Optical glass and optical components

Abstract

The present invention provides an optical glass comprising B in a glass composition expressed in terms of cation %. 3+ 、Si 4+ 、Al 3+ 、Li + and Zn 2+ As an essential component, Al 3+ The content is 5% or more of cations, Li + The content is more than 10 cation%, Ba 2+ The content is less than 10 cation %, the total content (Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) is 12% or more of cations, and the cation ratio {(Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) / (Mg 2+ +Ca 2+ +Sr 2+ +Ba 2+ )} is 0.80 or more, the total content (Li + +Na + +K + ) is 10 to 30% cation%, cation ratio (Si 4+ / B 3+ ) is 3.0 or less, and the Abbe number νd of the above-mentioned optical glass is 55 or more and 65 or less.

Description

Technical Field

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

[0002] Optical glass having medium dispersion characteristics is useful as a material for optical elements. For example, Patent Document 1 discloses an optical glass having such optical constants.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-174791 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] Optical glass is expected to be less susceptible to surface deterioration due to atmospheric moisture, that is, to have excellent weather resistance. One reason for this desire is that applying pressure to glass with surface deterioration can lead to significant blurring and scratches on the deteriorated surface.

[0008] In view of the above circumstances, an object of one embodiment of the present invention is to provide an optical glass having a medium dispersion characteristic and excellent weather resistance.

[0009] Solutions to the Problem

[0010] One embodiment of the present invention relates to an optical glass having a glass composition expressed in terms of cation %.

[0011] Contains B 3+ 、Si 4+ 、Al 3+ 、Li + and Zn 2+ As a necessary ingredient,

[0012] Al 3+ The content is 5% or more of cations,

[0013] Li + The content is 10% or more of cations,

[0014] Ba 2+ The content is less than 10 cation%,

[0015] Al 3+ 、Zn 2+ 、Y 3+ 、La 3+ 、Gd 3+ 、Ti 4+ 、Nb5+ 、Zr 4+ and Ta 5+ Total content (Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) is 12 cation % or more,

[0016] Al 3+ 、Zn 2+ 、Y 3+ 、La 3+ 、Gd 3+ 、Ti 4+ 、Nb 5+ 、Zr 4+ and Ta 5+ The total content relative to Mg 2+ , Ca 2+ 、Sr 2+ And Ba 2+ The total content of cation ratio {(Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) / (Mg 2+ +Ca 2+ ++Sr 2+ +Ba 2+ )} is 0.80 or above,

[0017] Li + 、Na + and K + Total content (Li + +Na + +K + ) is 10 to 30% cation%,

[0018] Si 4+ Content relative to B 3+ Cation ratio of content (Si 4+ / B 3+ ) is 3.0 or less,

[0019] Furthermore, the Abbe number νd of the optical glass is 55 or more and 65 or less.

[0020] The optical glass having the glass composition can have medium dispersion characteristics and exhibit excellent weather resistance.

[0021] Effects of the Invention

[0022] According to one embodiment of the present invention, an optical glass having a medium dispersion characteristic and excellent weather resistance can be provided. In addition, according to one embodiment of the present invention, an optical element made of such an optical glass can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic cross-sectional view of a precision press molding device is shown.

[0024] Explanation of symbols

[0025] 1: Upper mold

[0026] 2: Lower die

[0027] 3: Shell mold

[0028] 4: Preforms for precision pressing

[0029] 9: Support rod

[0030] 10: Holding components

[0031] 11: Quartz tube

[0032] 13: Putting

[0033] 14: Thermocouple DETAILED DESCRIPTION

[0034] [Optical glass]

[0035] In the present invention and this specification, unless otherwise specified, the refractive index refers to the refractive index nd under helium d-rays (wavelength 587.56 nm).

[0036] In the present invention and this specification, the Abbe number νd is used as a value indicating a property related to dispersion and is represented by the following mathematical formula.

[0037] νd=(nd-1) / (nF-nC)

[0038] In the above formula, nF is the refractive index under blue hydrogen F ray (wavelength 486.13 nm), and nC is the refractive index under red hydrogen C ray (656.27 nm).

[0039] In the present invention and this specification, the solubility of glass refers to the ease with which a single liquid phase can be formed when various glass raw materials are weighed and mixed in a given ratio and placed at a given temperature, and the devitrification resistance of glass refers to the difficulty with which molten glass crystallizes when solidifying.

[0040] In the present invention and this specification, unless otherwise specified, the content and total content of cationic components are expressed as cation %, and unless otherwise specified, the content and total content of anionic components are expressed as anion %.

[0041] Here, "cation %" is a value calculated as "(number of cations of interest / total number of cations in glass component) x 100", and represents the molar percentage of the amount of cations of interest relative to the total amount of cationic components.

[0042] Furthermore, "anion %" is a value calculated as "(number of anions of interest / total number of anions in glass component) x 100" and represents the molar percentage of the anion amount of interest relative to the total amount of anion components.

[0043] The molar ratio of the contents of the cationic components is equal to the content ratio of the cationic component of interest expressed as cation %.

[0044] The content of each component can be quantified by a known method, for example, inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), ion chromatography, or the like.

[0045] In the present invention and this specification, a component content of 0%, or "not contained" or "not introduced" means that the component is substantially absent and that the component is present at an impurity level or below. "Below an impurity level" means, for example, less than 0.01%.

[0046] Hereinafter, the above-mentioned optical glass (may be simply referred to as "glass") will be described in more detail.

[0047] <Glass Composition>

[0048] Hereinafter, the glass composition of the above optical glass expressed in terms of cation %.

[0049] The above optical glass contains B 3+ 、Si 4+ 、Al 3+ 、Li + and Zn 2+ Essential components are components whose content in the optical glass exceeds 0%.

[0050] From the perspective of improving weather resistance and acid resistance, Al 3+ The content is 5% or more, preferably 6% or more, 7% or more, 8% or more, and 9% or more in this order. 3+The content is preferably 15% or less, more preferably 14% or less, and even more preferably 13% or less.

