Optical glass and optical element

Abstract

An optical glass according to the present invention contains B2O3, La2O3, TiO2, Nb2O5, and BaO as essential components, wherein the temperature coefficient (Δn / ΔT) of the refractive index of the optical glass is reduced by the inclusion of the BaO component. This optical glass has a d-line refractive index (nd) of 2.08000 or higher, and has a temperature coefficient (Δn / ΔT) of relative refractive index of 7.0 [10-6 / K] or less for light (D line) when the temperature is changed from 40° to 60° for light with a wavelength of 589.29 nm. This optical glass not only has a low specific gravity and a high transmittance while retaining a high refractive index but also has a small temperature dependence of refractive index, and is suitable for use in optical elements for wearable devices and mobile devices.

Description

Optical Glass and Optical Elements

[0001] The present invention relates to an optical glass and an optical element, and in particular to an optical glass suitable for use in wearable devices and mobile devices.

[0002] Optical glass and optical elements can be used in applications such as combining lenses of different optical ranges to improve the optical characteristics of cameras and imaging devices, or incorporating them into optical equipment to realize various optical designs. In particular, reducing the weight of optical glass and optical elements leads to more compact and lightweight optical equipment bodies and modules. For example, in cameras with zoom and autofocus functions, lightweight optical elements allow for smoother power transmission between the actuator and lens, improving performance.

[0003] In recent years, the explosive spread of wearable and mobile devices has led to the research and development of optical glasses suitable for these devices. For example, eyeglass-type devices known as AR / MR glasses, which are compatible with augmented reality (AR) and mixed reality (MR) displays, have been attracting attention, and the market for AR / MR glasses is expanding as a next-generation device following smartphones.

[0004] In the technical field related to such wearable devices, high refractive index optical glasses with new glass compositions have been proposed that ensure a larger field of view (FOV) and enable the formation of large, clear images in order to provide users with a more realistic visual experience. For example, Patent Document 1 (CN102745894) discloses an La-based high refractive index glass, Patent Document 2 (JP4262256) discloses a P-Nb-based high refractive index glass, and Patent Document 3 (JP2020-19710A) discloses a Bi-based high refractive index glass.

[0005] Thus, optical glass for wearable and mobile devices is required to have a high refractive index and a low specific gravity to enable lighter and more sophisticated device designs, but optical transparency, such as high transmittance for blue wavelength light, is also required. In other words, optical glass for wearable and mobile devices is required to have a higher refractive index, a lower specific gravity, and a higher transmittance.

[0006] CN102745894 Patent No. 4262256 Specification JP2020-19710A

[0007] However, physical properties such as low specific gravity and high transmittance are in a trade-off relationship with high refractive index, and the challenge in development is how to obtain optical glass with a higher refractive index, lower specific gravity, and higher transmittance while taking this trade-off into account.

[0008] For example, in producing glass, the more the content of a component that increases the refractive index is increased, the greater the specific gravity tends to be. ２ O ３ Although the refractive index can be increased by including a large amount of components with a large specific gravity, the specific gravity also increases, which is problematic from the viewpoint of reducing the weight of optical glass.

[0009] In order to reduce the material cost of optical glass, it is desirable that the raw material cost of optical glass be as low as possible. However, the glass described in Patent Document 3 contains Nb, which is an expensive raw material. ２ O ５ However, since the composition contains a large amount of , it is difficult to say that it satisfies such a demand.

[0010] Furthermore, until now, little attention has been paid to the temperature dependence of the refractive index of optical glass used in wearable devices. However, as wearable devices become increasingly popular, their usage environments are expected to become more diverse. It is also expected that optical glass suitable for devices used in a variety of temperature environments other than wearable devices will be desired. In light of this situation, it is expected that low temperature dependence of the refractive index of optical glass will become an important factor, so that the original device characteristics can be guaranteed regardless of the temperature of the usage environment.

[0011] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an optical glass that has a high refractive index, a low specific gravity, and a high transmittance, and in addition, has a low temperature dependency of the refractive index.

[0012] The present inventors have conducted extensive research and experimentation to solve the above problems, and as a result have completed the invention of an optical glass that has a high refractive index, a low specific gravity, and high transmittance, and also has a low temperature dependency of the refractive index. Specifically, the present invention provides the following.

[0013] (1) B ２ O ３ , La ２ O ３ , TiO ２ , Nb ２ O ５ and BaO as essential components, and has a refractive index of d line (n ｄ ) is 2.08000 or more, and the temperature coefficient of relative refractive index (Δn / ΔT) when the temperature is changed from 40°C to 60°C for light (D line) with a wavelength of 589.29 nm is 7.0 [10 －６ / K] or less.

[0014] (2) SiO ２ The ratio of the mass % of the oxide-based oxide of the component to the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) (SiO ２ / RO) is 10.0 or less.

[0015] (3) TiO ２component and lanthanide component (Ln ２ O ３ ) based on the oxide mass % ratio (TiO ２ / Ln ２ O ３ ) is greater than 0 and not greater than 1.50.

[0016] (4) BaO component and lanthanide component (Ln ２ O ３ ) oxide-based mass % ratio (BaO / Ln ２ O ３ ) is greater than 0.

[0017] (5) An optical element made of the optical glass according to any one of (1) to (4).

[0018] (6) The optical element according to (5), characterized in that the optical element is used in a wearable device or a mobile device.

