Optical glass, optical elements, and optical instruments

Abstract

To provide an optical glass with excellent devitrification resistance, a high refractive index, and a low relative partial dispersion.SOLUTION: An optical glass includes the following components in molar percentage. SiO2: 25%-40%, B2O3: 1%-8%, La2O3: 1%-8%, BaO: 1%-6%, CaO: 5%-25%, Nb2O5: 5%-15%, TiO2: 8%-20%, and Li2O: 1.5%-15%. The optical glass offers excellent devitrification resistance due to appropriate amounts of components such as SiO2 and alkali metal oxide contained therein. The optical glass exhibits a high refractive index due to high refractive index components such as Nb2O5 and TiO2 contained therein. The optical glass achieves a low relative partial dispersion due to the reasonable design of the composition thereof.SELECTED DRAWING: None

Description

[Technical Field] 【0001】 The present invention relates to optical glass, and more particularly to optical glass that has excellent resistance to devitrification, a high refractive index, and low relative partial dispersion. [Background technology] 【0002】 In long focal length, wide field of view, and high-precision optical systems, secondary spectra are a major factor affecting image quality, and correcting secondary spectra is a prominent and difficult problem in the design of long focal length optical systems. Correcting secondary spectra in optical systems depends heavily on the selection of glass materials, which have high refractive indices and relative partial dispersion (P g,F Glass with a low ) is advantageous for removing secondary spectra when applied to coupling lenses, simplifying and optimizing the optical system and improving image quality. 【0003】 Secondary pressing of optical glass has advantages such as low production costs, low difficulty of production, and ease of mass production, and is widely used in the manufacture of glass elements. Secondary press molding is a production method in which glass material is placed in a mold, heated above its softening point, and then pressed into a predetermined shape by pressure. Secondary press molding of optical glass often requires heating the glass to 100-200°C above its transition temperature. At this point, the glass already has a certain degree of fluidity, and if the devitrification resistance of the glass is not good, there is a risk that the glass will devitrify and be discarded during the secondary press molding process. Chinese patent CN104583142A discloses optical glass with low relative partial dispersion, and its composition contains 5.0% to 55.0% by mass of B2O3 and 15% to 60% by mass of rare earth oxides. This optical glass has poor devitrification resistance, and the glass is at a relatively high risk of devitrification during secondary press molding. [Overview of the project] [Problems that the invention aims to solve] 【0004】 The problem that this invention aims to solve is to provide an optical glass that has excellent resistance to devitrification, a high refractive index, and low relative partial dispersion. [Means for solving the problem] 【0005】 The means to solve the problem is an optical glass whose composition, when expressed as a mole percentage, contains SiO2: 25%~40%, B2O3: 1%~8%, La2O3: 1%~8%, BaO: 1%~6%, CaO: 5%~25%, Nb2O5: 5%~15%, TiO2: 8%~20%, and Li2O: 1.5%~15%. 【0006】 Furthermore, the optical glass further contains, when its composition is expressed as a mole percentage, Al2O3: 0-5%, and / or Gd2O3: 0-8%, and / or Y2O3: 0-8%, and / or SrO: 0-15%, and / or MgO: 0-10%, and / or ZnO: 0-8%, and / or ZrO2: 0-5%, and / or WO3: 0-5%, and / or Bi2O3: 0-5%, and / or Ta2O5: 0-5%, and / or Na2O: 0-10%, and / or K2O: 0-10%, and / or Sb2O3: 0-1%. 【0007】 The optical glass, when its composition is expressed as a mole percentage, consists of SiO2: 25%~40%, B2O3: 1%~8%, La2O3: 1%~8%, BaO: 1%~6%, CaO: 5%~25%, Nb2O5: 5%~15%, TiO2: 8%~20%, Li2O: 1.5%~15%, Al2O3: 0~5%, Gd2O3: 0~8%, Y2O3: 0~8%, SrO: 0~15%, MgO: 0~10%, ZnO: 0~8%, ZrO2: 0~5%, WO3: 0~5%, Bi2O3: 0~5%, Ta2O5: 0~5%, Na2O: 0~10%, K2O: 0~10%, and Sb2O3: 0~1%. 【0008】 Furthermore, the optical glass, when its composition is expressed as a mole percentage, preferably has 27% to 45% SiO2 + B2O3, more preferably 28% to 43%, more preferably 30% to 41%, and / or 25% to 44% SiO2 + ZrO2, more preferably 27% to 42%, more preferably 29% to 40%, and / or 10% to 40% RO, more preferably 12% to 38%, more preferably 15% to 35%, and / or 1% to 20% Re2O3. The ratio of RO is 1.2% to 18%, more preferably 1.5% to 15%, and / or B2O3 + La2O3 is 2% to 14%, preferably 3% to 13%, more preferably 4% to 12%, and / or B2O3 + Al2O3 is 1% to 12%, preferably 2% to 11%, and more preferably 3% to 10%, where RO is the total content of BaO, SrO, CaO, and MgO, and Re2O3 is the total content of La2O3, Gd2O3, and Y2O3. 【0009】 Furthermore, if the composition of the optical glass is expressed as a mole percentage, 1) When the SiO2 / B2O3 ratio is 3.5 to 38.0, preferably 3.8 to 35.0, and more preferably 4.0 to 30.0, 2) When (SiO2 + ZrO2) / (B2O3 + Li2O) is 1.8 to 15.0, preferably (SiO2 + ZrO2) / (B2O3 + Li2O) is 1.9 to 12.0, and more preferably (SiO2 + ZrO2) / (B2O3 + Li2O) is 2.0 to 10.0, 3) When (Nb2O5 + TiO2 + WO3 + Bi2O3 + Ta2O5) / (SiO2 + B2O3) is 0.3 to 1.8, preferably (Nb2O5 + TiO2 + WO3 + Bi2O3 + Ta2O5) / (SiO2 + B2O3) is 0.4 to 1.6, and more preferably (Nb2O5 + TiO2 + WO3 + Bi2O3 + Ta2O5) / (SiO2 + B2O3) is 0.5 to 1.4, 4) When TiO2 / (Nb2O5 + La2O3) is 0.35 to 3.2, preferably TiO2 / (Nb2O5 + La2O3) is 0.4 to 3, and more preferably TiO2 / (Nb2O5 + La2O3) is 0.5 to 2.8, 5) When CaO / RO is 0.25 to 0.95, preferably CaO / RO is 0.3 to 0.8, and more preferably CaO / RO is 0.4 to 0.7, 6) When BaO / RO is 0.03 to 0.5, preferably BaO / RO is 0.04 to 0.4, and more preferably BaO / RO is 0.05 to 0.3, where RO is the total content of BaO, SrO, CaO, and MgO, satisfying one or more of the six cases. 