[0051] From the viewpoint of suppressing the increase in glass transition temperature, Li + The content is 10% or more, preferably 11% or more, 12% or more, 13% or more, 14% or more, and 15% or more. In addition, from the perspective of suppressing the deterioration of weather resistance and / or acid resistance, Li + The content is preferably 30% or less, more preferably 29% or less, 28% or less, 27% or less, and 26% or less in this order.

[0052] Li + 、Na + and K + From the viewpoint of improving weather resistance and acid resistance, the Li + 、Na + and K + Total content (Li + +Na + +K + ) is 30% or less, preferably 29% or less, 28% or less, and 27% or less in that order. In addition, from the viewpoint of suppressing the increase in the glass transition temperature, the total content (Li + +Na + +K + ) is 10% or more, preferably 11% or more, 12% or more, 13% or more, 14% or more, 15% or more, 16% or more, and 17% or more in this order.

[0053] From the viewpoint of suppressing the deterioration of weather resistance and / or acid resistance, Na + The content is preferably 10% or less, and more preferably 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, and 2% or less. + The glass may also contain Na + The Na content of the above optical glass is + The content may be 0%, 0% or more, more than 0%, 0.5% or more, or 1% or more.

[0054] From the viewpoint of suppressing the deterioration of weather resistance and / or acid resistance, K + The content is preferably 10% or less, more preferably 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, and 2% or less. +The content may be 0%, or may be 0% or more, or may exceed 0%. However, from the viewpoint of the devitrification resistance of the glass, it is preferably 0.5% or more, or 1% or more.

[0055] B 3+ B is an essential component of the above optical glass, so its content exceeds 0%. 3+ The content is 10% or more, preferably 11% or more, 12% or more, 13% or more, 14% or more, and 15% or more. In addition, from the perspective of further improving weather resistance and acid resistance, B 3+ The content is preferably 25% or less, more preferably 22% or less, further preferably 20% or less, even more preferably 19% or less, even more preferably 18% or less, and even more preferably 17% or less.

[0056] Si 4+ It is an essential component of the above optical glass, so its content exceeds 0%. Si 4+ The content can be, for example, 5% or more, 10% or more, 15% or more, 20% or more, or 25% or more. From the perspective of improving acid resistance, it is preferably 30% or more, and more preferably 31% or more, 32% or more, or 33% or more. In addition, from the perspective of improving solubility, Si 4+ The content is preferably 40% or less, more preferably 39% or less, 38% or less, and 37% or less in this order.

[0057] From the perspective of improving solubility and suppressing striae generation, Si 4+ Content relative to B 3+ Cation ratio of content (Si 4+ / B 3+ ) is 3.0 or less, and is more preferably in the order of 2.9 or less, 2.8 or less, 2.7 or less, 2.6 or less, 2.5 or less, and 2.4 or less. From the viewpoint of improving weather resistance and acid resistance, the cation ratio (Si 4+ / B 3+ ) is preferably 1.2 or more, more preferably 1.3 or more, 1.4 or more, 1.5 or more, and 1.6 or more in this order.

[0058] Zn 2+ It is an essential component of the above optical glass, so its content exceeds 0%. Zn 2+ There is a tendency to increase the refractive index and achieve higher dispersion of the glass. 2+ It has the effect of lowering the glass transition temperature. 2+ The content is preferably 0.5% or more, more preferably 1% or more. On the other hand, from the viewpoint of suppressing the decrease in Abbe number and / or the deterioration of acid resistance, Zn2+ The content is preferably 10% or less, more preferably 9% or less, 8% or less, and 7% or less in this order.

[0059] Ba 2+ Mg 2+ , Ca 2+ and Sr 2+ Among the alkaline earth metal cations, the optical glass may be free of Ba. 2+ Glass can also contain Ba 2+ From the perspective of improving weather resistance, the Ba of the above optical glass 2+ The content is preferably 10% or less, 9% or less, 8% or less, and 7% or less in this order. 2+ The content of Ba may be 0%, or may be 0% or more. On the other hand, from the perspective of increasing the refractive index of the glass, Ba 2+ The content is preferably 1% or more, 2% or more, and 3% or more in this order.

[0060] About Mg 2+ , the above optical glass may be Mg-free 2+ Glass can also contain Mg 2+ From the perspective of improving the solubility and / or resistance to devitrification of the glass, the Mg content of the optical glass is 2+ The content is preferably 5% or less, more preferably 4% or less, 3% or less, and 2% or less. 2+ The content may be 0%, or may be 0% or more, or may exceed 0%.

[0061] About Ca 2+ , the above optical glass may be free of Ca 2+ The glass may also contain Ca 2+ From the perspective of improving the solubility and / or resistance to devitrification of the glass, the Ca content of the above optical glass is 2+ The content is preferably 15% or less, more preferably 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, and 8% or less. 2+ The content may be 0%, or may be 0% or more, or may exceed 0%.

[0062] About Sr 2+ The above optical glass may be free of Sr 2+ The glass may also contain Sr 2+ From the perspective of improving weather resistance, the Sr content of the above optical glass 2+ The content is preferably 8% or less, more preferably 7% or less, and further preferably 6% or less.2+ The content may be 0%, or may be 0% or more, or may exceed 0%.

[0063] From the viewpoint of improving weather resistance and acid resistance, the Al content of the optical glass 3+ 、Zn 2+ 、Y 3+ 、La 3+ 、Gd 3 + 、Ti 4+ 、Nb 5+ 、Zr 4+ and Ta 5+ Total content (Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) is 12% or more, preferably 13% or more. In addition, from the perspective of improving the solubility and / or resistance to devitrification of the glass, the total content (Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) is preferably in the order of less than 25%, less than 24%, less than 23%, less than 22%, less than 21%, less than 20%, less than 19%, and less than 18%.