[0019] The optical glass of the present invention is B ２ O ３ , La ２ O ３ , TiO ２ , Nb ２ O ５ and BaO as essential components, and has a refractive index of d line (n ｄ ) is 2.08000 or more, and the temperature coefficient of relative refractive index (Δn / ΔT) when the temperature is changed from 40°C to 60°C for light (D line) with a wavelength of 589.29 nm is 7.0 [10 －６ / K] or less. According to the present invention, an optical glass is provided which has a high refractive index, a low specific gravity and a high transmittance, and in addition, the temperature dependency of the refractive index is low.

[0020] Hereinafter, embodiments of the optical glass of the present invention will be described in detail, but the present invention is not limited to the following embodiments and can be practiced with appropriate modifications within the scope of the object of the present invention. Note that redundant explanations may be omitted where appropriate, but this does not limit the spirit of the invention.

[0021] <Glass Components> The composition ranges of each component constituting the optical glass of the present invention are described below. Throughout this specification, unless otherwise specified, the content of each component is expressed as mass % relative to the total amount of glass material, calculated as an oxide. Here, "oxide-based composition" refers to a composition in which each component contained in the glass is expressed, assuming that the oxides, composite salts, metal fluorides, and other raw materials used as the glass constituent components of the present invention are all decomposed and converted to oxides during melting, with the total amount of oxides produced being 100 mass %.

[0022] [BaO Component] When the BaO component is contained in an amount exceeding 0%, it is a component that can adjust the refractive index, melting property, and devitrification resistance of the glass. Furthermore, as a result of investigations, the inventors have found that the BaO component is also a component that can adjust the temperature coefficient of refractive index (Δn / ΔT) of the optical glass. Specifically, it has been found that increasing the content of the BaO component can reduce the temperature coefficient of refractive index (Δn / ΔT). Therefore, the content of the BaO component is preferably greater than 0%, more preferably 3.00% or more, more preferably 5.00% or more, even more preferably 7.00% or more, and even more preferably 8.00% or more.

[0023] On the other hand, by setting the content of the BaO component to 20.00% or less, it is possible to suppress a decrease in the refractive index and reduce devitrification due to an excessive content of this component. Therefore, the content of the BaO component is preferably set to 20.00% or less, more preferably 18.00% or less, more preferably 16.00% or less, and even more preferably 14.00% or less.

[0024] [B ２ O ３ Ingredients] B ２ O ３ The component B is an oxide that can form a network by itself (a glass network-forming component) in the optical glass of the present invention containing a large amount of rare earth oxides, and is a component that enhances the stability of the glass, and is therefore an essential component that is indispensable as a glass-forming oxide. ２ O ３ By containing the component in an amount of more than 0%, the devitrification resistance of the glass can be improved and the specific gravity can be reduced. ２ O３ The content of the component is preferably more than 0%, more preferably 1.00% or more, even more preferably 2.00% or more, and even more preferably 3.00% or more.

[0025] On the other hand, B ２ O ３ Since the component B lowers the refractive index of the optical glass, its content must be kept below a predetermined amount in order to obtain an optical glass with a high refractive index. ２ O ３ By setting the content of the component to 15.00% or less, the decrease in refractive index and the increase in Abbe number can be suppressed, and the deterioration of chemical durability can also be suppressed. ２ O ３ The content of the component is preferably 10.00% or less, more preferably 9.00% or less, and even more preferably 8.00% or less.

[0026] [La ２ O ３ Ingredients] La ２ O ３ The component is an essential component that can increase the refractive index, and is also a component that does not easily color the glass. ２ O ３ The content of the component is preferably more than 0%, more preferably 10.00% or more, more preferably 15.00% or more, more preferably 20.00% or more, even more preferably more than 25.00%, and even more preferably 28.00% or more.

[0027] On the other hand, La ２ O ３ By making the content of the component 40.00% or less, the stability of the glass can be improved, devitrification can be reduced, and an increase in specific gravity can be suppressed. ２ O ３ The content of the component is preferably 40.00% or less, more preferably 38.00% or less, even more preferably 36.00% or less, and even more preferably 35.00% or less.

[0028] [TiO ２ Ingredients] TiO ２ The TiO component is an essential component that can increase the refractive index of the optical glass, reduce the specific gravity, and improve the devitrification resistance. ２The content of the component is preferably more than 0%, more preferably 10.00% or more, more preferably 15.00% or more, even more preferably 20.00% or more, even more preferably 25.00% or more, and even more preferably 27.00% or more.

[0029] On the other hand, TiO ２ The component also deteriorates the transmittance of the glass. ２ By limiting the content of the component to 40.00% or less, TiO ２ Therefore, deterioration of transmittance and devitrification due to excessive inclusion of TiO ２ The content of the component is preferably 40.00% or less, more preferably 38.00% or less, even more preferably 36.00% or less, even more preferably 34.00% or less, and even more preferably 32.00% or less.

[0030] [Nb ２ O ５ Component] Nb ２ O ５ When the content of Nb exceeds 0%, the Nb component increases the refractive index of the glass and lowers the liquidus temperature of the glass, thereby improving the devitrification resistance. ２ O ５ The content of the component is preferably more than 0%, more preferably 2.00% or more, more preferably 4.00% or more, and even more preferably 6.00% or more.

[0031] On the other hand, Nb ２ O ５ By keeping the content of the component at 18.0% or less, the material cost of the glass can be reduced and the decrease in the Abbe number can be suppressed. ２ O ５ This can reduce devitrification caused by excessive inclusion of Nb, and also suppress a decrease in the transmittance of the glass to visible light (particularly wavelengths of 500 nm or less). ２ O ５ The content of the component is preferably 18.00% or less, more preferably 15.00% or less, even more preferably 13.00% or less, and even more preferably 11.00% or less.

