Optical glass and optical components

Abstract

This invention relates to optical glass and optical elements. [Problem] To provide optical glass and optical elements with low specific gravity relative to refractive index but high stability. [Solution] An optical glass, based on oxide mass%, has the following composition: Ln₂O₃ content 10.0% or less (Ln is one or more selected from the group consisting of La, Y, Gd, and Yb); TiO₂ / RO mass ratio 0.5 or more and 1.5 or less (R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba); total Nb₂O₅ + WO₃ + Bi₂O₃ mass content 18.0% or less; and BaO / RO mass ratio 0.30 or more and 0.95 or less. The specific gravity is set as d, and the refractive index as n. d When d ≤ 6.17 × n d The relationship is -7.694.

Description

Technical Field

[0001] This invention relates to optical glass and optical components. Background Technology

[0002] Optical glass and optical components can be used to combine lenses from different optical fields to improve the optical properties of cameras, imaging devices, etc., and can be mounted in optical equipment to realize various optical designs.

[0003] In particular, lightweighting of optical glass and optical components is related to the compactness and lightweighting of the main body and modules of optical equipment. For example, in shooting devices such as digital cameras, which can achieve chromatic aberration correction and also have zoom and autofocus functions by combining multiple lenses, lightweight optical components make the power transmission between the actuator and the lens smoother, thereby improving performance.

[0004] On the other hand, as high-refractive-index glasses, La-based glasses are known in Patent Document 1, P-Nb-based glasses are known in Patent Document 2, and inventions aimed at making optical devices lightweight are known in Patent Documents 3 and 4.

[0005] Existing technical documents

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-035037

[0008] Patent Document 2: Japanese Patent Application Publication No. 2012-171848

[0009] Patent Document 3: WO2018 / 235725

[0010] Patent Document 4: Japanese Patent Application Publication No. 2006-219365 Summary of the Invention

[0011] The problem the invention aims to solve

[0012] The glass disclosed in Patent Document 1 contains a large amount of rare earth oxides with a higher specific gravity than other components; in Patent Document 2, the component with a high refractive index has a higher content of Nb, which increases the specific gravity.

[0013] Components that significantly increase the refractive index include rare earth oxides, TiO2, Nb2O5, WO3, and Bi2O3.

[0014] To obtain optical glass with a high refractive index, the content of the aforementioned components needs to be increased. However, these components are all relatively heavy compared to the others. Among the aforementioned components, although TiO2 has the lowest specific gravity, it is still a component that impairs stability and easily causes devitrification.

[0015] In glassmaking, there is a tendency to increase the content of components that improve the refractive index. The higher the refractive index, the greater the specific gravity tends to be.

[0016] The glass disclosed in Patent Document 3 has a relatively large specific gravity relative to its refractive index, therefore it cannot be said that the lightweighting of optical glass is sufficient. Furthermore, the glass disclosed in Patent Document 4 aims to: reduce the refractive index (n...) d When Y is set as Y and the specific gravity of the glass is set as X, Y≥0.175X+1.137 is satisfied, thus obtaining glass with a low specific gravity relative to the refractive index.

[0017] The present invention was made in view of the above-mentioned problems, and its object is to obtain a glass with a low specific gravity relative to its refractive index but high stability.

[0018] Solution for solving the problem

[0019] To address the aforementioned issues, the inventors conducted in-depth experimental research and discovered that by suppressing the contents of rare earth oxides, Nb₂O₅, WO₃, and Bi₂O₃, and adjusting the contents of TiO₂ and RO, and setting the specific gravity as d and the refractive index as n... d Let d ≤ 6.17 × n d The relationship of -7.694 is used to obtain a glass with low specific gravity but high stability relative to the refractive index, thus completing the present invention.

[0020] Specifically, the present invention provides the following invention.

[0021] (1) An optical glass, which, in terms of oxide-based mass percent

[0022] The Ln2O3 content is less than 10.0% (Ln is selected from one or more of the group consisting of La, Y, Gd, and Yb).