【0010】 Furthermore, when the composition of the optical glass is expressed in mole percentage, it is SiO2: 27% to 38%, preferably SiO2: 29% to 36%, and / or B2O3: 2% to 7%, preferably B2O3: 3% to 6%, and / or La2O3: 2% to 7%, preferably La2O3: 3% to 6%, and / or BaO: 1.5% to 5%, preferably BaO: 2% to 4%, and / or CaO: 7% to 22%, preferably CaO: 9% to 20%, and / or Nb2O5: 6% to 14%, preferably Nb2O5: 7% to 13%, and / or TiO2: 9% to 19%, preferably TiO2: 10% to 18%, and / or Li2O: 2% to 13%, preferably Li2O: 3% to 11%, and / or Al2O3: 0 to 3%, and / or Gd2O3: 0 to 6%, preferably Gd2O3: 0 to 4%, and / or Y2O3: 0 to 6%, preferably Y2O3: 0 to 4%, and / or SrO: 1% to 14%, preferably SrO: 2% to 12%, and / or MgO: 0 to 8%, preferably MgO: 0 to 5%, and / or ZnO: 0 to 6%, preferably ZnO: 0 to 4%, and / or ZrO2: 0 to 4%, preferably ZrO2: 0 to 3%, and / or WO3: 0 to 2%, and / or Bi2O3: 0 to 2%, and / or Ta2O5: 0 to 2%, and / or Na2O: 0 to 8%, preferably Na2O: 0 to 6%, and / or K2O: 0 to 8%, preferably K2O: 0 to 6%, and / or Sb2O3: 0 to 0.5%, preferably Sb2O3: 0 to 0.2%. 【0011】 Furthermore, the optical glass does not contain Al2O3, and / or does not contain WO3, and / or does not contain Bi2O3, and / or does not contain Ta2O5. 【0012】 Furthermore, the refractive index (n d ) of the optical glass is 1.87 to 1.93, preferably the refractive index (n d ) is 1.88 to 1.92, more preferably the refractive index (n d ) is 1.89 to 1.91, and the Abbe number (ν d ) is 24 to 30, preferably the Abbe number (ν d ) is 25 to 29, more preferably the Abbe number (ν d) is 26 to 28. 【0013】 Furthermore, the relative partial dispersion (P g,F ) is ≦ 0.6090, preferably the relative partial dispersion (P g,F ) is ≦ 0.6085, more preferably the relative partial dispersion (P g,F ) is ≦ 0.6080, and / or the internal transmittance (τ 400 ) is 0.68 or more, preferably the internal transmittance (τ 400 ) is 0.70 or more, more preferably the internal transmittance (τ 400 ) is 0.72 or more, and / or the weather resistance (CR) is class 2 or more, preferably the weather resistance (CR) is class 1, and / or the acid resistance stability is class 2 or more, preferably the acid resistance stability is class 1, and / or the density is 3.95 g / cm 3 or less, preferably the density is 3.90 g / cm 3 or less, more preferably the density is 3.85 g / cm 3 or less. 【0014】 A glass preform made by adopting the optical glass. 【0015】 An optical element made by adopting the optical glass or the glass preform. 【0016】 An optical device containing the optical glass and / or containing the optical element. 【Advantages of the Invention】 【0017】 The beneficial effects of the present invention are as follows. By containing appropriate amounts of components such as SiO2 and alkali metal oxides, the optical glass has excellent devitrification resistance. By containing components with high refractive indices such as Nb2O5 and TiO2, the optical glass has a high refractive index. Through a reasonable composition design, the glass has a low relative partial dispersion. 【Modes for Carrying Out the Invention】 【0018】 The embodiments of the optical glass of the present invention will be described in detail below, but the present invention is not limited to the embodiments described below and can be modified as appropriate within the scope of the object of the present invention. In addition, redundant explanations may be omitted as appropriate, but this does not limit the spirit of the invention. Hereinafter, the optical glass of the present invention may be simply referred to as glass. 【0019】 I. Optical Glass The following describes the range of each composition (component) of the optical glass of the present invention. In the present invention, unless otherwise specified, the content of each composition and the total content are all expressed in mole percentage (mol%), that is, as the mole percentage of the content of each composition and the total content relative to the total amount of glass material in terms of oxide composition. Here, the "oxide-equivalent composition" refers to the case where oxides, composite salts, hydroxides, etc., used as raw materials for the composition components of the optical glass of the present invention decompose into oxides during melting, and the total molar amount of said oxide is set to 100%. 【0020】 The numerical ranges described in this invention include upper and lower limits unless otherwise specified in particular cases. "Greater than or equal to" and "less than or equal to" include endpoint values ​​and all integers and fractions within this range, and are not limited to the specific values ​​stated when the range is limited. "And / or" as used herein is inclusive; for example, "A and / or B" means A only, or B only, or both A and B. 【0021】 <Required and Optional Ingredients> SiO2 is a glass network component and has the effect of improving the devitrification resistance of glass. If the SiO2 content is less than 25%, it is difficult to achieve the above effect. Therefore, the lower limit of the SiO2 content is 25%, preferably 27%, and more preferably 29%. If the SiO2 content exceeds 40%, the glass becomes difficult to melt, and it becomes difficult to obtain the desired refractive index of the present invention. Therefore, the upper limit of the SiO2 content is 40%, preferably 38%, and more preferably 36%. 【0022】 B2O3 can reduce the difficulty of melting glass and lower its high-temperature viscosity and transition temperature. Most importantly, in this invention, the devitrification resistance of glass can be significantly improved by including a small amount of B2O3. However, in this invention, if the B2O3 content is too high, it will lead to a decrease in the chemical stability of the glass, particularly a decrease in its acid resistance. Therefore, in this invention, the B2O3 content is 1% to 8%, preferably 2% to 7%, and more preferably 3% to 6%. 【0023】 In this invention, both SiO2 and B2O3 function as a glass network. If the total content of SiO2 and B2O3 (SiO2+B2O3) is too high, it becomes difficult to achieve high refractive index properties, and if it is too low, the resistance to devitrification deteriorates. Therefore, preferably, the SiO2+B2O3 content is 27% to 45%, more preferably 28% to 43%, and even more preferably 30% to 41%. 