[0032] [ZrO ２ Component] ZrO ２The component is a component that can increase the refractive index and Abbe number of the glass and improve the devitrification resistance. ２ The content of the component may be preferably more than 0%, more preferably 1.00% or more, more preferably 2.00% or more, even more preferably 3.00% or more, and even more preferably 4.00% or more.

[0033] On the other hand, ZrO ２ The ZrO component acts as a nucleating agent for the crystallization of glass, so if the content is high, the glass will tend to crystallize. ２ The content of the component is preferably 10.00% or less, more preferably 9.00% or less, and even more preferably 8.00% or less.

[0034] [Gd ２ O ３ Component] Gd ２ O ３ The component Gd is not only a component that can increase the refractive index and Abbe number of the glass, but also a component that can reduce the temperature coefficient of the refractive index (Δn / ΔT). ２ O ３ The raw material cost of this component is high, and a high content of this component increases the production cost and the specific gravity of the glass. ２ O ３ The content of the element is preferably 10.00% or less, more preferably 8.00% or less, even more preferably 7.00% or less, and even more preferably 5.00% or less. In particular, from the viewpoint of reducing material costs, Gd ２ O ３ It is most preferred that the composition contains no ingredients.

[0035] [SiO ２ Component] SiO ２ The component is a component that can increase the viscosity of the glass melt, reduce the coloring of the glass, and improve the devitrification resistance. ２ The component increases the liquidus temperature and also decreases the refractive index. ２ By keeping the content of the component at 15.0% or less, the decrease in refractive index can be suppressed and the specific gravity can be reduced. ２The content of the component is preferably 15.00% or less, more preferably 13.00% or less, even more preferably 11.00% or less, even more preferably 9.00% or less, and even more preferably 7.00% or less.

[0036] [Y ２ O ３ Ingredients] Y ２ O ３ When the content of Y exceeds 0%, it is possible to reduce the material cost of the glass and the specific gravity of the glass while maintaining a high refractive index and a high Abbe number. ２ O ３ The content of the component is preferably greater than 0%. ２ O ３ By making the content of the component 10.00% or less, the decrease in the refractive index of the glass can be suppressed, the stability of the glass can be increased, and the melting property of the glass raw material can be suppressed from being deteriorated. ２ O ３ The content of the component is preferably 10.00% or less, more preferably 9.00% or less, even more preferably 8.00% or less, and even more preferably 7.00% or less.

[0037] [Ta ２ O ５ Ingredients] Ta ２ O ５ The component is a component that, when contained in an amount of more than 0%, can increase the refractive index of the glass and improve the devitrification resistance. ２ O ５ The raw material price of this component is high, and if its content is high, the production cost will increase. ２ O ５ By keeping the content of Ta at 10.00% or less, the melting temperature of the raw materials is lowered, and the energy required to melt the raw materials is reduced, which also reduces the manufacturing cost of the optical glass. ２ O ５ The content of these elements is preferably 10.00% or less, more preferably 5.00% or less, even more preferably 3.00% or less, and even more preferably 2.50% or less. In particular, from the viewpoint of reducing material costs, Ta ２ O ５ It is most preferred that the composition contains no ingredients.

[0038] [W.O. ３ Ingredients] WO ３ When the WO content exceeds 0%, the WO component is a component that can increase the refractive index, lower the glass transition point, and improve the devitrification resistance while reducing the coloring of the glass caused by other high refractive index components. ３ By making the content of the component 10.00% or less, the material cost of the glass can be reduced, the decrease in the Abbe number can be suppressed, and the specific gravity can be reduced. ３ The coloring of the glass due to the WO component can be reduced and the visible light transmittance can be increased. ３ The content of the element is preferably 10.00% or less, more preferably 5.00% or less, even more preferably 3.00% or less, and even more preferably 2.50% or less.

[0039] [ZnO Component] When the ZnO component is contained in an amount exceeding 0%, it is a component that can enhance the stability of the glass and reduce coloration. It is also a component that can lower the glass transition temperature and improve chemical durability. On the other hand, by limiting the content of the ZnO component to 15.00% or less, it is possible to suppress a decrease in the refractive index of the glass and reduce devitrification due to excessive viscosity reduction. Therefore, the content of the ZnO component is preferably 15.00% or less, more preferably 12.00% or less, even more preferably 10.00% or less, even more preferably 8.00% or less, even more preferably 6.00% or less, even more preferably 3.00% or less, and even more preferably 2.50% or less.

[0040] [MgO Component, CaO Component, SrO Component] When the MgO component, CaO component, and SrO component are contained in an amount exceeding 0%, they are components that can adjust the refractive index, meltability, and devitrification resistance of the glass, but they also lower the refractive index and cause devitrification when contained in excessive amounts. Therefore, the contents of the MgO component, CaO component, and SrO component are each preferably 18.0% or less, more preferably 16.0% or less, even more preferably 14.0% or less, and even more preferably 12.0% or less.

[0041] [Li ２ O component, Na ２ O component, K ２ O component] Li２ O component, Na ２ O component, K ２ The O component is a component that can improve the meltability of the glass and lower the glass transition temperature when it is contained in an amount of more than 0%. ２ O component, Na ２ O component and K ２ By making each of the O components 10.00% or less, it is possible to make it difficult for the refractive index of the glass to decrease and to reduce devitrification of the glass. ２ O component, Na ２ O component and K ２ The content of each of the O components is preferably 10.00% or less, more preferably 5.00% or less, even more preferably 3.00% or less, and still more preferably 1.00% or less.