[0023] The mass ratio of TiO2 / RO is 0.5 or higher and 1.5 or lower (R is selected from one or more elements in the group consisting of Mg, Ca, Sr, and Ba).

[0024] The total mass of Nb₂O₅ + WO₃ + Bi₂O₃ is less than 18.0%.

[0025] The mass ratio of BaO / RO is above 0.30 and below 0.95.

[0026] Set the specific gravity to d and the refractive index to n. d hour,

[0027] Satisfying d≤6.17×n d The relationship is -7.694.

[0028] (2) The optical glass according to (1), wherein, in terms of mass % based on oxides,

[0029] The Nb2O5 content is 0-18.0%.

[0030] The WO3 content is 0-15.0%.

[0031] The La2O3 content ranges from 0% to 10.0%.

[0032] (3) The optical glass according to (1) or (2), wherein the total content of RO components is 20.0% or more.

[0033] (4) An optical element comprising any one of (1) to (3) optical glass.

[0034] The effects of the invention

[0035] According to the present invention, optical glass with low specific gravity relative to refractive index but high stability and optical elements can be provided. Attached Figure Description

[0036] Figure 1 It also describes the glass of the embodiments of this application, with a specific gravity of d and a refractive index of n. d The expression for time d≤6.17×n is given. d The formula relating -7.694, and the refractive index (n) described in Patent Document 4. d The graph shows the relationship between Y ≥ 0.175X + 1.137 when Y is set as Y and the specific gravity of glass is set as X (sometimes written as Y ≥ 0.175X + 1.137 below). Figure 1 The markings described are embodiments 11, 13, 19, and 22 of Japanese Patent Application Publication No. 2006-219365 (Patent Document 4).

[0037] Figure 2 The glass shown in the embodiment of this application has a specific gravity of d and a refractive index of n. d A diagram showing the relationship between time and space. Detailed Implementation

[0038] The embodiments of the optical glass of the present invention will be described in detail below. The present invention is not limited to any of the following embodiments, and suitable modifications can be made within the scope of the invention's objectives. It should be noted that sometimes repeated descriptions are appropriately omitted, but this is not intended to limit the scope of the invention.

[0039] [Glass Composition]

[0040] The composition range of each component constituting the optical glass of the present invention is described below. Unless otherwise stated in this specification, the content of each component is expressed as the mass percentage of the total oxide equivalent composition relative to the total mass of the glass. Here, "oxide equivalent composition" means: assuming that all oxides, complex salts, metal fluorides, etc., used as raw materials for the glass of the present invention decompose into oxides when melted, the total mass of the generated oxides is taken as 100% by mass and recorded as the composition of each component contained in the glass.

[0041] The SiO2 component is used to improve the devitrification resistance of glass by promoting the formation of stable glass through a content of 5.0% or more. In particular, by setting the SiO2 component content to 35.0% or less, the decrease in refractive index caused by the SiO2 component can be suppressed. Therefore, the SiO2 component content is preferably 35.0% or less, more preferably 33.0% or less, further preferably 30.0% or less, more preferably 28.0% or less, and most preferably 25.0% or less as an upper limit. On the other hand, the SiO2 component content is preferably 5.0% or more, more preferably 6.0% or more, further preferably 7.0% or more, and most preferably 8.0% or more as a lower limit.

[0042] TiO2 is an essential component of this invention, used to improve the refractive index and Abbe number of glass by setting its content to 21.0% or more. On the other hand, by setting the TiO2 content to 40.0% or less, devitrification caused by excessive content can be suppressed. Therefore, the TiO2 content is preferably 40.0% or less, more preferably 39.0% or less, and most preferably 38.0% or less as an upper limit. The TiO2 content is preferably 21.0% or more, more preferably 22.0% or more, further preferably 23.0% or more, more preferably 24.0% or more, and most preferably 25.0% or more as a lower limit.

