4.90, and more preferably 4.85, 4.80, 4.75, and 4.70, respectively.

[0057] The specific gravity of glass can be adjusted to a desired value by appropriately adjusting the content of each glass component. Components that relatively increase the specific gravity include BaO, La2O3, ZrO2, Nb2O5, and Ta2O5. On the other hand, components that relatively decrease the specific gravity include SiO2, B2O3, Li2O, Na2O, and K2O. Furthermore, for example, the specific gravity of glass can be adjusted to a desired value by appropriately adjusting the ratio of the above-mentioned content.

[0058] <Glass transition temperature Tg> The glass transition temperature Tg of the optical glass of the present invention is preferably 600 to 670 °C. The lower limit of the glass transition temperature Tg is preferably 602 °C, and more preferably 604 °C, 606 °C, 608 °C, 610 °C in sequence. Further, the upper limit of the glass transition temperature Tg is preferably 669 °C, and more preferably 668 °C, 667 °C, 666 °C, 665 °C, 664 °C, 663 °C, 662 °C in sequence.

[0059] The glass transition temperature Tg can be set to a desired value by adjusting the content of each glass component. Components that relatively lower the glass transition temperature Tg are BaO, ZnO, Na2O, etc. Components that relatively increase the glass transition temperature Tg are La2O3, ZrO2, Nb2O5, etc. Further, for example, the glass transition temperature Tg can be set to a desired value by appropriately adjusting the ratio of each of the above contents.

[0060] <Light transmittance of glass> The light transmittance of the optical glass of the present invention can be evaluated by the coloring degree λ 70 and λ5.

[0061] For a glass sample with a thickness of 10.0 mm ± 0.1 mm, the spectral transmittance in the wavelength range of 200 to 700 nm is measured, and the wavelength at which the external transmittance becomes 70% is λ 70 and the wavelength at which the external transmittance becomes 5% is taken as λ5.

[0062] λ 70 of the optical glass of the present invention is preferably 375 to 440 nm. The lower limit of λ 70 is preferably 376 nm, and more preferably 377 nm, 378 nm, 379 nm, 380 nm in sequence. The upper limit of λ 70 is preferably 439 nm, and more preferably 438 nm, 437 nm, 436 nm in sequence.

[0063] The λ5 of the optical glass of the present invention is preferably 350 to 370 nm. The lower limit of λ5 is preferably 351 nm, and more preferably 352 nm, 353 nm, 354 nm, 355 nm, and 356 nm, in that order. The upper limit of λ5 is preferably 369 nm, and more preferably 368 nm, 367 nm, 366 nm, and 365 nm, in that order.

[0064] The part that requires explanation is the λ of the optical glass of the present invention. 70 And λ5 can be brought to a desired range by adjusting the content of each glass component, and the sum or ratio of the above-mentioned contents.

[0065] (Manufacturing of optical glass) The glass of the present invention can be produced by blending glass raw materials to achieve the above-mentioned predetermined composition, and then using the blended glass raw materials by a known glass manufacturing method. For example, multiple types of compounds can be blended and thoroughly mixed to form a batch raw material, and the batch raw material can be placed in a quartz crucible or a platinum crucible and subjected to coarse melting. The molten material obtained from the coarse melting can be quenched and pulverized to produce crushed glass. Furthermore, the crushed glass can be placed in a platinum crucible and heated to remelt it into molten glass, and after further clarification and homogenization, the molten glass can be molded and cooled slowly to obtain optical glass. Known methods can be used for molding and slow cooling of the molten glass.

[0066] What needs to be explained is that, as long as the desired glass components can be introduced into the glass and the desired content is achieved, there are no particular limitations on the compounds used when blending the batch raw materials. Examples of such compounds include oxides, carbonates, nitrates, hydroxides, fluorides, and the like.

[0067] (Manufacturing of optical elements, etc.) When manufacturing optical elements using the optical glass of the present invention, known methods may be employed. For example, in the manufacture of the optical glass described above, molten glass is poured into a mold and formed into a plate to produce a glass material formed from the optical glass of the present invention. The obtained glass material is cut, ground, and polished as appropriate to produce fragments of a size and shape suitable for press molding. The fragments are heated to soften, and press molding (reheat press) is performed by known methods to produce an optical element blank with a shape similar to an optical element. The optical element blank is annealed, and the optical element is manufactured by grinding and polishing by known methods.

[0068] Depending on the intended use, the optical functional surface of the fabricated optical element may be covered with an anti-reflective coating, a total reflection coating, or the like.