[0042] [Sb ２ O ３ Component] Sb ２ O ３ The component is a component that can degas the glass melt when its content exceeds 0%. ２ O ３ If the amount is too large, the transmittance in the short wavelength region of the visible light range will be poor. ２ O ３ The content of the element is preferably 1.00% or less, more preferably 0.50% or less, and further preferably 0.30% or less.

[0043] The component that clarifies and defoams the glass is the above-mentioned Sb ２ O ３ There is no limitation on the components, and any fining agent, defoaming agent or combination thereof known in the art of glass manufacturing can be used.

[0044] [P ２ O ５ Ingredients] P ２ O ５ When the content of the component exceeds 0%, it can act as a glass-forming component, lowering the liquidus temperature of the glass and increasing the devitrification resistance. ２ O ５ By keeping the content of the component at 10.00% or less, the chemical durability of the glass, particularly the water resistance, can be prevented from decreasing. ２O ５ The content of the element is preferably 10.00% or less, more preferably 5.00% or less, even more preferably 3.00% or less, and even more preferably 1.00% or less.

[0045] [GeO ２ Component] GeO ２ The component is a component that can increase the refractive index of the glass and improve the devitrification resistance when contained in an amount of more than 0%. ２ The raw material price of GeO is high, and its high content increases the production cost. ２ The content of the element is preferably 10.00% or less, more preferably 5.00% or less, even more preferably 3.00% or less, and even more preferably 1.00% or less. In particular, from the viewpoint of reducing material costs, GeO ２ It may not contain any ingredients.

[0046] [Al ２ O ３ Components and Ga ２ O ３ Ingredients] Al ２ O ３ Components and Ga ２ O ３ The Al component is a component that can improve the chemical durability of the glass and can improve the devitrification resistance of the glass when contained in an amount of more than 0%. ２ O ３ Components and Ga ２ O ３ By limiting the content of each of the components to 10.00% or less, devitrification due to excessive content can be suppressed. ２ O ３ Components and Ga ２ O ３ The content of each of the components is preferably 10.00% or less, more preferably 5.00% or less, even more preferably 3.00% or less, and even more preferably 1.00% or less.

[0047] [Bi ２ O ３ Ingredients] Bi ２ O ３ The component is a component that, when contained in an amount of more than 0%, can increase the refractive index and decrease the glass transition point. ２O ３ By keeping the content of the component at 10.00% or less, the increase in specific gravity can be suppressed. ２ O ３ The content of the component is preferably 10.00% or less, more preferably 8.00% or less, even more preferably 7.00% or less, and even more preferably 6.00% or less. In particular, from the viewpoint of reducing the specific gravity, Bi ２ O ３ It may not contain any ingredients.

[0048] [TeO ２ Ingredients] TeO ２ The component is a component that, when contained in an amount of more than 0%, can increase the refractive index and decrease the glass transition point. ２ When glass raw materials are melted in a platinum crucible or a melting tank in which the parts that come into contact with the molten glass are made of platinum, there is a problem that TeO may be alloyed with platinum. ２ The content of the element is preferably 10.00% or less, more preferably 5.00% or less, even more preferably 3.00% or less, and even more preferably 1.00% or less.

[0049] [SnO ２ Component] SnO ２ When the content of SnO exceeds 0%, the SnO component reduces oxidation of the glass melt, resulting in clarification, and also increases the visible light transmittance of the glass. ２ By keeping the content of SnO at 3.00% or less, it is possible to reduce coloration of the glass due to reduction of the glass melt and devitrification of the glass. ２ Since alloying of the components with the melting equipment (especially precious metals such as Pt) is reduced, the life of the melting equipment can be extended. ２ The content of the element is preferably 3.00% or less, more preferably 2.00% or less, and further preferably 1.00% or less.

[0050] [F Component] When the F component is contained in an amount exceeding 0%, it increases the Abbe number of the glass, lowers the glass transition point, and improves devitrification resistance. However, if the content of the F component, i.e., the total amount of F in fluorides substituted for part or all of the oxides of one or more of the above-mentioned metal elements, exceeds 10.0%, the amount of volatilization of the F component increases, making it difficult to obtain stable optical constants and homogeneous glass. Therefore, the content of the F component is preferably 10.00% or less, more preferably 5.00% or less, even more preferably 3.00% or less, and even more preferably 1.00% or less.

[0051] [Sb ２ O ３ Component] Sb ２ O ３ The Sb component is an optional component that promotes fining and defoaming when melting the glass. ２ O ３ By keeping the content of Sb at 0.1% or less, it is possible to suppress coloring, particularly in high refractive index glass. In addition, by keeping the content of Sb at 0.1% or less, excessive foaming during glass melting is unlikely to occur, so Sb ２ O ３ The components can be made less likely to alloy with melting equipment (especially precious metals such as Pt). ２ O ３ The upper limit of the content of the element is preferably 0.1% or less, more preferably 0.08% or less, and even more preferably 0.05% or less, but may be 0%.

[0052] The component that clarifies and defoams the glass is the above-mentioned Sb ２ O ３ There is no limitation on the components, and any fining agent, defoaming agent or combination thereof known in the art of glass manufacturing can be used.