[0043] The Nb₂O₅ component is any component that, when present in quantities exceeding 0%, increases the refractive index and Abbe number of the glass, and, when present together with the TiO₂ component, improves stability. Conversely, by keeping the Nb₂O₅ content at 18.0% or less, the specific gravity can be reduced and devitrification resistance improved. Therefore, the Nb₂O₅ content is preferably 18.0% or less, more preferably 15.0% or less, even more preferably 12.0% or less, even more preferably 11.0% or less, and most preferably 10.0% or less as an upper limit. On the other hand, from the viewpoint of improving stability, the Nb₂O₅ content is preferably 1.0% or more, more preferably 2.0% or more, further preferably 3.0% or more, even more preferably 4.0% or more, and most preferably 5.0% or more as a lower limit, but can be 0%.

[0044] WO3 and Bi2O3 components, when present in amounts exceeding 0%, increase the refractive index of glass. However, higher concentrations lead to coloration and increased specific gravity in the glass. Preferred ranges for WO3 and Bi2O3 components are described below.

[0045] The content of WO3 is preferably 15.0% or less, more preferably 10.0% or less, more preferably 5.0% or less, more preferably 3.0% or less, and most preferably 1.0% or less as the upper limit.

[0046] The content of Bi2O3 is preferably 3.0% or less, more preferably 1.0% or less, even more preferably 0.8% or less, even more preferably 0.5% or less, even more preferably 0.3% or less, and most preferably 0.1% or less as the upper limit.

[0047] B2O3 is a component that, when present in amounts exceeding 0%, promotes the formation of stable glass and improves devitrification resistance; it can be any component. In particular, by keeping the B2O3 content at 20.0% or less, the decrease in refractive index caused by B2O3 can be suppressed, thus easily obtaining a high refractive index. Therefore, the B2O3 content is preferably 20.0% or less, more preferably 17.0% or less, further preferably 15.0% or less, and most preferably 12.0% or less as an upper limit. On the other hand, the B2O3 content is preferably greater than 0%, more preferably 0.5% or more, further preferably 0.8% or more, and most preferably 1.0% or more as a lower limit, but can be 0%.

[0048] BaO is a component that, when present in amounts exceeding 0%, improves the stability of glass and enhances its workability during grinding / sharpening. In particular, by keeping the BaO content at 35.0% or less, the specific gravity can be reduced. Therefore, the BaO content is preferably 35.0% or less, more preferably 33.5% or less, and most preferably 32.0% or less as an upper limit. On the other hand, the BaO content is preferably 10.0% or more, more preferably 12.0% or more, further preferably 14.0% or more, and most preferably 15.0% or more as a lower limit.

[0049] CaO is a component that reduces specific gravity when its content exceeds 0%. In particular, by keeping the CaO content at 15.0% or less, devitrification resistance can be improved. Therefore, the CaO content is preferably 15.0% or less, more preferably 14.0% or less, and most preferably 13.0% or less as an upper limit. On the other hand, the CaO content is preferably 0.5% or more, more preferably 1.0% or more, further preferably 2.0% or more, and most preferably 3.0% or more as a lower limit, but can be 0%.

[0050] MgO and SrO components, when present in amounts exceeding 0%, improve the devitrification resistance of glass; however, higher concentrations make it difficult to maintain the refractive index and Abbe number. Preferred ranges for MgO and SrO components are described below.

[0051] The content of MgO is preferably 10.0% or less, more preferably 7.0% or less, further preferably 5.0% or less, and most preferably 3.0% or less as an upper limit, but can be 0%.

[0052] The content of SrO is preferably 10.0% or less, more preferably 7.0% or less, further preferably 5.0% or less, and most preferably 3.0% or less as an upper limit, but can be 0%.

[0053] La2O3, Y2O3, Gd2O3, and Yb2O3 components, when present in amounts exceeding 0%, increase the refractive index of the glass, reduce wear during grinding, and minimize the occurrence of cracks, breakage, and deterioration of profile regularity. However, higher concentrations impair stability and increase specific gravity. The preferred ranges for La2O3, Y2O3, Gd2O3, and Yb2O3 components are described below.

[0054] The content of La2O3 is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 5.0% or less, even more preferably 3.0% or less, and most preferably 1.0% or less as the upper limit.

[0055] The content of Y2O3 is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 5.0% or less, even more preferably 3.0% or less, and most preferably 1.0% or less as the upper limit.

