Optical glass, optical element blanks, glass material for press molding, and optical elements

Abstract

To provide an optical glass having anomalous partial dispersibility and stability during re-heating, and provide an optical element blank, a glass material for press molding, and an optical element.SOLUTION: The present invention discloses an optical glass in which the molar ratio [F / Al] between an F content and an Al content is 2.50-15.0, the molar ratio [Ba / P] between a Ba content and a P content is 0.100-1.20, the molar ratio [P / Al] between the P content and the Al content is 0.200-2.00, and the molar ratio [O / P] between the O content and the P content is 3.05-4.20.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to optical glass, optical element blanks, glass materials for press molding, and optical elements.

Background Art

[0002] In recent years, lenses made of glass with low refractive index and anomalous partial dispersion have become less expensive with the improvement of productivity, and are increasingly being installed in a large number of cameras such as digital cameras and surveillance cameras. Therefore, in the future, glass used for such lenses is required to be mass-produced at low cost.

[0003] Conventionally, fluorophosphate glass widely used as a material for lenses with low refractive index and anomalous partial dispersion is likely to have veins because its composition easily varies due to the volatilization of glass components. Furthermore, increasing the refractive index requires the inclusion of rare earths, making it expensive, and there are also problems such as being prone to cracking. For example, in the past, to address the problem of veins, the blending amount of glass components that are easily volatilized was reduced, but such glass had a problem of low stability during reheating. In particular, F (fluorine) is a component that easily causes compositional variations due to volatilization and is a factor in the generation of veins. Therefore, when considering reducing the blending amount of F, it was found that in fluorophosphate glass with a low blending amount of F and a higher refractive index, the stability during reheating tended to decrease significantly.

[0004] In Patent Document 1, fluorophosphate glass with high refractive index and low dispersion and having anomalous partial dispersion is proposed. However, the glass in Patent Document 1 has a problem of inferior stability during reheating.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] As a result of diligent research by the present inventors, it was found that the glass disclosed in Patent Document 1 has a high amount of Al (aluminum) and a low amount of P (phosphorus), which is a network component, resulting in poor stability when reheated.

[0007] Therefore, the present invention aims to provide optical glass, optical element blanks, press-molded glass materials, and optical elements that possess anomalous partial dispersion and stability during reheating. With this objective in mind, the present invention was completed as a result of searching for a glass that can improve stability during reheating while maintaining anomalous partial dispersion. [Means for solving the problem]

[0008] The gist of this invention is as follows: (1) The molar ratio of F content to Al content [F / Al] is 2.50 to 15.0. The molar ratio of Ba content to P content [Ba / P] is 0.100 to 1.20. The molar ratio of P content to Al content [P / Al] is between 0.200 and 2.00. Optical glass with a molar ratio [O / P] of 3.05 to 4.20 between oxygen and phosphorus.

[0009] (2) The optical glass described in (1), wherein the total content of Li, Na, and K [Li+Na+K] is 0.00 to 10.0 mol%.

[0010] (3) The molar ratio of F content to Al content [F / Al] is 2.70 to 4.60. The molar ratio of Ba content to P content [Ba / P] is 0.100 to 1.10. The molar ratio of P content to Al content [P / Al] is 1.50 to 2.00. The optical glass described in (1) or (2), wherein the molar ratio [O / P] of the O content to the P content is 3.55 to 4.00.

[0011] (4) The molar ratio of F content to Al content [F / Al] is 2.50 to 4.60. The molar ratio of Ba content to P content [Ba / P] is 0.250 to 1.20. The molar ratio of P content to Al content [P / Al] is 1.50 to 2.00. The optical glass described in (1) or (2), wherein the molar ratio [O / P] of the O content to the P content is 3.55 to 3.80.

[0012] (5) The molar ratio of F content to Al content [F / Al] is 4.60 to 15.0. The molar ratio of Ba content to P content [Ba / P] is 0.100 to 1.20. The molar ratio of P content to Al content [P / Al] is between 0.200 and 0.900. The molar ratio of O content to P content [O / P] is 3.60 to 4.20. The molar ratio of the F content to the total content of O, F, and Cl [F / (O+F+Cl)] is between 0.010 and 0.790. The optical glass according to (1) or (2), wherein the molar ratio [(Sr+Ba) / (Mg+Ca+Sr+Ba+Zn)] of the total content of Sr and Ba to the total content of Mg, Ca, Sr, Ba, and Zn is 0.00 to 0.67.

[0013] (6) The molar ratio of F content to Al content [F / Al] is 4.60 to 15.0. The molar ratio of Ba content to P content [Ba / P] is 0.100 to 1.20. The molar ratio of P content to Al content [P / Al] is between 0.200 and 0.900. The molar ratio of O content to P content [O / P] is 3.60 to 4.20. The molar ratio of the content of F to the total content of O, F, and Cl [F / (O + F + Cl)] is 0.010 to 0.790, The optical glass according to (1), wherein the total content of Li, Na, and K [Li + Na + K] is 0.00 to 5.00 mol%.

[0014] (7) The molar ratio of the content of F to the content of Al [F / Al] is 4.60 to 15.0, The molar ratio of the content of Ba to the content of P [Ba / P] is 0.400 to 0.820, The molar ratio of the content of P to the content of Al [P / Al] is 0.20 to 1.25, The molar ratio of the content of O to the content of P [O / P] is 3.05 to 3.49, The molar ratio of the content of F to the total content of O, F, and Cl [F / (O + F + Cl)] is 0.010 to 0.790, The optical glass according to (1) or (2), wherein the molar ratio of the total content of Sr and Ba to the total content of Mg, Ca, Sr, Ba, and Zn [(Sr + Ba) / (Mg + Ca + Sr + Ba + Zn)] is 0.00 to 0.67.

[0015] (8) The molar ratio of the content of F to the content of Al [F / Al] is 4.60 to 15.0, The molar ratio of the content of Ba to the content of P [Ba / P] is 0.400 to 0.820, The molar ratio of the content of P to the content of Al [P / Al] is 0.20 to 1.25, The molar ratio of the content of O to the content of P [O / P] is 3.05 to 3.49, The molar ratio of the content of F to the total content of O, F, and Cl [F / (O + F + Cl)] is 0.010 to 0.790, The optical glass according to (1), wherein the total content of Li, Na, and K [Li + Na + K] is 0.00 to 6.40 mol%.

[0016] Let the contents in mass % of F, Al, Ba, P, and O be denoted as C(F), C(Al), C(Ba), C(P), and C(O) respectively. Let the atomic weights of F, Al, Ba, P, and O be denoted as M(F), M(Al), M(Ba), M(P), and M(O) respectively. A1 = {C(F) / M(F)} / {C(Al) / M(Al)} B1 = {C(Ba) / M(Ba)} / {C(P) / M(P)} C1 = {C(P) / M(P)} / {C(Al) / M(Al)} D1 = {C(O) / M(O)} / {C(P) / M(P)} When defined as such, A1 is 2.50 to 15.0, B1 is 0.100 to 1.20, C1 is 0.200 to 2.00, D1 is 3.05 to 4.20, an optical glass.

[0017] (10) An optical element blank made of the optical glass according to any one of (1) to (9) above.

[0018] (11) A glass material for press molding made of the optical glass according to any one of (1) to (9) above.

[0019] (12) An optical element made of the optical glass according to any one of (1) to (9) above.

Advantages of the Invention

[0020] According to the present invention, it is possible to provide an optical glass, an optical element blank, a glass material for press molding, and an optical element having abnormal partial dispersibility and stability during reheating.

Brief Description of the Drawings

[0021] [Figure 1] FIG. 1 is a reference diagram for calculating the rising temperature Tx of the exothermic peak of crystallization and the glass transition temperature Tg. [Modes for carrying out the invention]

[0022] Embodiments of the present invention will be described below. The content of the glass component can be quantified by known methods, such as inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The elements that form the anionic component, such as O, F, and Cl, can be identified and quantified by known analytical methods, such as ion chromatography and non-dispersive infrared absorption spectroscopy (ND-IR).

[0023] Furthermore, in this specification, both the thermal stability and reheating stability of glass refer to the resistance to crystal precipitation within the glass. In particular, thermal stability refers to the resistance to crystal precipitation when molten glass solidifies, and reheating stability refers to the resistance to crystal precipitation when solidified glass is reheated, such as during reheat pressing.

[0024] In this specification, unless otherwise specified, refractive index refers to the refractive index nd at the helium d-line (wavelength 587.56 nm).

[0025] The Abbe number νd is a value used to represent the properties related to dispersion and is expressed by the following formula. Here, nF is the refractive index of blue hydrogen at the F line (wavelength 486.13 nm), and nC is the refractive index of red hydrogen at the C line (656.27 nm). νd=(nd-1) / (nF-nC)

[0026] In this invention, the glass composition of optical glass is expressed in mole percent and mass percent. Mole percent is the mole percentage when the total content of all elements contained in the glass is set to 100%. Mole ratio is the ratio calculated based on the element content expressed in mole percent. Mass percent is the mass percentage when the total content of all elements contained in the glass is set to 100%. In this specification and the present invention, a component content of 0% means that the component is substantially absent, and it is permissible that the component may be present at an unavoidable impurity level.

[0027] Embodiments of the optical glass according to the present invention are described below. The first embodiment (Embodiment 1-1 and Embodiment 1-2), the second embodiment (Embodiment 2-1 and Embodiment 2-2), and the third embodiment (Embodiment 3-1 and Embodiment 3-2), which will be described later, are preferred forms of this embodiment.

[0028] This embodiment In this embodiment, by particularly controlling the ratio of Al content to F content, we have succeeded in creating an optical glass that ensures anomalous partial dispersion and improves stability during reheating. The optical glass according to this embodiment is as follows.

[0029] The optical glass according to this embodiment is The molar ratio of F content to Al content [F / Al] is between 2.50 and 15.0. The molar ratio of Ba content to P content [Ba / P] is 0.100 to 1.20. The molar ratio of P content to Al content [P / Al] is between 0.200 and 2.00. The molar ratio [O / P] of oxygen to phosphorus is between 3.05 and 4.20.

[0030] Furthermore, the optical glass according to this embodiment is The mass percentage content of F, Al, Ba, P, and O is expressed as C(F), C(Al), C(Ba), C(P), and C(O), respectively. Let the atomic weights of F, Al, Ba, P, and O be M(F), M(Al), M(Ba), M(P), and M(O), respectively. A1 = {C(F) / M(F)} / {C(Al) / M(Al)} B1 = {C(Ba) / M(Ba)} / {C(P) / M(P)} C1 = {C(P) / M(P)} / {C(Al) / M(Al)} D1 = {C(O) / M(O)} / {C(P) / M(P)} In that case, A1 is 2.50-15.0, B1 is between 0.100 and 1.20. C1 is between 0.200 and 2.00. D1 is between 3.05 and 4.20.

[0031] In this invention, the atomic weights of each element refer to the atomic weights listed in Table 2 of Reference 1 (Pure Appl. Chem., Vol. 75, No. 8, pp. 1107-1122, 2003). Furthermore, A1, B1, C1, and D1 are expressed in terms of their content and atomic weight, expressed in mass percent, for the molar ratios [F / Al], [Ba / P], [P / Al], and [O / P], respectively.

[0032] In this invention, the molar ratio [O / P] is the ratio of the O content to the P content in mole percent, but it can also be calculated as follows.

[0033] Method for calculating the O / P ratio The optical glass of the present invention is an insulator that does not absorb in at least the visible to near-infrared region, and its formal valency can be considered to be approximately 0 (electrically neutral). Therefore, the optical glass of the present invention is The mass percentage of elements α1, α2…αm that can form m-type cations, and elements β1, β2…βn that can form n-type anions, Let C(α1), C(α2), ...C(αm), and C(β1), C(β2), ...C(βn), 1) The atomic weights of elements α1, α2…αm that can become cations, and elements β1, β2…βn that can become anions. Let M(α1), M(α2), ... M(αm), and M(β1), M(β2), ... M(βn), 2) The valence of the cations α1, α2...αm and the anions β1, β2...βn When V(α1), V(α2), ..., V(αm), and V(β1), V(β2), ..., V(βn), Σ(i=1~m){C(αi) / M (αi) × V(αi) =-Σ(j=1~n){C(βj) / M (βj) × V(βj) It can be considered that they have a relationship.

[0034] Using this relationship, it is also possible to calculate the oxygen content from the mass percentage of elements other than oxygen. This is useful, for example, when it is difficult to measure the oxygen content or when there is a large variation in the measurement results of the oxygen content.

[0035] The following provides specific examples to illustrate this point. Calculation example As shown in Table I below, we will explain the case where, for a glass composed of elements F, Al, Ba, P, and O, the mass percentage content of each element except O is 27.035 mass%, 7.384 mass%, 52.614 mass%, and 5.086 mass%, respectively. [Table I]

[0036] F, Al, Ba, and P are related to O. 1) Let the formal valencies of F, Al, Ba, P, and O be V(F)=-1, V(Al)=+3, V(Ba)=+2, V(P)=+5, and V(O)=-2, respectively. 2) When the atomic weights of F, Al, Ba, P, and O are M(F)=18.9984, M(Al)=26.9815, M(Ba)=137.3277, M(P)=30.9738, and M(O)=15.9994, respectively, The following equation (1) holds true. {C(P) / M(P)×V(P)+C(Al) / M(Al)×V(Al)+C(Ba) / M(Ba)×V(Ba)}={C(O) / M(O)×V(O)+C(F) / M(F)×V(F)}…Equation (1) From equation (1) above, C(O) / M(O)={7.384 / 26.9815×3+52.614 / 137.3277×2+5.086 / 30.9738×5+27.035 / 18.9984×(-1)} / 2=0.4926… It can be calculated as follows. By dividing C(O) / M(O) by C(P) / M(P)=5.086 / 30.9738=0.1642..., D1 can be calculated as D1 = {C(O) / M(O)} / {C(P) / M(P)} = 3.00... D1 represents the molar ratio [O / P] expressed in terms of mass percentage content and atomic weight. Also, since C(O) = {C(O) / M(O)} × M(O), C(O) can also be calculated as C(O) = 0.4926… × 15.9994 = 7.881… (mass%).

[0037] In this case, depending on the method used to measure the glass component content, there may be, for example, small amounts of unmeasured elements, or the total mass percentage including the O content may not be exactly 100% due to measurement variability. However, if elements other than O are almost entirely quantified in mole percent, parameters such as D1 can be calculated using the above method even without measurement results for the O content.

[0038] For example, the acceptable range of variation in the total amount of elements when converted to mole percentages may be 100±5%, but it is preferably around 100±3%, and is preferred in the order of 100%±2%, 100%±1%, 100%±0.5%, 100%±0.3%, and 100%±0.1%. It is not necessary to measure unavoidable impurities.

[0039] The optical glass according to this embodiment will be described in detail below.

[0040] In the optical glass according to this embodiment, the molar ratio [F / Al] of F content to Al content is 2.50 to 15.0. The lower limit of the molar ratio [F / Al] is preferably 2.60, and more preferably in the order of 2.70, 2.75, 2.80, 2.90, 3.00, 3.50, 4.00, 4.25, 4.50, and 4.60. The upper limit of the molar ratio [F / Al] is preferably 7.50, and more preferably in the order of 7.00, 6.75, 6.50, 6.25, and 6.00. By setting the molar ratio [F / Al] within the above range, an optical glass with anomalous partial dispersion and stability during reheating can be obtained. If the molar ratio [F / Al] is too low, the stability during reheating may decrease. If the molar ratio [F / Al] is too high, the glass composition may fluctuate due to the volatilization of F, and striations may occur. Furthermore, from the viewpoint of particularly increasing the refractive index nd of the glass and improving stability during reheating, while suppressing striations caused by the volatilization of glass components, the upper limit of the molar ratio [F / Al] can also be set to 4.50, 4.25, 4.00, 3.75, or 3.50.

[0041] Furthermore, in the optical glass according to this embodiment, the mass percentage content of F and Al is expressed as C(F) and C(Al), respectively. Let the atomic weights of F and Al be M(F) and M(Al), respectively. A1 = {C(F) / M(F)} / {C(Al) / M(Al)} In that case, A1 is between 2.50 and 15.0. The lower limit of A1 is preferably 2.60, and more preferably in the order of 2.70, 2.75, 2.80, 2.90, 3.00, 3.50, 4.00, 4.25, 4.50, and 4.60. The upper limit of A1 is preferably 7.50, and more preferably in the order of 7.00, 6.75, 6.50, 6.25, and 6.00. By setting A1 within the above range, optical glass with anomalous partial dispersion and stability during reheating can be obtained. If A1 is too small, the stability during reheating may decrease. If A1 is too large, the glass composition may change due to the volatilization of F, and striations may occur. Furthermore, from the viewpoint of particularly increasing the refractive index of the glass, improving stability during reheating, and suppressing striations caused by the volatilization of glass components, the upper limit of A1 can also be set to 4.50, 4.25, 4.00, 3.75, or 3.50.

[0042] In the optical glass according to this embodiment, the molar ratio [Ba / P] of Ba content to P content is 0.100 to 1.20. The lower limit of the molar ratio [Ba / P] is preferably 0.200, and more preferably in the order of 0.300, 0.350, 0.375, 0.400, 0.425, 0.450, 0.460, 0.480, and 0.500. The upper limit of the molar ratio [Ba / P] is preferably 1.15, and more preferably in the order of 1.30, 1.20, 1.10, 1.05, 1.00, 0.900, 0.800, 0.700, 0.650, and 0.600. By setting the molar ratio [Ba / P] within the above range, an optical glass with anomalous partial dispersion can be obtained. If the molar ratio [Ba / P] is too low, the refractive index may decrease, and if used as a lens, it may affect image formation. If the molar ratio [Ba / P] is too high, a network structure may not be formed, preventing vitrification, and Ba may precipitate. In addition, the stability during reheating may decrease.

[0043] Furthermore, in the optical glass according to this embodiment, the mass percentage content of Ba and P is expressed as C(Ba) and C(P), respectively. Let the atomic weights of Ba and P be M(Ba) and M(P), respectively. B1 = {C(Ba) / M(Ba)} / {C(P) / M(P)} In that case, B1 is between 0.100 and 1.50. The lower limit of B1 is preferably 0.200, and more preferably in the order of 0.300, 0.350, 0.375, 0.400, 0.425, 0.450, 0.460, 0.480, and 0.500. The upper limit of B1 is preferably 1.40, and more preferably in the order of 1.30, 1.20, 1.10, 1.05, 1.00, 0.900, 0.800, 0.700, 0.650, and 0.600. By setting B1 within the above range, optical glass with anomalous partial dispersion can be obtained. If B1 is too small, the refractive index may decrease, and it may affect image formation when used as a lens. If B1 is too large, a network structure may not be formed, making vitrification impossible, and Ba may precipitate.

[0044] In the optical glass according to this embodiment, the molar ratio [P / Al] of P content to Al content is 0.200 to 2.00. The lower limit of the molar ratio [P / Al] is preferably 0.250, and more preferably in the order of 0.300, 0.350, 0.400, 0.450, 0.475, 1.00, 1.20, 1.30, 1.40, and 1.45. The upper limit of the molar ratio [P / Al] is preferably 1.95, and more preferably in the order of 1.90, 1.85, 1.80, and 1.75. By setting the molar ratio [P / Al] within the above range, an optical glass with anomalous partial dispersion and stability during reheating can be obtained. The preferred range of the molar ratio [P / Al] changes in conjunction with the F content. When the F content is high, it is necessary to increase the Al content to suppress the occurrence of striations, and as a result the molar ratio [P / Al] becomes smaller. Furthermore, if the F content is low, it is necessary to increase the P content and decrease the Al content to suppress the decrease in stability during reheating, resulting in a larger molar ratio [P / Al]. In addition, from the viewpoint of increasing the refractive index of the glass and improving stability during reheating while suppressing striations caused by the volatilization of glass components, the upper limit of the molar ratio [P / Al] can be set to 1.20, 1.00, 0.900, 0.800, 0.700, or 0.600.

[0045] Furthermore, in the optical glass according to this embodiment, the mass percentage content of Al and P is expressed as C(Al) and C(P), respectively. Let the atomic weights of Al and P be M(Al) and M(P), respectively. C1 = {C(P) / M(P)} / {C(Al) / M(Al)} In that case, C1 is between 0.200 and 2.00. The lower limit of C1 is preferably 0.250, and more preferably in the order of 0.300, 0.350, 0.400, 0.450, 0.475, 1.00, 1.20, 1.30, 1.40, and 1.45. The upper limit of C1 is preferably 1.95, and more preferably in the order of 1.90, 1.85, 1.80, and 1.75. By setting C1 within the above range, optical glass with anomalous partial dispersion and stability during reheating can be obtained. C1 changes in conjunction with the F content. If the F content is high, it is necessary to increase the Al content to suppress the occurrence of striations, and as a result C1 becomes low. Conversely, if the F content is low, it is necessary to increase the P content and decrease the Al content to suppress the decrease in stability during reheating, and as a result C1 becomes high. Furthermore, from the viewpoint of particularly increasing the refractive index of the glass, improving stability during reheating, and suppressing striations caused by the volatilization of glass components, the upper limit of C1 can also be set to 1.20, 1.00, 0.900, 0.800, 0.700, or 0.600.

[0046] In the optical glass according to this embodiment, the molar ratio [O / P] of O content to P content is 3.05 to 4.20. The lower limit of the molar ratio [O / P] is preferably 3.10, and more preferably in the order of 3.15, 3.20, 3.25, 3.30, 3.35, 3.40, 3.45, 3.50, 3.55, and 3.575. The upper limit of the molar ratio [O / P] is preferably 4.10, and more preferably in the order of 4.00, 3.95, 3.90, 3.85, 3.80, and 3.78. By setting the molar ratio [O / P] within the above range, an optical glass with abnormal partial dispersion and stability during reheating can be obtained. In the optical glass according to this embodiment, P is also more likely to volatilize due to the volatilization of F, so if the molar ratio [O / P] is too small, the effect of F volatilization becomes large, which may cause fluctuations in the glass composition and lead to striations. If the atomic ratio is too high, the anomalous partial dispersion may be impaired, and the thermal stability and stability during reheating of the glass may decrease. Furthermore, from the viewpoint of increasing the refractive index of the glass and improving stability during reheating while suppressing striations caused by the volatilization of glass components, the upper limit of the molar ratio [O / P] can be set to 3.49, 3.48, 3.44, or 3.40.

[0047] Furthermore, in the optical glass according to this embodiment, the mass percentage content of P and O is expressed as C(P) and C(O), respectively. Let the atomic weights of P and O be M(P) and M(O), respectively. D1 = {C(O) / M(O)} / {C(P) / M(P)} In that case, D1 is between 3.05 and 4.20. The lower limit of D1 is preferably 3.10, and more preferably in the order of 3.15, 3.20, 3.25, 3.30, 3.35, 3.40, 3.45, 3.50, 3.55, and 3.575. The upper limit of D1 is preferably 4.10, and more preferably in the order of 4.00, 3.95, 3.90, 3.85, 3.80, and 3.78. By setting D1 within the above range, optical glass with anomalous partial dispersion and stability during reheating can be obtained. In the optical glass according to this embodiment, P is also more likely to volatilize due to the volatilization of F, so if D1 is too small, the effect of F volatilization will be large, which may cause fluctuations in the glass composition and the occurrence of striations. If the atomic ratio is too large, the anomalous partial dispersion may be impaired, and the thermal stability and stability during reheating of the glass may decrease. Furthermore, from the viewpoint of particularly increasing the refractive index of the glass, improving stability during reheating, and suppressing striations caused by the volatilization of glass components, the upper limit of D1 can also be set to 3.49, 3.48, 3.44, or 3.40.

[0048] The following are non-limiting examples of the content and ratio of glass components other than those mentioned above in the optical glass according to this embodiment.

[0049] In the optical glass according to this embodiment, the lower limit of the total content of Li and Na [Li+Na] is preferably 0.00 mol%, and more preferably in the order of 0.03 mol%, 0.07 mol%, and 0.10 mol%, from the viewpoint of improving the solubility of the glass raw material. The upper limit of the total content [Li+Na] is preferably 10.0 mol%, and more preferably in the order of 7.0 mol%, 5.0 mol%, and 3.0 mol%, from the viewpoint of suppressing the volatilization of glass components.