[0064] From the viewpoint of improving weather resistance, the Al content of the above optical glass is 3+ 、Zn 2+ 、Y 3+ 、La 3+ 、Gd 3+ 、Ti 4+ 、Nb 5+ 、Zr 4 + and Ta 5+ The total content relative to Mg 2+ , Ca 2+ 、Sr 2+ And Ba 2+ The total content of cation ratio {(Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti4+ +Nb 5+ +Zr 4+ +Ta 5+ ) / (Mg 2+ +Ca 2+ +Sr 2+ +Ba 2+ )} is 0.80 or more, preferably 0.85 or more, 0.90 or more, and 0.95 or more in this order. From the viewpoint of improving solubility and / or resistance to devitrification, the cation ratio {(Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) / (Mg 2+ +Ca 2+ +Sr 2+ +Ba 2+ )} is preferably 3.00 or less, 2.80 or less, 2.60 or less, or 2.40 or less.

[0065] Y 3+ 、La 3+ and Gd 3+ In one embodiment, the optical glass may not contain Y 3+ 、La 3 + and Gd 3+ In another embodiment, the rare earth cations may include a compound selected from Y 3+ 、La 3+ and Gd 3+ At least one of the rare earth cations in the composition may also contain two or more. 3+ 、La 3+ and Gd 3+ Y is a component that increases the refractive index and improves weather resistance and / or acid resistance. 3+ 、La 3+ and Gd 3+ Total content (Y 3+ +La 3+ +Gd 3+ ) can be 0%, 0% or more, more than 0%, 0.1% or more, or 0.5% or more. On the other hand, from the perspective of improving the solubility and / or devitrification resistance of the glass, the total content (Y 3+ +La 3+ +Gd 3+ ) is preferably 5% or less, more preferably 4% or less, and then 3% or less.

[0066] About Y 3+ The above optical glass may be free of Y 3+ Glass can also contain Y 3+ From the perspective of improving the solubility and / or resistance to devitrification of the glass, the Y 3+ The content is preferably 3% or less, more preferably 2% or less, and further preferably 1% or less. 3+ The content may be 0%, or may be 0% or more, or may exceed 0%.

[0067] About La + The above optical glass may be La-free 3+ Glass can also contain La 3+ From the perspective of improving the solubility and / or resistance to devitrification of the glass, the La content of the above optical glass is 3+ The content is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less. 3+ The content may be 0%, or may be 0% or more, more than 0%, 0.1% or more, or 0.5% or more.

[0068] About Gd 3+ The above optical glass may be Gd-free 3+ The glass may also contain Gd 3+ From the perspective of improving the solubility and / or resistance to devitrification of the glass, the Gd 3+ The content is preferably 3% or less, more preferably 2% or less, and further preferably 1% or less. 3+ The content may be 0%, or may be 0% or more, or may exceed 0%.

[0069] Ti 4+ 、Nb 5+ 、Zr 4+ and Ta 5+ It is a component that has the effect of increasing the refractive index and improving weather resistance and / or acid resistance, but there is a tendency to significantly reduce the Abbe number of the glass. In one embodiment, the above optical glass may not contain Ti 4+ 、Nb 5+ 、Zr 4+ and Ta 5+ In another embodiment, the cations in the 4+ 、Nb 5+ 、Zr 4+ and Ta 5+ At least one of the cations in the optical glass may also contain two or more. 4+ 、Nb5+ 、Zr 4+ and Ta 5+ Total content (Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) can be 0%, 0% or more, more than 0%, 0.1% or more, or 0.5% or more. On the other hand, from the viewpoint of suppressing the decrease in the Abbe number of the glass, the total content (Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) is preferably 5% or less, more preferably 4% or less, and then 3% or less.

[0070] About Ti 4+ , the above optical glass may be free of Ti 4+ The glass may also contain Ti 4+ From the perspective of suppressing the decrease in the Abbe number of the glass, the Ti content of the optical glass is 4+ The content is preferably 3% or less, more preferably 2% or less, and further preferably 1% or less. 4+ The content may be 0%, or may be 0% or more, or may exceed 0%.

[0071] About Nb 5+ , the above optical glass may be free of Nb 5+ The glass may also contain Nb 5+ From the perspective of suppressing the decrease in the Abbe number of the glass, the Nb content of the above optical glass is 5+ The content is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less. 5+ The content may be 0%, or may be 0% or more, or may exceed 0%.

[0072] Zr 4+ It is a component that increases the refractive index and improves weather resistance and / or acid resistance, but it is also a component that significantly reduces the Abbe number of the glass and deteriorates the devitrification resistance of the glass. The above optical glass may not contain Zr. 4+ The glass may also contain Zr 4+ From the viewpoint of suppressing the decrease of the Abbe number of the glass and improving the devitrification resistance of the glass, the Zr content of the above optical glass is 4+ The content is preferably 3% or less, more preferably 2% or less, and further preferably 1% or less. 4+ The content may be 0%, or may be 0% or more, or may exceed 0%.

[0073] Ta 5+It is a component that has the function of increasing the refractive index. The above optical glass may not contain Ta. 5+ Glass can also contain Ta 5+ Glass. Among the glass raw materials, Ta compounds are relatively expensive. From the perspective of reducing the cost of glass, the Ta content of the above optical glass is 5+ The content is preferably 3% or less, more preferably 2% or less, further preferably 1% or less, and further preferably 0%. 5+ The content may be 0% or more or more than 0%.

[0074] In one embodiment, glass with excellent acid resistance is desired. This is because glass with excellent acid resistance is suitable for use as glass for optical elements installed in equipment such as surveillance cameras installed outdoors and car cameras that are exposed to acidic environments. From the perspective of improving acid resistance, the Al content of the above optical glass is 3+ 、Y 3+ 、La 3+ 、Gd 3+ 、Ti 4+ 、Nb 5+ 、Zr 4+ and Ta 5+ Total content (Al 3+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) is preferably 7% or more, more preferably 8% or more. From the viewpoint of improving acid resistance, the total content (Al 3+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) is preferably 15% or less, more preferably 14% or less.

[0075] Pb, As, Cd, Tl, Be, and Se are all toxic. Therefore, it is preferable not to contain these elements, that is, not to introduce these elements into the glass as glass components.

[0076] U, Th, and Ra are all radioactive elements. Therefore, it is preferable not to contain these elements, that is, not to introduce these elements into the glass as glass components.