[0056] The content of Gd2O3 is preferably 5.0% or less, more preferably 3.0% or less, even more preferably 2.0% or less, even more preferably 1.0% or less, and most preferably 0.5% or less as the upper limit.

[0057] The content of Yb2O3 is preferably 5.0% or less, more preferably 3.0% or less, even more preferably 2.0% or less, even more preferably 1.0% or less, and most preferably 0.5% or less as the upper limit.

[0058] ZrO2 is a component that promotes glass stability and improves devitrification resistance when its content exceeds 0%, and it can be any component. On the other hand, by keeping the ZrO2 content at 10.0% or less, glass processing by grinding / sharpening or the like becomes easier. Therefore, the ZrO2 content is preferably 10.0% or less, more preferably 9.0% or less, further preferably 8.0% or less, and most preferably 7.0% or less as an upper limit. On the other hand, the ZrO2 content is preferably 0.1% or more, more preferably 0.2% or more, further preferably 0.3% or more, but it can be 0%.

[0059] Li₂O, K₂O, and Na₂O components, when present in amounts exceeding 0%, lower the melting temperature of glass. However, higher concentrations impair stability and increase the glass's tendency to devitrify. Preferred ranges for Li₂O, K₂O, and Na₂O components are described below.

[0060] The content of Li2O is preferably 7.0% or less, more preferably 5.0% or less, further preferably 3.0% or less, and most preferably 1.0% or less as the upper limit.

[0061] The content of K2O is preferably 7.0% or less, more preferably 5.0% or less, further preferably 3.0% or less, and most preferably 1.0% or less as the upper limit.

[0062] The content of Na2O is preferably 10.0% or less, more preferably 8.0% or less, further preferably 6.0% or less, and most preferably 4.0% or less as an upper limit. On the other hand, the content of Na2O is preferably 0.1% or more, more preferably 0.3% or more, and most preferably 0.5% or more as a lower limit, but can be 0%.

[0063] The Al2O3 component, when present in amounts exceeding 0%, improves the chemical durability of glass while simultaneously increasing its viscosity during melting; it is any component. In particular, by keeping the Al2O3 content at 5.0% or less, it is possible to improve the glass's meltability while reducing its tendency to devitrify. Therefore, the Al2O3 content is preferably 5.0% or less, more preferably 3.0% or less, and most preferably 1.0% or less as an upper limit, but can be 0%.

[0064] The ZnO component is any component that lowers the liquidus temperature of the glass and improves its resistance to devitrification when present in amounts exceeding 0%. In particular, by keeping the ZnO content at 5.0% or less, high refractive index and low dispersion can be easily obtained. Therefore, the ZnO content is preferably 5.0% or less, more preferably 3.0% or less, and most preferably 1.0% or less as an upper limit, but can be 0%.

[0065] The Ta2O5 component is an arbitrary component that increases the refractive index and devitrification resistance of glass by including more than 0% of it. On the other hand, by keeping the Ta2O5 content at 5.0% or less, the amount of Ta2O5, a rare mineral resource, used is reduced, and the glass melts more easily at lower temperatures, thus reducing the production cost of the glass. Furthermore, this reduces devitrification of the glass caused by excessive Ta2O5 content. Therefore, the Ta2O5 content is preferably 5.0% or less, more preferably 3.0% or less, and even more preferably 1.0% or less as an upper limit, but can be 0%.

[0066] The content of P2O5 is preferably 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less as an upper limit, but can be 0%.

[0067] The content of component F is preferably 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, even more preferably 0.5% or less, even more preferably 0.3% or less as an upper limit, but can be 0%.

[0068] The content of TeO2 is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less as an upper limit, but can be 0%.

[0069] The content of GeO2 is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less as an upper limit, but can be 0%.

[0070] The content of CeO2 is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less as an upper limit, but can be 0%.

[0071] The content of Er2O3 and Pr2O3 is preferably 1.0% or less, more preferably 0.5% or less, more preferably 0.1% or less, and most preferably substantially non-existent.

[0072] The content of SnO2 is preferably 2.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less as an upper limit, but can be 0%.