[0050] Furthermore, in the optical glass according to this embodiment, the content of Li and Na in mass percent is expressed as C(Li) and C(Na), respectively. Let the atomic weights of Li and Na be M(Li) and M(Na), respectively. E1=[{C(Li) / M(Li)}+{C(Na) / M(Na)}]×100 In that case, The lower limit of E1 is preferably 0, and more preferably in the order of 0.09, 0.21, and 0.30, from the viewpoint of improving the melting properties of the glass raw material. The upper limit of E1 is preferably 30, and more preferably in the order of 21, 15, and 9, from the viewpoint of suppressing the volatilization of the glass component.

[0051] In the optical glass according to this embodiment, the lower limit of the total content of Li, Na, and K [Li+Na+K] is preferably 0.00 mol%, and more preferably in the order of 0.04 mol%, 0.08 mol%, 0.12 mol%, 0.16 mol%, and 0.18 mol%, from the viewpoint of improving the solubility of the glass raw material. The upper limit of the total content [Li+Na+K] is preferably 7.6 mol%, and more preferably in the order of 7.20 mol%, 6.40 mol%, 6.20 mol%, 6.00 mol%, 5.80 mol%, 5.60 mol%, 5.40 mol%, 5.20 mol%, 4.80 mol%, and 4.40 mol%, from the viewpoint of suppressing the volatilization of glass components.

[0052] Furthermore, in the optical glass according to this embodiment, the mass percentage content of Li, Na, and K is expressed as C(Li), C(Na), and C(K), respectively. Let the atomic weights of Li, Na, and K be M(Li), M(Na), and M(K), respectively. F1=[{C(Li) / M(Li)}+{C(Na) / M(Na)}+{C(K) / M(K)}]×100 In that case, The lower limit of F1 is preferably 0 from the viewpoint of improving the melting properties of the glass raw material, and more preferably in the order of 0.12, 0.24, 0.36, 0.48, and 0.54. The upper limit of F1 is preferably 24.0 from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 22.8, 21.6, 19.2, 18.6, 18.0, 17.4, 16.8, 16.2, 15.6, 14.4, and 13.2.

[0053] In the optical glass according to this embodiment, the lower limit of the molar ratio [F / (O+F+Cl)] of the F content to the total content of O, F, and Cl is preferably 0.010, and more preferably in the order of 0.110, 0.160, 0.220, 0.250, 0.280, 0.300, 0.320, 0.420, 0.450, 0.500, and 0.550, from the viewpoint of stabilizing the glass and suppressing volatilization, and more preferably in the order of 0.850, 0.820, 0.810, 0.800, 0.790, and 0.600. The upper limit of the molar ratio [F / (O+F+Cl)] can be set to 0.500, 0.460, 0.420, or 0.400, particularly from the viewpoint of increasing the refractive index of the glass, improving stability during reheating, and suppressing striations caused by the volatilization of glass components.

[0054] Furthermore, in the optical glass according to this embodiment, the mass percentage content of F, O, and Cl is expressed as C(F), C(O), and C(Cl), respectively. Let the atomic weights of F, O, and Cl be M(F), M(O), and M(Cl), respectively. G1=[{C(F) / M(F)} / [{C(O) / M(O)}+{C(F) / M(F)}+{C(Cl) / M(Cl)}]] In that case, The lower limit of G1 is preferably 0.010 from the viewpoint of imparting anomalous partial dispersion and improving thermal stability, and is more preferably in the order of 0.110, 0.160, 0.220, 0.250, 0.280, 0.300, 0.320, 0.420, 0.450, 0.500, 0.550, 0.600, 0.625, and 0.650. The upper limit of G1 is preferably 0.940 from the viewpoint of stabilizing the glass and suppressing volatilization, and is more preferably in the order of 0.890, 0.850, 0.820, 0.810, 0.800, 0.790, and 0.600. The upper limit of G1 can also be set to 0.550, 0.500, 0.460, 0.420, or 0.400, particularly from the viewpoint of increasing the refractive index of the glass, improving stability during reheating, and suppressing striations caused by the volatilization of glass components.

[0055] In the optical glass according to this embodiment, the lower limit of the molar ratio [(Sr+Ba) / (Mg+Ca+Sr+Ba+Zn)] between the total content of Sr and Ba and the total content of Mg, Ca, Sr, Ba, and Zn is preferably 0.100, and more preferably in the order of 0.200, 0.300, 0.340, 0.380, 0.420, and 0.460, from the viewpoint of increasing the refractive index nd. The upper limit of the molar ratio [(Sr+Ba) / (Mg+Ca+Sr+Ba+Zn)] is preferably 1.00, and more preferably in the order of 0.990, 0.980, 0.970, 0.850, 0.800, 0.750, 0.700, 0.650, and 0.600, from the viewpoint of increasing stability during reheating. The lower limit of the molar ratio [(Sr+Ba) / (Mg+Ca+Sr+Ba+Zn)] can be set to 0.500, 0.600, 0.700, or 0.750, particularly in glasses with a low fluorine content, from the viewpoint of increasing the refractive index nd of the glass.

[0056] Furthermore, in the optical glass according to this embodiment, the mass percentage content of Mg, Ca, Sr, Ba, and Zn is defined as C(Mg), C(Ca), C(Sr), C(Ba), and C(Zn), respectively. Let the atomic weights of Mg, Ca, Sr, Ba, and Zn be M(Mg), M(Ca), M(Sr), M(Ba), and M(Zn), respectively. H1=[{C(Sr) / M(Sr)}+{C(Ba) / M(Ba)}] / [{C(Mg) / M(Mg)}+{C(Ca) / M(Ca)}+{C(Sr) / M(Sr)}+{C(Ba) / M(Ba)}+{C(Zn) / M(Zn)}] In that case, The lower limit of H1 is preferably 0.100 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.200, 0.300, 0.340, 0.380, 0.420, and 0.460. The upper limit of H1 is preferably 1.00 from the viewpoint of increasing stability during reheating, and more preferably in the order of 0.990, 0.980, 0.970, 0.850, 0.800, 0.750, 0.700, 0.650, and 0.600. The lower limit of H1 can also be 0.500, 0.600, 0.700, 0.750, 0.800, 0.850, or 0.900, particularly in glasses with a low fluorine content, from the viewpoint of increasing the refractive index nd of the glass.

[0057] In the optical glass according to this embodiment, the lower limit of the molar ratio [(Ba+Sr+Zn) / P] of the total content of Ba, Sr, and Zn to the content of P is preferably 0.100 from the viewpoint of increasing the refractive index, and is more preferably in the order of 0.200, 0.300, 0.400, 0.500, 0.550, 0.600, 0.650, 0.700, 0.750, and 0.800. The upper limit of the molar ratio [(Ba+Sr+Zn) / P] is preferably 2.10 from the viewpoint of increasing stability during reheating, and is more preferably in the order of 1.90, 1.80, 1.70, 1.60, 1.50, 1.40, 1.30, 1.20, 1.15, 1.12, and 1.10.

[0058] Furthermore, in the optical glass according to this embodiment, the mass percentage content of P, Sr, Ba, and Zn is expressed as C(P), C(Sr), C(Ba), and C(Zn), respectively. Let the atomic weights of P, Sr, Ba, and Zn be M(P), M(Sr), M(Ba), and M(Zn), respectively. I1=[{C(Ba) / M(Ba)}+{C(Sr) / M(Sr)}+{C(Zn) / M(Zn)}] / {C(P) / M(P)} In that case, The lower limit of I1 is preferably 0.100 from the viewpoint of increasing the refractive index, and more preferably in the order of 0.200, 0.300, 0.400, 0.500, 0.550, 0.600, 0.650, 0.700, 0.750, 0.800, 0.850, 0.900, and 0.950. The upper limit of I1 is preferably 3.00 from the viewpoint of increasing stability during reheating, and more preferably in the order of 2.50, 2.20, 2.10, 2.00, 1.90, 1.80, 1.70, 1.60, 1.50, 1.40, 1.30, 1.20, 1.15, 1.12, and 1.10.

[0059] In the optical glass according to this embodiment, the lower limit of the total content of Sr and Li [Sr+Li] is preferably 0.0 mol%, and more preferably in the order of 0.2 mol%, 0.4 mol%, 0.6 mol%, 0.8 mol%, 1.0 mol%, and 1.2 mol%, from the viewpoint of improving the melting properties of the glass raw material. The upper limit of the total content [Sr+Li] is preferably 11.4 mol%, and more preferably in the order of 10.6 mol%, 9.8 mol%, 9.0 mol%, 4.0 mol%, 3.6 mol%, 3.2 mol%, 2.8 mol%, 2.4 mol%, 2.0 mol%, and 1.8 mol%, from the viewpoint of suppressing the volatilization of glass components.

[0060] Furthermore, in the optical glass according to this embodiment, the content of Li and Sr expressed in mass percent is defined as C(Li) and C(Sr), respectively. Let the atomic weights of Li and Sr be M(Li) and M(Sr), respectively. J1=[{C(Li) / M(Li)}+{C(Sr) / M(Sr)}]×100 In that case, The lower limit of J1 is preferably 0 from the viewpoint of improving the melting properties of the glass raw material, and more preferably in the order of 0.6, 1.2, 1.8, 2.4, 3.0, and 3.6. The upper limit of J1 is preferably 42.0 from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 39.0, 36.6, 34.2, 31.8, 29.4, 27.0, 12.0, 10.8, 9.6, 8.4, 7.2, 6.0, and 5.4.

[0061] In the optical glass according to this embodiment, the lower limit of the total content of Y, La, Gd, Yb, and Lu [Y+La+Gd+Yb+Lu] is preferably 0.0 mol%, and more preferably in the order of 0.04 mol%, 0.08 mol%, 0.12 mol%, 0.16 mol%, 0.20 mol%, 0.24 mol%, 0.28 mol%, 0.32 mol%, 0.36 mol%, and 0.40 mol%. The upper limit of the total content [Y+La+Gd+Yb+Lu] is preferably 2.0 mol%, and more preferably in the order of 1.6 mol%, 1.4 mol%, 1.2 mol%, 1.0 mol%, 0.90 mol%, and 0.80 mol%, from the viewpoint of improving the melting properties of the glass raw material and improving devitrification resistance during melting. The upper limit of the total content [Y+La+Gd+Yb+Lu] can be set to 0.52 mol%, 0.48 mol%, 0.44 mol%, or 0.40 mol%, from the viewpoint of improving stability during reheating and not reducing the brittleness of the glass.

[0062] Furthermore, in the optical glass according to this embodiment, the mass percentage content of Y, La, Gd, Yb, and Lu is defined as C(Y), C(La), C(Gd), C(Yb), and C(Lu), respectively. Let the atomic weights of Y, La, Gd, Yb, and Lu be M(Y), M(La), M(Gd), M(Yb), and M(Lu), respectively. K1=[{C(Y) / M(Y)}+{C(La) / M(La)}+{C(Gd) / M(Gd)}+{C(Yb) / M(Yb)}+{C(Lu) / M(Lu)}]×100 In that case, The lower limit of K1 is preferably 0 from the viewpoint of increasing the refractive index nd and improving chemical durability, and is more preferably 0.12, 0.24, 0.36, 0.48, 0.60, 0.72, 0.84, 0.96, 1.08, 1.20, 1.32, and 1.44 in that order. The upper limit of K1 is preferably 9.00 from the viewpoint of improving the melting properties of the glass raw material and improving devitrification resistance during melting, and is more preferably 7.50, 6.00, 4.80, 4.20, 3.60, 3.00, 2.70, 2.40, and 1.56 in that order. The upper limit of K1 can also be 1.44, 1.32, or 1.20 from the viewpoint of improving stability during reheating and not reducing the brittleness of the glass.

[0063] In the optical glass according to this embodiment, the lower limit of the O content is preferably 5 mol%, and more preferably in the order of 8 mol%, 10 mol%, 12 mol%, 13 mol%, and 14 mol%, from the viewpoint of suppressing the volatilization of glass components. The upper limit of the O content is preferably 47 mol%, and more preferably in the order of 46 mol%, 44 mol%, 42 mol%, 40 mol%, and 36 mol%, from the viewpoint of improving stability during reheating. Furthermore, the lower limit of the O content can also be 28 mol%, 32 mol%, 36 mol%, 38 mol%, or 39 mol%, particularly from the viewpoint of increasing the refractive index nd of the glass and suppressing striations caused by the volatilization of glass components. The upper limit of the O content can also be 32 mol%, 28 mol%, 26 mol%, 25 mol%, or 24 mol%, from the viewpoint of improving the melting properties of the glass raw material and improving devitrification resistance during melting.

[0064] Furthermore, in the optical glass according to this embodiment, the lower limit of the O content is preferably 2.42% by mass, from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 3.88% by mass, 4.85% by mass, 5.82% by mass, 6.30% by mass, and 6.79% by mass. The upper limit of the O content is preferably 32.00% by mass, from the viewpoint of improving stability during reheating, and more preferably in the order of 29.33% by mass, 27.73% by mass, 26.13% by mass, 25.07% by mass, 24.53% by mass, 23.47% by mass, 22.40% by mass, and 21.33% by mass. In addition, the lower limit of the O content can also be 13.58% by mass, 15.51% by mass, 17.45% by mass, 18.42% by mass, 18.91% by mass, or 19.39% by mass, particularly from the viewpoint of increasing the refractive index nd of the glass and suppressing striations caused by the volatilization of glass components. The upper limit of the O content can also be set to 19.20% by mass, 17.07% by mass, 14.93% by mass, 13.87% by mass, 13.33% by mass, or 12.80% by mass, from the viewpoint of improving the melting properties of the glass raw material and improving its resistance to devitrification during melting.

[0065] In the optical glass according to this embodiment, the lower limit of the F content is preferably 10 mol%, and more preferably in the order of 13 mol%, 16 mol%, 18 mol%, 19 mol%, and 20 mol%, from the viewpoint of improving stability during reheating. The upper limit of the F content is preferably 60 mol%, and more preferably in the order of 58 mol%, 57 mol%, 56 mol%, and 55 mol%, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the F content can also be 36 mol%, 40 mol%, 42 mol%, 44 mol%, or 45 mol%, from the viewpoint of further improving low dispersibility and anomalous partial dispersibility. The upper limit of the F content can also be 38 mol%, 34 mol%, 30 mol%, 28 mol%, 27 mol%, or 26 mol%, from the viewpoint of increasing the refractive index nd.

[0066] Furthermore, in the optical glass according to this embodiment, the lower limit of the F content is preferably 5.76% by mass, from the viewpoint of improving stability during reheating, and more preferably in the order of 7.48% by mass, 9.21% by mass, 10.36% by mass, 10.94% by mass, and 11.51% by mass. The upper limit of the F content is preferably 44.33% by mass, from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 41.16% by mass, 39.26% by mass, 38.00% by mass, 36.73% by mass, 36.10% by mass, 35.46% by mass, and 34.83% by mass. The lower limit of the F content can also be 20.73% by mass, 23.03% by mass, 24.18% by mass, 25.33% by mass, 25.91% by mass, or 26.48% by mass, from the viewpoint of further improving low dispersibility and anomalous partial dispersibility. The upper limit of the F content can also be set to 24.06 mass%, 21.53 mass%, 19.00 mass%, 17.73 mass%, 17.10 mass%, or 16.47 mass%, from the viewpoint of increasing the refractive index nd.

[0067] In the optical glass according to this embodiment, the lower limit of the Cl content is preferably 0.00 mol%, and more preferably in the order of 0.01 mol%, 0.02 mol%, 0.03 mol%, 0.04 mol%, and 0.05 mol%. The upper limit of the Cl content is preferably 2.40 mol%, and more preferably in the order of 1.60 mol%, 1.20 mol%, 0.80 mol%, 0.40 mol%, 0.32 mol%, 0.28 mol%, 0.24 mol%, 0.20 mol%, and 0.16 mol%.

[0068] Furthermore, in the optical glass according to this embodiment, the lower limit of the Cl content is preferably 0% by mass from the viewpoint of promoting clarity, and more preferably in the order of 0.01% by mass, 0.02% by mass, 0.03% by mass, 0.04% by mass, and 0.05% by mass. The upper limit of the Cl content is preferably 2.84% by mass from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 1.89% by mass, 1.42% by mass, 0.95% by mass, 0.47% by mass, 0.38% by mass, 0.33% by mass, 0.28% by mass, 0.24% by mass, and 0.19% by mass.

[0069] In the optical glass according to this embodiment, the lower limit of the P content is preferably 0.8 mol%, from the viewpoint of improving stability during reheating, and is more preferably in the order of 1.6 mol%, 2.0 mol%, 2.4 mol%, 2.8 mol%, 3.2 mol%, 3.6 mol%, 3.8 mol%, 4.0 mol%, 4.2 mol%, and 4.4 mol%. Furthermore, the upper limit of the P content is preferably 16.0 mol%, from the viewpoint of improving the refractive index nd, and is more preferably in the order of 15.0 mol%, 14.0 mol%, 13.6 mol%, 13.2 mol%, 12.8 mol%, 12.4 mol%, 12.0 mol%, 11.6 mol%, 11.4 mol%, and 11.2 mol%.

[0070] Furthermore, in the optical glass according to this embodiment, the lower limit of the P content is preferably 0.751 mass%, from the viewpoint of improving stability during reheating, and more preferably in the order of 1.500 mass%, 1.880 mass%, 2.250 mass%, 2.630 mass%, 3.000 mass%, 3.380 mass%, 3.570 mass%, 3.750 mass%, 3.940 mass%, and 4.130 mass%. Furthermore, the upper limit of the P content is preferably 18.58 mass%, from the viewpoint of improving the refractive index nd, and more preferably in the order of 17.55 mass%, 16.52 mass%, 15.49 mass%, 14.45 mass%, 14.04 mass%, 13.63 mass%, 13.22 mass%, 12.80 mass%, 12.39 mass%, 11.98 mass%, 11.77 mass%, and 11.56 mass%.

[0071] In the optical glass according to this embodiment, the lower limit of the Al content is preferably 2.00 mol%, and more preferably in the order of 2.60 mol%, 3.00 mol%, 3.40 mol%, 3.80 mol%, 4.20 mol%, 4.60 mol%, 5.00 mol%, 5.40 mol%, 5.80 mol%, and 6.20 mol%. Furthermore, the upper limit of the Al content is preferably 16.0 mol%, and more preferably in the order of 15.0 mol%, 14.0 mol%, 13.2 mol%, 12.6 mol%, 12.0 mol%, 11.6 mol%, 11.2 mol%, 10.8 mol%, and 10.4 mol%.

[0072] Furthermore, in the optical glass according to this embodiment, the lower limit of the Al content is preferably 1.64% by mass, from the viewpoint of improving chemical durability, and more preferably in the order of 2.13% by mass, 2.45% by mass, 2.78% by mass, 3.11% by mass, 3.43% by mass, 3.76% by mass, 4.09% by mass, 4.42% by mass, 4.74% by mass, 5.07% by mass, 5.40% by mass, and 5.56% by mass. Furthermore, the upper limit of the Al content is preferably 14.39% by mass, from the viewpoint of improving stability during reheating, and more preferably in the order of 13.49% by mass, 12.59% by mass, 11.87% by mass, 11.33% by mass, 10.79% by mass, 10.43% by mass, 10.07% by mass, 9.71% by mass, and 9.35% by mass.

[0073] In the optical glass according to this embodiment, the upper limit of the B content is preferably 1.6 mol%, and more preferably in the order of 1.2 mol%, 0.8 mol%, 0.6 mol%, 0.5 mol%, 0.4 mol%, 0.3 mol%, 0.2 mol%, and 0.1 mol%. The lower limit of the B content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material. The B content may also be 0 mol%.

[0074] Furthermore, in the optical glass according to this embodiment, the upper limit of the B content is preferably 0.58% by mass, from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 0.43% by mass, 0.29% by mass, 0.22% by mass, 0.18% by mass, 0.14% by mass, 0.11% by mass, 0.07% by mass, and 0.04% by mass. The lower limit of the B content is preferably 0% by mass, from the viewpoint of maintaining the melting properties of the glass raw material. The B content may also be 0% by mass.

[0075] In the optical glass according to this embodiment, the upper limit of the Si content is preferably 1.60 mol%, and more preferably in the order of 1.20 mol%, 0.80 mol%, 0.40 mol%, and 0.20 mol%, from the viewpoint of maintaining melting properties and thermal stability and suppressing the volatilization of glass components. The lower limit of the Si content is preferably 0 mol%, and the Si content may be 0 mol%.

[0076] Furthermore, in the optical glass according to this embodiment, the upper limit of the Si content is preferably 1.50% by mass, and more preferably in the order of 1.12% by mass, 0.75% by mass, 0.37% by mass, and 0.19% by mass, from the viewpoint of maintaining melting properties and thermal stability and suppressing the volatilization of glass components. The lower limit of the Si content is preferably 0% by mass. The Si content may also be 0% by mass.

[0077] In the glass according to this embodiment, the upper limit of the Li content is preferably 6.80 mol%, and more preferably in the order of 6.40 mol%, 6.00 mol%, 5.60 mol%, 5.20 mol%, 4.40 mol%, 4.00 mol%, 3.60 mol%, 3.20 mol%, 2.80 mol%, and 2.40 mol%. The lower limit of the Li content is preferably 0 mol%, and more preferably in the order of 0.08 mol%, 0.12 mol%, 0.14 mol%, 0.16 mol%, and 0.20 mol%.

[0078] Furthermore, in the glass according to this embodiment, the upper limit of the Li content is preferably 1.85% by mass, from the viewpoint of suppressing the volatilization of glass components, and is more preferably in the order of 1.67% by mass, 1.57% by mass, 1.48% by mass, 1.39% by mass, 1.30% by mass, 1.20% by mass, 1.02% by mass, 0.93% by mass, 0.83% by mass, 0.74% by mass, 0.65% by mass, and 0.56% by mass. Furthermore, the lower limit of the Li content is preferably 0% by mass, from the viewpoint of improving the melting properties of the glass raw material, and is more preferably in the order of 0.017% by mass, 0.025% by mass, 0.029% by mass, 0.034% by mass, and 0.042% by mass.

[0079] In the glass according to this embodiment, the upper limit of the Na content is preferably 6.00 mol%, and more preferably in the order of 5.20 mol%, 4.40 mol%, 3.60 mol%, 2.80 mol%, 2.00 mol%, 1.60 mol%, 1.20 mol%, 0.80 mol%, and 0.40 mol%. The lower limit of the Na content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material. The Na content may also be 0 mol%.

[0080] Furthermore, in the glass according to this embodiment, the upper limit of the Na content is preferably 4.60% by mass, from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 3.98% by mass, 3.37% by mass, 2.76% by mass, 2.15% by mass, 1.53% by mass, 1.23% by mass, 0.92% by mass, 0.61% by mass, and 0.31% by mass. The lower limit of the Na content is preferably 0% by mass, from the viewpoint of maintaining the solubility of the glass raw material. The Na content may also be 0% by mass.

[0081] In the optical glass according to this embodiment, the upper limit of the K content is preferably 5.20 mol%, and more preferably in the order of 4.40 mol%, 3.60 mol%, 2.80 mol%, 2.00 mol%, 1.60 mol%, 1.20 mol%, 0.80 mol%, and 0.40 mol%. The lower limit of the K content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material. The K content may also be 0 mol%.

[0082] Furthermore, in the optical glass according to this embodiment, the upper limit of the K content is preferably 6.78% by mass, from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 5.73% by mass, 4.69% by mass, 3.65% by mass, 2.61% by mass, 2.09% by mass, 1.56% by mass, 1.04% by mass, and 0.52% by mass. The lower limit of the K content is preferably 0% by mass, from the viewpoint of maintaining the melting properties of the glass raw material. The K content may also be 0% by mass.

[0083] In the optical glass according to this embodiment, the upper limit of the Cs content is preferably 1.60 mol%, and more preferably in the order of 1.20 mol%, 0.80 mol%, 0.40 mol%, and 0.20 mol%. The lower limit of the Cs content is preferably 0 mol%. The Cs content may be 0 mol%. Cs has the function of improving the thermal stability of the glass, but if the content is high, the chemical durability and weather resistance may decrease. For this reason, it is preferable to keep the Cs content within the above range.