[0053] [C component] The C component maintains a reducing atmosphere in the platinum crucible, suppresses the incorporation of platinum into the glass due to oxidation, and improves transmittance. However, if the C component content is high, the cationic components in the glass are reduced, causing coloration of the glass. Therefore, the upper limit of the C component content is preferably 10.0% or less, more preferably 8.0% or less, more preferably 6.0% or less, and most preferably 5.0% or less. On the other hand, the lower limit of the C component content is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, and most preferably 2.0% or more, but it may be 0%.

[0054] [S Component] The S component maintains a reducing atmosphere in the platinum crucible, inhibits the incorporation of platinum into the glass due to oxidation, and improves transmittance. However, if the S content is high, the cationic components in the glass are reduced, causing coloration of the glass. Therefore, the upper limit of the S component content is preferably 10.0% or less, more preferably 8.0% or less, more preferably 6.0% or less, and most preferably 5.0% or less. On the other hand, the lower limit of the S component content is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, and most preferably 2.0% or more, but it may be 0%.

[0055] [Organic components such as sucrose] Organic components such as sucrose are components that can maintain a reducing atmosphere in the platinum crucible, prevent platinum from being mixed into the glass due to oxidation, and improve transmittance, but if the content is too high, the cationic components in the glass will be reduced, causing coloration of the glass.Therefore, the content of organic components such as sucrose is preferably 10.0% or less, more preferably 8.0% or less, more preferably 6.0% or less, and most preferably 5.0% or less as the upper limit.On the other hand, the content of organic components such as sucrose is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, and most preferably 2.0% or more as the lower limit, but may be 0%.

[0056] [Rn ２ O component] Rn ２The O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) not only enhances the stability of the glass and improves the transmittance, but also reduces the temperature coefficient of refractive index (Δn / ΔT). ２ By making the mass sum of the O component more than 0%, it is possible to improve the meltability during glass production and improve the devitrification resistance. Therefore, this mass sum is preferably more than 0%, more preferably 3.00% or more, more preferably 5.00% or more, even more preferably 7.00% or more, and still more preferably 8.00% or more. On the other hand, ２ By making the mass sum of the O component 10.00% or less, it is possible to make it difficult for the refractive index of the glass to decrease and to reduce devitrification of the glass. ２ The sum of the masses of the O components is preferably 10.00% or less, more preferably 5.00% or less, even more preferably 3.00% or less, and still more preferably 1.00% or less.

[0057] [RO Component] The RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) not only enhances the stability of the glass and improves the transmittance, but also reduces the temperature coefficient of refractive index (Δn / ΔT). In particular, by making the mass sum of the RO components greater than 0%, the meltability during glass production can be improved and devitrification resistance can be improved. Therefore, this mass sum is preferably greater than 0%, more preferably 3.00% or more, more preferably 5.00% or more, even more preferably 7.00% or more, and even more preferably 8.00% or more.

[0058] On the other hand, the RO component not only decreases the refractive index of the glass but also tends to increase the specific gravity, so the total mass of the RO component is preferably 20.00% or less, more preferably 18.00% or less, more preferably 16.00% or less, even more preferably 14.00% or less, and still more preferably 13.50% or less.

[0059] [Ln ２ O ３ Ingredients] Ln ２ O ３ The component (wherein Ln is one or more selected from the group consisting of La, Y, Gd, and Yb) is a component that can increase the refractive index.２ O ３ The sum of the masses of the components is preferably greater than 0%, more preferably 10.00% or more, more preferably 15.00% or more, more preferably 20.00% or more, even more preferably greater than 25.00%, even more preferably 28.00% or more, and even more preferably 30.00% or more.

[0060] On the other hand, Ln ２ O ３ The component can increase the stability of the glass, reduce devitrification, and suppress an increase in specific gravity. ２ O ３ The sum of the masses of the components is preferably 50.00% or less, more preferably 48.00% or less, even more preferably 45.00% or less, even more preferably 43.00% or less, and even more preferably 40.00% or less.

[0061] [SiO ２ Ratio of mass % of oxides of SiO2 and RO components] ２ The RO component (where R is one or more elements selected from the group consisting of Mg, Ca, Sr, and Ba) not only enhances the stability of the glass and improves its transmittance, but also reduces the temperature coefficient of the refractive index (Δn / ΔT).

[0062] SiO ２ The ratio of the mass % of the oxide-based oxide of the component to the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, and Zn) (SiO ２ / RO) is preferably 10.00 or less, more preferably 5.00 or less, even more preferably 2.00 or less, even more preferably 1.00 or less, and even more preferably 0.80 or less.

[0063] On the other hand, SiO ２ The ratio of the mass % of the oxide-based oxide of the component to the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) (SiO ２ / RO) is preferably greater than 0. It is more preferably 0.10 or greater, even more preferably 0.15 or greater, even more preferably 0.20 or greater, even more preferably 0.25 or greater, and even more preferably 0.30 or greater.

[0064] [TiO ２ Components and Ln ２ O ３ Ratio of mass % of components based on oxides] As described above, TiO ２ The Yb component is a component that can increase the refractive index of optical glass, reduce the specific gravity, and improve the devitrification resistance, but it is also a component that deteriorates the transmittance of the glass. ２ O ３ Ingredients and Lu ２ O ３ Lanthanide components such as Ln ２ O ３ ) is a component that, when contained in a certain amount, increases the refractive index while stabilizing the glass, but increases the content thereof, resulting in a decrease in transmittance and an increase in specific gravity. In other words, increasing the content of the Ln component can increase the refractive index while stabilizing the glass, while decreasing the content of the Ln component can increase the transmittance while decreasing the specific gravity.