【0024】 In some embodiments of the present invention, controlling the ratio of SiO2 to B2O3, SiO2 / B2O3, within the range of 3.5 to 38.0 is advantageous for the glass to obtain excellent chemical stability and devitrification resistance. Therefore, preferably SiO2 / B2O3 is 3.5 to 38.0, more preferably SiO2 / B2O3 is 3.8 to 35.0, and even more preferably SiO2 / B2O3 is 4.0 to 30.0. 【0025】 Al2O3 can improve the weather resistance of glass, but it also increases the melting temperature and high-temperature viscosity of the glass, increasing the difficulty of production. When the Al2O3 content exceeds 5%, the glass tends to become less meltable and its devitrification resistance decreases. Therefore, in this invention, the Al2O3 content is 0-5%, preferably 0-3%, and more preferably Al2O3-free. 【0026】 In some embodiments of the present invention, controlling the total content of B2O3 and Al2O3, B2O3+Al2O3, within the range of 1% to 12% is advantageous for maintaining the relative partial dispersion of the glass within the design range. Therefore, preferably B2O3+Al2O3 is 1% to 12%, more preferably B2O3+Al2O3 is 2% to 11%, and even more preferably B2O3+Al2O3 is 3% to 10%. 【0027】 La2O3 is a high-refractive index, low-dispersion component that can significantly reduce the relative partial dispersion of glass. However, if its content is too high, the acid resistance of the glass deteriorates. Therefore, the La2O3 content of the present invention is 1% to 8%, preferably 2% to 7%, and more preferably 3% to 6%. 【0028】 Since B2O3 and La2O3 severely corrode the glass melting furnace during production, limiting the total amount of B2O3 and La2O3 can extend the lifespan of the glass melting furnace, reduce the difficulty of glass production, and improve the quality of the glass. At the same time, our research has shown that B2O3 and La2O3 have a significant impact on the acid resistance of the glass of the present invention, and that too much content affects the acid resistance of the glass. Therefore, preferably, the amount of B2O3 + La2O3 is 2% to 14%, more preferably 3% to 13%, and even more preferably 4% to 12%. 【0029】 Gd2O3 is a high-refractive index, low-dispersion component that can play a role in reducing the relative partial dispersion of glass; however, its high raw material cost limits its use in glass. Therefore, the Gd2O3 content is 0-8%, preferably 0-6%, and more preferably 0-4%. 【0030】 Y2O3 can improve the meltability and weather resistance of glass, but if its content is too high, it reduces the glass's devitrification resistance. Therefore, the Y2O3 content is 0-8%, preferably 0-6%, and more preferably 0-4%. 【0031】 La2O3, Gd2O3, and Y2O3 can play a role in improving the refractive index and reducing relative partial dispersion in glass. However, if the content is too low, it becomes difficult to achieve the desired high refractive index and low dispersion optical properties of the present invention, and if the content is too high, the devitrification resistance of the glass deteriorates. Therefore, in the present invention, the total content of La2O3, Gd2O3, and Y2O3, specifically Re2O3, is preferably 1% to 20%, more preferably 1.2% to 18%, and even more preferably 1.5% to 15%. 【0032】 BaO is inexpensive and readily available, and can effectively improve the refractive index of glass. However, BaO is detrimental to reducing the density of glass, and if the BaO content is too high, the weather resistance of the glass deteriorates. Therefore, the BaO content is limited to 1% to 6%, preferably 1.5% to 5%, and more preferably 2% to 4%. 【0033】 An appropriate amount of SrO can improve the weather resistance of glass and reduce its density, but since SrO is expensive, too much of it will increase the cost of the glass. Therefore, the SrO content is limited to 0-15%, preferably 1-14%, and more preferably 2-12%. 【0034】 CaO can improve the hardness, mechanical strength, and weather resistance of glass. More importantly, compared to BaO and SrO, CaO is more advantageous in reducing the density of glass, and CaO is also advantageous in controlling and adjusting optical constants during production. However, if the CaO content is too high, the glass becomes difficult to melt, and a hard, calcium-enriched shell tends to form in the melt pool during the production process. Therefore, the CaO content is limited to 5% to 25%, preferably 7% to 22%, and more preferably 9% to 20%. 【0035】 While MgO helps improve the weather resistance of glass, too much MgO makes it difficult for the glass's refractive index to meet design requirements, reduces its resistance to devitrification and stability, and simultaneously causes a rapid increase in the glass's cost. Therefore, the MgO content is limited to 0-10%, preferably 0-8%, and more preferably 0-5%. 【0036】 BaO, SrO, CaO, and MgO all belong to the alkaline earth metal oxide group. However, in this invention, in order to obtain excellent devitrification resistance and mechanical strength, the total content RO of the alkaline earth metal oxides BaO, SrO, CaO, and MgO is preferably 10% to 40%, more preferably 12% to 38%, and even more preferably 15% to 35%. 【0037】 The present invention reduces the density of glass and improves its properties, such as crystallization stability, by controlling the relative content of each component of alkaline earth metal oxides. In some embodiments, controlling the ratio of CaO to RO (CaO / RO) to within the range of 0.25 to 0.95 can reduce the density of glass, improve its acid resistance, and enhance its devitrification resistance. Therefore, preferably, CaO / RO is 0.25 to 0.95, more preferably 0.3 to 0.8, and even more preferably 0.4 to 0.7. In some embodiments, controlling the ratio of BaO to RO (BaO / RO) to within the range of 0.03 to 0.5 is advantageous for improving the devitrification resistance of glass. Therefore, preferably, BaO / RO is 0.03 to 0.5, more preferably 0.04 to 0.4, and even more preferably 0.05 to 0.3. 【0038】 ZnO can improve the acid resistance and stability of glass, enhance its weather resistance, and lower its transition temperature. However, if its content is too high, it increases the erosion of platinum equipment during melting and reduces the service life of the melting furnace. Therefore, the ZnO content in the glass of the present invention is 0-8%, preferably 0-6%, and more preferably 0-4%. 