[0069] According to one aspect of the present invention, an optical element formed from the above-mentioned optical glass can be provided. Examples of optical elements include lenses such as spherical lenses and aspherical lenses, prisms, diffraction gratings, etc. Examples of lens shapes include various shapes such as biconvex lenses, plano-convex lenses, biconcave lenses, plano-concave lenses, convex meniscus lenses, and concave meniscus lenses. The optical element can be manufactured by a method that includes a process of processing a glass molded body formed from the above-mentioned optical glass. Examples of processing include cutting, machining, rough grinding, fine grinding, polishing, etc. By using the above-mentioned glass when performing such processing, breakage can be reduced, and high-quality optical elements can be stably provided. [Examples]

[0070] The present invention will be described in more detail below through examples. However, the present invention is not limited to the embodiments shown in the examples.

[0071] Glass samples with the glass compositions shown in Tables 1 to 5 were prepared in the following order and evaluated in various ways.

[0072] [Manufacturing of optical glass] First, oxides, hydroxides, carbonates, and nitrates corresponding to the constituent components of glass are prepared as raw materials. These raw materials are weighed and blended so that the resulting optical glass has the composition shown in Tables 1 to 5, and the raw materials are thoroughly mixed. The resulting blended raw materials (batch raw materials) are placed in a platinum crucible and heated at 1350°C to 1400°C for 2 to 4 hours to form molten glass. Homogenization is achieved by stirring, and after clarification, the molten glass is poured into a mold preheated to an appropriate temperature. The poured glass is heat-treated at an arbitrary temperature between Tg and 100°C below the glass transition temperature Tg for 30 minutes, and then naturally cooled to room temperature in the furnace to obtain a glass sample.

[0073] [Confirmation of glass component composition] The content of each glass component was measured in the obtained glass samples using inductively coupled plasma atomic emission spectroscopy (ICP-AES), and it was confirmed that the compositions matched those shown in Tables 1 to 5.

[0074] [Measurement of optical properties] The obtained glass samples were further annealed for approximately 30 minutes to 2 hours near the glass transition temperature Tg, and then cooled to room temperature in a furnace at a cooling rate of -30°C / hour to obtain annealed samples. The refractive index, Abbe number vd, specific gravity, glass transition temperature Tg, and λ of the obtained annealed samples were measured. 70 The λ5 was also measured, and the results are shown in Tables 1 to 5, respectively.

[0075] (i) Refractive index and Abbe number vd For the above annealed samples, the refractive index was measured at the 12 wavelengths shown in Table A, according to the Japanese Industrial Standard (JIS) JIS B 7071-1 Method for measuring the refractive index of optical glass - Part 1: Minimum declination method.

[0076] Next, the refractive index of each radiation obtained by measurement is substituted into the shot dispersion formula specified in Annex B of the Japanese Industrial Standard (JIS) JIS B 7071-1 Method for measuring the refractive index of optical glass - Part 1: Minimum deflection method, and the constant of the shot dispersion formula is determined by the least squares method. Then, the Abbe number vd is calculated using the shot dispersion formula with the determined constant.

[0077] (ii) Specific gravity Specific gravity is measured by the Archimedes method.

[0078] (iii) Glass transition temperature Tg The glass transition temperature (Tg) was measured using a differential scanning calorimetry analyzer (DSC3300SA) manufactured by NETZSCH JAPAN at a heating rate of 10°C / min.

[0079] (iv)λ 70 λ5 The above annealed sample is processed to have a thickness of 10 mm and parallel, optically polished planes, and the spectral transmittance in the wavelength range of 280 nm to 700 nm is measured. The intensity of light rays incident perpendicularly on one optically polished plane is defined as intensity A, and the intensity of light rays emitted from the other plane is defined as intensity B, and the spectral transmittance B / A is calculated. The wavelength at which the spectral transmittance is 70% is defined as λ. 70 Let λ5 be the wavelength at which the spectral transmittance is 5%. It is important to note that spectral transmittance includes the reflection loss of light rays from the sample surface.

[0080] [Table 1]

[0081] [Table 2]

[0082] [Table 3]

[0083] [Table 4]

[0084] [Table 5]

[0085] From Tables 1 to 5 above, it can be confirmed that the present invention can reduce costs while simultaneously providing optical glass with a high refractive index and low specific gravity.

[0086] It must be understood that all embodiments disclosed herein are illustrative and do not constitute limitations. The scope of the present invention is defined by the claims rather than the above description and is intended to include all variations equivalent to the claims in meaning and scope.

[0087] For example, by performing the compositional adjustments described herein on the glass composition exemplified above, an optical glass according to one embodiment of the present invention can be produced.