[0073] Sb₂O₃ is an ingredient that promotes clarity and defoaming during glass melting, and can be any component. Here, by keeping the Sb₂O₃ content at 0.1% or less, coloration in high-refractive-index glasses can be particularly suppressed. Furthermore, by setting it to 0.1% or less, excessive foaming during glass melting becomes less likely, thus preventing the Sb₂O₃ from alloying with melting equipment (especially precious metals such as Pt). Therefore, the Sb₂O₃ content is preferably 0.1% or less, more preferably 0.08% or less, and even more preferably 0.05% or less as an upper limit, but can be 0%.

[0074] It should be noted that the components used to clarify and defoam the glass are not limited to the Sb2O3 component mentioned above; clarifiers, defoamers, or combinations thereof known in the glass manufacturing industry can be used.

[0075] By setting the total content (total mass) of Ln2O3 components (where Ln is one or more selected from the group consisting of La, Y, Gd, and Yb) to 10.0% or less, devitrification caused by excessive content is suppressed, and the specific gravity is reduced. Therefore, it is preferable to set the content to 10.0% or less, more preferably 9.0% or less, even more preferably 6.0% or less, even more preferably 4.0% or less, and even more preferably 2.0% or less as an upper limit.

[0076] By setting the total content of Rn2O components (where Rn is one or more selected from the group consisting of Li, Na, and K) to 10.0% or less, the deterioration of reheat pressing moldability can be suppressed. Therefore, the total content of Rn2O components is preferably 10.0% or less, more preferably 9.0% or less, and most preferably 8.0% or less as an upper limit. On the other hand, in order to achieve good meltability, the total content of Rn2O components is preferably 0.5% or more, more preferably 0.8% or more, and even more preferably 1.0% or more as a lower limit, but it can be 0%.

[0077] When the total content of RO components (where R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) exceeds 0%, the stability of the glass can be improved. In particular, the RO components have the effect of suppressing devitrification caused by TiO2 components. The total content of RO components is preferably 20.0% or more, more preferably 21.5% or more, further preferably 23.0% or more, and most preferably 25.0% or more. On the other hand, in order to suppress the decrease in refractive index, the total content of RO components is preferably 40.0% or less, more preferably 39.0% or less, more preferably 38.0% or less, further preferably 37.0% or less, and most preferably 36.0% or less as an upper limit.

[0078] By setting the mass ratio of TiO2 to RO (TiO2 component) to be 0.50 or higher and 1.50 or lower, it is possible to produce glass with high stability and reduced devitrification caused by TiO2. Producing glass with high stability is beneficial for improving mass production. Therefore, a mass ratio of TiO2 / RO of 0.50 or higher is preferred, more preferably 0.55 or higher, further preferably 0.60 or higher, even more preferably 0.65 or higher, and most preferably 0.70 or higher as a lower limit. On the other hand, a mass ratio of TiO2 / RO of 1.50 or lower is preferred, more preferably 1.45 or lower, even more preferably 1.40 or lower, even more preferably 1.35 or lower, and most preferably 1.30 or lower as an upper limit.

[0079] By setting the total mass of Nb2O5, WO3, and Bi2O3 (Nb2O5+WO3+Bi2O3) to 18.0% or less, the increase in specific gravity can be suppressed. Since the components contributing to high refractive index have a higher specific gravity than other components, suppressing the content of Nb2O5, WO3, and Bi2O3, which contribute to high refractive index, can suppress the increase in specific gravity, thus contributing to the miniaturization and weight reduction of optical devices. Therefore, the total mass of Nb2O5+WO3+Bi2O3 is preferably 18.0% or less, more preferably 15.0% or less, more preferably 13.0% or less, even more preferably 11.0% or less, and even more preferably 10.0% or less as an upper limit. On the other hand, from the viewpoint of improving refractive index and dispersion, the total mass of Nb2O5+WO3+Bi2O3 can be 1.0% or more. Therefore, the total mass of Nb2O5+WO3+Bi2O3 can preferably be 1.0% or more, 2.0% or more, 3.0% or more, 4.0% or more, 5.0% or more, or 6.0% or more.