【0039】 ZrO2 improves the weather resistance and devitrification resistance of glass, and at the same time, it can significantly reduce the relative partial dispersion of glass within the glass. However, ZrO2 does not have high solubility in this glass system, and if the content is too high, it tends to be released outside the glass system, forming crystallization nuclei and further worsening the devitrification resistance of the glass. Therefore, in this invention, the ZrO2 content is 0 to 5%, preferably 0 to 4%, and more preferably 0 to 3%. 【0040】 Both SiO2 and ZrO2 can improve the acid resistance of glass, and at the same time, SiO2 and ZrO2 are two components that are relatively difficult to melt in this invention. Through numerous experimental studies by the inventors, it has been found that in some embodiments, by controlling the total content of SiO2 and ZrO2 (SiO2 + ZrO2) to within the range of 25% to 44%, the glass can not only obtain excellent acid resistance but also good production performance. Therefore, preferably, SiO2 + ZrO2 is 25% to 44%, more preferably SiO2 + ZrO2 is 27% to 42%, and even more preferably SiO2 + ZrO2 is 29% to 40%. 【0041】 Nb2O5 is an essential component of the glass of this invention and is a crucial component that guarantees the glass's high refractive index, low dispersion, low density, and low relative partial dispersion properties. Through the inventors' intensive research, it has been found that when the Abbe number is in the range of 24 to 30, the contribution of Nb2O5 to the relative partial dispersion of the glass and to the Abbe number are almost identical, that is, as the amount of Nb2O5 in the glass increases, the relative partial dispersion deviation (ΔP) of the glass increases. g,F It was found that the ) remains essentially unchanged. Therefore, in the present invention, the Nb2O5 content is 5% to 15%, preferably 6% to 14%, and more preferably 7% to 13%. 【0042】 TiO2 can improve the refractive index and dispersion of glass and improve the devitrification resistance of glass, but TiO2 in glass contains P g,F It causes a rapid increase. When the TiO2 content in the glass exceeds 20%, the P content of the glass increases. g,F The properties make it difficult to meet the design requirements, and if the TiO2 content in the glass is less than 8%, the high refractive index properties of the glass are difficult to meet the design requirements. Therefore, the TiO2 content is 8% to 20%, preferably 9% to 19%, and more preferably 10% to 18%. 【0043】 TiO2, Nb2O5, and La2O3 all have the effect of improving the refractive index in this invention, but TiO2 is P g,FWhile it rapidly increases glass P g,F The effect on the refractive index and P is small. The present invention limits the ratio TiO2 / (Nb2O5+La2O3) between the total content of TiO2, Nb2O5 and La2O3 to 0.35-3.2, thereby improving the refractive index and P of the glass. g,F This can satisfy the design requirements. Therefore, preferably TiO2 / (Nb2O5+La2O3) is 0.35 to 3.2, more preferably TiO2 / (Nb2O5+La2O3) is 0.4 to 3.0, and even more preferably TiO2 / (Nb2O5+La2O3) is 0.5 to 2.8. 【0044】 WO3 can improve the refractive index and dispersion of glass, but the P of glass g,F This causes a rapid increase in the light transmittance of the glass, while simultaneously decreasing its light transmittance. Therefore, in this invention, the WO3 content is 0-5%, preferably 0-2%, and more preferably no WO3 is present. 【0045】 Bi2O3 can improve the refractive index and dispersion of glass, but the P of glass g,F This causes a rapid increase in the concentration. Furthermore, because Bi2O3 causes severe corrosion to platinum instruments during melting, its content is limited to 0-5%, preferably 0-2%, and more preferably does not contain Bi2O3. 【0046】 Ta2O5 is a high-refractive index, low-dispersion component of glass, P g,F While it is possible to reduce the value, improve the devitrification resistance of the glass, and enhance the stability of the glass, the high cost of the raw material significantly limits the use of Ta2O5. In the present invention, the Ta2O5 content is 0-5%, preferably 0-2%, and more preferably no Ta2O5 is present. 【0047】 Nb2O5, TiO2, WO3, Bi2O3, and Ta2O5 can all improve the refractive index of glass, but their ability to support the glass network structure is weak, and excessive content leads to poor devitrification resistance. Numerous experimental studies by the inventors have shown that when the ratio (Nb2O5+TiO2+WO3+Bi2O3+Ta2O5) / (SiO2+B2O3) between the total content of Nb2O5, TiO2, WO3, Bi2O3, and Ta2O5 and the total content of SiO2 and B2O3 is within the range of 0.3 to 1.8, the glass can obtain excellent melting performance and devitrification resistance. Therefore, preferably (Nb2O5+TiO2+WO3+Bi2O3+Ta2O5) / (SiO2+B2O3) is 0.3 to 1.8, more preferably (Nb2O5+TiO2+WO3+Bi2O3+Ta2O5) / (SiO2+B2O3) is 0.4 to 1.6, and even more preferably (Nb2O5+TiO2+WO3+Bi2O3+Ta2O5) / (SiO2+B2O3) is 0.5 to 1.4. 【0048】 Li2O belongs to the alkali metal oxide group and is an important component in the present invention that reduces the difficulty of glass production. Li2O can be used as a flux to reduce the difficulty of melting glass. At the same time, Li2O can lower the high-temperature viscosity and transition temperature of glass, making glass production and processing easier. Through the inventors' extensive research, it was found that by incorporating Li2O into glass, the weather resistance of the glass can be improved by utilizing the accumulation effect of Li2O. However, if the Li2O content is too high, the acid resistance stability of the glass decreases. Therefore, in the glass of the present invention, the Li2O content is 1.5% to 15%, preferably 2% to 13%, and more preferably 3% to 11%. 