[0088] Furthermore, naturally, two or more of the items exemplified or described as preferred in this specification may be arbitrarily combined.

Claims

1. An optical glass, wherein the glass composition of the optical glass, expressed in mass%, SiO ２ The content is 0-20%, B ２ O ３ The content is 5-30%, The BaO content is 0-6.5%, La ２ O ３ The content is 29-55%, TiO ２ The content is 5-50%, Nb ２ O ５ The content is 0-5%, WO ３ The content is 0 to 0.6% and The CaO content is 15% or less. The ZnO content is 0-20%. ZrO ２ The content is 0-20%, TiO ２ and ZrO ２ The mass ratio of the total content to the CaO content ((TiO ２ +ZrO ２ Optical glass with a ratio of ) / CaO greater than 3.

3.

2. In mass percent, Y ２ O ３ The content is 4.31% or less. Na ２ The oxygen content is 1.16% or less. Gd ２ O ３ The content is 3% or less. Ta ２ O ５ The content is 3% or less. The optical glass according to claim 1, satisfying at least one of the following conditions.

3. The optical glass according to claim 1 or 2, wherein the mass ratio of the CaO content to the total content of CaO, BaO, SrO, and ZnO (CaO / (CaO+BaO+SrO+ZnO)) is greater than 0.

4. TiO ２ The mass ratio of the content to the ZnO content (TiO ２ The optical glass according to any one of claims 1 to 3, wherein the ratio of (ZnO) is greater than 0.

85.

5. B ２ O ３ SiO content ２ Mass ratio of content (B ２ O ３ / SiO ２ The optical glass according to any one of claims 1 to 4, wherein the coefficient of the optical glass is 1.5 to 5.

87.

6. La ２ O ３ , Gd ２ O ３ and Y ２ O ３ Total content (La ２ O ３ +Gd ２ O ３ +Y ２ O ３ The optical glass according to any one of claims 1 to 5, wherein the percentage of ) is 29 to 55%.

7. B ２ O ３ ZrO content ２ Mass ratio of content (B ２ O ３ / ZrO ２ The optical glass according to any one of claims 1 to 6, wherein the coefficient of the coefficient is greater than 0 and less than or equal to 6.

1.

8. Nb ２ O ５ Nb content ２ O ５ , TiO ２ WO ３ and Ta ２ O ５ Mass ratio (Nb) of total content ２ O ５ / (Nb ２ O ５ +TiO ２ +WO ３ +Ta ２ O ５ The optical glass according to any one of claims 1 to 7, wherein the coefficient of the optical glass is 0 to 0.

24.

9. Y ２ O ３ Content, B ２ O ３ Mass ratio to content (Y ２ O ３ / B ２ O ３ The optical glass according to any one of claims 1 to 8, wherein the coefficient of the optical glass is 0 to 0.

35.

10. Nb ２ O ５ The content is 0-4%; SiO ２ The content is 1-18%; B ２ O ３ The content is 7-28%; The BaO content is 0-5.5%; The ZnO content is 1-18%; La ２ O ３ The content is 31-53%; Y ２ O ３ The content is 3% or less; TiO ２ The content is 7-45%; WO ３ The content is 0-0.5%; ZrO ２ The content is 1-19%; The CaO content is 1-13%; Na ２ The oxygen content is 0.8% or less; Gd ２ O ３ The content is 2% or less; Ta ２ O ５ The content is 2% or less; TiO ２ and ZrO ２ The mass ratio of the total content of TiO ２ and ZrO ２ to the CaO content ((TiO ２ + ZrO ２ ) / CaO) is 3.35 or more; The mass ratio of the CaO content to the total content of CaO, BaO, SrO, and ZnO (CaO / (CaO+BaO+SrO+ZnO)) is between 0.05 and 1.0; B ２ O ３ The content of, SiO ２ The mass ratio of the content to the SiO content (B ２ O ３ / SiO ２ ) is 1.6 to 5.5; La ２ O ３ , Gd ２ O ３ and Y ２ O ３ Total content (La ２ O ３ +Gd ２ O ３ +Y ２ O ３ ) is between 33% and 55%; B ２ O ３ ZrO content ２ Mass ratio of content (B ２ O ３ / ZrO ２ ) is between 0.4 and 5.7; Nb ２ O ５ Nb content ２ O ５ , TiO ２ WO ３ and Ta ２ O ５ Mass ratio (Nb) of total content ２ O ５ / (Nb ２ O ５ +TiO ２ +WO ３ +Ta ２ O ５ )) is between 0 and 0.2; TiO ２ The mass ratio of the content to the ZnO content (TiO ２ The value of ZnO is 0.9 or greater; Y ２ O ３ Content, B ２ O ３ Mass ratio to content (Y ２ O ３ / B ２ O ３ ) is between 0 and 0.3; The refractive index nd is between 1.8800 and 1.9200; The Abbe number vd is between 28 and 33; The specific gravity is 4.00 to 5.00; The glass transition temperature Tg is 600-670°C; λ ７０ The wavelength is 375–440 nm; λ ５ The wavelength is 350-370 nm. An optical glass according to any one of claims 1 to 9, satisfying at least one of the following conditions.