[0080] By setting the mass ratio of BaO to RO (BaO / RO) to be 0.30 or higher and 0.95 or lower, glass with high stability can be obtained. In particular, BaO is the component in the RO composition that best improves stability. Furthermore, it prevents cracking / breakage and deterioration of contour uniformity during processing such as grinding. Therefore, a mass ratio of BaO / RO of 0.30 or higher is preferred, more preferably 0.40 or higher, even more preferably 0.50 or higher, and even more preferably 0.55 or higher as a lower limit. On the other hand, a mass ratio of BaO / RO of 0.95 or lower is preferred, more preferably 0.93 or lower, and even more preferably 0.90 or lower as an upper limit.

[0081] By setting the mass ratio Nb2O5 / TiO2, which is the ratio of Nb2O5 to TiO2, to 0.50 or less, the refractive index is increased and the specific gravity is reduced. The mass ratio Nb2O5 / TiO2 is preferably 0.50 or less, more preferably 0.48 or less, further preferably 0.45 or less, even more preferably 0.42 or less, and most preferably 0.40 or less as an upper limit. On the other hand, from the viewpoint of obtaining glass with high stability and suppressed devitrification caused by TiO2, the mass ratio Nb2O5 / TiO2 can be 0.05 or more. Therefore, the mass ratio Nb2O5 / TiO2 is preferably 0.05 or more, more preferably 0.08 or more, further preferably 0.10 or more, and most preferably 0.13 or more as a lower limit.

[0082] Setting the mass ratio ZrO2 / (TiO2+Nb2O5), which is the ratio of ZrO2 content to the total content of TiO2 and Nb2O5, to 0.25 or less is effective in improving devitrification resistance. Excessive ZrO2 content relative to the total content of TiO2 and Nb2O5 becomes a cause of devitrification. The mass ratio ZrO2 / (TiO2+Nb2O5) is preferably 0.25 or less, more preferably 0.20 or less, and even more preferably 0.19 or less as an upper limit.

[0083] The mass ratio (Nb2O5+WO3) / (TiO2+Nb2O5+WO3), which represents the total content of Nb2O5 and WO3 relative to the total content of TiO2, Nb2O5, and WO3, is preferably 0.50 or less to suppress the increase in the proportion caused by Nb2O5 and WO3. The mass ratio (Nb2O5+WO3) / (TiO2+Nb2O5+WO3) is preferably 0.50 or less, more preferably 0.40 or less, further preferably 0.30 or less, and even more preferably 0.28 or less. On the other hand, from the viewpoint of improving refractive index and dispersion, the mass ratio (Nb2O5+WO3) / (TiO2+Nb2O5+WO3) can be 0.05 or more. The mass ratio (Nb2O5+WO3) / (TiO2+Nb2O5+WO3) is preferably 0.05 or more, more preferably 0.07 or more, even more preferably 0.08 or more, and even more preferably 0.10 or more as a lower limit.

[0084] <Regarding ingredients that should not be present>

[0085] Next, the components that should not be contained in the optical glass of the present invention, and the components that are not preferably contained therein, will be explained.

[0086] Other components may be added as needed without impairing the properties of the glass of this invention. Among them, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, various transition metal components such as Nd, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, when contained individually in small amounts or in combination in small amounts, also have the property of coloring the glass and exhibiting absorption at specific wavelengths in the visible region. Therefore, it is particularly preferable to exclude them substantially, especially in optical glass using specific wavelengths in the visible region.

[0087] In addition, lead compounds such as PbO and arsenic compounds such as As2O3 are components with high environmental impact, so it is desirable to be substantially free of them, that is, completely free of them except for unavoidable contamination.

[0088] Furthermore, the use of various components such as Th, Cd, Tl, Os, Be, and Se has become increasingly restricted in recent years due to their status as hazardous chemicals. Environmental measures are needed not only in the glass manufacturing process but also in processing and post-product disposal. Therefore, given the importance of environmental impact, it is preferable to avoid products that substantially do not contain these elements.