【0049】 SiO2 and ZrO2 can improve the acid resistance of the glass in this invention, but they are also two compositions that are relatively difficult to melt in this invention. However, B2O3 and Li2O have the effect of assisting melting, but if their content is too high, the chemical stability of the glass decreases. Through numerous experimental studies by the inventors, it has been found that when the ratio of the total content of SiO2 and ZrO2 to the total content of B2O3 and Li2O, (SiO2 + ZrO2) / (B2O3 + Li2O), is between 1.8 and 15.0, the glass can obtain excellent melting performance and chemical stability. Therefore, preferably (SiO2 + ZrO2) / (B2O3 + Li2O) is 1.8 to 15.0, more preferably (SiO2 + ZrO2) / (B2O3 + Li2O) is 1.9 to 12.0, and even more preferably (SiO2 + ZrO2) / (B2O3 + Li2O) is 2.0 to 10.0. 【0050】 Na2O and K2O can also lower the melting temperature and high-temperature viscosity of glass, thereby reducing the difficulty of glass production. However, compared to the accumulation effect of Li2O, Na2O and K2O cause the breakdown of the silicon network structure of glass, and glass P g,F This leads to an increase in [something]. Therefore, the Na2O content in the glass of the present invention is 0-10%, preferably 0-8%, more preferably 0-6%, and the K2O content is 0-10%, preferably 0-8%, more preferably 0-6%. 【0051】 Sb2O3 can be used as a clarifying agent in the present invention to improve the clarifying effect of glass, and its content range is 0 to 1%, preferably 0 to 0.5%, and more preferably 0 to 0.2%. 【0052】 <Prohibited ingredients> In the glass of the present invention, even if oxides of transition metals such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo are included in small amounts, either individually or in combination, the glass becomes colored, absorption occurs at specific wavelengths in the visible light region, and thereby weakens the property of the present invention that improves the visible light transmittance effect. Therefore, it is preferable that they are substantially omitted, especially in optical glass where transmittance in the visible light region is required. 【0053】 Oxides of Th, Cd, Tl, Os, Be, and Se have recently been increasingly discouraged from use as hazardous chemicals, and environmental protection measures are necessary not only in the glass manufacturing process but also in the processing process and disposal after the product is finished. Therefore, when environmental impact is a priority, it is preferable to substantially omit them unless they are inevitably mixed in. As a result, the optical glass will be substantially free of substances that pollute the environment. Consequently, the optical glass of the present invention can be manufactured, processed, and disposed of without taking any special environmental protection measures. 【0054】 For environmental reasons, the optical glass of this invention does not contain As2O3 or PbO. While As2O3 has the effect of removing air bubbles and preventing discoloration of the glass, the addition of As2O3 increases platinum erosion in the glass melting furnace, especially the platinum melting furnace, causing more platinum ions to enter the glass and negatively affecting the service life of the platinum melting furnace. Although PbO can significantly improve the high refractive index and high dispersion performance of the glass, both PbO and As2O3 are environmental pollutants. 【0055】 The terms "not contained" and "0%" as used herein mean that the compound, molecule, or element in question is not intentionally added to the optical glass of the present invention as a raw material. However, some impurities or components that were not intentionally added may be present in the raw materials and / or equipment used to produce the optical glass, and these may be present in small or trace amounts in the final optical glass. Such cases are also within the scope of protection of the patent of the present invention. 【0056】 The performance of the optical glass of the present invention will be described below. 【0057】 <Refractive index and Abbe number> Refractive index of optical glass (n d ) and Abbe number (ν d ) shall be tested according to the method specified in GB / T 7962.1-2010. 【0058】 In some embodiments, the refractive index (n) of the optical glass of the present invention is determined by the present invention. d The ratio is 1.87 to 1.93, preferably 1.88 to 1.92, and more preferably 1.89 to 1.91. 【0059】 In some embodiments, the Abbe number (ν) of the optical glass of the present invention is used. d ) is 24-30, preferably 25-29, more preferably 26-28. 【0060】 <Relative partial variance> Relative partial dispersion of optical glass (P g,F The calculation method for P g,F =(n g -n F ) / (n F -n C ) is the case. n in the formula g , n F and n C It shall be tested according to the method specified in GB / T 7962.1-2010. 【0061】 In some embodiments, the relative partial dispersion (P) of the optical glass of the present invention g,F ) ≤ 0.6090, preferably relative partial variance (P g,F ) ≤ 0.6085, more preferably relative partial variance (P g,F ) ≤ 0.6080. 【0062】 <Internal transmittance> Internal transmittance of glass (τ 400 ) is the internal transmittance at 400 nm of a 10 mm thick sample, tested according to the method specified in GB / T 7962.12-2010. 【0063】 In some embodiments, the internal transmittance (τ) of the optical glass of the present invention is 400 ) is 0.68 or higher, preferably internal transmittance (τ 400 ) is 0.70 or higher, more preferably internal transmittance (τ 400 ) is 0.72 or higher. 【0064】 <Devitrification resistance performance> The test method for the devitrification resistance of optical glass is as follows: The sample is T g The sample is placed in a muffle furnace at +230°C and kept warm for 15 minutes before being removed. After further cooling at room temperature and polishing both sides, the number of crystallized particles per cubic centimeter in the sample (A) is observed. 【0065】 In some embodiments, the number of crystals (A) in the optical glass of the present invention is 5 or less, preferably 3 or less, and more preferably 0. 