[0084] In the optical glass according to this embodiment, the upper limit of the Cs content is preferably 7.09% by mass, and more preferably in the order of 5.32% by mass, 3.54% by mass, 1.77% by mass, and 0.89% by mass. The lower limit of the Cs content is preferably 0% by mass. The Cs content may be 0% by mass. Cs has the function of improving the thermal stability of the glass, but if the content is high, the chemical durability and weather resistance may decrease. For this reason, it is preferable to keep the Cs content within the above range.

[0085] In the optical glass according to this embodiment, the lower limit of the Mg content is preferably 0 mol%, and more preferably in the order of 0.08 mol%, 0.16 mol%, 0.24 mol%, 0.32 mol%, 0.36 mol%, and 0.40 mol%, from the viewpoint of improving stability during reheating, mechanical strength, and thermal shock resistance. Furthermore, the upper limit of the Mg content is preferably 9.2 mol%, and more preferably in the order of 8.4 mol%, 7.6 mol%, 6.8 mol%, 6.0 mol%, 5.2 mol%, 4.4 mol%, 3.6 mol%, and 2.8 mol%, from the viewpoint of improving devitrification resistance during melting.

[0086] Furthermore, in the optical glass according to this embodiment, the lower limit of the Mg content is preferably 0% by mass, from the viewpoint of improving stability during reheating, mechanical strength, and thermal shock resistance, and is more preferably in the order of 0.06% by mass, 0.12% by mass, 0.18% by mass, 0.24% by mass, 0.27% by mass, and 0.29% by mass. Furthermore, the upper limit of the Mg content is preferably 7.45% by mass, from the viewpoint of improving resistance to devitrification during melting, and is more preferably in the order of 6.81% by mass, 6.16% by mass, 5.51% by mass, 4.86% by mass, 4.21% by mass, 3.56% by mass, 2.92% by mass, and 2.27% by mass.

[0087] In the optical glass according to this embodiment, the lower limit of the Ca content is preferably 0 mol%, and more preferably in the order of 0.04 mol%, 0.08 mol%, 0.12 mol%, 0.16 mol%, 0.18 mol%, and 0.20 mol%, from the viewpoint of improving stability during reheating, mechanical strength, and thermal shock resistance. Furthermore, the upper limit of the Ca content is preferably 13.8 mol%, and more preferably in the order of 13.0 mol%, 12.2 mol%, 11.4 mol%, 10.6 mol%, 9.8 mol%, 9.0 mol%, 8.2 mol%, and 7.4 mol%, from the viewpoint of improving devitrification resistance during melting.

[0088] Furthermore, in the optical glass according to this embodiment, the lower limit of the Ca content is preferably 0 mass%, and more preferably in the order of 0.05 mass%, 0.10 mass%, 0.15 mass%, 0.19 mass%, 0.22 mass%, and 0.24 mass%, from the viewpoint of improving stability during reheating, mechanical strength, and thermal shock resistance. Furthermore, the upper limit of the Ca content is preferably 18.44 mass%, and more preferably in the order of 17.37 mass%, 16.30 mass%, 15.23 mass%, 14.16 mass%, 13.09 mass%, 12.02 mass%, 10.95 mass%, and 9.89 mass%, from the viewpoint of improving devitrification resistance during melting.

[0089] In the optical glass according to this embodiment, the lower limit of the Sr content is preferably 0 mol%, and more preferably in the order of 0.02 mol%, 0.04 mol%, 0.06 mol%, 0.08 mol%, and 0.10 mol%, from the viewpoint of increasing the refractive index nd. Furthermore, the upper limit of the Sr content is preferably 12.2 mol%, and more preferably in the order of 11.4 mol%, 10.6 mol%, 9.8 mol%, 9.0 mol%, 8.2 mol%, 7.4 mol%, 6.6 mol%, and 5.8 mol%, from the viewpoint of increasing stability during reheating.

[0090] Furthermore, in the optical glass according to this embodiment, the lower limit of the Sr content is preferably 0 mass%, from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.05 mass%, 0.11 mass%, 0.16 mass%, 0.21 mass%, and 0.27 mass%. Furthermore, from the viewpoint of improving stability during reheating, the upper limit of the Sr content is preferably 35.63 mass%, and more preferably in the order of 33.30 mass%, 30.96 mass%, 28.62 mass%, 26.29 mass%, 23.95 mass%, 21.61 mass%, 19.28 mass%, and 16.94 mass%.

[0091] In the optical glass according to this embodiment, the lower limit of the Ba content is preferably 0.4 mol%, from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.8 mol%, 1.2 mol%, 1.6 mol%, 2.0 mol%, 2.2 mol%, 2.4 mol%, 2.6 mol%, 2.8 mol%, 3.0 mol%, and 3.1 mol%. The upper limit of the Ba content is preferably 17.0 mol%, from the viewpoint of improving stability during reheating, and more preferably in the order of 16.0 mol%, 15.0 mol%, 14.0 mol%, 13.2 mol%, 12.6 mol%, 11.8 mol%, 11.4 mol%, 11.0 mol%, 10.8 mol%, and 10.6 mol%.

[0092] Furthermore, in the optical glass according to this embodiment, the lower limit of the Ba content is preferably 1.66 mass%, from the viewpoint of increasing the refractive index nd, and more preferably in the order of 3.33 mass%, 4.99 mass%, 6.66 mass%, 8.32 mass%, 9.16 mass%, 9.99 mass%, 10.82 mass%, 11.65 mass%, 12.48 mass%, and 12.90 mass%. The upper limit of the Ba content is preferably 86.97 mass%, from the viewpoint of increasing stability during reheating, and more preferably in the order of 82.40 mass%, 77.82 mass%, 73.24 mass%, 68.66 mass%, 64.09 mass%, 60.42 mass%, 57.68 mass%, 54.02 mass%, 52.18 mass%, 50.35 mass%, 49.44 mass%, and 48.52 mass%.

[0093] In the optical glass according to this embodiment, the upper limit of the Zn content is preferably 2.0 mol%, and more preferably 1.6 mol%, 1.2 mol%, 0.8 mol%, and 0.4 mol%, in that order, from the viewpoint of improving the solubility of the glass raw material. The lower limit of the Zn content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd. The Zn content may also be 0 mol%.

[0094] Furthermore, in the optical glass according to this embodiment, the upper limit of the Zn content is preferably 4.36% by mass, from the viewpoint of improving the melting properties of the glass raw material, and more preferably in the order of 3.49% by mass, 2.62% by mass, 1.74% by mass, and 0.87% by mass. The lower limit of the Zn content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd. The Zn content may also be 0% by mass.

[0095] In the optical glass according to this embodiment, the lower limit of the total content of Mg, Ca, Sr, Ba, and Zn [Mg+Ca+Sr+Ba+Zn] is preferably 8.0 mol%, and more preferably in the order of 10.0 mol%, 11.0 mol%, 11.0 mol%, and 12.0 mol%, from the viewpoint of increasing the refractive index nd. The upper limit of the total content is preferably 25.0 mol%, and more preferably in the order of 23.0 mol%, 21.0 mol%, 19.0 mol%, 18.0 mol%, and 17.0 mol%, from the viewpoint of increasing stability during reheating.

[0096] Furthermore, in the optical glass according to this embodiment, the mass percentage content of Mg, Ca, Sr, Ba, and Zn is defined as C(Mg), C(Ca), C(Sr), C(Ba), and C(Zn), respectively. Let the atomic weights of Mg, Ca, Sr, Ba, and Zn be M(Mg), M(Ca), M(Sr), M(Ba), and M(Zn), respectively. L1=[{C(Mg) / M(Mg)}+{C(Ca) / M(Ca)}+{C(Sr) / M(Sr)}+{C(Ba) / M(Ba)}+{C(Zn) / M(Zn)}]×100 In that case, The lower limit of L1 is preferably 24.0 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 30.0, 33.0, and 36.0. The upper limit of L1 is preferably 75.0 from the viewpoint of increasing stability during reheating, and more preferably in the order of 69.0, 63.0, 60.0, and 58.0.

[0097] In the optical glass according to this embodiment, the lower limit of the total content of Sr, Ba, and Zn [Sr+Ba+Zn] is preferably 3.0 mol%, and more preferably in the order of 4.0 mol%, 5.0 mol%, 6.0 mol%, 7.0 mol%, and 8.0 mol%, from the viewpoint of increasing the refractive index nd. The upper limit of the total content is preferably 20.0 mol%, and more preferably in the order of 18.0 mol%, 16.0 mol%, 14.0 mol%, 13.0 mol%, and 12.0 mol%, from the viewpoint of increasing stability during reheating.

[0098] In the optical glass according to this embodiment, the mass percentage content of Sr, Ba, and Zn is expressed as C(Sr), C(Ba), and C(Zn), respectively. Let the atomic weights of Sr, Ba, and Zn be M(Sr), M(Ba), and M(Zn), respectively. M1=[{C(Sr) / M(Sr)}+{C(Ba) / M(Ba)}+{C(Zn) / M(Zn)}]×100 In that case, The lower limit of M1 is preferably 9.0 from the viewpoint of increasing the refractive index, and more preferably in the order of 12.0, 15.0, 18.0, 21.0, and 24.0. The upper limit of M1 is preferably 60 from the viewpoint of increasing stability during reheating, and more preferably in the order of 54, 48, 42, 39, and 37.

[0099] In the optical glass according to this embodiment, the lower limit of the total content of Sr and Ba [Sr+Ba] is preferably 2.8 mol%, and more preferably in the order of 3.8 mol%, 4.8 mol%, 5.8 mol%, 6.8 mol%, and 7.8 mol%, from the viewpoint of increasing the refractive index nd. The upper limit of the total content is preferably 19.8 mol%, and more preferably in the order of 17.8 mol%, 15.8 mol%, 13.8 mol%, 12.8 mol%, and 11.8 mol%, from the viewpoint of increasing stability during reheating.

[0100] In the optical glass according to this embodiment, the mass percentage content of Sr and Ba is expressed as C(Sr) and C(Ba), respectively. Let the atomic weights of Sr, Ba, and Zn be M(Sr) and M(Ba), respectively. M2=[{C(Sr) / M(Sr)}+{C(Ba) / M(Ba)}]×100 In that case, The lower limit of M2 is preferably 8.8 from the viewpoint of increasing the refractive index, and more preferably in the order of 11.8, 14.8, 17.8, 20.8, and 23.8. The upper limit of M2 is preferably 59.8 from the viewpoint of increasing stability during reheating, and more preferably in the order of 53.8, 47.8, 41.8, 38.8, and 36.8.

[0101] In the optical glass according to this embodiment, the upper limit of the La content is preferably 2.0 mol%, and more preferably 1.6 mol%, 1.2 mol%, 0.8 mol%, and 0.4 mol%, in that order, from the viewpoint of improving the solubility of the glass raw material. The lower limit of the La content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd. The La content may be 0 mol%.

[0102] Furthermore, in the optical glass according to this embodiment, the upper limit of the La content is preferably 9.26% by mass, from the viewpoint of improving the melting properties of the glass raw material, and more preferably in the order of 7.41% by mass, 5.56% by mass, 3.70% by mass, and 1.85% by mass. The lower limit of the La content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd. The La content may also be 0% by mass.

[0103] In the glass according to this embodiment, the upper limit of the Gd content is preferably 2.0 mol%, and more preferably 1.6 mol%, 1.2 mol%, 0.8 mol%, and 0.4 mol%, in that order, from the viewpoint of improving the melting properties of the glass raw material, suppressing the rise in raw material costs, and stabilizing the raw material supply. The lower limit of the Gd content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd. The Gd content may also be 0 mol%.

[0104] Furthermore, in the glass according to this embodiment, the upper limit of the Gd content is preferably 10.48% by mass, from the viewpoint of improving the melting properties of the glass raw material, suppressing the rise in raw material costs, and stabilizing the raw material supply, and is more preferably 8.39% by mass, 6.29% by mass, 4.19% by mass, and 2.10% by mass, in that order. Also, the lower limit of the Gd content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd. The Gd content may be 0% by mass.

[0105] In the glass according to this embodiment, the lower limit of the Y content is preferably 0 mol%, from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.04 mol%, 0.08 mol%, 0.12 mol%, 0.16 mol%, 0.20 mol%, 0.22 mol%, and 0.24 mol%. Furthermore, the upper limit of the Y content is preferably 3.0 mol%, from the viewpoint of increasing the melting properties of the glass raw material, and more preferably in the order of 2.4 mol%, 2.0 mol%, 1.6 mol%, 1.2 mol%, 1.0 mol%, 0.8 mol%, 0.6 mol%, and 0.4 mol%.

[0106] Furthermore, in the glass according to this embodiment, the lower limit of the Y content is preferably 0 mass%, from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.11 mass%, 0.22 mass%, 0.32 mass%, 0.43 mass%, 0.54 mass%, 0.59 mass%, and 0.65 mass%. Furthermore, the upper limit of the Y content is preferably 8.89 mass%, from the viewpoint of increasing the melting properties of the glass raw material, and more preferably in the order of 7.11 mass%, 5.93 mass%, 4.74 mass%, 3.56 mass%, 2.96 mass%, 2.37 mass%, 1.78 mass%, and 1.19 mass%.

[0107] In the glass according to this embodiment, the upper limit of the Lu content is preferably 1.6 mol%, and more preferably in the order of 1.2 mol%, 0.8 mol%, 0.4 mol%, and 0.2 mol%, from the viewpoint of improving the melting properties of the glass raw material, suppressing the rise in raw material costs, and stabilizing the raw material supply. The lower limit of the Lu content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd. The Lu content may also be 0 mol%.

[0108] Furthermore, in the glass according to this embodiment, the upper limit of the Lu content is preferably 9.33% by mass, from the viewpoint of improving the melting properties of the glass raw material, suppressing the rise in raw material costs, and stabilizing the raw material supply, and is more preferably 7.00% by mass, 4.67% by mass, 2.33% by mass, and 1.17% by mass, in that order. Also, the lower limit of the Lu content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd. The Lu content may be 0% by mass.

[0109] In the glass according to this embodiment, the upper limit of the Yb content is preferably 1.6 mol%, and more preferably in the order of 1.2 mol%, 0.8 mol%, 0.4 mol%, and 0.2 mol%, from the viewpoint of improving the melting properties of the glass raw material, suppressing the rise in raw material costs, and stabilizing the raw material supply. The lower limit of the Yb content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd. The Yb content may also be 0 mol%.

[0110] Furthermore, in the glass according to this embodiment, the upper limit of the Yb content is preferably 9.23% by mass, from the viewpoint of improving the melting properties of the glass raw material, suppressing the rise in raw material costs, and stabilizing the raw material supply, and is more preferably 6.92% by mass, 4.61% by mass, 2.31% by mass, and 1.15% by mass, in that order. Also, the lower limit of the Yb content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd. The Yb content may be 0% by mass.

[0111] In the optical glass according to this embodiment, the upper limit of the Nb content is preferably 2.00 mol%, and more preferably in the order of 1.60 mol%, 1.20 mol%, 0.80 mol%, 0.40 mol%, 0.20 mol%, 0.14 mol%, 0.10 mol%, 0.06 mol%, and 0.02 mol%, from the viewpoint of providing absorption in the ultraviolet region and suppressing variations in the ultraviolet absorption edge during manufacturing, and more preferably in the order of 0.002 mol%, 0.004 mol%, and 0.008 mol%, from the viewpoint of providing absorption in the ultraviolet region and suppressing variations in the ultraviolet absorption edge during manufacturing. The lower limit of the Nb content is preferably 0 mol%, and more preferably in the order of 0.002 mol%, 0.004 mol%, and 0.008 mol%, from the viewpoint of providing absorption in the ultraviolet region and suppressing variations in the ultraviolet absorption edge during manufacturing. The Nb content may also be 0 mol%.

[0112] Furthermore, in the optical glass according to this embodiment, the upper limit of the Nb content is preferably 6.19 mass%, in order of preference, from the viewpoint of suppressing the formation of fluorides with high vapor pressure, thereby suppressing the occurrence of striations, and further maintaining low dispersibility, and more preferably 4.96 mass%, 3.72 mass%, 2.48 mass%, 1.24 mass%, 0.62 mass%, 0.43 mass%, 0.31 mass%, 0.19 mass%, and 0.06 mass%. The lower limit of the Nb content is preferably 0 mass%, in order of preference, from the viewpoint of providing absorption in the ultraviolet region and suppressing variations in the ultraviolet absorption edge during manufacturing, and more preferably 0.006 mass%, 0.011 mass%, and 0.023 mass%. The Nb content may also be 0 mass%.

[0113] In the optical glass according to this embodiment, the upper limit of the Ti content is preferably 2.0 mol%, and more preferably in the order of 1.6 mol%, 1.2 mol%, 0.8 mol%, and 0.4 mol%. The lower limit of the Ti content is preferably 0 mol%. The Ti content may be 0 mol%. From the viewpoint of suppressing the formation of fluorides with high vapor pressure, thereby suppressing the occurrence of striations, and further maintaining low dispersibility, it is preferable to set the Ti content within the above range.

[0114] Furthermore, in the optical glass according to this embodiment, the upper limit of the Ti content is preferably 3.19% by mass, and more preferably in the order of 2.55% by mass, 1.91% by mass, 1.28% by mass, and 0.64% by mass. The lower limit of the Ti content is preferably 0% by mass. The Ti content may be 0% by mass. From the viewpoint of suppressing the formation of fluorides with high vapor pressure, thereby suppressing the occurrence of striations, and further maintaining low dispersibility, it is preferable to set the Ti content within the above range.

[0115] In the optical glass according to this embodiment, the upper limit of the W content is preferably 2.0 mol%, and more preferably in the order of 1.6 mol%, 1.2 mol%, 0.8 mol%, and 0.4 mol%. The lower limit of the W content is preferably 0 mol%. The W content may be 0 mol%. From the viewpoint of suppressing the formation of fluorides with high vapor pressure, thereby suppressing the occurrence of striations, and further maintaining low dispersibility, it is preferable to set the W content within the above range.

[0116] Furthermore, in the optical glass according to this embodiment, the upper limit of the W content is preferably 12.26% by mass, and more preferably in the order of 9.80% by mass, 7.35% by mass, 4.90% by mass, and 2.45% by mass. The lower limit of the W content is preferably 0% by mass. The W content may be 0% by mass. From the viewpoint of suppressing the formation of fluorides with high vapor pressure, thereby suppressing the occurrence of striations, and further maintaining low dispersibility, it is preferable to set the W content within the above range.

[0117] In the optical glass according to this embodiment, the upper limit of the Bi content is preferably 2.0 mol%, and more preferably in the order of 1.6 mol%, 1.2 mol%, 0.8 mol%, and 0.4 mol%. The lower limit of the Bi content is preferably 0 mol%. The Bi content may be 0 mol%. From the viewpoint of suppressing the formation of fluorides with high vapor pressure, thereby suppressing the occurrence of striations, and further maintaining low dispersibility, it is preferable to set the Bi content within the above range.

[0118] Furthermore, in the optical glass according to this embodiment, the upper limit of the Bi content is preferably 13.93% by mass, and more preferably in the order of 11.15% by mass, 8.36% by mass, 5.57% by mass, and 2.79% by mass. The lower limit of the Bi content is preferably 0% by mass. The Bi content may be 0% by mass. From the viewpoint of suppressing the formation of fluorides with high vapor pressure, thereby suppressing the occurrence of striations, and further maintaining low dispersibility, it is preferable to set the Bi content within the above range.

[0119] In the optical glass according to this embodiment, the upper limit of the Zr content is preferably 2.0 mol%, and more preferably 1.6 mol%, 1.2 mol%, 0.8 mol%, and 0.4 mol%, in that order, from the viewpoint of improving the melting properties of the glass raw material. The lower limit of the Zr content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd. The Zr content may be 0 mol%.

[0120] Furthermore, in the optical glass according to this embodiment, the upper limit of the Zr content is preferably 6.08% by mass, from the viewpoint of improving the melting properties of the glass raw material, and more preferably in the order of 4.87% by mass, 3.65% by mass, 2.43% by mass, and 1.22% by mass. The lower limit of the Zr content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd. The Zr content may be 0% by mass.

[0121] In the optical glass according to this embodiment, the upper limit of the Ta content is preferably 2.0 mol%, and more preferably in the order of 1.6 mol%, 1.2 mol%, 0.8 mol%, and 0.4 mol%. The lower limit of the Ta content is preferably 0 mol%. The Ta content may be 0 mol%. From the viewpoint of suppressing the formation of fluorides with high vapor pressure, thereby suppressing the occurrence of striations, and further maintaining low dispersibility, it is preferable to set the Ta content within the above range.

[0122] Furthermore, in the optical glass according to this embodiment, the upper limit of the Ta content is preferably 12.06% by mass, and more preferably in the order of 9.65% by mass, 7.24% by mass, 4.83% by mass, and 2.41% by mass. The lower limit of the Ta content is preferably 0% by mass. The Ta content may be 0% by mass. From the viewpoint of suppressing the formation of fluorides with high vapor pressure, thereby suppressing the occurrence of striations, and further maintaining low dispersibility, it is preferable to set the Ta content within the above range.

[0123] In the glass according to this embodiment, the Sc content is preferably 2 mol% or less. Furthermore, the lower limit of the Sc content is preferably 0 mol%.

[0124] Furthermore, in the glass according to this embodiment, the Sc content is preferably 2.0% by mass or less, more preferably 1.0% by mass or less. The lower limit of the Sc content is preferably 0% by mass.

[0125] In the glass according to this embodiment, the Hf content is preferably 2 mol% or less. Furthermore, the lower limit of the Hf content is preferably 0 mol%.

[0126] Furthermore, in the glass according to this embodiment, the Hf content is preferably 3.0% by mass or less, preferably 1.5% by mass or less, and more preferably 0.8% by mass or less. The lower limit of the Hf content is preferably 0% by mass.

[0127] Sc and Hf enhance the high dispersibility of glass and are also expensive components. Therefore, it is preferable that the respective contents of Sc and Hf are within the above ranges.

[0128] In the glass according to this embodiment, the Ge content is preferably 2 mol% or less. Furthermore, the lower limit of the Ge content is preferably 0 mol%.

[0129] Furthermore, in the glass according to this embodiment, the Ge content is preferably 2% by mass, and preferably 1% by mass. The lower limit of the Ge content is preferably 0% by mass.

[0130] Ge enhances the high dispersibility of glass and is by far the most expensive component among commonly used glass components. Therefore, from the viewpoint of reducing the cost of glass manufacturing, it is preferable that the Ge content be within the above range.

[0131] The glass according to this embodiment is preferably composed mainly of the above-mentioned glass components, namely, O, F, P, Al, and Ba as essential components, and B, Si, Li, Na, K, Cs, Mg, Ca, Sr, Zn, La, Gd, Y, Lu, Yb, Nb, Ti, W, Bi, Zr, Ta, Sc, Hf, and Ge as optional components. The total content of the above-mentioned glass components is preferably 95 mol% or more, more preferably 98 mol% or more, even more preferably 99 mol% or more, and particularly preferably 99.5 mol% or more. Furthermore, the total content of the above-mentioned glass components is preferably 95% by mass or more, more preferably 98% by mass or more, even more preferably 99% by mass or more, and particularly preferably 99.5% by mass or more.

[0132] While the glass according to this embodiment is preferably composed of the above-mentioned glass components, it may also contain other components as long as they do not hinder the effects of the present invention. Furthermore, the present invention does not exclude the inclusion of unavoidable impurities.

[0133] In addition to the above components, the optical glass may also contain a small amount of Sb as a clarifying agent. The upper limit of the Sb content (amount added externally) is preferably 0.20 mol%, and more preferably in the order of 0.16 mol%, 0.12 mol%, 0.08 mol%, 0.04 mol%, 0.01 mol%, 0.008 mol%, 0.006 mol%, 0.004 mol%, and 0.002 mol%. The lower limit of the Sb content (amount added externally) is 0 mol%. The Sb content (amount added externally) may be 0 mol%. Furthermore, the upper limit of the Sb content (amount added externally) is preferably 0.81 mass%, and more preferably in the order of 0.65 mass%, 0.49 mass%, 0.32 mass%, 0.16 mass%, 0.04 mass%, 0.03 mass%, 0.02 mass%, and 0.01 mass%. The lower limit of the Sb content (amount added externally) is 0% by mass. The Sb content (amount added externally) may be 0% by mass.