[0089] [physical properties]

[0090] The refractive index (n) of the optical glass of this invention dThe preferred values ​​are, in descending order: 1.80500 and above, 1.81000 and above, 1.82000 and above, 1.83000 and above, 1.84000 and above, 1.85000 and above, 1.86000 and above, 1.87000 and above, 1.88000 and above, 1.89000 and above, and 1.90000 and above. On the other hand, this refractive index (n...) d The Abbe number (ν) can be less than 2.00000, less than 1.99000, less than 1.98000, less than 1.97000, or less than 1.96000. The Abbe number (ν) of this invention... d The preferred values ​​are, in order, 17.00 or higher, 18.00 or higher, 19.00 or higher, 20.00 or higher, and 21.00 or higher. On the other hand, this Abbe number (ν) d The preferred values ​​are below 30.00, below 28.00, below 27.00, and below 26.00, in that order.

[0091] The specific gravity (d) of the optical glass of the present invention is preferably 4.43 or less, 4.30 or less, 4.20 or less, 4.10 or less, and 4.05 or less, respectively.

[0092] In addition to the above, the specific gravity (d) of the optical glass of the present invention is preferably relative to the refractive index (n). d The condition d ≤ 6.17 × n is satisfied. d The relationship is -7.694. In glass manufacturing, the component that increases the refractive index has a higher proportion than other components. Therefore, there is a tendency to increase the content of the component that increases the refractive index, and the higher the refractive index, the greater the proportion. The inventors discovered that by satisfying d ≤ 6.17 × n... d The relationship of -7.694, thus reducing the specific gravity relative to the refractive index, becomes useful in optical design. Specific gravity (d) relative to refractive index (n) d Ideally, the condition d ≤ 6.17 × n should be satisfied. d The relationship is -7.694, and more preferably, d ≤ 6.17 × n. d The relationship is -7.800; further optimization satisfies d ≤ 6.17 × n. d -7.914.

[0093] like Figure 1 As shown, it is confirmed that, compared to Y≥0.175X+1.137 as described in Patent Document 4, by making the present invention satisfy d≤6.17×n d The relationship -7.694 is a formula representing glass with a low specific gravity relative to its refractive index.

[0094] [Manufacturing Method]

[0095] The optical glass of the present invention can be manufactured, for example, as follows: The above-mentioned raw materials are uniformly mixed in such a way that each component is within a specified content range. The resulting mixture is placed in a platinum crucible and melted in an electric furnace at a temperature range of 1100 to 1500°C for 2 to 5 hours, depending on the melting difficulty of the glass raw materials. After stirring and homogenizing, the mixture is lowered to a suitable temperature and then cast into a mold. It is then slowly cooled to produce the glass.

[0096] [Glass forming]

[0097] The glass of the present invention can be melted and formed using known methods. It should be noted that the apparatus for forming the molten glass is not limited.

[0098] [Optical Components]

[0099] Optical glass can be molded into glass bodies using, for example, grinding equipment or molding equipment such as hot pressing or precision stamping. In other words, glass bodies can be manufactured by machining optical glass, such as grinding and polishing. It should be noted that the equipment used to manufacture glass bodies is not limited to these specific methods.

[0100] Thus, the optical glass of the present invention is useful for various optical elements and optical designs. In particular, it is preferred for manufacturing optical elements such as lenses and prisms. As a result, in addition to the lightweighting of optical elements, it enables high-precision and high-resolution imaging and projection characteristics when used in optical devices such as cameras and projectors.

[0101] Example

[0102] The composition of the glass of the present invention in the embodiments and comparative examples, and the refractive index (n) of these glasses are described. d Abbe number (ν) d ), specific gravity (d), and 6.17×n d -7.694, 6.17×n d -7.800, 6.17×n d The value of -7.914 is shown in Tables 1 and 2. Comparative Example B is Example 13 of WO2018 / 235725.