[0065] TiO ２ Components and Ln ２ O ３ The mass % ratio of the components based on the oxides (TiO ２ / Ln ２ O ３ ) is preferably greater than 0, and is preferably 1.50 or less, more preferably 1.00 or less, and even more preferably 0.95 or less.

[0066] On the other hand, TiO ２ Components and Ln ２ O ３ The mass % ratio of the components based on the oxides (TiO ２ / Ln ２ O ３ ) is preferably greater than 0. It is more preferably 0.10 or greater, even more preferably 0.20 or greater, even more preferably 0.30 or greater, even more preferably 0.40 or greater, even more preferably 0.50 or greater, and even more preferably 0.60 or greater.

[0067] [BaO component and Ln ２ O ３ Ratio of Components by Mass Percentage on an Oxide Basis] As described above, the BaO component is a component that can adjust the refractive index, meltability, and devitrification resistance of the glass. In addition, according to the results of the studies by the present inventors, it is also a component that can adjust the temperature coefficient of refractive index (Δn / ΔT) of the optical glass. However, when a certain amount of BaO component is contained, if the content of Ln component is high, the glass becomes unstable. Therefore, the ratio of Ba component to lanthanoid component (Ln) by mass percent on an oxide basis (BaO / Ln ２ O ３ ) is preferably greater than 0, more preferably greater than 0.15, even more preferably 0.18 or more, and even more preferably 0.20 or more. On the other hand, if the content of the BaO component is high, it will cause a decrease in the refractive index and devitrification. Therefore, it is necessary to use a Ba component and a lanthanoid component (Ln ２ O ３ ) oxide-based mass % ratio (BaO / Ln ２ O ３ ) is preferably 2.00 or less, more preferably 1.00 or less, still more preferably 0.80 or less, and even more preferably 0.50 or less.

[0068] [B ２ O ３ Ingredients and SiO ２ Ratio of mass % of components based on oxides] ２ If the B component is contained in a relatively large amount, the coloring becomes strong and the devitrification tendency during pressing increases, so it is necessary to contain a certain amount of the Si component. ２ O ３ Ingredients and SiO ２ By adjusting the mass % ratio of the components based on oxides, a stable and highly viscous glass can be obtained, and formability can be improved. ２ O ３ component and SiO ２ Ingredients and B ２ O ３ The sum of the components (SiO ２ +B ２ O ３ )) based on oxide mass % ratio (B ２ O ３ / (SiO２ +B ２ O ３ )) is preferably greater than 0, more preferably greater than 0.10, even more preferably greater than 0.20, even more preferably greater than 0.30, and even more preferably greater than 0.35. ２ O ３ / (SiO ２ +B ２ O ３ ) is preferably 1.00 or less, more preferably 0.90 or less, and even more preferably 0.80 or less.

[0069] [Components that are not preferably contained] Next, components that are not preferably contained in the optical glass of the present invention will be described.

[0070] Transition metal components such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, have the property of coloring the glass and causing absorption at specific wavelengths in the visible range, even when contained in small amounts alone or in combination. Therefore, it is preferable that optical glass used in applications with wavelengths in the visible range, in particular, be substantially free of these metals.

[0071] In addition, lead compounds such as PbO and As ２ O ３ Arsenic compounds such as those mentioned above are components that have a high environmental impact, and therefore it is desirable that they are not contained substantially, that is, that they are not contained at all except for unavoidable contamination.

[0072] Furthermore, in recent years, there has been a trend to reduce the use of Th, Cd, Tl, Os, Be, and Se components as harmful chemical substances, and environmental measures are required not only in the glass manufacturing process but also in the processing process and disposal after commercialization. Therefore, when environmental impact is important, it is preferable that these components are substantially not contained.

[0073] <Manufacturing Method> The optical glass of the present invention is manufactured, for example, as follows: The above-mentioned raw materials are mixed uniformly so that the respective components fall within the prescribed content ranges, the mixture is placed in a platinum crucible, and melted and stirred in an electric furnace at a temperature ranging from 1100 to 1500°C for 2 to 5 hours depending on the melting difficulty of the glass raw materials, followed by homogenization. After the temperature is lowered to an appropriate level, the mixture is poured into a mold and slowly cooled.

[0074] <Physical Properties> The optical glass of the present invention is an optical glass that has a high refractive index, a low specific gravity, and high transmittance, and in addition, the temperature dependence of the refractive index is low. Specifically, it has the following physical properties.

[0075] [Refractive Index] The optical glass of the present invention preferably has a high refractive index. ｄ Although there is no particular limitation on the refractive index (n) of the optical glass of the present invention, it is preferable that the refractive index be high (low dispersion). ｄ The lower limit of this refractive index (n ｄ ) is preferably 2.08000 or more, more preferably 2.09000 or more, even more preferably 2.10000 or more, even more preferably 2.10200 or more, even more preferably 2.10400 or more, even more preferably 2.10600 or more, and even more preferably 2.10800 or more.

[0076] [Abbe Number] As described above, in the optical glass of the present invention, the Abbe number (ν ｄ Although there is no particular limitation on the Abbe number (ν), it is preferable that the Abbe number (ν) of the optical glass of the present invention is high (low dispersion). ｄ ) is preferably 20.00 or more, more preferably 21.00 or more, and even more preferably 21.50 or more.