[0134] External addition amount refers to the amount of fining agent added, expressed as a mole percentage or mass percentage, when the total content of all glass components excluding the fining agent is taken as 100%.

[0135] Furthermore, the above optical glass provides high transmittance over a wide range of the visible spectrum. To take advantage of these features, it is preferable that the glass does not contain coloring elements. Examples of coloring elements include Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, and V. It is preferable that the amount of any of these elements be less than 100 ppm by mass, more preferably 0 to 80 ppm by mass, even more preferably 0 to 50 ppm by mass, and particularly preferable that they be substantially absent.

[0136] Ga, Te, Tb, etc. are components that do not need to be introduced and are also expensive components. Therefore, the content of Ga, Te, and Tb is preferably 0 to 0.1 mol%, more preferably 0 to 0.05 mol%, even more preferably 0 to 0.01 mol%, even more preferably 0 to 0.005 mol%, and even more preferably 0 to 0.001 mol%. Furthermore, the content of Ga, Te, and Tb is preferably 0 to 0.1 mass%, more preferably 0 to 0.05 mass%, even more preferably 0 to 0.01 mass%, even more preferably 0 to 0.005 mass%, and even more preferably 0 to 0.001 mass%. It is particularly preferable that Ga, Te, and Tb are substantially absent.

[0137] (Glass properties) <Abbe number νd> In the optical glass according to this embodiment, the lower limit of the Abbe number νd is preferably 60.0, but can also be 65.0, 68.0, 68.5, 69.0, 69.5, or 70.0. The upper limit of the Abbe number νd is preferably 94, but can also be 92, 91, 90, 89, 79, 77, 75, 74, 73, or 72. From the viewpoint of improving low dispersion and suppressing the occurrence of chromatic aberration (color bleeding) when combined with high-dispersion glass, the lower limit of the Abbe number νd can also be 82.0, 83.0, 84.0, or 84.5.

[0138] The Abbe number νd can be adjusted to a desired value by appropriately adjusting the content of each glass component. Components that relatively increase the Abbe number νd, i.e., low-dispersion components, include Si, B, Li, Na, K, La, Ba, Ca, Sr, etc. On the other hand, components that relatively decrease the Abbe number νd, i.e., high-dispersion components, include Nb, Ti, Zr, W, Bi, Ta, etc.

[0139] <refractive index nd> In the optical glass according to this embodiment, the lower limit of the refractive index nd is preferably 1.30, but can also be 1.35, 1.40, 1.42, 1.43, 1.44, or 1.45. The upper limit of the refractive index nd is preferably 1.65, but can also be 1.62, 1.61, 1.60, 1.59, 1.55, 1.54, 1.53, 1.52, 1.51, or 1.50. The lower limit of the refractive index nd can also be 1.50, 1.51, 1.52, or 1.53, from the viewpoint of shortening the focal length of the optical element by having a high refractive index and suppressing aberrations such as field curvature.

[0140] The refractive index nd can be adjusted to the desired value by appropriately adjusting the content of each glass component. Components that relatively increase the refractive index nd (high refractive index components) include Nb, Ti, Zr, Ta, La, Y, Gd, Ba, Sr, and Zn. On the other hand, components that relatively decrease the refractive index nd (low refractive index components) include Si, B, P, Li, Na, K, Mg, and Ca.

[0141] <Stability during reheating> In this embodiment, it is preferable that the optical glass does not become cloudy when heated for 10 minutes in a test furnace set to a temperature 130 to 160°C higher than the glass transition temperature Tg. More preferably, no devitrification is observed inside the glass by visual inspection, even more preferably, no crystals are observed when the inside of the glass is observed under a microscope, and even more preferably, no crystals precipitate inside the glass. The stability during reheating can be controlled by adjusting the molar ratios [O / P], [P / Al], [F / Al], [Ba / P], etc.

[0142] The stability during reheating is measured as follows: The length, width, and height dimensions are 10.0 mm ± 5.0 mm, and the volume of the sample is 512 mm³. 3 The above describes the procedure for performing primary and secondary heating on glass samples that are generally rectangular in shape. Both primary and secondary heating are performed using two test furnaces with sufficiently large heat capacities for the glass samples. Hereafter, these test furnaces will be referred to as the primary heating furnace and the secondary heating furnace.

[0143] The aforementioned rectangular glass sample is placed in a primary heating furnace maintained at a predetermined primary heating temperature. Primary heating is performed under conditions that ensure the glass sample is thoroughly heated during secondary heating and that do not promote crystal precipitation or the formation of crystal nuclei during primary heating. Specifically, the lower limit of the primary heating temperature is set to 20°C lower than the glass transition temperature Tg of the glass sample (Tg-20°C), and the upper limit of the primary heating temperature is set to 15°C higher than the glass transition temperature Tg of the glass sample (Tg+15°C). The primary heating time is set to 10 to 30 minutes.

[0144] After the primary heating is complete, the glass sample is removed from the furnace and immediately transferred to a secondary heating furnace maintained at a predetermined secondary heating temperature. The secondary heating temperature should be 130-160°C higher than the glass transition temperature (Tg) of the glass sample. The secondary heating time should be 10 minutes.

[0145] After secondary heating is complete, remove the glass sample from the furnace and allow it to cool to room temperature in the air. Visually inspect the glass sample for any clouding or devitrification. Also, examine the inside of the glass under a microscope to check for the presence of crystals.

[0146] During primary and secondary heating, to ensure consistent heating conditions for the glass sample placed in the test furnace, the glass sample is placed in the center of the furnace on a refractory plate or base. The primary and secondary heating temperatures mentioned above refer to the temperature at the location where the glass sample is placed. Furthermore, to suppress adhesion of the glass sample, reduce heat transfer from the furnace body, and heat the glass primarily through heat transfer from the furnace atmosphere, the glass sample is placed on a low-reactivity powder such as boron nitride or alumina. The contact surface between these powders and the glass sample is excluded from observation in the stability test.

[0147] <Specific gravity> In the optical glass according to this embodiment, the specific gravity is preferably 4.25 or less, and more preferably 4.20 or less, 4.18 or less, and 4.15 or less, in that order. The lower limit of the specific gravity is not particularly limited, but is usually 3.50. The specific gravity is measured by the Archimedes method. The specific gravity tends to increase with the introduction of elements with large atomic weights, such as Ba, La, Gd, Lu, and Yb, and tends to decrease with the introduction of elements with small atomic weights, such as Mg and P. On the other hand, even with elements with relatively small atomic weights, the specific gravity tends to increase with the introduction of components that contribute to increasing the elemental packing density in the glass, such as Li and Al. The specific gravity can be controlled by adjusting the content of these components.

[0148] <Glass transition temperature Tg and stabilization index ΔT> The stability of the optical glass according to this embodiment during reheating can also be evaluated using the stabilization index ΔT described in Reference 2 (Yamane, NEW GLASS No. 7, pp. 19-30 (1987)). Here, Tx is the rise temperature of the exothermic peak of crystallization, and Tg is the glass transition temperature. ΔT is the difference between Tx and Tg, and is expressed as ΔT = Tx - Tg. Tg and Tx can be obtained by analysis according to the figure (Figure 1) disclosed in Reference 2.

[0149] In the optical glass according to this embodiment, the glass transition temperature Tg is preferably 550°C or lower, and more preferably in the order of 540°C or lower, 535°C or lower, 530°C or lower, and 520°C or lower, from the viewpoint of lowering the temperature at which the glass is slowly cooled, the temperature at which it is heated and softened, or the press temperature. The lower limit of the glass transition temperature Tg is not particularly limited, but is usually 380°C. From the viewpoint of making the network structure of the glass stronger and suppressing glass cracking, or from the viewpoint of reducing the thermal expansion of the glass and improving the heat resistance of the glass, the lower limit of the glass transition temperature Tg is preferably 390°C, and more preferably in the order of 400°C, 410°C, 420°C, 430°C, and 440°C or higher. In particular, for glass with a high refractive index, the F content is small and in order of increasing the heat resistance of the glass, the lower limit of the glass transition temperature Tg can be preferably 460°C, and more preferably in the order of 480°C, 500°C, 510°C, 520°C, 530°C, and 535°C or higher. The glass transition temperature (Tg) can be controlled primarily by adjusting the content of Li, Na, and K, their total content, the content of F, and the content, molar ratio [P / Al], and molar ratio [Ba / P] of Zn.

[0150] In the optical glass according to this embodiment, the stabilization index ΔT, which is the difference (Tx-Tg) between the rise temperature Tx of the crystallization exothermic peak and the glass transition temperature Tg, is preferably 100°C or higher, and more preferably 110°C or higher, 115°C or higher, 120°C or higher, 125°C or higher, and 130°C or higher, in that order, with the most preferable being that the rise temperature of the crystallization exothermic peak is no longer observed. The upper limit of the stabilization index ΔT is not particularly limited, but is usually 300°C. ΔT is one of the factors that contribute to improving reheating stability, and can be controlled by adjusting the molar ratios [O / P], [P / Al], [F / Al], [Ba / P], etc., in roughly the same way as reheating stability.

[0151] (Manufacturing of optical glass) The optical glass according to this embodiment is a glass having a high refractive index and low dispersion characteristics, that is, a glass with anomalous partial dispersion, and is suitable for any of the direct press method, reheat press method, or precision press molding method.

[0152] The optical glass according to this embodiment can be obtained by weighing and blending raw materials such as phosphates, fluorides, and oxides to obtain the desired glass composition, thoroughly mixing them to form a mixed batch, heating and melting it in a melting vessel, degassing and stirring to produce a homogeneous and bubble-free molten glass, and then molding it. Specifically, it can be manufactured using known melting methods.

[0153] [Optical element blanks, glass materials for press molding, and methods for manufacturing the same] Another aspect of the present invention is, An optical element blank made of the aforementioned optical glass; Glass material for press molding, consisting of the optical glass described above; A method for manufacturing a press-formable glass material, comprising a step of forming the optical glass described above into a press-formable glass material; and, A method for manufacturing an optical element blank, comprising the step of producing an optical element blank by press molding using a press molding die after softening the above-mentioned press-molding glass material by heating, Regarding.

[0154] An optical element blank is an optical element base material that approximates the shape of the target optical element and includes processing allowances such as polishing allowances. The optical element is finished by polishing the surface of the optical element blank at least. An optical element blank can be manufactured by press molding using a press molding die after softening the press molding glass material made of the above-mentioned optical glass by heating. The above-mentioned optical glass exhibits excellent devitrification resistance, which prevents crystal precipitation in the glass due to heating during press molding.

[0155] Heating and press forming of glass materials for press forming can both be performed in the atmosphere. For example, by uniformly applying a powdered release agent such as boron nitride to the surface of the glass material for press forming, and then heating and press forming it, it is possible to reliably prevent the glass from fusing with the mold and to smoothly stretch the glass along the molding surface of the press forming die. By annealing the glass after press forming to reduce internal distortion, a homogeneous optical element blank can be obtained.

[0156] On the other hand, glass materials for press molding, also called preforms, include not only those that are used for press molding in their original state (hereinafter referred to as "material 1"), but also those that are used for press molding after undergoing known machining (hereinafter referred to as "material 2"). For example, the optical glass described above can be formed into a glass material for press molding by the method illustrated below. (1) A method of forming a glass plate by casting molten glass into a mold (hereinafter referred to as "Method 1"); (2) A method of producing multiple glass pieces called cut pieces by annealing the glass plate produced by Method 1 and then cutting it to a desired size; (3) A method of barrel polishing multiple glass pieces prepared by Method 2 (hereinafter referred to as "Method 3"); (4) A method of forming a glass mass by letting molten glass flow down from a pipe and receiving it with a mold (hereinafter referred to as "Method 4"); (5) A method of barrel polishing after annealing the glass ingot obtained by Method 4 (hereinafter referred to as "Method 5").

[0157] Examples of material 1 mentioned above include glass materials produced by methods 3, 4, and 5 described above. On the other hand, examples of material 2 include materials produced by methods 1, 2, and 4.

[0158] [Optical elements and methods for manufacturing the same] Another aspect of the present invention is, An optical element made of the aforementioned optical glass; A method for manufacturing an optical element, comprising the step of producing an optical element by at least polishing the optical element blank described above (hereinafter referred to as "Method A"); A method for manufacturing an optical element (hereinafter referred to as "Method B") comprising the step of manufacturing an optical element by precision press molding using a press molding die after softening the above-mentioned press-molded glass material by heating, Regarding.

[0159] In Method A, polishing can be performed using known methods, and by thoroughly cleaning and drying the surface of the optical element after processing, an optical element with high internal and surface quality can be obtained. Method A is suitable as a method for manufacturing various spherical lenses, prisms, and other optical elements. The optical element blank may be ground using known methods before the polishing process.

[0160] Method B, also known as mold optics molding, is a method of forming the optical functional surface of an optical element by transferring the molding surface of a press molding die. Here, the surface of an optical element that transmits, refracts, diffracts, or reflects light rays is called the optical functional surface. For example, in the case of a lens, the lens surface, such as the aspherical surface of an aspherical lens or the spherical surface of a spherical lens, corresponds to the optical functional surface. The precision press molding method is a method of forming the optical functional surface by press molding by precisely transferring the molding surface of a press molding die to glass. In other words, there is no need to add mechanical processing such as grinding or polishing to finish the optical functional surface. The precision press molding method is suitable for manufacturing optical elements such as lenses, lens arrays, diffraction gratings, and prisms, and is particularly optimal as a method for manufacturing aspherical lenses with high productivity.

[0161] In one embodiment of the precision press forming method, a preform with a clean surface is formed, and the viscosity of the glass constituting the preform is 10 5 ~10 11The preform is reheated to a temperature within the range of Pa·s, and then press-molded using a mold equipped with an upper and lower die. A release film may be provided on the molding surface of the mold as needed. It is preferable to perform the press molding in a nitrogen gas or inert gas atmosphere to prevent oxidation of the molding surface of the mold. The press-molded product is removed from the mold and slowly cooled as needed. If the molded product is an optical element such as a lens, an optical thin film may be coated on the surface as needed. In this way, optical elements such as lenses, lens arrays, diffraction gratings, and prisms made of optical glass suitable for various molding methods can be manufactured.

[0162] The first, second, and third embodiments of the above-described embodiment are described below as preferred embodiments.

[0163] First Embodiment The first embodiment is one of the preferred embodiments of the above-described embodiment. In the first embodiment, by controlling the ratio of P content to Al content and the ratio of O content to P content, we succeeded in creating an optical glass that ensures a relatively high refractive index and anomalous partial dispersion, suppresses striations by reducing the volatilization of glass components, and improves stability during reheating. As preferred embodiments of the first embodiment, the 1-1 embodiment and the 1-2 embodiment are shown.

[0164] Embodiment 1-1 The optical glass according to the 1-1 embodiment is preferably, The molar ratio of F content to Al content [F / Al] is 2.70 to 4.60. The molar ratio of Ba content to P content [Ba / P] is 0.100 to 1.10. The molar ratio of P content to Al content [P / Al] is 1.50 to 2.00. The molar ratio [O / P] of oxygen to phosphorus is between 3.55 and 4.00.

[0165] Furthermore, the optical glass according to the 1-1 embodiment is preferably, The mass percentage content of F, Al, Ba, P, and O is expressed as C(F), C(Al), C(Ba), C(P), and C(O), respectively. Let the atomic weights of F, Al, Ba, P, and O be M(F), M(Al), M(Ba), M(P), and M(O), respectively. A1 = {C(F) / M(F)} / {C(Al) / M(Al)} B1 = {C(Ba) / M(Ba)} / {C(P) / M(P)} C1 = {C(P) / M(P)} / {C(Al) / M(Al)} D1 = {C(O) / M(O)} / {C(P) / M(P)} In that case, A1 is 2.70-4.60, B1 is between 0.100 and 1.10. C1 is between 1.50 and 2.00. D1 is between 3.55 and 4.00.

[0166] Embodiments 1-2 The optical glass according to the first and second embodiments is preferably, The molar ratio of F content to Al content [F / Al] is 2.50 to 4.60. The molar ratio of Ba content to P content [Ba / P] is 0.250 to 1.20. The molar ratio of P content to Al content [P / Al] is 1.50 to 2.00. The molar ratio [O / P] of oxygen to phosphorus is between 3.55 and 3.80.

[0167] Furthermore, the optical glass according to the first and second embodiments is preferably, The mass percentage content of F, Al, Ba, P, and O is expressed as C(F), C(Al), C(Ba), C(P), and C(O), respectively. Let the atomic weights of F, Al, Ba, P, and O be M(F), M(Al), M(Ba), M(P), and M(O), respectively. A1 = {C(F) / M(F)} / {C(Al) / M(Al)} B1 = {C(Ba) / M(Ba)} / {C(P) / M(P)} C1 = {C(P) / M(P)} / {C(Al) / M(Al)} D1 = {C(O) / M(O)} / {C(P) / M(P)} In that case, A1 is between 2.50 and 4.60. B1 is between 0.250 and 1.20. C1 is between 1.50 and 2.00. D1 is between 3.55 and 3.80.

[0168] The content and ratio of glass components in the optical glass according to the first embodiment (Embodiment 1-1 and Embodiment 1-2) will be described in detail below.

[0169] In the optical glass according to the first embodiment, the lower limit of the molar ratio [F / Al] of F content to Al content is preferably 2.50 from the viewpoint of improving stability during reheating, and is more preferably in the order of 2.55, 2.60, 2.65, and 2.70. Furthermore, the upper limit of the molar ratio [F / Al] is preferably 4.60 from the viewpoint of suppressing the volatilization of glass components, and is more preferably in the order of 4.50, 4.20, 3.90, 3.60, and 3.40.

[0170] Furthermore, in the optical glass according to the first embodiment, the mass percentage content of F and Al is expressed as C(F) and C(Al), respectively. Let the atomic weights of F and Al be M(F) and M(Al), respectively. A1 = {C(F) / M(F)} / {C(Al) / M(Al)} In that case, The lower limit of A1 is preferably 2.50 from the viewpoint of improving stability during reheating, and more preferably in the order of 2.55, 2.60, 2.65, and 2.70. The upper limit of A1 is preferably 4.60 from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 4.50, 4.20, 3.90, 3.60, and 3.40.

[0171] In the optical glass according to the first embodiment, the lower limit of the molar ratio [Ba / P] of Ba content to P content is preferably 0.100 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.250, 0.700, 0.740, 0.770, 0.790, and 0.800. Furthermore, the upper limit of the molar ratio [Ba / P] is preferably 1.20 from the viewpoint of increasing stability during reheating, and more preferably in the order of 1.15, 1.10, 1.05, and 1.00.

[0172] Furthermore, in the optical glass according to the first embodiment, the mass percentage content of Ba and P is expressed as C(Ba) and C(P), respectively. Let the atomic weights of Ba and P be M(Ba) and M(P), respectively. B1 = {C(Ba) / M(Ba)} / {C(P) / M(P)} In that case, The lower limit of B1 is preferably 0.100 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.250, 0.700, 0.740, 0.770, 0.790, and 0.800. The upper limit of B1 is preferably 1.20 from the viewpoint of increasing stability during reheating, and more preferably in the order of 1.15, 1.10, 1.07, 1.05, 1.03, and 1.00.

[0173] In the optical glass according to the first embodiment, the lower limit of the molar ratio [P / Al] of P content to Al content is preferably 1.50 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 1.51, 1.52, and 1.53. The upper limit of the molar ratio [P / Al] is preferably 2.00 from the viewpoint of increasing stability during reheating, and more preferably in the order of 1.90, 1.85, 1.80, and 1.75.

[0174] Furthermore, in the optical glass according to the first embodiment, the mass percentage content of Al and P is expressed as C(Al) and C(P), respectively. Let the atomic weights of Al and P be M(Al) and M(P), respectively. C1 = {C(P) / M(P)} / {C(Al) / M(Al)} In that case, The lower limit of C1 is preferably 1.50 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 1.51, 1.52, and 1.53. The upper limit of C1 is preferably 2.00 from the viewpoint of improving stability during reheating, and more preferably in the order of 1.90, 1.85, 1.80, and 1.75.

[0175] In the optical glass according to the first embodiment, the lower limit of the molar ratio [O / P] of O content to P content is preferably 3.55 from the viewpoint of suppressing the volatilization of glass components, and is more preferably in the order of 3.53, 3.55, 3.57, and 3.59. Furthermore, the upper limit of the molar ratio [O / P] is preferably 4.00 from the viewpoint of improving stability during reheating, and is more preferably in the order of 3.90, 3.85, 3.82, and 3.80.

[0176] Furthermore, in the optical glass according to the first embodiment, the mass percentage content of P and O is expressed as C(P) and C(O), respectively. Let the atomic weights of P and O be M(P) and M(O), respectively. D1 = {C(O) / M(O)} / {C(P) / M(P)} In that case, The lower limit of D1 is preferably 3.55 from the viewpoint of suppressing the volatilization of glass components, and is more preferably in the order of 3.53, 3.55, 3.57, and 3.59. The upper limit of D1 is preferably 4.00 from the viewpoint of improving stability during reheating, and is more preferably in the order of 3.90, 3.85, 3.82, and 3.80.

[0177] In the optical glass according to the first embodiment, the lower limit of the molar ratio [(Ba+Sr+Zn) / P] of the total content of Ba, Sr, and Zn to the content of P is preferably 0.700 from the viewpoint of increasing the refractive index, and more preferably in the order of 0.750, 0.800, 0.850, and 0.900. The upper limit of the molar ratio [(Ba+Sr+Zn) / P] is preferably 1.30 from the viewpoint of increasing stability during reheating, and more preferably in the order of 1.25, 1.20, 1.15, and 1.10.

[0178] Furthermore, in the optical glass according to the first embodiment, the mass percentage content of P, Sr, Ba, and Zn is defined as C(P), C(Sr), C(Ba), and C(Zn), respectively. Let the atomic weights of P, Sr, Ba, and Zn be M(P), M(Sr), M(Ba), and M(Zn), respectively. I1=[{C(Ba) / M(Ba)}+{C(Sr) / M(Sr)}+{C(Zn) / M(Zn)}] / {C(P) / M(P)} In that case, The lower limit of I1 is preferably 0.700 from the viewpoint of increasing the refractive index, and more preferably in the order of 0.750, 0.800, 0.850, and 0.900. The upper limit of I1 is preferably 1.30 from the viewpoint of increasing stability during reheating, and more preferably in the order of 1.25, 1.20, 1.15, and 1.10.

[0179] In the optical glass according to the first embodiment, the upper limit of the total content of Sr and Li [Sr+Li] is preferably 12 mol%, and more preferably 10 mol%, 8 mol%, 6 mol%, and 5 mol%, in that order, from the viewpoint of suppressing the volatilization of the glass components. The lower limit of the total content [Sr+Li] is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material.

[0180] Furthermore, in the optical glass according to the first embodiment, the content of Li and Sr expressed in mass percent is defined as C(Li) and C(Sr), respectively. Let the atomic weights of Li and Sr be M(Li) and M(Sr), respectively. J1=[{C(Li) / M(Li)}+{C(Sr) / M(Sr)}]×100 In that case, The upper limit of J1 is preferably 12, and more preferably 10, 8, 6, and 5 in that order, from the viewpoint of suppressing the volatilization of glass components. The lower limit of J1 is preferably 0, from the viewpoint of maintaining the melting properties of the glass raw material.

[0181] In the optical glass according to the first embodiment, the lower limit of the molar ratio [(Ba+Sr) / P] of the total content of Ba and Sr to the content of P is preferably 0.700, and more preferably in the order of 0.740, 0.770, 0.790, and 0.800, from the viewpoint of improving the melting properties of the glass raw material. Furthermore, the upper limit of the molar ratio [(Ba+Sr) / P] is preferably 1.20, and more preferably in the order of 1.15, 1.10, 1.05, and 1.00, from the viewpoint of suppressing the volatilization of glass components.