[0077] V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Ce may increase the coloration of the glass or become a source of fluorescence, and are therefore not preferred elements for inclusion in glass for optical components. Therefore, it is preferred that these elements not be included, that is, not be introduced into the glass as glass components.

[0078] Sb and Sn are optionally added elements that function as clarifiers.

[0079] The Sb content of the optical glass may be, for example, 0.40% or less, 0.20% or less, 0.10% or less, 0.05% or less, 0.02% or less, or 0.01% or less, based on the mass fraction (%) of Sb2O3 per 100 mass of the glass. On the other hand, the Sb content may be 0.00% or more, or 0.00%, based on the mass fraction (%) of Sb2O3 per 100 mass of the glass.

[0080] The Sn content of the optical glass may be, for example, 0.40% or less, 0.20% or less, 0.10% or less, 0.05% or less, 0.02% or less, or 0.01% or less, based on the mass fraction (%) of SnO2 when the mass of the glass is set to 100. On the other hand, the Sn content may be 0.00% or more, or 0.00%, based on the mass fraction (%) of SnO2 when the mass of the glass is set to 100.

[0081] The cationic components have been described above. Next, the anionic components will be described.

[0082] The above optical glass may be an oxide glass, which may contain O 2- As anionic component. 2- The content is preferably 95.0 anion % or more, more preferably 97.0 anion % or more, further preferably 98.0 anion % or more, further preferably 99.0 anion % or more, further preferably 99.5 anion % or more, further preferably 100 anion %.

[0083] As a 2- Anion components other than F - 、Cl - Br - and I - However, F - 、Cl - Br - and I -The volatilization of these components will cause the physical properties of the glass to change, the homogeneity of the glass to decrease, and the consumption of the melting equipment to become significant. - 、Cl - Br - and I - The total content of the anion content is 100% minus the amount of O 2- The amount of content.

[0084] <Glass Properties>

[0085] (refractive index nd)

[0086] From the perspective of usefulness as a material for optical elements, the refractive index nd of the optical glass is preferably 1.55 or greater, and may be 1.56 or greater, or 1.57 or greater. Furthermore, from the perspective of usefulness as a material for optical elements, the refractive index nd of the optical glass is preferably 1.65 or less, and may be 1.64 or less, 1.63 or less, 1.62 or less, 1.61 or less, 1.60 or less, or 1.59 or less.

[0087] (Abbe number νd)

[0088] The optical glass has an Abbe number νd of 55 or more and 65 or less and exhibits medium dispersion characteristics, and is useful as a material for optical elements. The Abbe number νd of the optical glass may be 56 or more, 57 or more, or 58 or more, and may be 64 or less, 63 or less, or 62 or less.

[0089] (DH 96 )

[0090] DH 96 It is the difference in the amount of fog before and after the weather resistance test and can be used as an indicator of weather resistance.

[0091] The weather resistance test is a weather resistance test performed by changing the treatment time of the weather resistance test for optical glass specified in ISO 22531 to 96 hours.

[0092] As a general method for evaluating weather resistance, the weather resistance test for optical glass specified in ISO 22531 can be cited. In such a weather resistance test, a 30 mm × 30 mm × 3 mm glass sample with its opposite sides polished is subjected to a temperature cycle test under high temperature and high humidity as described in ISO 22531. The difference in haze (haze, %) between the glass sample before and after the test is determined. The smaller the difference, the better the weather resistance. It should be noted that the haze can be measured using a haze meter as described in ISO 14782.

[0093] ISO 22531 specifies a temperature cycling test duration of 24 cycles (or 48 hours), with one cycle lasting 2 hours. However, depending on the intended use of optical glass, more stringent weather resistance standards may be required. In such cases, it is preferable to extend the treatment time to 48 cycles (or 96 hours), for example, to perform evaluation under more stringent test conditions.

[0094] The optical glass can exhibit very excellent weather resistance by having the glass composition described in detail above. Specifically, in one embodiment, when the high temperature and high humidity temperature cycle test specified in ISO 22531 is changed to 48 cycles with one cycle of 2 hours, that is, the treatment time is changed to 96 hours, the difference in haze amount DH of the optical glass sample before and after the test can be shown. 96 (Unit: %) Achieve weather resistance of 3.0% or less. DH 96 It is more preferably 2.9% or less, further more preferably 2.5% or less, 2.0% or less, 1.5% or less, 1.0% or less, 0.5% or less, and 0.3% or less in this order, and the smaller the content, the more preferred.

[0095] (Mass reduction rate DA)

[0096] In one embodiment, the optical glass can exhibit excellent acid resistance. Acid resistance can be evaluated according to the Japan Optical Glass Industry Association Standard JOGIS06-2019, "Determination of Chemical Durability of Optical Glass (Powder Method)." The specific determination method is as follows.

[0097] The mass equivalent to the specific gravity (M before , unit: g) of powdered glass (particle size 425μm to 600μm) was placed in a platinum basket and immersed in 80ml of a 0.01mol / l nitric acid aqueous solution placed in a round-bottom flask made of quartz glass or borosilicate glass-1 specified in JIS R 3503. The treatment was carried out in a boiling water bath for 60 minutes. The mass M of the powdered glass after the treatment was calculated. after (Unit: g) was measured, and the mass reduction rate DA (%) was calculated by DA (%) = [(M before -M after ) / M before ]×100 and find the answer.

[0098] Acid resistance can be evaluated based on the magnitude of this DA.

[0099] As one embodiment of the optical glass, the DA value of the glass having excellent acid resistance may be 0.35% or less, or may be less than 0.35%.

[0100] (Glass transition temperature Tg)

[0101] From the perspective of precision pressing suitability, a low glass transition temperature Tg is preferred. From this perspective, the glass transition temperature Tg of the optical glass is preferably 535°C or lower, more preferably 530°C or lower, further preferably 525°C or lower, and even more preferably 520°C or lower.