【0066】 <Weather resistance> The test method for the weather resistance (CR) of glass is as follows: The sample is placed in a test box with a saturated water vapor atmosphere at 90% relative humidity and circulated alternately at 40°C to 50°C every hour for 15 cycles. The weather resistance class is determined by the change in turbidity before and after the sample is left standing, and the classification of weather resistance is shown in the table below. [Table 0] 【0067】 In some embodiments, the weather resistance (CR) of the optical glass of the present invention is Class 2 or higher, preferably Class 1. 【0068】 <Acid resistance stability> The acid resistance stability RA(S) of glass is tested according to the method specified in GB / T 7962.14-2010. 【0069】 In some embodiments, the acid resistance stability of the optical glass of the present invention is Class 2 or higher, preferably Class 1. 【0070】 <density> The density (ρ) of the glass shall be tested according to the method specified in GB / T 7962.20-2010. 【0071】 In some embodiments, the density (ρ) of the optical glass of the present invention is 3.95 g / cm³. 3 Preferably, 3.90 g / cm³ 3 More preferably, 3.85 g / cm³ 3 The following applies: 【0072】 [Manufacturing method] The method for manufacturing the optical glass of the present invention is as follows. The glass of the present invention is produced using conventional raw materials and conventional processes, using composite salts (e.g., carbonates, nitrates, sulfates), hydroxides, oxides, etc. as raw materials, and after compounding the raw materials in a conventional manner, the compounded furnace material is placed in a melting furnace at 1250°C to 1450°C and melted, and after clarification, stirring, and homogenization, a homogeneous molten glass free of bubbles and undissolved substances is obtained, and this molten glass is cast in a mold and annealed to produce the glass. Those skilled in the art can appropriately select the raw materials, process methods, and process parameters as required in practice. 【0073】 II. Glass Preforms and Optical Elements Glass preforms can be manufactured from the fabricated optical glass using methods such as polishing, reheat press molding, and precision press molding. Specifically, glass preforms can be manufactured by machining optical glass, such as grinding and polishing; a preform for compression molding can be manufactured from optical glass, and then the preform can be reheat press molded and polished to produce a glass preform; or a preform manufactured by polishing can be precision press molded to produce a glass preform. The means for manufacturing glass preforms are not limited to those described above. 【0074】 As described above, the optical glass of the present invention is useful for various optical elements and optical designs, and it is particularly preferable to form a preform from the optical glass of the present invention and then use the preform to manufacture optical elements such as lenses and prisms by performing reheat press molding, precision press molding, etc. 【0075】 Both the glass preform and the optical element of the present invention are formed from the optical glass of the present invention as described above. The glass preform of the present invention has the excellent properties of optical glass, and the optical element of the present invention has the excellent properties of optical glass, making it possible to provide various optical elements such as lenses and prisms with high optical value. 【0076】 Examples of lenses include various types of lenses whose lens surfaces are spherical or aspherical, such as concave meniscus lenses, convex meniscus lenses, biconvex lenses, biconcave lenses, plano-convex lenses, and plano-concave lenses. 【0077】 III.Optical equipment Optical elements formed from the optical glass of the present invention can be used to manufacture optical devices such as photographic equipment, in-vehicle equipment, imaging equipment, display equipment, and monitoring equipment. 【0078】 The optical glass of the present invention has high refractive index and low relative partial dispersion performance, making it particularly suitable for telephoto lenses and high-resolution interchangeable lenses. 【0079】 Examples <Examples of optical glass applications> To further clarify and illustrate the technical solutions of the present invention, the following non-limiting embodiments are provided. 【0080】 In this embodiment, optical glass shown in Tables 1 to 4 is obtained using the optical glass manufacturing method described above. Furthermore, the properties of each glass are measured according to the test method described in the present invention, and the measurement results are shown in Tables 1 to 4. 【0081】 [Table 1-1] [Table 1-2] 【0082】 [Table 2-1] [Table 2-2] 【0083】 [Table 3-1] [Table 3-2] 【0084】 [Table 4-1] [Table 4-2] 【0085】 <Examples of glass preforms> From the glass obtained in Examples 1 to 40 of optical glass, various lenses such as concave meniscus lenses, convex meniscus lenses, biconvex lenses, biconcave lenses, plano-convex lenses, plano-concave lenses, and preforms such as prisms are fabricated using compression molding methods such as polishing, reheat press molding, and precision press molding. 【0086】 <Examples of optical elements> The preforms obtained in the above-described examples of glass preforms are annealed and finely adjusted while reducing deformation inside the glass so that the optical properties such as the refractive index reach the desired values. 【0087】 Next, each preform is ground and polished to produce various lenses and prisms, such as concave meniscus lenses, convex meniscus lenses, biconvex lenses, biconcave lenses, plano-convex lenses, and plano-concave lenses. An anti-reflective coating can also be applied to the surface of the resulting optical elements. 【0088】 <Examples of optical instruments> Optical elements fabricated from the above-described embodiments can be used, by optical design, to form optical members or optical assemblies using one or more optical elements, for example, in imaging equipment, sensors, microscopes, medical technology, digital projection, communications, optical communication technology / information transmission, optics / illumination in the automotive field, lithography technology, excimer lasers, wafers, computer chips, and integrated circuits and electronic devices including such circuits and chips.