[0182] Furthermore, in the optical glass according to the first embodiment, the mass percentage content of P, Sr, and Ba is defined as C(P), C(Sr), and C(Ba), respectively. Let the atomic weights of P, Sr, and Ba be M(P), M(Sr), and M(Ba), respectively. N1=[{C(Ba) / M(Ba)}+{C(Sr) / M(Sr)}] / {C(P) / M(P)} In that case, The lower limit of N1 is preferably 0.700, and more preferably in the order of 0.740, 0.770, 0.790, and 0.800, from the viewpoint of improving the melting properties of the glass raw material. The upper limit of N1 is preferably 1.20, and more preferably in the order of 1.15, 1.10, 1.05, and 1.00, from the viewpoint of suppressing the volatilization of glass components.

[0183] In the optical glass according to the first embodiment, the lower limit of the O content is preferably 30 mol%, and more preferably in the order of 33 mol%, 35 mol%, 36 mol%, 37 mol%, and 38 mol%, from the viewpoint of suppressing the volatilization of glass components. The upper limit of the O content is preferably 60 mol%, and more preferably in the order of 56 mol%, 52 mol%, 50 mol%, 49 mol%, and 48 mol%, from the viewpoint of improving stability during reheating.

[0184] Furthermore, in the optical glass according to the first embodiment, the lower limit of the O content is preferably 16.00% by mass, from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 17.60% by mass, 18.67% by mass, 19.2% by mass, 19.73% by mass, and 20.27% by mass. The upper limit of the O content is preferably 29.09% by mass, from the viewpoint of improving stability during reheating, and more preferably in the order of 27.15% by mass, 25.21% by mass, 24.24% by mass, 23.76% by mass, and 23.27% by mass.

[0185] In the optical glass according to the first embodiment, the lower limit of the F content is preferably 8 mol%, and more preferably in the order of 11 mol%, 14 mol%, 16 mol%, 17 mol%, and 18 mol%, from the viewpoint of improving stability during reheating. The upper limit of the F content is preferably 35 mol%, and more preferably in the order of 33 mol%, 31 mol%, 29 mol%, 28 mol%, and 27 mol%, from the viewpoint of suppressing the volatilization of glass components.

[0186] Furthermore, in the optical glass according to the first embodiment, the lower limit of the F content is preferably 5.07% by mass, from the viewpoint of improving stability during reheating, and more preferably in the order of 6.97% by mass, 8.87% by mass, 10.13% by mass, 10.77% by mass, and 11.40% by mass. The upper limit of the F content is preferably 20.15% by mass, from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 19.00% by mass, 17.85% by mass, 16.70% by mass, 16.12% by mass, and 15.54% by mass.

[0187] In the optical glass according to the first embodiment, the lower limit of the P content is preferably 2.0 mol%, and more preferably in the order of 4.0 mol%, 6.0 mol%, 8.0 mol%, and 9.0 mol%, from the viewpoint of improving stability during reheating. Furthermore, the upper limit of the P content is preferably 25 mol%, and more preferably in the order of 22 mol%, 18 mol%, 15 mol%, 14 mol%, and 13 mol%, from the viewpoint of improving the refractive index nd.

[0188] Furthermore, in the optical glass according to the first embodiment, the lower limit of the P content is preferably 2.10% by mass, from the viewpoint of improving stability during reheating, and more preferably in the order of 4.13% by mass, 6.19% by mass, 8.26% by mass, and 9.29% by mass. Furthermore, the upper limit of the P content is preferably 23.46% by mass, from the viewpoint of improving the refractive index nd, and more preferably in the order of 20.65% by mass, 16.89% by mass, 14.08% by mass, 13.14% by mass, and 12.20% by mass.

[0189] In the optical glass according to the first embodiment, the lower limit of the Al content is preferably 1.0 mol%, and more preferably in the order of 2.0 mol%, 3.0 mol%, 4.0 mol%, and 5.0 mol%, from the viewpoint of improving chemical durability. The upper limit of the Al content is preferably 18 mol%, and more preferably in the order of 12 mol%, 11 mol%, 10 mol%, and 9 mol%, from the viewpoint of improving stability during reheating.

[0190] Furthermore, in the optical glass according to the first embodiment, the lower limit of the Al content is preferably 0.9% by mass, and more preferably in the order of 1.8% by mass, 2.7% by mass, 3.6% by mass, and 4.5% by mass, from the viewpoint of improving chemical durability. Furthermore, the upper limit of the Al content is preferably 14.72% by mass, and more preferably in the order of 12.26% by mass, 9.81% by mass, 8.99% by mass, 8.18% by mass, and 7.36% by mass, from the viewpoint of improving stability during reheating.

[0191] In the optical glass according to the first embodiment, the upper limit of the B content is preferably 10 mol%, and more preferably 8 mol%, 6 mol%, 4 mol%, 3 mol%, and 2 mol%, in that order, from the viewpoint of suppressing the volatilization of the glass components. The lower limit of the B content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material. The B content may also be 0 mol%.

[0192] Furthermore, in the optical glass according to the first embodiment, the upper limit of the B content is preferably 3.28% by mass, from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 2.62% by mass, 1.97% by mass, 1.31% by mass, 0.98% by mass, and 0.66% by mass. Also, the lower limit of the B content is preferably 0% by mass, from the viewpoint of maintaining the melting properties of the glass raw material. The B content may also be 0% by mass.

[0193] In the glass according to the first embodiment, the upper limit of the Li content is preferably 10 mol%, and more preferably in the order of 8 mol%, 6 mol%, 4 mol%, 3 mol%, and 2 mol%, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the Li content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material.

[0194] Furthermore, in the glass according to the first embodiment, the upper limit of the Li content is preferably 2.10% by mass, from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 1.68% by mass, 1.26% by mass, 0.84% ​​by mass, 0.63% by mass, and 0.42% by mass. Also, the lower limit of the Li content is preferably 0% by mass, from the viewpoint of maintaining the melting properties of the glass raw material.

[0195] In the glass according to the first embodiment, the upper limit of the Na content is preferably 10 mol%, and more preferably in the order of 8 mol%, 6 mol%, 4 mol%, 3 mol%, and 2 mol%, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the Na content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material. The Na content may be 0 mol%.

[0196] Furthermore, in the glass according to the first embodiment, the upper limit of the Na content is preferably 6.97% by mass, from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 5.57% by mass, 4.18% by mass, 2.79% by mass, 2.09% by mass, and 1.39% by mass. The lower limit of the Na content is preferably 0% by mass, from the viewpoint of maintaining the solubility of the glass raw material. The Na content may also be 0% by mass.

[0197] In the optical glass according to the first embodiment, the upper limit of the K content is preferably 10 mol%, and more preferably in the order of 8 mol%, 6 mol%, 4 mol%, 3 mol%, and 2 mol%, from the viewpoint of suppressing the volatilization of the glass components. The lower limit of the K content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material. The K content may be 0 mol%.

[0198] Furthermore, in the optical glass according to the first embodiment, the upper limit of the K content is preferably 11.85% by mass, from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 9.48% by mass, 7.11% by mass, 4.74% by mass, 3.55% by mass, and 2.37% by mass. The lower limit of the K content is preferably 0% by mass, from the viewpoint of maintaining the melting properties of the glass raw material. The K content may also be 0% by mass.

[0199] In the optical glass according to the first embodiment, the upper limit of the Mg content is preferably 10 mol%, and more preferably in the order of 8 mol%, 6 mol%, 4 mol%, 3 mol%, and 2 mol%, from the viewpoint of improving resistance to devitrification during melting. The lower limit of the Mg content is preferably 0 mol%, from the viewpoint of maintaining stability during reheating.

[0200] Furthermore, in the optical glass according to the first embodiment, the upper limit of the Mg content is preferably 7.37% by mass, and more preferably in the order of 5.89% by mass, 4.42% by mass, 2.95% by mass, and 2.21% by mass, from the viewpoint of improving resistance to devitrification during melting. The lower limit of the Mg content is preferably 0% by mass, from the viewpoint of maintaining stability during reheating.

[0201] In the optical glass according to the first embodiment, the upper limit of the Ca content is preferably 10 mol%, and more preferably in the order of 8 mol%, 6 mol%, 4 mol%, 3 mol%, and 2 mol%, from the viewpoint of improving resistance to devitrification during melting. The lower limit of the Ca content is preferably 0 mol%, from the viewpoint of maintaining stability during reheating.

[0202] Furthermore, in the optical glass according to the first embodiment, the upper limit of the Ca content is preferably 12.14% by mass, from the viewpoint of improving resistance to devitrification during melting, and more preferably in the order of 9.72% by mass, 7.29% by mass, 4.86% by mass, and 3.64% by mass. Also, the lower limit of the Ca content is preferably 0% by mass, from the viewpoint of maintaining stability during reheating.

[0203] In the optical glass according to the first embodiment, the upper limit of the Sr content is preferably 10 mol%, and more preferably in the order of 8 mol%, 6 mol%, 4 mol%, 3 mol%, and 2 mol%, from the viewpoint of improving resistance to devitrification during melting. The lower limit of the Sr content is preferably 0 mol%, from the viewpoint of maintaining stability during reheating.

[0204] Furthermore, in the optical glass according to the first embodiment, the upper limit of the Sr content is preferably 26.55% by mass, from the viewpoint of improving resistance to devitrification during melting, and more preferably in the order of 21.24% by mass, 15.93% by mass, 10.62% by mass, and 5.31% by mass. Also, the lower limit of the Sr content is preferably 0% by mass, from the viewpoint of maintaining stability during reheating.

[0205] In the optical glass according to the first embodiment, the lower limit of the Ba content is preferably 1 mol%, and more preferably 3 mol%, 5 mol%, 7 mol%, and 8 mol%, in that order, from the viewpoint of increasing the refractive index nd. The upper limit of the Ba content is preferably 20 mol%, and more preferably 18 mol%, 16 mol%, 14 mol%, 13 mol%, and 12 mol%, in that order, from the viewpoint of increasing stability during reheating.

[0206] Furthermore, in the optical glass according to the first embodiment, the lower limit of the Ba content is preferably 4.58 mass%, from the viewpoint of increasing the refractive index nd, and more preferably in the order of 13.73 mass%, 22.89 mass%, 32.04 mass%, and 36.62 mass%. The upper limit of the Ba content is preferably 83.23 mass%, from the viewpoint of increasing stability during reheating, and more preferably in the order of 74.91 mass%, 66.58 mass%, 58.26 mass%, 54.1 mass%, and 49.94 mass%.

[0207] In the optical glass according to the first embodiment, the upper limit of the Zn content is preferably 10 mol%, and more preferably 8 mol%, 6 mol%, 4 mol%, 3 mol%, and 2 mol%, in that order, from the viewpoint of improving the solubility of the glass raw material. The lower limit of the Zn content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd. The Zn content may also be 0 mol%.

[0208] Furthermore, in the optical glass according to the first embodiment, the upper limit of the Zn content is preferably 19.82% by mass, from the viewpoint of improving the solubility of the glass raw material, and more preferably in the order of 15.86% by mass, 11.89% by mass, 7.93% by mass, 5.95% by mass, and 3.96% by mass. Also, the lower limit of the Zn content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd. The Zn content may be 0% by mass.

[0209] In the optical glass according to the first embodiment, the upper limit of the La content is preferably 8 mol%, and more preferably in the order of 6 mol%, 4 mol%, 3 mol%, 2 mol%, and 1 mol%, from the viewpoint of improving the melting properties of the glass raw material. The lower limit of the La content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd. The La content may also be 0 mol%.

[0210] Also, in the optical glass according to the first embodiment, the upper limit of the La content is preferably 33.67% by mass from the viewpoint of enhancing the melting property of the glass raw materials, and more preferably 25.26% by mass, 16.84% by mass, 12.63% by mass, 8.42% by mass, 4.21% by mass in this order. Also, the lower limit of the La content is preferably 0% by mass from the viewpoint of maintaining the refractive index nd. The La content may be 0% by mass.

[0211] In the glass according to the first embodiment, the upper limit of the Gd content is preferably 4.0 mol% from the viewpoints of enhancing the melting property of the glass raw materials, suppressing the increase in raw material costs, and stabilizing the raw material supply, and more preferably 3.2 mol%, 1.6 mol%, 0.8 mol%, 0.4 mol%, 0.2 mol% in this order. Also, the lower limit of the Gd content is preferably 0 mol% from the viewpoint of maintaining the refractive index nd. The Gd content may be 0 mol%.

[0212] Also, in the glass according to the first embodiment, the upper limit of the Gd content is preferably 19.06% by mass from the viewpoints of enhancing the melting property of the glass raw materials, suppressing the increase in raw material costs, and stabilizing the raw material supply, and more preferably 15.25% by mass, 7.62% by mass, 3.81% by mass, 1.91% by mass, 0.95% by mass in this order. Also, the lower limit of the Gd content is preferably 0% by mass from the viewpoint of maintaining the refractive index nd. The Gd content may be 0% by mass.

[0213] In the glass according to the first embodiment, the upper limit of the Y content is preferably 8 mol% from the viewpoint of enhancing the melting property of the glass raw materials, and more preferably 6 mol%, 4 mol%, 3 mol%, 2 mol%, 1 mol% in this order. Also, the lower limit of the Y content is preferably 0 mol% from the viewpoint of maintaining the refractive index nd.

[0214] Furthermore, in the glass according to the first embodiment, the upper limit of the Y content is preferably 21.55% by mass, from the viewpoint of improving the melting properties of the glass raw material, and more preferably in the order of 16.16% by mass, 10.78% by mass, 8.08% by mass, 5.39% by mass, and 2.69% by mass. Also, the lower limit of the Y content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd.

[0215] In the glass according to the first embodiment, the upper limit of the Lu content is preferably 4.0 mol%, and more preferably in the order of 3.0 mol%, 2.0 mol%, 1.0 mol%, 0.5 mol%, and 0.2 mol%, from the viewpoint of improving the melting properties of the glass raw material, suppressing the rise in raw material costs, and stabilizing the raw material supply. The lower limit of the Lu content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd. The Lu content may also be 0 mol%.

[0216] Furthermore, in the glass according to the first embodiment, the upper limit of the Lu content is preferably 21.21% by mass, from the viewpoint of improving the melting properties of the glass raw material, suppressing the rise in raw material costs, and stabilizing the raw material supply, with 15.91% by mass, 10.6% by mass, 5.3% by mass, 2.65% by mass, and 1.06% by mass being more preferred in that order. Also, the lower limit of the Lu content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd. The Lu content may also be 0% by mass.

[0217] In the glass according to the first embodiment, the upper limit of the Yb content is preferably 4.0 mol%, from the viewpoint of improving the melting properties of the glass raw material, suppressing the rise in raw material costs, and stabilizing the raw material supply, and is more preferably 3.0 mol%, 2.0 mol%, 1.0 mol%, 0.5 mol%, and 0.2 mol%, in that order. The lower limit of the Yb content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd. The Yb content may also be 0 mol%.

[0218] Furthermore, in the glass according to the first embodiment, the upper limit of the Yb content is preferably 20.97% by mass, from the viewpoint of improving the melting properties of the glass raw material, suppressing the rise in raw material costs, and stabilizing the raw material supply, and is more preferably 15.73% by mass, 10.49% by mass, 5.24% by mass, 2.62% by mass, and 1.05% by mass, in that order. Also, the lower limit of the Yb content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd. The Yb content may also be 0% by mass.

[0219] In the optical glass according to the first embodiment, the upper limit of the Nb content is preferably 0.90 mol%, and more preferably in the order of 0.40 mol%, 0.20 mol%, 0.09 mol%, 0.04 mol%, and 0.02 mol%, from the viewpoint of suppressing the formation of fluorides with high vapor pressure, thereby suppressing the occurrence of striations, and further maintaining low dispersibility. The lower limit of the Nb content is preferably 0 mol%, and more preferably in the order of 0.001 mol%, 0.003 mol%, 0.005 mol%, 0.007 mol%, and 0.009 mol%, from the viewpoint of providing absorption in the ultraviolet region and suppressing variations in the ultraviolet absorption edge during manufacturing. The Nb content may also be 0 mol%.

[0220] Furthermore, in the optical glass according to the first embodiment, the upper limit of the Nb content is preferably 2.53% by mass, in order of preference, 1.13% by mass, 0.56% by mass, 0.25% by mass, 0.11% by mass, and 0.06% by mass, from the viewpoint of suppressing the formation of fluorides with high vapor pressure, thereby suppressing the occurrence of striations, and further maintaining low dispersibility. The lower limit of the Nb content is preferably 0% by mass, in order of preference, 0.01% by mass, 0.02% by mass, and 0.03% by mass, from the viewpoint of providing absorption in the ultraviolet region and suppressing variations in the ultraviolet absorption edge during manufacturing. The Nb content may also be 0% by mass.

[0221] In the optical glass according to the first embodiment, the upper limit of the Zr content is preferably 10 mol%, and more preferably in the order of 8 mol%, 6 mol%, 4 mol%, 3 mol%, and 2 mol%, from the viewpoint of improving the melting properties of the glass raw material. The lower limit of the Zr content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd. The Zr content may be 0 mol%.

[0222] Furthermore, in the optical glass according to the first embodiment, the upper limit of the Zr content is preferably 1.0% by mass, and more preferably 0.5% by mass, 0.2% by mass, and 0.1% by mass, from the viewpoint of improving the melting properties of the glass raw material. The lower limit of the Zr content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd. The Zr content may also be 0% by mass.

[0223] In the optical glass according to the first embodiment, the content and ratio of glass components other than those mentioned above can be the same as in the embodiment described above.

[0224] In the optical glass according to the first embodiment, the glass properties can be the same as those of the embodiment described above.

[0225] The manufacturing of optical glass, optical element blanks, and optical elements according to the first embodiment can be carried out in the same manner as described in the embodiment above.

[0226] Second Embodiment The second embodiment is one of the preferred embodiments of the above-described embodiment. In the second embodiment, by particularly controlling the ratio of F content to Al content to a high level, we were able to enhance low dispersibility, ensure abnormal partial dispersion, suppress striations by inhibiting the volatilization of glass components, and create an optical glass that can improve stability during reheating. As preferred embodiments of the second embodiment, the 2-1 embodiment and the 2-2 embodiment are shown.

[0227] Embodiment 2-1 The optical glass according to the 2-1st Embodiment preferably satisfies the following conditions: The molar ratio [F / Al] of the content of F to the content of Al is 4.60 to 15.0. The molar ratio [Ba / P] of the content of Ba to the content of P is 0.100 to 1.20. The molar ratio [P / Al] of the content of P to the content of Al is 0.200 to 0.900. The molar ratio [O / P] of the content of O to the content of P is 3.60 to 4.20. The molar ratio [F / (O + F + Cl)] of the content of F to the total content of O, F, and Cl is 0.010 to 0.790. The molar ratio [(Sr + Ba) / (Mg + Ca + Sr + Ba + Zn)] of the total content of Sr and Ba to the total content of Mg, Ca, Sr, Ba, and Zn is 0.00 to 0.67.

[0228] Also, the optical glass according to the 2-1st Embodiment preferably satisfies the following conditions: Let the contents of F, Al, Ba, P, O, Cl, Mg, Ca, Sr, Ba, and Zn in mass % be C(F), C(Al), C(Ba), C(P), C(O), C(Cl), C(Mg), C(Ca), C(Sr), C(Ba), and C(Zn), respectively. Let the atomic weights of F, Al, Ba, P, O, Cl, Mg, Ca, Sr, Ba, and Zn be M(F), M(Al), M(Ba), M(P), M(O), M(Cl), M(Mg), M(Ca), M(Sr), M(Ba), and M(Zn), respectively. A1 = {C(F) / M(F)} / {C(Al) / M(Al)} B1 = {C(Ba) / M(Ba)} / {C(P) / M(P)} C1 = {C(P) / M(P)} / {C(Al) / M(Al)} D1 = {C(O) / M(O)} / {C(P) / M(P)} G1 = [{C(F) / M(F)} / [{C(O) / M(O)} + {C(F) / M(F)} + {C(Cl) / M(Cl)}]] H1=[{C(Sr) / M(Sr)}+{C(Ba) / M(Ba)}] / [{C(Mg) / M(Mg)}+{C(Ca) / M(Ca)}+{C(Sr) / M(Sr)}+{C(Ba) / M(Ba)}+{C(Zn) / M(Zn)}] In that case, A1 is 4.60-15.0. B1 is between 0.100 and 1.20. C1 is between 0.200 and 0.900. D1 is 3.60-4.20, G1 is between 0.010 and 0.790. H1 is between 0.00 and 0.67.

[0229] Embodiment 2-2 The optical glass according to the second embodiment is preferably, The molar ratio of F content to Al content [F / Al] is 4.60 to 15.0. The molar ratio of Ba content to P content [Ba / P] is 0.100 to 1.20. The molar ratio of P content to Al content [P / Al] is 0.200 to 0.900. The molar ratio of O content to P content [O / P] is 3.60 to 4.20. The molar ratio of the F content to the total content of O, F, and Cl [F / (O+F+Cl)] is between 0.010 and 0.790. The total content of Li, Na, and K [Li+Na+K] is between 0.00 and 5.00 mol%.

[0230] Furthermore, the optical glass according to the second-second embodiment is preferably, The mass percentages of F, Al, Ba, P, O, Cl, Li, Na, and K are expressed as C(F), C(Al), C(Ba), C(P), C(O), C(Cl), C(Li), C(Na), and C(K), respectively. Let the atomic weights of F, Al, Ba, P, O, Cl, Li, Na, and K be M(F), M(Al), M(Ba), M(P), M(O), M(Cl), M(Li), M(Na), and M(K), respectively. A1 = {C(F) / M(F)} / {C(Al) / M(Al)} B1 = {C(Ba) / M(Ba)} / {C(P) / M(P)} C1 = {C(P) / M(P)} / {C(Al) / M(Al)} D1 = {C(O) / M(O)} / {C(P) / M(P)} G1=[{C(F) / M(F)} / [{C(O) / M(O)}+{C(F) / M(F)}+{C(Cl) / M(Cl)}]] F1=[{C(Li) / M(Li)}+{C(Na) / M(Na)}+{C(K) / M(K)}]×100 In that case, A1 is 4.60-15.0. B1 is between 0.100 and 1.20. C1 is between 0.200 and 0.900. D1 is 3.60-4.20, G1 is between 0.010 and 0.79. F1 ranges from 0.0 to 5.0.

[0231] The content and ratio of glass components in the optical glass according to the second embodiment (Embodiment 2-1 and Embodiment 2-2) will be described in detail below.

[0232] In the optical glass according to the second embodiment, the lower limit of the molar ratio [F / Al] of F content to Al content is preferably 4.60 from the viewpoint of improving stability during reheating, and more preferably in the order of 4.65, 4.70, 4.75, and 4.80. The upper limit of the molar ratio [F / Al] is preferably 15.0 from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 10.0, 8.0, 7.0, and 6.5.

[0233] Furthermore, in the optical glass according to the second embodiment, the mass percentage content of F and Al is expressed as C(F) and C(Al), respectively. Let the atomic weights of F and Al be M(F) and M(Al), respectively. A1 = {C(F) / M(F)} / {C(Al) / M(Al)} In that case, The lower limit of A1 is preferably 4.60 from the viewpoint of improving stability during reheating, and more preferably in the order of 4.65, 4.70, 4.75, and 4.80. The upper limit of A1 is preferably 15.0 from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 10.0, 8.0, 7.0, and 6.5.

[0234] In the optical glass according to the second embodiment, the lower limit of the molar ratio [Ba / P] of Ba content to P content is preferably 0.100 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.350, 0.400, 0.450, and 0.500. Furthermore, the upper limit of the molar ratio [Ba / P] is preferably 1.20 from the viewpoint of increasing stability during reheating, and more preferably in the order of 1.10, 1.08, 1.06, and 1.05.