[0102] The glass transition temperature Tg can be determined as follows. In differential scanning calorimetry, when the temperature of a glass sample is increased, an endothermic behavior accompanied by a change in specific heat, that is, an endothermic peak, will appear. When the temperature is further increased, an exothermic peak will appear. In differential scanning calorimetry, a differential scanning calorimetry curve (DSC curve) can be obtained with temperature as the horizontal axis and the amount corresponding to the exothermic and endothermic properties of the sample as the vertical axis. In this curve, the intersection of the tangent from the baseline to the point where the slope reaches the maximum when the endothermic peak appears and the above-mentioned baseline is set as the glass transition temperature Tg. The glass transition temperature Tg can be measured by using a material that is fully crushed in a mortar or the like as a sample, using a differential scanning calorimeter, and setting the heating rate to 10°C / min.

[0103] (proportion)

[0104] The refractive power of optical elements in optical systems is determined by the refractive index of the glass forming the element and the curvature of the element's optically functional surface (the surface through which light enters and exits, which is the intended target). Increasing the curvature of the optically functional surface also increases the thickness of the optical element, which results in a heavier optical element. In contrast, using glass with a high refractive index allows for greater refractive power without increasing the curvature of the optically functional surface.

[0105] It can be seen that if the refractive index can be increased while suppressing the increase in the specific gravity of the glass, it is possible to achieve a lightweight optical element having a certain refractive power.

[0106] From the above perspectives, the specific gravity d of the optical glass is preferably 3.5 or less, with a more preferred range being 3.4 or less, 3.3 or less, 3.2 or less, and 3.1 or less. A lower specific gravity is more preferred from the perspective of lightweighting the optical element. Therefore, there is no particular lower limit for the specific gravity of the optical glass. In one embodiment, the specific gravity may be 2.5 or greater, 2.6 or greater, or 2.7 or greater.

[0107] (coloring degree λ5, λ 70 ,λ 80 )

[0108] Regarding the light transmittance of the glass, specifically, the suppression of the long wavelength of the light absorption end on the short wavelength side, the coloring degree λ5, λ 70 and λ 80The coloration degree λ5 is the wavelength at which the spectral transmittance (including surface reflection loss) of glass with a thickness of 10 mm reaches 5% from the ultraviolet region to the visible region. 70 It indicates the wavelength at which the spectral transmittance reaches 70% as measured by the method described for λ5. 80 The wavelength at which the spectral transmittance reaches 80% as measured by the method described for λ5 is shown in the following Examples. 70 and λ 80 It is a value measured in the wavelength range of 250 to 700 nm. It should be noted that the spectral transmittance T (%) of the glass in the present invention and this specification can be expressed as follows: for a glass sample having two parallel planes after optical polishing, the intensity of light perpendicularly incident on one of the two planes is set to I in , and the intensity of the light emitted from the other side after passing through the glass sample is set to I out When T(%)=I out / I in ×100 indicates.

[0109] According to the shading degree λ5, λ 70 and λ 80 , the absorption end on the short wavelength side of the spectral transmittance can be quantitatively evaluated. When lenses are bonded together with an ultraviolet curing adhesive to produce a bonded lens, the following operation can be performed: the adhesive is irradiated with ultraviolet light through an optical element to cure the adhesive. From the perspective of efficiently curing the ultraviolet curing adhesive, it is preferred that the absorption end on the short wavelength side of the spectral transmittance be in a short wavelength range. As an indicator for quantitatively evaluating the absorption end on the short wavelength side, the coloring degree λ5, λ 70 and λ 80 One or more of.

[0110] The optical glass preferably exhibits a λ5 of 360 nm or less. λ5 is more preferably 350 nm or less, 340 nm or less, and 330 nm or less, in this order. A shorter λ5 wavelength is more preferred, and there is no particular lower limit.

[0111] The optical glass preferably exhibits a λ of 400 nm or less. 70 λ 70 More preferably, the wavelength is 390 nm or less, 380 nm or less, 370 nm or less, and 360 nm or less in this order. 70 The shorter the wavelength, the more preferred, and the lower limit is not particularly limited.

[0112] The above optical glass preferably can show a λ below 420nm. 80 λ 80More preferably, the wavelength is 410 nm or less, 400 nm or less, 390 nm or less, 380 nm or less, and 370 nm or less in this order. 80 The shorter the wavelength, the more preferred, and the lower limit is not particularly limited.

[0113] <Glass Manufacturing Method>

[0114] The optical glass can be obtained as follows: raw materials such as oxides, carbonates, sulfates, nitrates, and hydroxides are weighed and blended to obtain the desired glass composition, thoroughly mixed to form a mixed batch, heated and melted in a melting vessel, degassed and stirred to produce a homogeneous, bubble-free molten glass, and then molded to obtain the optical glass. Specifically, the optical glass can be produced using a known melting method.

[0115] [Glass material for press molding, method for producing the same, and method for producing a glass molded body]

[0116] According to the embodiments of the present invention, there are provided a press-molding glass material made of the above-described optical glass, a glass molded body made of the above-described optical glass, and methods for producing the same.

[0117] The press-molding glass material refers to a glass block to be heated and subjected to press molding.

[0118] Examples of press-molding glass materials include glass blocks having a mass equivalent to that of press-molded products, such as glass materials (press-molding glass gobs) used for press-molding of precision press-molding preforms and optical element blanks.

[0119] The glass raw material for press molding can be produced by processing a glass molded body. The glass molded body can be produced by heating and melting the glass raw material as described above and then molding the resulting molten glass. Examples of processing methods for the glass molded body include cutting, grinding, and polishing.

[0120] [Optical element blank and method for manufacturing the same]

[0121] According to one embodiment of the present invention, an optical element blank made of the above-mentioned optical glass can be provided. The optical element blank is a glass molded body having a shape similar to the shape of the optical element to be manufactured. The optical element blank can be manufactured by a method such as molding glass into a shape that is the shape of the optical element to be manufactured, plus a processing allowance that will be removed by machining. For example, the optical element blank can be manufactured by a method of heating and softening a glass raw material for press molding and then press molding (reheat pressing method); or by a method of supplying a molten glass block to a press molding mold by a known method and then press molding (direct pressing method).