Claims

[Claim 1] When the composition is expressed in mole percentages, SiO ２ : 25% to 40%, B ２ O ３ : 1% to 8%, La ２ O ３ : 1% to 8%, BaO: 1% to 6%, CaO: 5% to 25%, Nb ２ O ５ : 5% to 15%, TiO ２ : 8% to 20%, Li ２ O: 1.5% to 15%, ZrO ２ : 0 to 5%, Na ２ O: 0 to 10%, does not contain PbO, and CaO / RO is 0.25 to 0.7, where RO is the total content of BaO, SrO, CaO, and MgO. An optical glass characterized by this. [Claim 2] When the composition is expressed as a mole percentage, Al ２ O ３ : 0-5%, and / or Gd ２ O ３ : 0-8%, and / or Y ２ O ３ : 0-8%, and / or SrO: 0-15%, and / or MgO: 0-10%, and / or ZnO: 0-8%, and / or WO ３ : 0-5%, and / or Bi ２ O ３ : 0-5%, and / or Ta ２ O ５ : 0-5%, and / or K ２ O: 0-10%, and / or Sb ２ O ３ The optical glass according to claim 1, further containing 0 to 1%. [Claim 3] When the composition is expressed as a mole percentage, SiO ２ :25%~40%, B ２ O ３ : 1% to 8%, La ２ O ３ : 1% to 8%, BaO: 1% to 6%, CaO: 5% to 25%, Nb ２ O ５ :5% to 15%, TiO ２ :8%~20%, Li ２ O: 1.5% to 15%, Al ２ O ３ : 0-5%, Gd ２ O ３ : 0-8%, Y ２ O ３ : 0-8%, SrO: 0-15%, MgO: 0-10%, ZnO: 0-8%, ZrO ２ : 0-5%, WO ３ : 0-5%, Bi ２ O ３ : 0-5%, Ta ２ O ５ : 0-5%, Na ２ O: 0-10%, K ２ O: 0-10%, Sb ２ O ３ An optical glass characterized by comprising 0-1%, having a CaO / RO ratio of 0.25-0.7, where RO is the total content of BaO, SrO, CaO, and MgO. [Claim 4] When the composition is expressed as a mole percentage, SiO ２ +B ２ O ３ is 27% to 45%, and / or SiO ２ +ZrO ２ is 25% to 44%, and / or RO is 10% to 40%, and / or Re ２ O ３ is 1% to 20%, and / or B ２ O ３ +La ２ O ３ is 2% to 14%, and / or B ２ O ３ +Al ２ O ３ The content is 1% to 12%, and the RO is the total content of BaO, SrO, CaO, and MgO, and Re ２ O ３ La ２ O ３ , Gd ２ O ３ , Y ２ O ３ The optical glass according to any one of claims 1 to 3, characterized in that it is the total content of the following. [Claim 5] When the composition is expressed in mole percentages, SiO ２ + B ２ O ３ is 30% to 41%, and / or SiO ２ + ZrO ２ is 29% to 40%, and / or RO is 15% to 35%, and / or Re ２ O ３ is 1.5% to 15%, and / or B ２ O ３ + La ２ O ３ is 4% to 12%, and / or B ２ O ３ + Al ２ O ３ is 3% to 10%, wherein the RO is the total content of BaO, SrO, CaO, and MgO, and Re ２ O ３ is the total content of La ２ O ３ , Gd ２ O ３ , Y ２ O ３ The optical glass according to any one of claims 1 to 3, characterized in that. [Claim 6] When the composition is expressed as a mole percentage, 1) SiO ２ / B ２ O ３ is 3.5 to 38.0, 2) (SiO ２ +ZrO ２ ) / (B ２ O ３ +Li ２ O) is between 1.8 and 15.

0. 3) (Nb ２ O ５ +TiO ２ +WO ３ +Bi ２ O ３ +Ta ２ O ５ ) / (SiO ２ +B ２ O ３ ) is between 0.3 and 1.