[0235] Furthermore, in the optical glass according to the second embodiment, the mass percentage content of Ba and P is expressed as C(Ba) and C(P), respectively. Let the atomic weights of Ba and P be M(Ba) and M(P), respectively. B1 = {C(Ba) / M(Ba)} / {C(P) / M(P)} In that case, The lower limit of B1 is preferably 0.100 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.350, 0.400, 0.450, and 0.500. The upper limit of B1 is preferably 1.50 from the viewpoint of improving stability during reheating, and more preferably in the order of 1.10, 1.08, 1.06, and 1.05.

[0236] In the optical glass according to the second embodiment, the upper limit of the molar ratio [P / Al] of P content to Al content is preferably 0.900 from the viewpoint of high refractive index and low dispersion, and more preferably in the order of 0.800 and 0.700. The lower limit of the molar ratio [P / Al] is preferably 0.200 from the viewpoint of improving devitrification resistance during melting and stability during reheating, and more preferably in the order of 0.250, 0.300 and 0.350.

[0237] Furthermore, in the optical glass according to the second embodiment, the mass percentage content of Al and P is expressed as C(Al) and C(P), respectively. Let the atomic weights of Al and P be M(Al) and M(P), respectively. C1 = {C(P) / M(P)} / {C(Al) / M(Al)} In that case, The upper limit of C1 is preferably 0.900 from the viewpoint of high refractive index and low dispersion, and more preferably in the order of 0.800 and 0.700. The lower limit of C1 is preferably 0.200 from the viewpoint of improving resistance to devitrification during melting and stability during reheating, and more preferably in the order of 0.250, 0.300 and 0.350.

[0238] In the optical glass according to the second embodiment, the lower limit of the molar ratio [O / P] of O content to P content is preferably 3.60 from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 3.62, 3.64, and 3.66. Furthermore, the upper limit of the molar ratio [O / P] is preferably 4.20 from the viewpoint of improving stability during molding and reheating, and more preferably in the order of 4.10, 4.00, and 3.95.

[0239] Furthermore, in the optical glass according to the second embodiment, the mass percentage content of P and O is expressed as C(P) and C(O), respectively. Let the atomic weights of P and O be M(P) and M(O), respectively. D1 = {C(O) / M(O)} / {C(P) / M(P)} In that case, The lower limit of D1 is preferably 3.60 from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 3.62, 3.64, and 3.66. The upper limit of D1 is preferably 4.20 from the viewpoint of improving stability during molding and reheating, and more preferably in the order of 4.10, 4.00, and 3.95.

[0240] In the optical glass according to the second embodiment, the lower limit of the molar ratio [F / (O+F+Cl)] of the F content to the total content of O, F, and Cl is preferably 0.010 from the viewpoint of improving low dispersibility and anomalous partial dispersibility, and is more preferably in the order of 0.160, 0.220, 0.250, 0.280, 0.30, 0.320, 0.420, 0.450, 0.50, 0.550, 0.600, 0.625, and 0.650. The upper limit of the molar ratio [F / (O+F+Cl)] is preferably 0.940 from the viewpoint of improving the stability of the glass and suppressing volatilization, and is more preferably in the order of 0.890, 0.850, 0.820, 0.810, 0.800, 0.790, 0.780, 0.770, 0.760, 0.750, and 0.710.

[0241] Furthermore, in the optical glass according to the second embodiment, the mass percentage content of F, O, and Cl is defined as C(F), C(O), and C(Cl), respectively. Let the atomic weights of F, O, and Cl be M(F), M(O), and M(Cl), respectively. G1=[{C(F) / M(F)} / [{C(O) / M(O)}+{C(F) / M(F)}+{C(Cl) / M(Cl)}]] In that case, The lower limit of G1 is preferably 0.010 from the viewpoint of improving low dispersibility and anomalous partial dispersibility, and is more preferably in the order of 0.110, 0.160, 0.220, 0.250, 0.280, 0.30, 0.320, 0.40, 0.420, 0.450, 0.50, 0.550, 0.600, 0.625, and 0.650. The upper limit of G1 is preferably 0.940 from the viewpoint of improving stability during reheating and suppressing volatilization of glass components, and is more preferably in the order of 0.890, 0.850, 0.820, 0.810, 0.800, 0.790, 0.780, 0.770, 0.760, 0.750, and 0.710.

[0242] In the optical glass according to the second embodiment, the lower limit of the molar ratio [(Sr+Ba) / (Mg+Ca+Sr+Ba+Zn)] between the total content of Sr and Ba and the total content of Mg, Ca, Sr, Ba, and Zn is preferably 0.00, and more preferably in the order of 0.300, 0.350, 0.400, 0.450, and 0.500, from the viewpoint of increasing the refractive index nd. The upper limit of the molar ratio [(Sr+Ba) / (Mg+Ca+Sr+Ba+Zn)] is preferably 0.67, and more preferably in the order of 0.667, 0.650, 0.640, 0.630, and 0.620, from the viewpoint of increasing stability during reheating.

[0243] Furthermore, in the optical glass according to the second embodiment, the mass percentage content of Mg, Ca, Sr, Ba, and Zn is defined as C(Mg), C(Ca), C(Sr), C(Ba), and C(Zn), respectively. Let the atomic weights of Mg, Ca, Sr, Ba, and Zn be M(Mg), M(Ca), M(Sr), M(Ba), and M(Zn), respectively. H1=[{C(Sr) / M(Sr)}+{C(Ba) / M(Ba)}] / [{C(Mg) / M(Mg)}+{C(Ca) / M(Ca)}+{C(Sr) / M(Sr)}+{C(Ba) / M(Ba)}+{C(Zn) / M(Zn)}] In that case, The lower limit of H1 is preferably 0.00 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.300, 0.350, 0.400, 0.450, and 0.500. The upper limit of H1 is preferably 0.67 from the viewpoint of improving stability during reheating, and more preferably in the order of 0.667, 0.650, 0.640, 0.630, and 0.620.

[0244] In the optical glass according to the second embodiment, the lower limit of the total content of Li, Na, and K [Li+Na+K] is preferably 0.00 mol%, and more preferably 0.20 mol%, 0.40 mol%, and 0.60 mol%, in that order, from the viewpoint of improving the solubility of the glass raw material. The upper limit of the total content [Li+Na+K] is preferably 6.50 mol%, and more preferably 6.00 mol%, 5.50 mol%, and 5.00 mol%, in that order, from the viewpoint of suppressing the volatilization of glass components.

[0245] In the optical glass according to the second embodiment, the mass percentage content of Li, Na, and K is expressed as C(Li), C(Na), and C(K), respectively. Let the atomic weights of Li, Na, and K be M(Li), M(Na), and M(K), respectively. F1=[{C(Li) / M(Li)}+{C(Na) / M(Na)}+{C(K) / M(K)}]×100 In that case, The lower limit of F1 is preferably 0, and more preferably in the order of 0.6, 1.2, and 1.8, from the viewpoint of improving the melting properties of the glass raw material. The upper limit of F1 is preferably 19.5, and more preferably in the order of 18.0, 16.5, and 15.0, from the viewpoint of suppressing the volatilization of glass components.

[0246] In the optical glass according to the second embodiment, the lower limit of the total content of Y, La, Gd, Yb, and Lu [Y+La+Gd+Yb+Lu] is preferably 0.0 mol%, and more preferably in the order of 0.05 mol%, 0.10 mol%, and 0.15 mol%, from the viewpoint of increasing the refractive index nd and improving chemical durability. The upper limit of the total content [Y+La+Gd+Yb+Lu] is preferably 1.62 mol%, and more preferably in the order of 1.40 mol%, 1.20 mol%, and 1.00 mol%, from the viewpoint of increasing the melting properties of the glass raw material and improving devitrification resistance during melting.

[0247] Furthermore, in the optical glass according to the second embodiment, the mass percentage content of Y, La, Gd, Yb, and Lu is set to C(Y), C(La), C(Gd), C(Yb), and C(Lu), respectively. Let the atomic weights of Y, La, Gd, Yb, and Lu be M(Y), M(La), M(Gd), M(Yb), and M(Lu), respectively. K1=[{C(Y) / M(Y)}+{C(La) / M(La)}+{C(Gd) / M(Gd)}+{C(Yb) / M(Yb)}+{C(Lu) / M(Lu)}]×100 In that case, The lower limit of K1 is preferably 0, and more preferably 0.15, 0.30, and 0.45, from the viewpoint of increasing the refractive index nd and improving chemical durability. The upper limit of K1 is preferably 4.86, and more preferably 4.20, 3.60, and 3.00, from the viewpoint of increasing the melting properties of the glass raw material and improving devitrification resistance during melting.

[0248] In the optical glass according to the second embodiment, the lower limit of the molar ratio [(Ba+Sr) / P] of the total content of Ba and Sr to the content of P is preferably 1.05 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 1.15, 1.25, 1.35, and 1.45. Also, the upper limit of the molar ratio [(Ba+Sr) / P] is preferably 2.25 from the viewpoint of increasing stability during reheating, and more preferably in the order of 2.15, 2.05, 1.95, and 1.85.

[0249] Furthermore, in the optical glass according to the second embodiment, the mass percentage content of P, Sr, and Ba is defined as C(P), C(Sr), and C(Ba), respectively. Let the atomic weights of P, Sr, Ba, and Zn be M(P), M(Sr), and M(Ba), respectively. N1=[{C(Ba) / M(Ba)}+{C(Sr) / M(Sr)}] / {C(P) / M(P)} In that case, The lower limit of N1 is preferably 1.05 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 1.15, 1.25, 1.35, and 1.45. The upper limit of N1 is preferably 2.25 from the viewpoint of improving stability during reheating, and more preferably in the order of 2.15, 2.05, 1.95, and 1.85.

[0250] In the optical glass according to the second embodiment, the lower limit of the molar ratio [(Ba+Sr+Zn) / P] of the total content of Ba, Sr, and Zn to the content of P is preferably 1.1 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 1.2, 1.3, 1.4, and 1.5. Also, the upper limit of the molar ratio [(Ba+Sr+Zn) / P] is preferably 2.3 from the viewpoint of increasing stability during reheating, and more preferably in the order of 2.2, 2.1, 2.0, and 1.9.

[0251] Furthermore, in the optical glass according to the second embodiment, the mass percentage content of P, Sr, Ba, and Zn is defined as C(P), C(Sr), C(Ba), and C(Zn), respectively. Let the atomic weights of P, Sr, Ba, and Zn be M(P), M(Sr), M(Ba), and M(Zn), respectively. I1=[{C(Ba) / M(Ba)}+{C(Sr) / M(Sr)}+{C(Zn) / M(Zn)}] / {C(P) / M(P)} In that case, The lower limit of I1 is preferably 1.1 from the viewpoint of increasing the refractive index, and more preferably in the order of 1.2, 1.3, 1.4, and 1.5. The upper limit of I1 is preferably 2.3 from the viewpoint of increasing stability during reheating, and more preferably in the order of 2.2, 2.1, 2.0, and 1.9.

[0252] In the optical glass according to the second embodiment, the lower limit of the O content is preferably 12 mol%, and more preferably 13 mol%, and 14 mol%, in that order, from the viewpoint of suppressing the volatilization of the glass components. The upper limit of the O content is preferably 26 mol%, and more preferably 25 mol%, and 24 mol%, in that order, from the viewpoint of improving the melting properties of the glass raw material and improving the resistance to devitrification during melting.

[0253] Furthermore, in the optical glass according to the second embodiment, the lower limit of the O content is preferably 6.40% by mass, and more preferably 6.93% by mass and 7.47% by mass, from the viewpoint of suppressing the volatilization of glass components. The upper limit of the O content is preferably 12.61% by mass, and more preferably 12.12% by mass and 11.64% by mass, from the viewpoint of improving the melting properties of the glass raw material and improving the resistance to devitrification during melting.

[0254] In the optical glass according to the second embodiment, the lower limit of the F content is preferably 30 mol%, and more preferably 31 mol%, and 32 mol%, in that order, from the viewpoint of improving the melting properties of the glass raw material and improving the resistance to devitrification during melting. The upper limit of the F content is preferably 54 mol%, and more preferably 53 mol%, and 52 mol%, in that order, from the viewpoint of suppressing the volatilization of the glass components.

[0255] Furthermore, in the optical glass according to the second embodiment, the lower limit of the F content is preferably 17.27% by mass, and more preferably 17.85% by mass and 18.42% by mass, from the viewpoint of improving the melting properties of the glass raw material and improving the resistance to devitrification during melting. The upper limit of the F content is preferably 40.00% by mass, and more preferably 39.00% by mass, 38.00% by mass, 37.00% by mass, 36.00% by mass, 35.00% by mass, 34.20% by mass, 33.56% by mass and 32.93% by mass, from the viewpoint of suppressing the volatilization of glass components.

[0256] In the optical glass according to the second embodiment, the lower limit of the Cl content is preferably 0.00 mol%, and more preferably 0.02 mol%, and 0.04 mol%, in that order, from the viewpoint of promoting clarity. The upper limit of the Cl content is preferably 0.20 mol%, and more preferably 0.15 mol%, and 0.10 mol%, in that order, from the viewpoint of suppressing the volatilization of glass components.

[0257] Furthermore, in the optical glass according to the second embodiment, the lower limit of the Cl content is preferably 0% by mass, and more preferably 0.02% by mass and 0.05% by mass, from the viewpoint of promoting clarity. The upper limit of the Cl content is preferably 0.21% by mass, and more preferably 0.16% by mass and 0.11% by mass, from the viewpoint of suppressing the volatilization of glass components.

[0258] In the optical glass according to the second embodiment, the lower limit of the P content is preferably 1.0 mol%, and more preferably 2.0 mol%, 3.0 mol%, and 3.2 mol%, in that order, from the viewpoint of improving devitrification resistance during melting and improving stability during reheating. Furthermore, the upper limit of the P content is preferably 9.0 mol%, and more preferably 8.0 mol%, 7.0 mol%, and 6.5 mol%, in that order, from the viewpoint of improving the refractive index nd.

[0259] Furthermore, in the optical glass according to the second embodiment, the lower limit of the P content is preferably 1.03% by mass, and more preferably in the order of 2.06% by mass, 3.10% by mass, and 3.30% by mass, from the viewpoint of improving devitrification resistance during melting and improving stability during reheating. Furthermore, the upper limit of the P content is preferably 8.45% by mass, and more preferably in the order of 7.51% by mass, 6.57% by mass, and 6.10% by mass, from the viewpoint of improving the refractive index nd.

[0260] In the optical glass according to the second embodiment, the lower limit of the Al content is preferably 7.0 mol%, and more preferably in the order of 7.5 mol%, 8.0 mol%, and 8.5 mol%, from the viewpoint of high refractive index and low dispersion. The upper limit of the Al content is preferably 12 mol%, and more preferably in the order of 11.0 mol%, 10.5 mol%, and 10.0 mol%, from the viewpoint of improving resistance to devitrification during melting and improving stability during reheating.

[0261] Furthermore, in the optical glass according to the second embodiment, the lower limit of the Al content is preferably 6.30% by mass from the viewpoint of high refractive index and low dispersion, and more preferably in the order of 6.75% by mass, 7.20% by mass, and 7.64% by mass. Furthermore, the upper limit of the Al content is preferably 9.81% by mass from the viewpoint of improving resistance to devitrification during melting and improving stability during reheating, and more preferably in the order of 8.99% by mass, 8.59% by mass, and 8.18% by mass.

[0262] In the optical glass according to the second embodiment, the upper limit of the B content is preferably 1.0 mol%, and more preferably 0.5 mol%, 0.2 mol%, and 0.1 mol%, in that order, from the viewpoint of suppressing the volatilization of the glass components. The lower limit of the B content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material. The B content may also be 0 mol%.

[0263] Furthermore, in the optical glass according to the second embodiment, the upper limit of the B content is preferably 0.36% by mass, and more preferably 0.18% by mass, 0.07% by mass, and 0.04% by mass, in that order, from the viewpoint of suppressing the volatilization of the glass components. The lower limit of the B content is preferably 0% by mass, from the viewpoint of maintaining the melting properties of the glass raw material. The B content may also be 0% by mass.

[0264] In the optical glass according to the second embodiment, the upper limit of the Si content is preferably 1.0 mol%, and more preferably 0.5 mol%, 0.2 mol%, and 0.1 mol%, in that order, from the viewpoint of maintaining melting properties and thermal stability and suppressing the volatilization of glass components. The lower limit of the Si content is preferably 0 mol%, and the Si content may be 0 mol%.

[0265] Furthermore, in the optical glass according to the second embodiment, the upper limit of the Si content is preferably 0.94% by mass, and more preferably 0.47% by mass, 0.19% by mass, and 0.09% by mass, in that order, from the viewpoint of maintaining melting properties and thermal stability and suppressing the volatilization of glass components. The lower limit of the Si content is preferably 0% by mass. The Si content may also be 0% by mass.

[0266] In the glass according to the second embodiment, the upper limit of the Li content is preferably 6.5 mol%, and more preferably 6.0 mol%, 5.5 mol%, and 5.0 mol%, in that order, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the Li content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material.

[0267] Furthermore, in the glass according to the second embodiment, the upper limit of the Li content is preferably 1.37% by mass, and more preferably 1.26% by mass, 1.16% by mass, and 1.05% by mass, in that order, from the viewpoint of suppressing the volatilization of the glass components. Also, the lower limit of the Li content is preferably 0% by mass, from the viewpoint of maintaining the solubility of the glass raw material.

[0268] In the glass according to the second embodiment, the upper limit of the Na content is preferably 2.0 mol%, and more preferably 1.5 mol%, 1.0 mol%, and 0.5 mol%, in that order, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the Na content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material. The Na content may be 0 mol%.

[0269] Furthermore, in the glass according to the second embodiment, the upper limit of the Na content is preferably 1.39% by mass, and more preferably 1.04% by mass, 0.70% by mass, and 0.35% by mass, in that order, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the Na content is preferably 0% by mass, from the viewpoint of maintaining the solubility of the glass raw material. The Na content may also be 0% by mass.

[0270] In the optical glass according to the second embodiment, the upper limit of the K content is preferably 2.0 mol%, and more preferably 1.5 mol%, 1.0 mol%, and 0.5 mol%, in that order, from the viewpoint of suppressing the volatilization of the glass components. The lower limit of the K content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material. The K content may be 0 mol%.

[0271] Furthermore, in the optical glass according to the second embodiment, the upper limit of the K content is preferably 2.37% by mass, and more preferably 1.78% by mass, 1.18% by mass, and 0.59% by mass, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the K content is preferably 0% by mass, from the viewpoint of maintaining the melting properties of the glass raw material. The K content may also be 0% by mass.

[0272] In the optical glass according to the second embodiment, the lower limit of the Mg content is preferably 0.3 mol%, and more preferably in the order of 0.6 mol%, 0.8 mol%, and 1.0 mol%, from the viewpoint of improving stability during reheating and improving mechanical strength and thermal shock resistance. The upper limit of the Mg content is preferably 5.0 mol%, and more preferably in the order of 4.0 mol%, 3.5 mol%, and 3.0 mol%, from the viewpoint of improving devitrification resistance during melting.

[0273] Furthermore, in the optical glass according to the second embodiment, the lower limit of the Mg content is preferably 0.24% by mass, and more preferably in the order of 0.49% by mass, 0.65% by mass, and 0.81% by mass, from the viewpoint of improving stability during reheating and improving mechanical strength and thermal shock resistance. The upper limit of the Mg content is preferably 3.68% by mass, and more preferably in the order of 2.95% by mass, 2.58% by mass, and 2.21% by mass, from the viewpoint of improving devitrification resistance during melting.

[0274] In the optical glass according to the second embodiment, the lower limit of the Ca content is preferably 2.0 mol%, and more preferably in the order of 2.5 mol%, 3.0 mol%, and 3.5 mol%, from the viewpoint of improving stability during reheating and enhancing mechanical strength and thermal shock resistance. Furthermore, the upper limit of the Ca content is preferably 9.0 mol%, and more preferably in the order of 8.5 mol%, 8.0 mol%, and 7.8 mol%, from the viewpoint of improving devitrification resistance during melting.

[0275] Furthermore, in the optical glass according to the second embodiment, the lower limit of the Ca content is preferably 2.67% by mass, and more preferably in the order of 3.34% by mass, 4.01% by mass, and 4.68% by mass, from the viewpoint of improving stability during reheating and improving mechanical strength and thermal shock resistance. Furthermore, the upper limit of the Ca content is preferably 10.93% by mass, and more preferably in the order of 10.32% by mass, 9.72% by mass, and 9.47% by mass, from the viewpoint of improving devitrification resistance during melting.

[0276] In the optical glass according to the second embodiment, the upper limit of the Sr content is preferably 7.2 mol%, and more preferably in the order of 7.0 mol%, 6.8 mol%, and 6.6 mol%, from the viewpoint of improving stability during reheating. The lower limit of the Sr content is preferably 1.0 mol%, and more preferably in the order of 1.2 mol%, 1.4 mol%, and 1.6 mol%, from the viewpoint of improving the refractive index nd.

[0277] Furthermore, in the optical glass according to the second embodiment, the upper limit of the Sr content is preferably 19.12% by mass, and more preferably in the order of 18.59% by mass, 18.06% by mass, and 17.52% by mass, from the viewpoint of improving stability during reheating. Furthermore, the lower limit of the Sr content is preferably 2.92% by mass, and more preferably in the order of 3.50% by mass, 4.09% by mass, and 4.67% by mass, from the viewpoint of improving the refractive index nd.

[0278] In the optical glass according to the second embodiment, the upper limit of the Ba content is preferably 7.2 mol%, and more preferably in the order of 7.0 mol%, 6.8 mol%, and 6.6 mol%, from the viewpoint of improving stability during reheating. The lower limit of the Ba content is preferably 1.0 mol%, and more preferably in the order of 1.2 mol%, 1.4 mol%, and 1.6 mol%, from the viewpoint of improving the refractive index nd.

[0279] Furthermore, in the optical glass according to the second embodiment, the upper limit of the Ba content is preferably 29.96% by mass, and more preferably in the order of 29.13% by mass, 28.3% by mass, and 27.47% by mass, from the viewpoint of improving stability during reheating. The lower limit of the Ba content is preferably 4.58% by mass, and more preferably in the order of 5.49% by mass, 6.41% by mass, and 7.32% by mass, from the viewpoint of improving the refractive index nd.

[0280] In the optical glass according to the second embodiment, the upper limit of the Zn content is preferably 1.0 mol%, and more preferably 0.8 mol%, 0.5 mol%, and 0.2 mol%, in that order, from the viewpoint of suppressing high dispersion. The lower limit of the Zn content is preferably 0 mol%, and the Zn content may be 0 mol%.

[0281] Furthermore, in the optical glass according to the second embodiment, the upper limit of the Zn content is preferably 2.18% by mass, and more preferably in the order of 1.98% by mass, 1.59% by mass, 0.99% by mass, and 0.40% by mass, from the viewpoint of suppressing high dispersion. The lower limit of the Zn content is preferably 0% by mass. The Zn content may also be 0% by mass.

[0282] In the optical glass according to the second embodiment, the upper limit of the La content is preferably 1.0 mol%, and more preferably 0.9 mol%, and then 0.8 mol%, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the La content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The La content may be 0 mol%.

[0283] Furthermore, in the optical glass according to the second embodiment, the upper limit of the La content is preferably 4.21% by mass, and more preferably 3.79% by mass and 3.37% by mass, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the La content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The La content may be 0% by mass.

[0284] In the glass according to the second embodiment, the upper limit of the Gd content is preferably 1.0 mol%, more preferably 0.9 mol%, and then 0.8 mol%, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the Gd content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The Gd content may be 0 mol%.

[0285] Furthermore, in the glass according to the second embodiment, the upper limit of the Gd content is preferably 4.77% by mass, from the viewpoint of improving the melting properties of the glass raw material and the stability during reheating, and more preferably 4.29% by mass and 3.81% by mass, in that order. The lower limit of the Gd content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The Gd content may also be 0% by mass.

[0286] In the glass according to the second embodiment, the upper limit of the Y content is preferably 1.0 mol%, and more preferably 0.9 mol%, and then 0.8 mol%, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the Y content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability.

[0287] Furthermore, in the glass according to the second embodiment, the upper limit of the Y content is preferably 2.69% by mass, and more preferably 2.42% by mass and 2.16% by mass, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. Furthermore, the lower limit of the Y content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability.