[0077] [Temperature Coefficient of Refractive Index (Δn / ΔT)] The optical glass of the present invention is an optical glass that has a high refractive index, a low specific gravity, and high transmittance, and in addition, has a low temperature dependency of the refractive index. In constructing an optical system that is less susceptible to the effects of temperature fluctuations on imaging performance, etc., it is preferable to use in combination an optical element made of glass whose refractive index decreases as the temperature increases and whose temperature coefficient of the relative refractive index is negative, and an optical element made of glass whose refractive index increases as the temperature increases and whose temperature coefficient of the relative refractive index is positive, in order to be able to correct the effects of temperature changes on imaging performance, etc.

[0078] The optical glass of the present invention has a low temperature coefficient of relative refractive index (Δn / ΔT). More specifically, the temperature coefficient of relative refractive index of the optical glass of the present invention is preferably +10.0×10 －６ °C －１ , more preferably +8.0×10 －６ °C －１ , and more preferably +6.0×10 －６ °C －１ is the upper limit value, and the value can be this upper limit value or a value lower than that (on the negative side).

[0079] On the other hand, the temperature coefficient of the relative refractive index of the optical glass of the present invention is preferably −1.0×10 －６ °C －１ , more preferably 0x10 －６ °C －１ , and more preferably +1.0 × 10 －６ °C －１ is the lower limit, and the value can be this lower limit or a value higher (on the positive side).

[0080] Glass with such a low temperature coefficient of relative refractive index broadens the options for correcting image shifts due to temperature changes, making such corrections easier. Therefore, setting the temperature coefficient of relative refractive index within this range can contribute to correcting image shifts due to temperature changes.

[0081] The temperature coefficient of the relative refractive index of the optical glass of the present invention is the temperature coefficient of the refractive index for light (D-line) with a wavelength of 589.29 nm in air at the same temperature as the optical glass, and is the amount of change per degree Celsius (°C) when the temperature is changed from 40°C to 60°C. －１ )

[0082] [Specific Gravity] The specific gravity (g / cm ３ From the viewpoint of contributing to weight reduction of optical elements and optical devices, the upper limit of the refractive index is preferably 5.50 or less, more preferably 5.20 or less, even more preferably 5.00 or less, and even more preferably 4.90 or less.

[0083] [Specific gravity (d) and refractive index (n ｄ The optical glass of the present invention has a refractive index (n ｄ The relationship between the specific gravity (d) and the specific gravity (d) is d≦1.4286×n ｄ +2.0786. The refractive index (n ｄ In the past, only high-cost glasses were known that have a refractive index (n ) of 2.08000 or more and a low specific gravity. In contrast, the present invention satisfies the above relational expression, and therefore, ｄ The use of optical glass having a small specific gravity (d) relative to the refractive index (n ｄ The relationship between the specific gravity (d) and the specific gravity (d) is preferably d≦1.4286×n ｄ +2.0786, and more preferably d≦1.4286×n ｄ +2.0286, and more preferably d≦1.4286×n ｄ +1.9786, and more preferably d≦1.4286×n ｄ The relationship is +1.9286.

[0084] [Transmittance] The optical glass of the present invention is an optical glass with a high refractive index, low specific gravity, and high transmittance. The optical glass of the present invention has a transmittance of 60% or more for visible light with a wavelength of 500 nm or less. More specifically, the λ70 (nm: wavelength at which transmittance is 70%) of the optical glass of the present invention is preferably 520 nm or less, more preferably 510 nm or less, even more preferably 500 nm or less, and even more preferably 495 nm or less. Furthermore, the λ5 (nm: wavelength at which transmittance is 5%) of the optical glass of the present invention is preferably 400 nm or less, even more preferably 390 nm or less.

[0085] [Preform and optical element] From the produced optical glass, for example, by using polishing means or mold press molding means such as reheat press molding or precision press molding, glass molded body can be produced.That is, by carrying out mechanical processing such as grinding and polishing on optical glass to produce glass molded body, or by producing a preform for mold press molding from optical glass, carrying out reheat press molding on this preform and then carrying out polishing to produce glass molded body, or by carrying out precision press molding on the preform produced by polishing or the preform molded by known floating molding etc. to produce glass molded body.It should be noted that the means for producing glass molded body are not limited to these means.

[0086] Thus, the optical glass of the present invention is useful for various optical elements and optical designs. Among these, it is particularly preferable to form a preform from the optical glass of the present invention and use this preform to produce optical elements such as lenses and prisms by reheat press molding or precision press molding. This makes it possible to form preforms with large diameters, which allows for larger optical elements to be produced, while still achieving high-definition, high-precision imaging and projection characteristics when used in optical equipment such as cameras and projectors.

[0087] The optical glass according to the present invention is an optical glass that has a high refractive index, a low specific gravity, and high transmittance, and in addition, the temperature dependency of the refractive index is low, making it suitable for use in wearable devices or mobile devices.

[0088] The compositions of the examples (No. 1 to No. 123) of the present invention and the refractive index (n ｄ ), Abbe number (ν ｄ The results of the temperature coefficient of refractive index (Δn / ΔT) are shown in Tables 1 to 13, and Table 13 shows the compositions of Examples 1 to 123 and the maximum (Max) and minimum (Min) values ​​of each property. The temperature coefficient of refractive index (Δn / ΔT) shown in each table is in units of 10 －６ °C －１ ([10 －６ / K). In Example 117, Cs ２ Example 118 contains 0.61 mass % of O, and Example 118 contains 0.61 mass % of P ２ O ５ These examples are for illustrative purposes only and are not intended to be limiting.