8. 4) TiO ２ / (Nb ２ O ５ +La ２ O ３ ) is between 0.35 and 3.

2. 5) The optical glass according to any one of claims 1 to 3, characterized in that it satisfies one or more of the following five conditions: BaO / RO is 0.03 to 0.5, and RO is the total content of BaO, SrO, CaO, and MgO. [Claim 7] When the composition is expressed as a mole percentage, 1) SiO ２ / B ２ O ３ The value is between 3.8 and 35.

0. 2) (SiO ２ +ZrO ２ ) / (B ２ O ３ +Li ２ O) is between 1.9 and 12.

0. 3) (Nb ２ O ５ +TiO ２ +WO ３ +Bi ２ O ３ +Ta ２ O ５ ) / (SiO ２ +B ２ O ３ ) is between 0.4 and 1.

6. 4) TiO ２ / (Nb ２ O ５ +La ２ O ３ ) is between 0.4 and 3. 5) The CaO / RO ratio is 0.3 to 0.

8. 6) The optical glass according to any one of claims 1 to 3, characterized in that it satisfies one or more of the following six conditions: BaO / RO is 0.04 to 0.4, and RO is the total content of BaO, SrO, CaO, and MgO. [Claim 8] When the composition is expressed as a mole percentage, 1) SiO ２ / B ２ O ３ The value must be between 4.0 and 30.

0. 2) (SiO ２ +ZrO ２ ) / (B ２ O ３ +Li ２ O) is between 2.0 and 10.

0. 3) (Nb ２ O ５ +TiO ２ +WO ３ +Bi ２ O ３ +Ta ２ O ５ ) / (SiO ２ +B ２ O ３ ) is between 0.5 and 1.

4. 4) TiO ２ / (Nb ２ O ５ +La ２ O ３ ) is between 0.5 and 2.

8. 5) The CaO / RO ratio is 0.4 to 0.

7. 6) The optical glass according to any one of claims 1 to 3, characterized in that it satisfies one or more of the following six conditions: BaO / RO is 0.05 to 0.3, and RO is the total content of BaO, SrO, CaO, and MgO. [Claim 9] When the composition is expressed as a mole percentage, SiO ２ : 27% to 38%, and / or B ２ O ３ : 2% to 7%, and / or La ２ O ３ : 2% to 7%, and / or BaO: 1.5% to 5%, and / or CaO: 7% to 22%, and / or Nb ２ O ５ : 6% to 14%, and / or TiO ２ : 9% to 19%, and / or Li ２ O: 2% to 13%, and / or Al ２ O ３ : 0-3%, and / or Gd ２ O ３ : 0-6%, and / or Y ２ O ３ : 0-6%, and / or SrO: 1-14%, and / or MgO: 0-8%, and / or ZnO: 0-6%, and / or ZrO ２ : 0-4%, and / or WO ３ : 0-2%, and / or Bi ２ O ３ : 0-2%, and / or Ta ２ O ５ : 0-2%, and / or Na ２ O: 0-8%, and / or K ２ O: 0-8%, and / or Sb ２ O ３ The optical glass according to any one of claims 1 to 3, characterized in that the content is 0 to 0.5%. [Claim 10] When the composition is expressed as a mole percentage, SiO ２ : 29% to 36%, and / or B ２ O ３ : 3% to 6%, and / or La ２ O ３ : 3% to 6%, and / or BaO: 2% to 4%, and / or CaO: 9% to 20%, and / or Nb ２ O ５ : 7% to 13%, and / or TiO ２ : 10% to 18%, and / or Li ２ O: 3% to 11%, and / or Gd ２ O ３ : 0-4%, and / or Y ２ O ３ : 0-4%, and / or SrO: 2-12%, and / or MgO: 0-5%, and / or ZnO: 0-4%, and / or ZrO ２ : 0-3%, and / or Na ２ O: 0-6%, and / or K ２ O: 0-6%, and / or Sb ２ O ３ : 0-0.2%, and / or Composition is Al ２ O ３ Does not contain and / or WO ３ It does not contain and / or Bi ２ O ３ It does not contain and / or Ta ２ O ５ The optical glass according to any one of claims 1 to 3, characterized in that it does not contain [the specified substance]. [Claim 11] The refractive index n of the optical glass ｄ is 1.87 to 1.93, and / or Abbe number ν ｄ The ratio is 24 to 30, and / or the relative partial dispersion P of the optical glass. ｇ，Ｆ ≤ 0.6090 and / or internal transmittance τ ４００ The ratio is 0.68 or higher, and / or the weather resistance CR is Class 2 or higher, and / or the acid resistance stability is Class 2 or higher, and / or the density is 3.95 g / cm³. ３ The optical glass according to any one of claims 1 to 3, characterized in that it is as follows: [Claim 12] The refractive index n of the optical glass ｄ is 1.89 to 1.91, and / or Abbe number ν ｄ The ratio is 26 to 28, and / or the relative partial dispersion P of the optical glass. ｇ，Ｆ ≤ 0.6080 and / or internal transmittance τ ４００ The ratio is 0.72 or higher, and / or the weather resistance CR is Class 1, and / or the acid resistance stability is Class 1, and / or the density is 3.85 g / cm³. ３ The optical glass according to any one of claims 1 to 3, characterized in that it is as follows: [Claim 13] A glass preform characterized by being manufactured using the optical glass described in any one of claims 1 to 3. [Claim 14] An optical element characterized by being manufactured using the glass preform described in claim 13. [Claim 15] An optical device characterized by containing the optical element described in claim 14.