[0288] In the glass according to the second embodiment, the upper limit of the Lu content is preferably 1.0 mol%, more preferably 0.9 mol%, and more preferably 0.8 mol%, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the Lu content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The Lu content may be 0 mol%.

[0289] Furthermore, in the glass according to the second embodiment, the upper limit of the Lu content is preferably 5.30% by mass, with 4.77% by mass and 4.24% by mass being more preferred, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the Lu content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The Lu content may also be 0% by mass.

[0290] In the glass according to the second embodiment, the upper limit of the Yb content is preferably 1.0 mol%, and more preferably 0.9 mol%, and then 0.8 mol%, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the Yb content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The Yb content may be 0 mol%.

[0291] Furthermore, in the glass according to the second embodiment, the upper limit of the Yb content is preferably 5.24% by mass, and more preferably 4.72% by mass and 4.19% by mass, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the Yb content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The Yb content may also be 0% by mass.

[0292] In the optical glass according to the second embodiment, the upper limit of the Zr content is preferably 1.0 mol%, and more preferably 0.5 mol%, 0.2 mol%, and 0.1 mol%, in that order, from the viewpoint of improving the melting properties of the glass raw material and improving the resistance to devitrification during melting. The lower limit of the Zr content is preferably 0 mol%, and the Zr content may be 0 mol%.

[0293] Furthermore, in the optical glass according to the second embodiment, the upper limit of the Zr content is preferably 3.04% by mass, and more preferably 1.52% by mass, 0.61% by mass, and 0.30% by mass, in that order, from the viewpoint of improving the melting properties of the glass raw material and improving the resistance to devitrification during melting. The lower limit of the Zr content is preferably 0% by mass. The Zr content may also be 0% by mass.

[0294] In the optical glass according to the second embodiment, the content and ratio of glass components other than those mentioned above can be the same as in the embodiment described above.

[0295] In the optical glass according to the second embodiment, the glass properties can be the same as those of the embodiment described above.

[0296] The manufacturing of optical glass, optical element blanks, and optical elements according to the second embodiment can be carried out in the same manner as described in the embodiment above.

[0297] Third Embodiment The third embodiment is one of the preferred embodiments of the above-described embodiment. In the third embodiment, by particularly controlling the ratio of F content to Al content to a high level, low dispersibility is enhanced, anomalous partial dispersion is ensured, and stability during reheating is prioritized over suppressing the volatilization of glass components, resulting in the completion of an optical glass that can further improve stability during reheating. As preferred embodiments of the third embodiment, the 3-1 embodiment and the 3-2 embodiment are shown.

[0298] Embodiment 3-1 The optical glass according to the 3-1 embodiment is preferably, The molar ratio of F content to Al content [F / Al] is 4.60 to 15.0. The molar ratio of Ba content to P content [Ba / P] is 0.400 to 0.820. The molar ratio of P content to Al content [P / Al] is 0.20 to 1.25. The molar ratio of O content to P content [O / P] is 3.05 to 3.49. The molar ratio of the F content to the total content of O, F, and Cl [F / (O+F+Cl)] is between 0.010 and 0.790. The molar ratio [(Sr+Ba) / (Mg+Ca+Sr+Ba+Zn)] of the total content of Sr and Ba to the total content of Mg, Ca, Sr, Ba, and Zn is between 0.00 and 0.67.

[0299] Furthermore, the optical glass according to the 3-1 embodiment is preferably, The mass percentage content of F, Al, Ba, P, O, Cl, Mg, Ca, Sr, Ba, and Zn is expressed as C(F), C(Al), C(Ba), C(P), C(O), C(Cl), C(Mg), C(Ca), C(Sr), C(Ba), and C(Zn), respectively. Let the atomic weights of F, Al, Ba, P, O, Cl, Mg, Ca, Sr, Ba, and Zn be M(F), M(Al), M(Ba), M(P), M(O), M(Cl), M(Mg), M(Ca), M(Sr), M(Ba), and M(Zn), respectively. A1 = {C(F) / M(F)} / {C(Al) / M(Al)} B1 = {C(Ba) / M(Ba)} / {C(P) / M(P)} C1 = {C(P) / M(P)} / {C(Al) / M(Al)} D1 = {C(O) / M(O)} / {C(P) / M(P)} G1=[{C(F) / M(F)} / [{C(O) / M(O)}+{C(F) / M(F)}+{C(Cl) / M(Cl)}]] H1=[{C(Sr) / M(Sr)}+{C(Ba) / M(Ba)}] / [{C(Mg) / M(Mg)}+{C(Ca) / M(Ca)}+{C(Sr) / M(Sr)}+{C(Ba) / M(Ba)}+{C(Zn) / M(Zn)}] In that case, A1 is 4.60-15.0. B1 is between 0.400 and 0.820. C1 is between 0.20 and 1.25. D1 is 3.05-3.49, G1 is between 0.010 and 0.790. H1 is between 0.00 and 0.67.

[0300] Embodiment 3-2 The optical glass according to the 3-2 embodiment is preferably, The molar ratio of F content to Al content [F / Al] is 4.60 to 15.0. The molar ratio of Ba content to P content [Ba / P] is 0.400 to 0.820. The molar ratio of P content to Al content [P / Al] is 0.20 to 1.25. The molar ratio of O content to P content [O / P] is 3.05 to 3.49. The molar ratio of the F content to the total content of O, F, and Cl [F / (O+F+Cl)] is between 0.010 and 0.790. The total content of Li, Na, and K [Li+Na+K] is between 0.00 and 6.40 mol%.

[0301] Furthermore, the optical glass according to the 3-2 embodiment is preferably, The mass percentages of F, Al, Ba, P, O, Cl, Li, Na, and K are expressed as C(F), C(Al), C(Ba), C(P), C(O), C(Cl), C(Li), C(Na), and C(K), respectively. Let the atomic weights of F, Al, Ba, P, O, Cl, Li, Na, and K be M(F), M(Al), M(Ba), M(P), M(O), M(Cl), M(Li), M(Na), and M(K), respectively. A1 = {C(F) / M(F)} / {C(Al) / M(Al)} B1 = {C(Ba) / M(Ba)} / {C(P) / M(P)} C1 = {C(P) / M(P)} / {C(Al) / M(Al)} D1 = {C(O) / M(O)} / {C(P) / M(P)} G1=[{C(F) / M(F)} / [{C(O) / M(O)}+{C(F) / M(F)}+{C(Cl) / M(Cl)}]] F1=[{C(Li) / M(Li)}+{C(Na) / M(Na)}+{C(K) / M(K)}]×100 In that case, A1 is 4.60-15.0. B1 is between 0.400 and 0.820. C1 is between 0.20 and 1.25. D1 is 3.05-3.49, G1 is between 0.010 and 0.790. F1 ranges from 0.0 to 6.4.

[0302] The content and ratio of glass components in the optical glass according to the third embodiment (Embodiment 3-1 and Embodiment 3-2) are described in detail below.

[0303] In the optical glass according to the third embodiment, the lower limit of the molar ratio [F / Al] of F content to Al content is preferably 4.60 from the viewpoint of improving stability during reheating, and is more preferably in the order of 4.70, 4.80, 4.90, 5.00, 5.10, and 5.20. The upper limit of the molar ratio [F / Al] is preferably 15.0 from the viewpoint of suppressing the volatilization of glass components, and is more preferably in the order of 10.0, 8.0, 7.5, 7.0, 6.8, and 6.5.

[0304] Furthermore, in the optical glass according to the third embodiment, the mass percentage content of F and Al is expressed as C(F) and C(Al), respectively. Let the atomic weights of F and Al be M(F) and M(Al), respectively. A1 = {C(F) / M(F)} / {C(Al) / M(Al)} In that case, The lower limit of A1 is preferably 4.60 from the viewpoint of improving stability during reheating, and more preferably in the order of 4.70, 4.80, 4.90, 5.00, 5.10, and 5.20. The upper limit of A1 is preferably 15.0 from the viewpoint of suppressing the volatilization of glass components, and more preferably in the order of 10.0, 8.0, 7.5, 7.0, 6.8, and 6.5.

[0305] In the optical glass according to the third embodiment, the lower limit of the molar ratio [Ba / P] of Ba content to P content is preferably 0.400 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.410, 0.420, and 0.430. Furthermore, the upper limit of the molar ratio [Ba / P] is preferably 0.820 from the viewpoint of improving stability during reheating, and more preferably in the order of 0.700, 0.650, and 0.600.

[0306] Furthermore, in the optical glass according to the third embodiment, the mass percentage content of Ba and P is expressed as C(Ba) and C(P), respectively. Let the atomic weights of Ba and P be M(Ba) and M(P), respectively. B1 = {C(Ba) / M(Ba)} / {C(P) / M(P)} In that case, The lower limit of B1 is preferably 0.400 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.410, 0.420, and 0.430. Furthermore, the upper limit of B1 is preferably 0.820 from the viewpoint of improving stability during reheating, and more preferably in the order of 0.700, 0.650, and 0.600.

[0307] In the optical glass according to the third embodiment, the upper limit of the molar ratio [P / Al] of P content to Al content is preferably 1.25 from the viewpoint of high refractive index and low dispersion, and is more preferably in the order of 1.20, 1.15, 1.10, 1.00, 0.950, 0.900, and 0.850. The lower limit of the molar ratio [P / Al] is preferably 0.20 from the viewpoint of improving devitrification resistance during melting and stability during reheating, and is more preferably in the order of 0.400, 0.450, 0.500, and 0.550.

[0308] Furthermore, in the optical glass according to the third embodiment, the mass percentage content of Al and P is expressed as C(Al) and C(P), respectively. Let the atomic weights of Al and P be M(Al) and M(P), respectively. C1 = {C(P) / M(P)} / {C(Al) / M(Al)} In that case, The upper limit of C1 is preferably 1.25 from the viewpoint of high refractive index and low dispersion, and more preferably in the order of 1.20, 1.15, 1.10, 1.00, 0.950, 0.900, and 0.850. The lower limit of C1 is preferably 0.20 from the viewpoint of improving resistance to devitrification during melting and stability during reheating, and more preferably in the order of 0.400, 0.450, 0.500, and 0.550.

[0309] In the optical glass according to the third embodiment, the lower limit of the molar ratio [O / P] of O content to P content is preferably 3.05 from the viewpoint of suppressing the volatilization of glass components, and is more preferably in the order of 3.06, 3.07, 3.08, 3.09, 3.10, 3.15, 3.25, and 3.30. Furthermore, the upper limit of the molar ratio [O / P] is preferably 3.49 from the viewpoint of improving stability during molding and reheating, and is more preferably in the order of 3.45, 3.42, and 3.40.

[0310] Furthermore, in the optical glass according to the third embodiment, the mass percentage content of P and O is expressed as C(P) and C(O), respectively. Let the atomic weights of P and O be M(P) and M(O), respectively. D1 = {C(O) / M(O)} / {C(P) / M(P)} In that case, The lower limit of D1 is preferably 3.05 from the viewpoint of suppressing the volatilization of glass components, and is more preferably in the order of 3.06, 3.07, 3.08, 3.09, 3.10, 3.15, 3.25, and 3.30. The upper limit of D1 is preferably 3.49 from the viewpoint of improving stability during molding and reheating, and is more preferably in the order of 3.45, 3.42, and 3.40.

[0311] In the optical glass according to the third embodiment, the lower limit of the molar ratio [F / (O+F+Cl)] of the F content to the total content of O, F, and Cl is preferably 0.010 from the viewpoint of improving low dispersibility and anomalous partial dispersibility, and is more preferably in the order of 0.400, 0.420, 0.450, 0.500, 0.550, 0.600, 0.625, and 0.650. The upper limit of the molar ratio [F / (O+F+Cl)] is preferably 0.940 from the viewpoint of improving the stability of the glass and suppressing volatilization, and is more preferably in the order of 0.890, 0.850, 0.820, 0.810, 0.800, 0.790, 0.780, 0.770, 0.760, and 0.750.

[0312] Furthermore, in the optical glass according to the third embodiment, the mass percentage content of F, O, and Cl is expressed as C(F), C(O), and C(Cl), respectively. Let the atomic weights of F, O, and Cl be M(F), M(O), and M(Cl), respectively. G1=[{C(F) / M(F)} / [{C(O) / M(O)}+{C(F) / M(F)}+{C(Cl) / M(Cl)}]] In that case, The lower limit of G1 is preferably 0.010 from the viewpoint of improving low dispersibility and abnormal partial dispersibility, and is more preferably in the order of 0.400, 0.420, 0.450, 0.50, 0.550, 0.600, 0.625, and 0.650. The upper limit of G1 is preferably 0.940 from the viewpoint of improving stability during reheating and suppressing volatilization, and is more preferably in the order of 0.890, 0.850, 0.820, 0.810, 0.800, 0.790, 0.780, 0.770, 0.760, and 0.750.

[0313] In the optical glass according to the third embodiment, the lower limit of the molar ratio [(Sr+Ba) / (Mg+Ca+Sr+Ba+Zn)] of the total content of Sr and Ba to the total content of Mg, Ca, Sr, Ba, and Zn is preferably 0.00, and more preferably in the order of 0.300, 0.350, 0.400, 0.450, and 0.480, from the viewpoint of increasing the refractive index nd. The upper limit of the molar ratio [(Sr+Ba) / (Mg+Ca+Sr+Ba+Zn)] is preferably 0.67, and more preferably in the order of 0.667, 0.650, 0.640, 0.630, and 0.620, from the viewpoint of increasing stability during reheating.

[0314] Furthermore, in the optical glass according to the third embodiment, the mass percentage content of Mg, Ca, Sr, Ba, and Zn is defined as C(Mg), C(Ca), C(Sr), C(Ba), and C(Zn), respectively. Let the atomic weights of Mg, Ca, Sr, Ba, and Zn be M(Mg), M(Ca), M(Sr), M(Ba), and M(Zn), respectively. H1=[{C(Sr) / M(Sr)}+{C(Ba) / M(Ba)}] / [{C(Mg) / M(Mg)}+{C(Ca) / M(Ca)}+{C(Sr) / M(Sr)}+{C(Ba) / M(Ba)}+{C(Zn) / M(Zn)}] In that case, The lower limit of H1 is preferably 0.00 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.300, 0.350, 0.400, 0.450, and 0.480. The upper limit of H1 is preferably 0.67 from the viewpoint of improving stability during reheating, and more preferably in the order of 0.667, 0.650, 0.640, 0.630, and 0.620.

[0315] In the optical glass according to the third embodiment, the lower limit of the total content of Li, Na, and K [Li+Na+K] is preferably 0.00 mol%, and more preferably in the order of 0.20 mol%, 0.40 mol%, and 0.60 mol%, from the viewpoint of improving the solubility of the glass raw material. The upper limit of the total content [Li+Na+K] is preferably 6.50 mol%, and more preferably in the order of 6.40 mol%, 6.00 mol%, 5.50 mol%, and 5.00 mol%, from the viewpoint of suppressing the volatilization of glass components.

[0316] Furthermore, in the optical glass according to the third embodiment, the mass percentage content of Li, Na, and K is expressed as C(Li), C(Na), and C(K), respectively. Let the atomic weights of Li, Na, and K be M(Li), M(Na), and M(K), respectively. F1=[{C(Li) / M(Li)}+{C(Na) / M(Na)}+{C(K) / M(K)}]×100 In that case, The lower limit of F1 is preferably 0, and more preferably in the order of 0.6, 1.2, and 1.8, from the viewpoint of improving the melting properties of the glass raw material. The upper limit of F1 is preferably 19.5, and more preferably in the order of 18.0, 16.5, and 15.0, from the viewpoint of suppressing the volatilization of glass components.

[0317] In the optical glass according to the third embodiment, the lower limit of the total content of Y, La, Gd, Yb, and Lu [Y+La+Gd+Yb+Lu] is preferably 0.0 mol%, and more preferably in the order of 0.05 mol%, 0.10 mol%, and 0.15 mol%, from the viewpoint of increasing the refractive index nd and improving chemical durability. The upper limit of the total content [Y+La+Gd+Yb+Lu] is preferably 2.0 mol%, and more preferably in the order of 1.5 mol%, 1.4 mol%, 1.2 mol%, and 1.0 mol%, from the viewpoint of increasing the melting properties of the glass raw material and improving devitrification resistance during melting.

[0318] Furthermore, in the optical glass according to the third embodiment, the mass percentage content of Y, La, Gd, Yb, and Lu is set to C(Y), C(La), C(Gd), C(Yb), and C(Lu), respectively. Let the atomic weights of Y, La, Gd, Yb, and Lu be M(Y), M(La), M(Gd), M(Yb), and M(Lu), respectively. K1=[{C(Y) / M(Y)}+{C(La) / M(La)}+{C(Gd) / M(Gd)}+{C(Yb) / M(Yb)}+{C(Lu) / M(Lu)}]×100 In that case, The lower limit of K1 is preferably 0, and more preferably in the order of 0.15, 0.30, and 0.45, from the viewpoint of increasing the refractive index nd and improving chemical durability. The upper limit of K1 is preferably 6.0, and more preferably in the order of 4.5, 3.6, and 3.0, from the viewpoint of increasing the melting properties of the glass raw material and improving devitrification resistance during melting.

[0319] In the optical glass according to the third embodiment, the lower limit of the molar ratio [(Ba+Sr) / P] of the total content of Ba and Sr to the content of P is preferably 0.72, and more preferably in the order of 0.82, 0.92, 1.02, 1.07, and 1.12, from the viewpoint of improving stability during reheating. The upper limit of the molar ratio [(Ba+Sr) / P] is preferably 1.70, and more preferably in the order of 1.63, 1.58, 1.53, and 1.48, from the viewpoint of suppressing the volatilization of glass components.

[0320] Furthermore, in the optical glass according to the third embodiment, the mass percentage content of P, Sr, and Ba is expressed as C(P), C(Sr), and C(Ba), respectively. Let the atomic weights of P, Sr, Ba, and Zn be M(P), M(Sr), and M(Ba), respectively. N1=[{C(Ba) / M(Ba)}+{C(Sr) / M(Sr)}] / {C(P) / M(P)} In that case, The lower limit of N1 is preferably 0.72 from the viewpoint of improving stability during reheating, and is more preferably 0.82, 0.92, 1.02, 1.07, and 1.12 in that order. The upper limit of N1 is preferably 1.70 from the viewpoint of suppressing the volatilization of glass components, and is more preferably 1.63, 1.58, 1.53, and 1.48 in that order.

[0321] In the optical glass according to the third embodiment, the lower limit of the molar ratio [(Ba+Sr+Zn) / P] of the total content of Ba, Sr, and Zn to the content of P is preferably 0.40 from the viewpoint of increasing the refractive index nd, and is more preferably in the order of 0.50, 0.60, 0.67, 0.77, 0.87, 0.97, and 1.07. Furthermore, the upper limit of the molar ratio [(Ba+Sr+Zn) / P] is preferably 1.70 from the viewpoint of increasing stability during reheating, and is more preferably in the order of 1.65, 1.60, 1.55, and 1.50.

[0322] Furthermore, in the optical glass according to the third embodiment, the mass percentage content of P, Sr, Ba, and Zn is defined as C(P), C(Sr), C(Ba), and C(Zn), respectively. Let the atomic weights of P, Sr, Ba, and Zn be M(P), M(Sr), M(Ba), and M(Zn), respectively. I1=[{C(Ba) / M(Ba)}+{C(Sr) / M(Sr)}+{C(Zn) / M(Zn)}] / {C(P) / M(P)} In that case, The lower limit of I1 is preferably 0.40 from the viewpoint of increasing the refractive index nd, and more preferably in the order of 0.50, 0.60, 0.67, 0.77, 0.87, 0.97, and 1.07. The upper limit of I1 is preferably 1.70 from the viewpoint of improving stability during reheating, and more preferably in the order of 1.65, 1.60, 1.55, and 1.50.

[0323] In the optical glass according to the third embodiment, the lower limit of the O content is preferably 12 mol%, and more preferably 13 mol%, and 14 mol%, in that order, from the viewpoint of suppressing the volatilization of the glass components. The upper limit of the O content is preferably 26 mol%, and more preferably 25 mol%, and 24 mol%, in that order, from the viewpoint of improving the melting properties of the glass raw material and improving the resistance to devitrification during melting.

[0324] Furthermore, in the optical glass according to the third embodiment, the lower limit of the O content is preferably 6.40% by mass, and more preferably 6.93% by mass and 7.47% by mass, from the viewpoint of suppressing the volatilization of glass components. The upper limit of the O content is preferably 18% by mass, and more preferably 16% by mass, 14% by mass, 13.5% by mass, 12.61% by mass, 12.12% by mass and 11.64% by mass, from the viewpoint of improving the melting properties of the glass raw material and improving the resistance to devitrification during melting.

[0325] In the optical glass according to the third embodiment, the lower limit of the F content is preferably 30 mol%, and more preferably 31 mol%, and 32 mol%, in that order, from the viewpoint of improving the melting properties of the glass raw material and improving the resistance to devitrification during melting. The upper limit of the F content is preferably 54 mol%, and more preferably 53 mol%, and 52 mol%, in that order, from the viewpoint of suppressing the volatilization of the glass components.

[0326] Furthermore, in the optical glass according to the third embodiment, the lower limit of the F content is preferably 17.27% by mass, and more preferably 17.85% by mass and 18.42% by mass, from the viewpoint of improving the melting properties of the glass raw material and improving the resistance to devitrification during melting. The upper limit of the F content is preferably 38.00% by mass, and more preferably 36% by mass, 34.20% by mass, 33.56% by mass and 32.93% by mass, from the viewpoint of suppressing the volatilization of glass components.

[0327] In the optical glass according to the third embodiment, the lower limit of the Cl content is preferably 0.00 mol%, and more preferably 0.02 mol%, and 0.04 mol%, in that order, from the viewpoint of promoting clarity. The upper limit of the Cl content is preferably 0.20 mol%, and more preferably 0.15 mol%, and 0.10 mol%, in that order, from the viewpoint of suppressing the volatilization of glass components.

[0328] Furthermore, in the optical glass according to the third embodiment, the lower limit of the Cl content is preferably 0% by mass, and more preferably 0.02% by mass and 0.05% by mass, from the viewpoint of promoting clarity. The upper limit of the Cl content is preferably 0.21% by mass, and more preferably 0.16% by mass and 0.11% by mass, from the viewpoint of suppressing the volatilization of glass components.

[0329] In the optical glass according to the third embodiment, the lower limit of the P content is preferably 2.0 mol%, and more preferably 3.0 mol%, 4.0 mol%, and 4.5 mol%, in that order, from the viewpoint of improving devitrification resistance during melting and improving stability during reheating. Furthermore, the upper limit of the P content is preferably 15 mol%, and more preferably 12 mol%, 10 mol%, and 9 mol%, in that order, from the viewpoint of improving the refractive index nd.

[0330] Furthermore, in the optical glass according to the third embodiment, the lower limit of the P content is preferably 2.06 mass%, and more preferably 3.10 mass%, 4.13 mass%, and 4.65 mass%, in that order, from the viewpoint of improving devitrification resistance during melting and improving stability during reheating. Furthermore, the upper limit of the P content is preferably 14.08 mass%, and more preferably 11.26 mass%, 9.39 mass%, and 8.45 mass%, in that order, from the viewpoint of improving the refractive index nd.

[0331] In the optical glass according to the third embodiment, the lower limit of the Al content is preferably 3.0 mol%, and more preferably 4.0 mol%, 5.0 mol%, and 6.0 mol%, in that order, from the viewpoint of high refractive index and low dispersion. The upper limit of the Al content is preferably 12 mol%, and more preferably 11.0 mol%, 10.5 mol%, and 10.0 mol%, in that order, from the viewpoint of improving resistance to devitrification during melting and improving stability during reheating.

[0332] Furthermore, in the optical glass according to the third embodiment, the lower limit of the Al content is preferably 2.7% by mass from the viewpoint of high refractive index and low dispersion, and more preferably in the order of 3.6% by mass, 4.5% by mass, and 5.4% by mass. Furthermore, the upper limit of the Al content is preferably 9.81% by mass from the viewpoint of improving resistance to devitrification during melting and improving stability during reheating, and more preferably in the order of 8.99% by mass, 8.59% by mass, and 8.18% by mass.