[0089] For the glasses of the Examples, high-purity raw materials used in ordinary optical glass, such as the corresponding oxides, hydroxides, carbonates, sulfates, nitrates, fluorides, and metaphosphate compounds, were selected as the raw materials for each component, and these were weighed out and uniformly mixed to obtain the composition ratios of each Example shown in the Table. The mixture was then placed in a platinum crucible and melted in an electric furnace at a temperature ranging from 1100 to 1500°C for 2 to 5 hours, depending on the melting difficulty of the glass raw materials. The mixture was then stirred to homogenize, poured into a mold, etc., and slowly cooled to produce the glass.

[0090] The refractive index (n ｄ ) and Abbe number (ν ｄ ) was measured in accordance with the V-block method specified in JIS B 7071-2:2018. ｄ ) is shown as a measurement value for the d line (587.56 nm) of a helium lamp. ｄ ) is the refractive index of the d-line, the refractive index (nF) of the F-line (486.13 nm) of the hydrogen lamp, and the refractive index (n Ｃ ) value, the Abbe number (ν ｄ ) = [(n ｄ −1) / (n Ｆ -n Ｃ) was calculated from the formula. ｄ Using the value of d≦7.494×n ｄ The relationship of -10.961 was calculated.

[0091] The transmittance of the glasses in the examples and comparative examples was measured in accordance with the Japan Optical Glass Industry Association standard JOGIS02-2019. In the present invention, the presence and degree of coloration of the glass was determined by measuring the transmittance of the glass. Specifically, the spectral transmittance of a 10±0.1 mm thick, parallel-polished specimen from 200 to 800 nm was measured in accordance with JIS Z8722, and the λ ５ (wavelength at transmittance 5%) and λ ７０ (wavelength at transmittance of 70%) was determined.

[0092] The specific gravity of the glasses in the examples and comparative examples was measured in accordance with the Japan Optical Glass Industry Association standard JOGIS05-2019 "Method for measuring the specific gravity of optical glass."

[0093] The temperature coefficient of the relative refractive index (Δn / ΔT) of the glasses of the examples and comparative examples was measured by an interference method, one of the methods described in the Japan Optical Glass Industry Association Standard JOGIS18-2019 "Method for measuring the temperature coefficient of refractive index of optical glass," in which the temperature was changed from 40°C to 60°C for light with a wavelength of 589.29 nm (D-line).

[0094]

[0095]

[0096]

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105]

[0106]

[0107] In any of the examples shown in Tables 1 to 13, B ２ O ３ , La ２ O ３ , TiO ２ , Nb ２ O ５ The optical glass contains BaO as an essential component, and the temperature coefficient of refractive index (Δn / ΔT) of the optical glass is reduced by including the BaO component. ｄ ) is 2.08000 or more, and the temperature coefficient of relative refractive index (Δn / ΔT) when the temperature is changed from 40°C to 60°C for light (D line) with a wavelength of 589.29 nm is 7.0 [10 －６ / K] or less. Such optical glass has a high refractive index, a low specific gravity, and high transmittance, and in addition, the refractive index is low in dependence on temperature, making it suitable for optical elements such as wearable devices and mobile devices.

[0108] As described above, the optical glass according to the present invention is ２ O ３ , La ２ O ３ , TiO ２ , Nb ２ O ５ and BaO as essential components, and has a refractive index of d line (n ｄ) is 2.08000 or more. According to the studies of the present inventors, the BaO component is not only a component that can adjust the refractive index, melting property, and devitrification resistance of the glass, but also a component that can adjust the temperature coefficient of refractive index (Δn / ΔT) of the optical glass. Based on the new finding that the temperature coefficient of refractive index (Δn / ΔT) can be reduced by increasing the content of the BaO component, the present inventors have determined that the BaO component is an essential component, and as a result, the temperature coefficient of relative refractive index (Δn / ΔT) for light with a wavelength of 589.29 nm (D-line) when the temperature is changed from 40° C. to 60° C. is reduced to 7.0 [10 －６ / K] or less optical glass is obtained.

[0109] As described above, it has been found that the present invention provides optical glass that has a high refractive index, a low specific gravity, and high transmittance, and also has a low temperature dependency of the refractive index.

[0110] The present invention provides an optical glass that has a high refractive index, a low specific gravity, and high transmittance, and in addition, has a low temperature dependency of the refractive index. The optical glass according to the present invention is suitable for use in wearable devices and mobile devices.

Claims

1. B ２ O ３ , La ２ O ３ , TiO ２ , Nb ２ O ５ and BaO as essential components, and has a refractive index of d line (n ｄ ) is 2.08000 or more, and the temperature coefficient of the relative refractive index (Δn / ΔT) when the temperature is changed from 40° C. to 60° C. for light (D line) with a wavelength of 589.29 nm is 7.0 [10 －６ / K] or less.

2. SiO ２ The ratio of mass % of the oxide-based oxide of the component and the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) (SiO ２ 2. The optical glass according to claim 1, wherein R(.alpha. / RO) is 10.0 or less.

3. TiO ２ component and lanthanide component (Ln ２ O ３ ) based on oxide mass % (TiO ２ / Ln ２ O ３ 2. The optical glass according to claim 1 , wherein n is greater than 0 and is equal to or less than 1.

50.

4. BaO component and lanthanide component (Ln ２ O ３ ) based on oxide mass% ratio (BaO / Ln ２ O ３ 2. The optical glass of claim 1 , wherein n is greater than 0.

5. An optical element made of the optical glass according to any one of claims 1 to 4.

6. The optical element according to claim 5, which is used in a wearable device or a mobile device.

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