[0122] [Optical element and method of manufacturing the same]

[0123] According to one embodiment of the present invention, an optical element made of the above-mentioned optical glass can be provided. Examples of the types of optical elements include spherical lenses, aspherical lenses, prisms, diffraction gratings, and the like. Examples of lens shapes include biconvex lenses, plano-convex lenses, biconcave lenses, plano-concave lenses, convex meniscus lenses, and concave meniscus lenses.

[0124] One method for manufacturing an optical element involves heating a preform for precision press molding and then performing precision press molding. Precision press molding can be performed using known press molds and molding methods. This method of manufacturing optical elements using precision press molding is suitable for the production of aspheric lenses, microlenses, diffraction gratings, and the like.

[0125] Another method for manufacturing an optical element is to mechanically process an optical element blank to produce the optical element. Examples of mechanical processing include cutting, milling, rough grinding, fine grinding, and polishing. This method is suitable for the manufacture of spherical lenses, prisms, and the like.

[0126] Regarding the results of quantitative analysis of glass composition, the glass components are sometimes expressed on an oxide basis, and the content of the glass components is expressed as mass %. Such a composition expressed as mass % on an oxide basis can be converted into a composition expressed as cation % and anion % by, for example, the method described below.

[0127] When the glass contains N glass components, the kth glass component is represented by A(k). m O n . Wherein, k is any integer greater than 1 and less than N.

[0128] A(k) is a cation, O is oxygen, and m and n are integers that can be determined stoichiometrically. For example, in the case of B2O3 based on an oxide standard, m=2 and n=3, and in the case of SiO2, m=1 and n=2.

[0129] Next, A(k) m O n The content of A(k) is X(k) [mass %]. Here, when the atomic weight of A(k) is P(k) and the atomic number of oxygen O is Q, A(k) m O n The formal molecular weight R(k) is R(k)=P(k)×m+Q×n.

[0130] Furthermore, when B=100 / {Σ[m×X(k) / R(k)]}, the cationic component A(k) s+ The content (cation %) is [X(k) / R(k)]×m×B(cation %). Here, Σ represents the sum of m×X(k) / R(K) for k=1 to N. m varies depending on k. s is 2n / m.

[0131] The molecular weight R(k) can be calculated by rounding off to the fourth decimal place and using the value expressed to the third decimal place. The molecular weights of several glass components and additives expressed based on oxides are shown in Table 1 below.

[0132] [Table 1]

[0133] oxides Molecular weight oxides Molecular weight <![CDATA[B2O3]]> 69.621 <![CDATA[Cs2O]]> 281.810 <![CDATA[SiO2]]> 60.084 ZnO 81.389 <![CDATA[La2O3]]> 325.809 MgO 40.304 <![CDATA[Y2O3]]> 225.810 CaO 56.077 <![CDATA[Gd2O3]]> 362.498 SrO 81.389 <![CDATA[Yb2O3]]> 394.084 BaO 153.326 <![CDATA[Nb205]]> 265.810 <![CDATA[Al2O3]]> 101.961 <![CDATA[TiO2]]> 79.882 <![CDATA[Ga2O3]]> 187.444 <![CDATA[WO3]]> 231.839 <![CDATA[In2O3]]> 277.634 <![CDATA[Ta2O5]]> 441.893 <![CDATA[Sc2O3]]> 137.910 <![CDATA[Bi2O3]]> 465.959 <![CDATA[HfO2]]> 210.489 <![CDATA[ZrO2]]> 123.223 <![CDATA[Lu2O3]]> 397.932 <![CDATA[Li2O]]> 29.882 <![CDATA[GeO2]]> 104.629 <![CDATA[Na2O]]> 61.979 <![CDATA[P2O5]]> 141.945 <![CDATA[K2O]]> 94.196 <![CDATA[TeO2]]> 159.599 <![CDATA[Rb2O]]> 186.935 <![CDATA[Sb2O3]]> 291.518

[0134] Example

[0135] The present invention will be described in more detail below with reference to the following examples, but the present invention is not limited to the embodiments shown in the examples.

[0136] <Examples 1 to 31, Comparative Examples 1 to 6>

[0137] In order to achieve the glass composition shown in the table below, corresponding nitrates, sulfates, carbonates, hydroxides, oxides, boric acid, etc. were used as raw materials for introducing each component, and the raw materials were weighed and thoroughly mixed to prepare a mixed raw material.

[0138] The prepared raw materials were placed in a platinum crucible, heated, and melted. After melting, the molten glass was poured into a mold and naturally cooled to near the glass transition temperature. After that, it was immediately placed in an annealing furnace and maintained at a temperature around the glass transition temperature for about 1 hour. Then, it was slowly cooled at a slow cooling rate of -30°C / hour for 4 hours, and then naturally cooled in the furnace to room temperature. Thus, the optical glasses (oxide glasses) shown in Table 1 were obtained.

[0139] Regarding the anion components of each optical glass shown in the following table, 2- The content is 100% anion.

[0140] Various physical properties of the optical glass obtained in this manner are shown in the table below.

[0141] Various physical properties of the optical glass were measured by the methods shown below.

[0142] <Evaluation of optical glass properties>

[0143] (1) Refractive index nd Abbe number νd

[0144] The refractive index nd and the Abbe number νd of the obtained glass were measured by the refractive index measurement method according to the Japan Optical Glass Industries Association standard.

[0145] (2) Glass transition temperature Tg

[0146] Glass sufficiently pulverized in a mortar or the like was used as a sample, and the glass transition temperature Tg was measured using a differential scanning calorimeter (DSC3300SA) manufactured by NETZSCH at a heating rate of 10° C. / min.

[0147] (3) Specific gravity

[0148] The specific gravity was measured by the Archimedes method.

[0149] (4) Coloring degree λ5, λ 70 ,λ 80

[0150] The spectral transmittance T (%) was measured using a spectrophotometer using a glass sample with two optically polished flat surfaces facing each other and a thickness of 10 ± 0.1 mm. The wavelength (nm) at which T reached 5% was defined as λ5, and the wavelength (nm) at which T reached 70% was defined as λ. 70 , the wavelength (nm) at which T reaches 80% is set as λ 80 .