[0103] For the glass of the embodiments and comparative examples of the present invention, each component is made from high-purity raw materials commonly used in optical glass, such as oxides, hydroxides, carbonates, nitrates, fluorides, and metaphosphates. These raw materials are weighed in the manner shown in the table for each embodiment, mixed uniformly, and then placed into a platinum crucible. Depending on the ease of melting the glass raw materials, the mixture is melted in an electric furnace at a temperature range of 1100 to 1400°C for 2 to 5 hours. After stirring and homogenizing, the mixture is cast into a mold or the like and slowly cooled to produce the glass.

[0104] The refractive index (n) of the glass in the examples and comparative examples d Abbe number (ν) d The refractive index (n) was determined according to the V-block method specified in JIS B 7071-2:2018. Here, the refractive index (n) is... d The value is expressed as a measurement of the d-line (587.56 nm) relative to the helium lamp. Additionally, the Abbe number (ν) is... d ), using the refractive index (n) relative to the d-line of the helium lamp. d ), and the refractive index (n) relative to the F line (486.13 nm) of the hydrogen lamp. F ), refractive index (n) relative to the C line (656.27 nm) C The value of ) is determined by the Abbe number (ν). d )=[(n d -1) / (n F -n C These refractive indices (n) are calculated using the formula. d Abbe number (ν) d The value was determined by measuring glass obtained by slow cooling at a rate of -25°C / hour.

[0105] The specific gravity in the glass in the embodiment was determined based on the method of determining density and specific gravity by weighing in liquids according to JIS Z8807:2012.

[0106] [Table 1]

[0107]

[0108] [Table 2]

[0109]

[0110] As shown in the table, the glass used in the embodiments of the present invention has a refractive index (n). d The refractive index (n) is above 1.80500, more specifically above 1.85000, and the refractive index (n) is also above 1.80500. d A value below 2.00000, or more specifically below 1.97000, is within the expected range.

[0111] For the glass used in the embodiments of the present invention, the Abbe number (ν) is... d The value is 17.00 or higher, more specifically 21.00 or higher, and the Abbe number (ν) is also... d A price below 30.00, or more specifically below 26.00, is within the expected range.

[0112] The glasses in the embodiments of the present invention are all highly stable and do not exhibit devitrification. On the other hand, Comparative Example A, with a TiO2 / RO mass ratio exceeding 1.50, exhibits devitrification and fails to achieve vitrification.

[0113] The glass in all embodiments of the present invention satisfies d ≤ 6.17 × n. d The relationship is -7.694, or more specifically, it satisfies d ≤ 6.17 × n. d -7.800. On the other hand, such as Figure 1 As shown, the glass of Examples 11, 13, 19, and 22 of Japanese Patent Application Publication No. 2006-219365, such as... Figure 2 The glass in Comparative Example B does not satisfy d ≤ 6.17 × n d The relationship of -7.694 is poor from the perspective of product weight reduction.

[0114] Therefore, it has been confirmed that the optical glass of the embodiments of the present invention is a glass with a low refractive index and high stability.

[0115] The present invention has been described in detail above for illustrative purposes. However, it should be understood that this embodiment is merely for illustrative purposes, and those skilled in the art can make various modifications without departing from the spirit and scope of the present invention.

Claims

1. An optical glass, wherein, based on oxides by mass%, The total content of Ln2O3 components is less than 2.0%, of which, Ln is selected from one or more elements in the group consisting of La, Y, Gd, and Yb. The ZrO2 content is below 7.0%. The total content of RO components is 23.0% to 40.0%, wherein R is selected from one or more components chosen from the group consisting of Mg, Ca, Sr, and Ba. The mass ratio of TiO2 / RO is above 0.5 and below 1.

5. The total mass of Nb₂O₅ + WO₃ + Bi₂O₃ is above 3.0% and below 18.0%. The mass ratio of BaO / RO is above 0.60 and below 0.

95. Set the specific gravity to d and the refractive index to n. d hour, Satisfying d≤6.17×n d The relationship is -7.

694.

2. The optical glass according to claim 1, wherein, based on oxides by mass%, The Nb2O5 content is 0-18.0%. The WO3 content is 0-15.0%. The La2O3 content ranges from 0% to 10.0%.

3. An optical element comprising the optical glass of claim 1 or 2.

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