11. Nb ２ O ５ The content is 0-3%; SiO ２ The content is 2-16%; B ２ O ３ The content is 9-26%; The BaO content is 0.1 to 4.5%; The ZnO content is 2-16%; La ２ O ３ The content is 33-51%; Y ２ O ３ The content is 2% or less; TiO ２ The content is 9-40%; WO ３ The content is 0-0.4%; ZrO ２ The content is between 2% and 18%; The CaO content is 2-12%; Na ２ The oxygen content is 0.4% or less; Gd ２ O ３ The content is 1% or less; Ta ２ O ５ The content is 1% or less; TiO ２ and ZrO ２ The mass ratio of the total content to the CaO content ((TiO ２ +ZrO ２ The ratio of ) / CaO is 3.40 or higher; The mass ratio of the CaO content to the total content of CaO, BaO, SrO, and ZnO (CaO / (CaO+BaO+SrO+ZnO)) is between 0.10 and 0.8; B ２ O ３ SiO content ２ Mass ratio of content (B ２ O ３ / SiO ２ ) is between 1.7 and 5.0; La ２ O ３ , Gd ２ O ３ and Y ２ O ３ Total content (La ２ O ３ +Gd ２ O ３ +Y ２ O ３ ) is between 36.4% and 55%; B ２ O ３ ZrO content ２ Mass ratio of content (B ２ O ３ / ZrO ２ ) is between 0.8 and 4.9; Nb ２ O ５ Nb content ２ O ５ , TiO ２ WO ３ and Ta ２ O ５ Mass ratio (Nb) of total content ２ O ５ / (Nb ２ O ５ +TiO ２ +WO ３ +Ta ２ O ５ )) is between 0 and 0.15; TiO ２ The mass ratio of the content to the ZnO content (TiO ２ The value of ZnO is 0.95 or higher; Y ２ O ３ Content, B ２ O ３ Mass ratio to content (Y ２ O ３ / B ２ O ３ ) is between 0 and 0.2; The refractive index nd is between 1.8850 and 1.9180; The Abbe number vd is between 28.5 and 32.6; The specific gravity is 4.05 to 4.90; The glass transition temperature Tg is 604–668°C; λ ７０ The wavelength is 376–439 nm; λ ５ The wavelength is 352-368 nm. An optical glass according to any one of claims 1 to 9, satisfying at least one of the following conditions.

12. Nb ２ O ５ The content is 0-2%; SiO ２ The content is 3-12%; B ２ O ３ The content is 11-24%; The BaO content is 0.1 to 3.5%; The ZnO content is 3-15%; La ２ O ３ The content is 35-49%; Y ２ O ３ The content is 1% or less; TiO ２ The content is 11-30%; WO ３ The content is 0-0.3%; ZrO ２ The content is 3-17%; The CaO content is 2.5 to 11%; Na ２ The oxygen content is 0%; Gd ２ O ３ The content is 0%; Ta ２ O ５ The content is 0%; TiO ２ and ZrO ２ The mass ratio of the total content to the CaO content ((TiO ２ +ZrO ２ The ratio of ) / CaO is 3.45 or higher; The mass ratio of the CaO content to the total content of CaO, BaO, SrO, and ZnO (CaO / (CaO+BaO+SrO+ZnO)) is between 0.15 and 0.7; B ２ O ３ SiO content ２ Mass ratio of content (B ２ O ３ / SiO ２ ) is between 1.8 and 4.5; La ２ O ３ , Gd ２ O ３ and Y ２ O ３ Total content (La ２ O ３ +Gd ２ O ３ +Y ２ O ３ ) is between 37% and 51%; B ２ O ３ ZrO content ２ Mass ratio of content (B ２ O ３ / ZrO ２ ) is between 1.2 and 4.1; Nb ２ O ５ Nb content ２ O ５ , TiO ２ WO ３ and Ta ２ O ５ Mass ratio (Nb) of total content ２ O ５ / (Nb ２ O ５ +TiO ２ +WO ３ +Ta ２ O ５ )) is between 0 and 0.1; TiO ２ The mass ratio of the content to the ZnO content (TiO ２ The (ZnO) value is 1.00 or greater; Y ２ O ３ Content, B ２ O ３ Mass ratio to content (Y ２ O ３ / B ２ O ３ ) is between 0 and 0.1; The refractive index nd is between 1.8900 and 1.9160; The Abbe number vd is between 29 and 32.2; The specific gravity is 4.10 to 4.85; The glass transition temperature Tg is 606–666°C; λ ７０ The wavelength is 378–438 nm; λ ５ The wavelength is 354-367 nm. An optical glass according to any one of claims 1 to 9, satisfying at least one of the following conditions.