[0151] (5)DH 96

[0152] As an index of weather resistance, DH was obtained by the method described in detail above. 96 (%). That is, a high-temperature and high-humidity temperature cycle test specified in ISO 22531 was performed on a glass sample with a surface polished on a surface of 30 mm × 30 mm × 3 mm, with a cycle of 2 hours and 48 cycles, i.e., a treatment time of 96 hours. The haze amount (%) before and after the test was measured using a haze meter based on ISO 17482, and the difference in haze amount before and after the test, DH, was calculated. 96 (%).

[0153] (6) Mass reduction rate DA

[0154] As an indicator of acid resistance, the mass reduction rate (DA) (%) was calculated using the method described in detail above. Specifically, a mass (g) of powdered glass (particle size 425 μm to 600 μm) corresponding to its specific gravity was placed in a platinum basket and immersed in 80 ml of a 0.01 mol / l nitric acid aqueous solution in a round-bottom flask. The basket was then treated in a boiling water bath for 60 minutes. The mass of the powdered glass before and after treatment was measured to determine the mass reduction rate (DA) (%).

[0155] The above evaluation results are shown in the following table. In the table, the unit of the content of each component and the total content is cation %, and the ratio is the cation ratio.

[0156] For Comparative Example 6, the glass contained a large amount of striae, so the refractive index and Abbe number could not be measured. The reason for this is presumably that in the glass of Comparative Example 6, the cation ratio (Si 4+ / B 3+ ) exceeds 3.0. In the following table, the nd and νd columns of Comparative Example 6 are indicated as "rib NG".

[0157] As shown in the table below, Comparative Examples 1 to 5 have inferior weather resistance compared to the glasses of Examples 1 to 31. The reason for this is presumably that the total content (Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) is less than 12 cation %.

[0158] According to the comparison between the examples, it can be confirmed that Al 3+ 、Y 3+ 、La 3+ 、Gd 3+ 、Ti 4+ 、Nb 5+ 、Zr 4+ and Ta 5+ Total content (Al 3+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) is 7 cation % or more and 15 cation % or less, and has better acid resistance than Examples 1 and 2 in which the total content is outside the above range.

[0159]

[0160]

[0161]

[0162]

[0163]

[0164]

[0165]

[0166]

[0167]

[0168]

[0169]

[0170]

[0171]

[0172]

[0173]

[0174]

[0175] [Production of Preforms for Precision Press Molding]

[0176] For each of Examples 1 to 31, corresponding nitrates, sulfates, carbonates, hydroxides, oxides, boric acid, etc. are used as raw materials for introducing each component in order to achieve the glass composition shown in the above table. The raw materials are weighed and fully mixed to prepare the formulated raw materials.

[0177] The prepared raw materials are placed in a platinum crucible, heated, and melted. The clarified and homogenized molten glass is then discharged at a constant flow rate from a platinum alloy pipe, which is adjusted to a temperature range where it can flow stably without devitrification. The glass is then separated into molten glass blocks of the desired preform mass by dropwise addition or drop-cutting. A mold with a gas outlet at the bottom receives the separated molten glass blocks, which are then floated by gas ejected from the outlets to form a preform for precision press molding. By adjusting and setting the separation distance between the molten glass blocks, a flat, spherical preform is obtained.

[0178] [Fabrication of optical elements (aspherical lenses)]

[0179] Figure 1 A schematic cross-sectional view of a precision press molding device is shown in FIG.

[0180] use Figure 1 The precision pressing and molding device shown performs precision pressing and molding on the preform obtained above to obtain an aspheric lens.

[0181] Specifically, after the preform is placed between the lower mold 2 and the upper mold 1 constituting the press mold, a nitrogen atmosphere is formed in the quartz tube 11, and a heater (not shown) is energized to heat the inside of the quartz tube 11. The temperature inside the press mold is set so that the glass to be formed shows 10 6 ~10 10 dPa·s, and while maintaining this temperature, the push rod 13 is lowered to push the upper mold 1, thereby pressurizing the preform placed in the molding die. The pressure of the pressurization is set to 8 MPa and the pressurization time is set to 30 seconds. After the pressurization, the pressurization pressure is released, and the press-molded glass molded product is slowly cooled while maintaining contact with the lower mold 2 and the upper mold 1 until the viscosity of the glass reaches 10 12 dPa·s or higher, and then rapidly cooled to room temperature, the glass molded product was removed from the molding die to obtain an aspheric lens. Figure 1 In the embodiment, the holding member 10 holds the lower mold 2 and the shell mold 3, and the support rod 9 supports the upper mold 1, the lower mold 2, the shell mold 3, and the holding member 10, and is subjected to pressure from the push rod 13. A thermocouple 14 is inserted into the interior of the lower mold 2 to monitor the temperature inside the press mold.

[0182] Regarding Examples 1 to 31, the surfaces of the obtained lenses were observed with the naked eye, and as a result, no fogging or scratches were observed.

[0183] Finally, the above-mentioned embodiments are summarized.

[0184] [1] An optical glass comprising:

[0185] Contains B 3+ 、Si 4+ 、Al 3+ 、Li + and Zn 2+ As a necessary ingredient,

[0186] Al 3+ The content is 5% or more of cations,

[0187] Li + The content is 10% or more of cations,

[0188] Ba 2+ The content is less than 10 cation%,

[0189] Al 3+ 、Zn 2+ 、Y 3+ 、La 3+ 、Gd 3+ 、Ti4+ 、Nb 5+ 、Zr 4+ and Ta 5+ Total content (Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) is 12 cation % or more,

[0190] Al 3+ 、Zn 2+ 、Y 3+ 、La 3+ 、Gd 3+ 、Ti 4+ 、Nb 5+ 、Zr 4+ and Ta 5+ The total content relative to Mg 2+ , Ca 2+ 、Sr 2+ And Ba 2+ The total content of cation ratio {(Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) / (Mg 2+ +Ca 2+ +Sr 2+ +Ba 2+ )} is 0.80 or above,

[0191] Li + 、Na + and K + Total content (Li + +Na + +K + ) is 10 to 30% cation%,

[0192] Si 4+ Content relative to B 3+ Cation ratio of content (Si 4+ / B 3+ ) is 3.0 or less,

[0193] Furthermore, the Abbe number νd is greater than or equal to 55 and less than or equal to 65.