[0333] In the optical glass according to the third embodiment, the upper limit of the B content is preferably 1.0 mol%, and more preferably 0.5 mol%, 0.2 mol%, and 0.1 mol%, in that order, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the B content is preferably 0 mol%, and the B content may be 0 mol%.

[0334] Furthermore, in the optical glass according to the third embodiment, the upper limit of the B content is preferably 0.36% by mass, and more preferably 0.18% by mass, 0.07% by mass, and 0.04% by mass, in that order, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the B content is preferably 0% by mass. The B content may also be 0% by mass.

[0335] In the optical glass according to the third embodiment, the upper limit of the Si content is preferably 1.0 mol%, and more preferably 0.5 mol%, 0.2 mol%, and 0.1 mol%, in that order, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the Si content is preferably 0 mol%, and the Si content may be 0 mol%.

[0336] Furthermore, in the optical glass according to the third embodiment, the upper limit of the Si content is preferably 0.94% by mass, and more preferably 0.47% by mass, 0.19% by mass, and 0.09% by mass, in that order, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the Si content is preferably 0% by mass. The Si content may also be 0% by mass.

[0337] In the glass according to the third embodiment, the upper limit of the Li content is preferably 6.5 mol%, and more preferably 6.0 mol%, 5.5 mol%, and 5.0 mol%, in that order, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the Li content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material.

[0338] Furthermore, in the glass according to the third embodiment, the upper limit of the Li content is preferably 1.37% by mass, and more preferably 1.26% by mass, 1.16% by mass, and 1.05% by mass, in that order, from the viewpoint of suppressing the volatilization of the glass components. Also, the lower limit of the Li content is preferably 0% by mass, from the viewpoint of maintaining the solubility of the glass raw material.

[0339] In the glass according to the third embodiment, the upper limit of the Na content is preferably 2.0 mol%, and more preferably 1.5 mol%, 1.0 mol%, and 0.5 mol%, in that order, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the Na content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material. The Na content may be 0 mol%.

[0340] Furthermore, in the glass according to the third embodiment, the upper limit of the Na content is preferably 1.39% by mass, and more preferably 1.04% by mass, 0.70% by mass, and 0.35% by mass, in that order, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the Na content is preferably 0% by mass, from the viewpoint of maintaining the solubility of the glass raw material. The Na content may also be 0% by mass.

[0341] In the optical glass according to the third embodiment, the upper limit of the K content is preferably 2.0 mol%, and more preferably 1.5 mol%, 1.0 mol%, and 0.5 mol%, in that order, from the viewpoint of suppressing the volatilization of the glass components. The lower limit of the K content is preferably 0 mol%, from the viewpoint of maintaining the solubility of the glass raw material. The K content may be 0 mol%.

[0342] Furthermore, in the optical glass according to the third embodiment, the upper limit of the K content is preferably 2.37% by mass, and more preferably 1.78% by mass, 1.18% by mass, and 0.59% by mass, from the viewpoint of suppressing the volatilization of glass components. The lower limit of the K content is preferably 0% by mass, from the viewpoint of maintaining the melting properties of the glass raw material. The K content may also be 0% by mass.

[0343] In the optical glass according to the third embodiment, the lower limit of the Mg content is preferably 0.3 mol%, and more preferably in the order of 0.6 mol%, 0.8 mol%, and 1.0 mol%, from the viewpoint of improving stability during reheating and improving mechanical strength and thermal shock resistance. The upper limit of the Mg content is preferably 5.0 mol%, and more preferably in the order of 4.0 mol%, 3.5 mol%, 3.0 mol%, and 2.5 mol%, from the viewpoint of improving devitrification resistance during melting.

[0344] Furthermore, in the optical glass according to the third embodiment, the lower limit of the Mg content is preferably 0.24% by mass, and more preferably in the order of 0.49% by mass, 0.65% by mass, and 0.81% by mass, from the viewpoint of improving stability during reheating and improving mechanical strength and thermal shock resistance. The upper limit of the Mg content is preferably 3.68% by mass, and more preferably in the order of 2.95% by mass, 2.58% by mass, and 2.21% by mass, from the viewpoint of improving devitrification resistance during melting.

[0345] In the optical glass according to the third embodiment, the lower limit of the Ca content is preferably 2.0 mol%, and more preferably in the order of 2.5 mol%, 3.0 mol%, and 3.5 mol%, from the viewpoint of improving stability during reheating and improving mechanical strength and thermal shock resistance. Furthermore, the upper limit of the Ca content is preferably 9.0 mol%, and more preferably in the order of 8.5 mol%, 8.0 mol%, 7.8 mol%, 7.5 mol%, and 7.0 mol%, from the viewpoint of improving devitrification resistance during melting.

[0346] Furthermore, in the optical glass according to the third embodiment, the lower limit of the Ca content is preferably 2.67% by mass, and more preferably in the order of 3.34% by mass, 4.01% by mass, and 4.68% by mass, from the viewpoint of improving stability during reheating and improving mechanical strength and thermal shock resistance. Furthermore, the upper limit of the Ca content is preferably 10.93% by mass, and more preferably in the order of 10.32% by mass, 9.72% by mass, and 9.47% by mass, from the viewpoint of improving devitrification resistance during melting.

[0347] In the optical glass according to the third embodiment, the upper limit of the Sr content is preferably 7.2 mol%, and more preferably in the order of 7.0 mol%, 6.8 mol%, 6.6 mol%, 6.0 mol%, and 5.5 mol%, from the viewpoint of improving stability during reheating. The lower limit of the Sr content is preferably 1.0 mol%, and more preferably in the order of 1.2 mol%, 1.4 mol%, and 1.6 mol%, from the viewpoint of improving the refractive index nd.

[0348] Furthermore, in the optical glass according to the third embodiment, the upper limit of the Sr content is preferably 19.12% by mass, and more preferably in the order of 18.59% by mass, 18.06% by mass, and 17.52% by mass, from the viewpoint of improving stability during reheating. Furthermore, the lower limit of the Sr content is preferably 2.92% by mass, and more preferably in the order of 3.50% by mass, 4.09% by mass, and 4.67% by mass, from the viewpoint of improving the refractive index nd.

[0349] In the optical glass according to the third embodiment, the upper limit of the Ba content is preferably 7.2 mol%, and more preferably in the order of 6.4 mol%, 5.8 mol%, 5.4 mol%, 5.0 mol%, 4.8 mol%, 4.4 mol%, 4.2 mol%, and 4.0 mol%, from the viewpoint of increasing the refractive index nd, and more preferably in the order of 1.2 mol%, 1.4 mol%, and 1.6 mol%, from the viewpoint of increasing the refractive index nd.

[0350] Furthermore, in the optical glass according to the third embodiment, the upper limit of the Ba content is preferably 29.96% by mass, from the viewpoint of improving stability during reheating, and more preferably in the order of 26.63% by mass, 24.14% by mass, 22.47% by mass, 20.81% by mass, 19.97% by mass, 18.31% by mass, 17.48% by mass, and 16.65% by mass. The lower limit of the Ba content is preferably 4.58% by mass, from the viewpoint of improving the refractive index nd, and more preferably in the order of 5.49% by mass, 6.41% by mass, and 7.32% by mass.

[0351] In the optical glass according to the third embodiment, the upper limit of the Zn content is preferably 1.0 mol%, and more preferably 0.8 mol%, 0.5 mol%, and 0.2 mol%, in that order, from the viewpoint of suppressing high dispersion. The lower limit of the Zn content is preferably 0 mol%, and the Zn content may be 0 mol%.

[0352] Furthermore, in the optical glass according to the third embodiment, the upper limit of the Zn content is preferably 2.18% by mass, and more preferably in the order of 1.98% by mass, 1.59% by mass, 0.99% by mass, and 0.40% by mass, from the viewpoint of suppressing high dispersion. The lower limit of the Zn content is preferably 0% by mass. The Zn content may also be 0% by mass.

[0353] In the optical glass according to the third embodiment, the upper limit of the La content is preferably 1.0 mol%, more preferably 0.9 mol%, and then 0.8 mol%, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the La content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The La content may be 0 mol%.

[0354] Furthermore, in the optical glass according to the third embodiment, the upper limit of the La content is preferably 4.21% by mass, more preferably 3.79% by mass and 3.37% by mass, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the La content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The La content may also be 0% by mass.

[0355] In the glass according to the third embodiment, the upper limit of the Gd content is preferably 1.0 mol%, more preferably 0.9 mol%, and then 0.8 mol%, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the Gd content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The Gd content may be 0 mol%.

[0356] Furthermore, in the glass according to the third embodiment, the upper limit of the Gd content is preferably 4.77% by mass, from the viewpoint of improving the melting properties of the glass raw material and the stability during reheating, and more preferably 4.29% by mass and 3.81% by mass, in that order. The lower limit of the Gd content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The Gd content may also be 0% by mass.

[0357] In the glass according to the third embodiment, the upper limit of the Y content is preferably 2.0 mol%, and more preferably in the order of 1.8 mol%, 1.4 mol%, 1.0 mol%, 0.9 mol%, and 0.8 mol%, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the Y content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability.

[0358] Furthermore, in the glass according to the third embodiment, the upper limit of the Y content is preferably 5.39% by mass, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating, and more preferably in the order of 4.85% by mass, 3.77% by mass, 2.69% by mass, 2.42% by mass, and 2.16% by mass. Furthermore, the lower limit of the Y content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability.

[0359] In the glass according to the third embodiment, the upper limit of the Lu content is preferably 1.0 mol%, more preferably 0.9 mol%, and more preferably 0.8 mol%, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the Lu content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The Lu content may be 0 mol%.

[0360] Furthermore, in the glass according to the third embodiment, the upper limit of the Lu content is preferably 5.30% by mass, with 4.77% by mass and 4.24% by mass being more preferred, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the Lu content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The Lu content may also be 0% by mass.

[0361] In the glass according to the third embodiment, the upper limit of the Yb content is preferably 1.0 mol%, and more preferably 0.9 mol%, and then 0.8 mol%, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the Yb content is preferably 0 mol%, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The Yb content may be 0 mol%.

[0362] Furthermore, in the glass according to the third embodiment, the upper limit of the Yb content is preferably 5.24% by mass, more preferably 4.72% by mass and 4.19% by mass, from the viewpoint of improving the melting properties of the glass raw material and improving stability during reheating. The lower limit of the Yb content is preferably 0% by mass, from the viewpoint of maintaining the refractive index nd and maintaining chemical durability. The Yb content may also be 0% by mass.

[0363] In the optical glass according to the third embodiment, the upper limit of the Zr content is preferably 1.0 mol%, and more preferably 0.5 mol%, 0.2 mol%, and 0.1 mol%, in that order, from the viewpoint of improving the melting properties of the glass raw material and improving the resistance to devitrification during melting. The lower limit of the Zr content is preferably 0 mol%. The Zr content may be 0 mol%.

[0364] Furthermore, in the optical glass according to the third embodiment, the upper limit of the Zr content is preferably 3.04% by mass, and more preferably 1.52% by mass, 0.61% by mass, and 0.30% by mass, in that order, from the viewpoint of improving the melting properties of the glass raw material and improving the resistance to devitrification during melting. The lower limit of the Zr content is preferably 0% by mass. The Zr content may also be 0% by mass.

[0365] In the optical glass according to the third embodiment, the content and ratio of glass components other than those mentioned above can be the same as in the embodiment described above.

[0366] In the optical glass according to the third embodiment, the glass properties can be the same as those of the embodiment described above.

[0367] The manufacturing of optical glass, optical element blanks, and optical elements according to the third embodiment can be carried out in the same manner as described in the embodiment above. [Examples]

[0368] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the embodiments shown in the examples.

[0369] (Example 1) Glass samples having the glass compositions shown in Table 1 (Table 1-1(1), Table 1-1(2), Table 1-1(3), Table 1-2(1), Table 1-2(2), Table 1-2(3), Table 1-3(1), Table 1-3(2), Table 1-3(3)), and Table 2 (Table 2-1(1), Table 2-1(2), Table 2-1(3), Table 2-1(4), Table 2-2(1), Table 2-2(2), Table 2-2(3), Table 2-2(4), Table 2-3(1), Table 2-3(2), Table 2-3(3), Table 2-3(4)), and Table A (Table A-1(1), Table A-1(2), Table A-1(3)) were prepared using the following procedure and evaluated in various ways. Note that in Tables 1 and A, the glass composition is shown in molar percentage. Mole percentage refers to the molar percentage when the total content of all elements contained in the glass is set to 100%. Table 2 shows the glass composition in mass percentage. Mass percentage refers to the mass percentage when the total content of all elements contained in the glass is set to 100%. Although the method of displaying the glass composition differs between Table 1 and Table 2, optical glass with the same sample number means the same optical glass with the same composition. Therefore, Table 1 and Table 2 show essentially the same optical glass and results.

[0370] Tables 1-1(1), 1-1(2), 1-1(3), 2-1(1), 2-1(2), 2-1(3), and 2-1(4) correspond to the first embodiment. Tables 1-2(1), 1-2(2), 1-2(3), 2-2(1), 2-2(2), 2-2(3), and 2-2(4) correspond to the second embodiment. Tables 1-3(1), 1-3(2), 1-3(3), 2-3(1), 2-3(2), 2-3(3), and 2-3(4) correspond to the third embodiment. Samples No. A1 to A3 and A5 in Table A correspond to the third embodiment.

[0371] [Manufacturing of optical glass] First, oxides, hydroxides, fluorides, chlorides, carbonates, and nitrates corresponding to the constituent components of glass were prepared as raw materials. These raw materials were weighed and blended so that the glass composition of the resulting optical glass would be as shown in Tables 1 and 2, and the raw materials were thoroughly mixed. The resulting blended raw materials (batch raw materials) were placed in a platinum crucible and heated at 800°C to 1000°C for 0.5 to 2 hours to form molten glass. The mixture was then stirred to homogenize it, clarified, and the molten glass was cast into a mold preheated to an appropriate temperature. The cast glass was heat-treated at a temperature 50°C higher than the glass transition temperature (Tg) to 100°C lower than the Tg for 15 to 120 minutes, and then allowed to cool to room temperature in a furnace to obtain glass samples.

[0372] [Measurement of optical properties] The obtained glass samples were further annealed at approximately 15 to 120 minutes near the glass transition temperature Tg, and then cooled to room temperature in a furnace at a cooling rate of -30°C / hour to obtain annealed samples. The refractive index nd, Abbe number νd, and ΔT of the obtained annealed samples were measured as follows.

[0373] (i) refractive index nd and Abbe number νd For the above annealed samples, the refractive index nd, nF, and nC were measured according to the refractive index measurement method of JIS standard JIS B 7071-1, and the Abbe number νd was calculated based on the following formula. νd=(nd-1) / (nF-nC)

[0374] (ii) Stabilization index ΔT(Tx-Tg) For the above annealed samples, the glass transition temperature (Tg) and the rise temperature (Tx) of the exothermic peak during crystallization were measured using a differential scanning calorimeter (DSC3300S) manufactured by Netch Japan. The above annealed samples were crushed to a weight of approximately 0.02 cc, placed in a φ5 mm Pt pan, and measured under conditions of a heating rate of 10°C / min and a maximum temperature of 1000°C. Alumina (Al2O3) was used as the standard sample.

[0375] [Stability during reheating] A glass sample measuring 10 mm × 10 mm × 7.5 mm was first heated for 10 minutes in a test furnace set and maintained so that the temperature at the location of the glass sample was within the range of the glass transition temperature Tg to 5°C higher than Tg (Tg ~ Tg + 5°C). Then, it was secondarily heated for 10 minutes in a test furnace set and maintained at a temperature 130 to 160°C higher than the glass transition temperature Tg of the glass sample. During both the first and second heating, the glass sample was placed on an alumina plate covered with alumina powder, and the glass sample was transported together with the plate. Afterward, the glass sample was allowed to cool to room temperature in the air. The inside of the glass was observed under a microscope to confirm the presence or absence of crystals. Furthermore, after visually confirming devitrification of the entire glass, it was evaluated according to the following criteria. A: During secondary heating, it softens at a temperature Tg + 160°C. No crystals are observed under a microscope. B: Softens at a temperature Tg + 150°C during secondary heating. No crystals are observed under a microscope. C: Softens at a temperature Tg + 130°C during secondary heating. No crystals are observed under a microscope. D: Softening occurs during secondary heating at a temperature Tg + 130°C. Crystals are observed under a microscope. No overall devitrification of the glass is observed visually. E: During secondary heating, the material does not soften due to crystallization of the surface or interior at a temperature Tg + 130°C.

[0376] [Table 1-1(1)]

[0377]

Table 1-1(2)

[0378]

Table 1-1(3)

[0379]

Table 1-2(1)

[0380]

Table 1-2(2)

[0381]

Table 1-2(3)

[0382]

Table 1-3(1)

[0383]

Table 1-3(2)

[0384]

Table 1-3(3)

[0385] Table 2-1(1)

[0386]

Table 2-1(2)

[0387]

Table 2-1(3)

[0388]

Table 2-1(4)

[0389]

Table 2-2(1)

[0390]

Table 2-2(2)

[0391]

Table 2-2(3)

[0392]

Table 2-2(4)

[0393]

Table 2-3(1)

[0394]

Table 2-3(2)

[0395]

Table 2-3(3)

[0396]

Table 2-3(4)

[0397] [Table A-1(1)]

[0398] [Table A-1(2)]

[0399] [Table A-1(3)]

[0400] (Example 2) Using the optical glass prepared in Example 1, lens blanks were fabricated by known methods, and various lenses were manufactured by processing the lens blanks by known methods such as polishing. The optical lenses fabricated include various types such as biconvex lenses, biconcave lenses, plano-convex lenses, plano-concave lenses, concave meniscus lenses, and convex meniscus lenses. By combining various lenses with lenses made of other types of optical glass, it was possible to effectively correct higher-order chromatic aberration.

[0401] Furthermore, because glass has a relatively low specific gravity, each lens is lighter than lenses with equivalent optical properties and size, making them suitable for various imaging devices, especially autofocus imaging devices, due to their energy-saving properties. Similarly, prisms were fabricated using the various optical glasses prepared in Example 1.

[0402] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended.

[0403] For example, by adjusting the composition described in the specification with respect to the glass composition exemplified above, an optical glass according to one aspect of the present invention can be produced. Furthermore, it is certainly possible to arbitrarily combine two or more items that are described as examples or preferred scopes in the specification.

Claims

1. The P content is 2.0 to 25 mol%, The Al content is 1.0 to 18 mol%, The Ba content is 1 to 20 mol%, The O content is 30-60 mol%, The content of F is 8 to 35 mol%, The Abbe number νd is 68.0 or greater. The molar ratio of F content to Al content [F / Al] is between 2.70 and 4.

60. The molar ratio of Ba content to P content [Ba / P] is between 0.100 and 1.

10. The molar ratio of P content to Al content [P / Al] is 1.50 to 1.

75. The molar ratio of O content to P content [O / P] is 3.55 to 4.

00. The molar ratio of the total content of Sr and Ba to the total content of Mg, Ca, Sr, Ba, and Zn [(Sr + Ba) / (Mg + Ca + Sr + Ba + Zn)] is 0.970 or less. Optical glass.

2. The P content is 2.0 to 25 mol%, The Al content is 1.0 to 18 mol%, The Ba content is 1 to 20 mol%, The O content is 30-60 mol%, The content of F is 8 to 35 mol%, The Abbe number νd is 68.0 or greater. The molar ratio of F content to Al content [F / Al] is 2.50 to 4.

60. The molar ratio of Ba content to P content [Ba / P] is between 0.250 and 1.

20. The molar ratio of P content to Al content [P / Al] is 1.50 to 1.

75. The molar ratio of O content to P content [O / P] is 3.55 to 3.

80. The molar ratio of the total content of Sr and Ba to the total content of Mg, Ca, Sr, Ba, and Zn [(Sr + Ba) / (Mg + Ca + Sr + Ba + Zn)] is 0.970 or less. Optical glass.

3. The P content is 1.0 to 9.0 mol%, The Al content is 7.0 to 12 mol%, The Ba content is 1.0 to 7.2 mol%, The O content is 12 to 26 mol%, The content of F is 30 to 54 mol%, The Ti content is 0.4 mol% or less. The Abbe number νd is 82.0 or greater. The molar ratio of F content to Al content [F / Al] is 4.60 to 6.

00. The molar ratio of Ba content to P content [Ba / P] is between 0.100 and 1.

05. The molar ratio of P content to Al content [P / Al] is 0.450 to 0.

700. The molar ratio of O content to P content [O / P] is 3.60 to 4.

20. The molar ratio of the F content to the total content of O, F, and Cl [F / (O+F+Cl)] is between 0.010 and 0.

790. The molar ratio of the total content of Sr and Ba to the total content of Mg, Ca, Sr, Ba, and Zn [(Sr + Ba) / (Mg + Ca + Sr + Ba + Zn)] is between 0.00 and 0.

67. The molar ratio of the total content of Ba, Sr, and Zn to the content of P [(Ba + Sr + Zn) / P] is between 1.4 and 2.

1. The total content of Li, Na, and K [Li + Na + K] is 5.00 mol% or less. Optical glass.

4. The P content is 1.0 to 9.0 mol%, The Al content is 7.0 to 12 mol%, The Ba content is 1.0 to 7.2 mol%, The O content is 12 to 26 mol%, The content of F is 30 to 54 mol%, The Ti content is 0.4 mol% or less. The Abbe number νd is 82.0 or greater. The molar ratio of F content to Al content [F / Al] is 4.60 to 6.

00. The molar ratio of Ba content to P content [Ba / P] is between 0.100 and 1.

05. The molar ratio of P content to Al content [P / Al] is 0.450 to 0.

900. The molar ratio of O content to P content [O / P] is 3.60 to 4.

20. The molar ratio of the F content to the total content of O, F, and Cl [F / (O+F+Cl)] is between 0.010 and 0.

790. The total content of Li, Na, and K [Li + Na + K] is between 0.00 and 5.00 mol%, The molar ratio of the total content of Ba, Sr, and Zn to the content of P [(Ba + Sr + Zn) / P] is 2.1 or less. Optical glass.

5. The P content is 2.0 to 15 mol%, The Al content is 3.0 to 12 mol%, The Ba content is 1.0 to 7.2 mol%, The O content is 12 to 26 mol%, The content of F is 30 to 54 mol%, The Abbe number νd is 82.0 or greater. The molar ratio of F content to Al content [F / Al] is 4.60 to 15.

0. The molar ratio of Ba content to P content [Ba / P] is 0.400 to 0.

820. The molar ratio of P content to Al content [P / Al] is 0.200 to 1.

25. The molar ratio of O content to P content [O / P] is 3.05 to 3.

49. The molar ratio of the F content to the total content of O, F, and Cl [F / (O+F+Cl)] is between 0.010 and 0.

790. Optical glass in which the molar ratio [(Sr + Ba) / (Mg + Ca + Sr + Ba + Zn)] of the total content of Sr and Ba to the total content of Mg, Ca, Sr, Ba, and Zn is between 0.00 and 0.

67.

6. The P content is 2.0 to 15 mol%, The Al content is 3.0 to 12 mol%, The Ba content is 1.0 to 7.2 mol%, The O content is 12 to 26 mol%, The content of F is 30 to 54 mol%, The Abbe number νd is 82.0 or greater. The molar ratio of F content to Al content [F / Al] is 4.60 to 15.

0. The molar ratio of Ba content to P content [Ba / P] is 0.400 to 0.

820. The molar ratio of P content to Al content [P / Al] is 0.200 to 1.

25. The molar ratio of O content to P content [O / P] is 3.05 to 3.

49. The molar ratio of the F content to the total content of O, F, and Cl [F / (O+F+Cl)] is between 0.010 and 0.

790. Optical glass having a total content of Li, Na, and K [Li + Na + K] of 0.00 to 6.40 mol%.

7. An optical element blank made of optical glass according to any one of claims 1 to 6.

8. A glass material for press molding, comprising the optical glass described in any one of claims 1 to 6.

9. An optical element made of optical glass according to any one of claims 1 to 6.

Images