13. Nb ２ O ５ The content is 0-1%; SiO ２ The content is 4-10%; B ２ O ３ The content is 12-22%; The BaO content is 0.2 to 2.5%; La ２ O ３ The content is 37-47%; Y ２ O ３ The content is 0%; TiO ２ The content is 12-20%; WO ３ The content is 0-0.2%; ZrO ２ The content is 4-16%; The CaO content is 3-10%; TiO ２ and ZrO ２ The mass ratio of the total content to the CaO content ((TiO ２ +ZrO ２ The ratio of ) / CaO is 3.50 or higher; The mass ratio of CaO content to the total content of CaO, BaO, SrO, and ZnO (CaO / (CaO+BaO+SrO+ZnO)) is between 0.20 and 0.60; B ２ O ３ SiO content ２ Mass ratio of content (B ２ O ３ / SiO ２ ) is between 1.9 and 4.0; La ２ O ３ , Gd ２ O ３ and Y ２ O ３ Total content (La ２ O ３ +Gd ２ O ３ +Y ２ O ３ ) is 38-49%; B ２ O ３ ZrO content ２ Mass ratio of content (B ２ O ３ / ZrO ２ ) is between 1.6 and 3.3; Nb ２ O ５ Nb content ２ O ５ , TiO ２ WO ３ and Ta ２ O ５ Mass ratio (Nb) of total content ２ O ５ / (Nb ２ O ５ +TiO ２ +WO ３ +Ta ２ O ５ )) is between 0 and 0.05; TiO ２ The mass ratio of the content to the ZnO content (TiO ２ The value of ZnO is 1.10 or greater; Y ２ O ３ Content, B ２ O ３ Mass ratio to content (Y ２ O ３ / B ２ O ３ ) is 0; The refractive index nd is between 1.8950 and 1.9120; The Abbe number vd is between 30 and 31.8; The specific gravity is 4.15 to 4.80; The glass transition temperature Tg is 610 to 664°C; λ ７０ The wavelength is 379–437 nm; λ ５ The wavelength is 355-366 nm. An optical glass according to any one of claims 1 to 9, satisfying at least one of the following conditions.

14. Nb ２ O ５ The content is 0%; B ２ O ３ The content is 13-20%; The BaO content is 0.2 to 1.5%; La ２ O ３ The content is 39-45%; WO ３ The content is 0-0.1%; ZrO ２ The content is 5-15%; TiO ２ and ZrO ２ The mass ratio of the total content to the CaO content ((TiO ２ +ZrO ２ The ratio of ) / CaO is 3.55 or higher; The mass ratio of the CaO content to the total content of CaO, BaO, SrO, and ZnO (CaO / (CaO+BaO+SrO+ZnO)) is between 0.20 and 0.50; B ２ O ３ SiO content ２ Mass ratio of content (B ２ O ３ / SiO ２ ) is between 2.0 and 3.5; La ２ O ３ , Gd ２ O ３ and Y ２ O ３ Total content (La ２ O ３ +Gd ２ O ３ +Y ２ O ３ ) is 39-45%; Nb ２ O ５ Nb content ２ O ５ , TiO ２ WO ３ and Ta ２ O ５ Mass ratio (Nb) of total content ２ O ５ / (Nb ２ O ５ +TiO ２ +WO ３ +Ta ２ O ５ )) is 0; The refractive index nd is between 1.9000 and 1.9100; The Abbe number vd is between 31 and 31.6; Its specific gravity is 4.20 to 4.70; λ ７０ The wavelength is 380–436 nm; λ ５ The wavelength is 356-365 nm. An optical glass according to any one of claims 1 to 9, satisfying at least one of the following conditions.

15. The BaO content is 0.3-0.5%; WO ３ The content is 0%. An optical glass according to any one of claims 1 to 9, satisfying at least one of the following conditions.

16. An optical element comprising the optical glass described in any one of claims 1 to 15.

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