[0194] [2] The optical glass according to [1], wherein:

[0195] B 3+ The content is 10 cation % or more and 25 cation % or less.

[0196] [3] The optical glass according to [1] or [2], wherein:

[0197] Si 4+ The content is 30 cation % or more and 40 cation % or less.

[0198] [4] The optical glass according to any one of [1] to [3], wherein

[0199] Al 3+ The content is 5 cation % or more and 15 cation % or less.

[0200] [5] The optical glass according to any one of [1] to [4], wherein

[0201] Al 3+ 、Y 3+ 、La 3+ 、Gd 3+ 、Ti 4+ 、Nb 5+ 、Zr 4+ and Ta 5+ Total content (Al 3+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) is 7 cation % or more and 15 cation % or less.

[0202] [6] The optical glass according to any one of [1] to [5], wherein the glass transition temperature Tg is 535° C. or lower.

[0203] [7] The optical glass according to any one of [1] to [6], wherein the difference in haze value DH before and after the weathering test is 96 is less than 3.0%,

[0204] The weather resistance test is a weather resistance test performed by changing the treatment time of the weather resistance test for optical glass specified in ISO 22531 to 96 hours.

[0205] [8] The optical glass according to any one of [1] to [7], wherein the mass reduction rate DA after the acid resistance test specified in JOGIS06:2019 is 0.35% or less.

[0206] [9] An optical element made of the optical glass described in any one of [1] to [8].

[0207] The above optical glass can exhibit excellent weather resistance.

[0208] It should be understood that the embodiments disclosed herein are all illustrative and not restrictive. The scope of the present invention is defined by the claims, not the foregoing description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0209] For example, by adjusting the composition of the glass composition exemplified above as described in the specification, the optical glass of one embodiment of the present invention can be obtained.

[0210] Furthermore, it is of course possible to arbitrarily combine two or more of the items exemplified or described as preferred ranges in the specification.

Claims

1. An optical glass comprising: Contains B 3+ 、Si 4+ 、Al 3+ 、Li + and Zn 2+ As a necessary ingredient, Al 3+ The content is 5% or more of cations, Li + The content is 10% or more of cations, Ba 2+ The content is less than 10 cation%, La 3+ The content is 0% or more and 2% or less, Y 3+ 、La 3+ and Gd 3+ Total content (Y 3+ +La 3+ +Gd 3+ ) is 0% or more and 3% or less, Al 3+ 、Zn 2+ 、Y 3+ 、La 3+ 、Gd 3+ 、Ti 4+ 、Nb 5+ 、Zr 4+ and Ta 5+ Total content (Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) is 12 cation % or more, Al 3+ 、Zn 2+ 、Y 3+ 、La 3+ 、Gd 3+ 、Ti 4+ 、Nb 5+ 、Zr 4+ and Ta 5+ The total content relative to Mg 2+ , Ca 2+ 、Sr 2+ And Ba 2+ The total content of cation ratio {(Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) / (Mg 2+ +Ca 2+ +Sr 2+ +Ba 2 + )} is 0.80 or above, Li + 、Na + and K + Total content (Li + +Na + +K + ) is 10 to 30% cation%, Si 4+ Content relative to B 3+ Cation ratio of content (Si 4+ / B 3+ ) is 3.0 or less, Furthermore, the Abbe number νd of the optical glass is greater than or equal to 55 and less than or equal to 65.

2. The optical glass according to claim 1, wherein B 3+ The content is 10 cation % or more and 25 cation % or less.

3. The optical glass according to claim 1 or 2, wherein: Si 4+ The content is 30 cation % or more and 40 cation % or less.

4. The optical glass according to claim 1 or 2, wherein: Al 3+ The content is 5 cation % or more and 15 cation % or less.

5. The optical glass according to claim 1 or 2, wherein: Al 3+ 、Y 3+ 、La 3+ 、Gd 3+ 、Ti 4+ 、Nb 5+ 、Zr 4+ and Ta 5+ Total content (Al 3+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) is 7 cation % or more and 15 cation % or less.

6. The optical glass according to claim 1 or 2, wherein: Al 3+ 、Zn 2+ 、Y 3+ 、La 3+ 、Gd 3+ 、Ti 4+ 、Nb 5+ 、Zr 4+ and Ta 5+ The total content relative to Mg 2+ , Ca 2+ 、Sr 2+ And Ba 2+ The total content of cation ratio {(Al 3+ +Zn 2+ +Y 3+ +La 3+ +Gd 3+ +Ti 4+ +Nb 5+ +Zr 4+ +Ta 5+ ) / (Mg 2+ +Ca 2+ +Sr 2+ +Ba 2 + )} is below 3.

00.

7. The optical glass according to claim 1 or 2, wherein: Zn 2+ The content is 0.5 cation % or more.

8. The optical glass according to claim 1 or 2, wherein: Zn 2+ The content is 1% or more of cations.

9. The optical glass according to claim 1 or 2, wherein: In the glass composition expressed as anion %, O 2- The content is 95.0 anion % or more.

10. The optical glass according to claim 1 or 2, wherein: In the glass composition expressed as anion %, O 2- The content is 100% anion. The optical glass according to claim 1 or 2, which has a glass transition temperature (Tg) of 535°C or lower.

12. The optical glass according to claim 1 or 2, wherein the difference DH of the haze amount before and after the weathering test is 96 is less than 3.0%, The weather resistance test is a weather resistance test performed by changing the treatment time of the weather resistance test for optical glass specified in ISO 22531 to 96 hours. The optical glass according to claim 1 or 2, wherein the mass reduction rate DA after being subjected to an acid resistance test specified in JOGIS06:2019 is 0.35% or less.

14. An optical element made of the optical glass according to any one of claims 1 to 13.

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