TWI658021B - Optical glass, preform and optical element - Google Patents

Abstract

The present invention provides an optical glass and an optical element which can more inexpensively obtain a glass having a refractive index and an Abbe number within a desired range and having a relatively small partial dispersion.

The optical glass of the present invention contains 5.0 to 60.0% of the SiO ₂ component in terms of mass%, the content of the Ta ₂ O ₅ component is 20.0% or less, and the partial dispersion ratio (θg, F) is equal to the Abbe number (ν _d ). room, in relation ν _d ≦ ≦ (θg, F) ≦ ( -0.00421 × ν d +0.72070) within the range of 25 to satisfy (-0.00160 × ν _d +0.63460), in ν _d> 25 as to satisfy the range of (- 0.00250 × ν _d +0.65710) ≦ (θg, F) ≦ (-0.00421 × ν _d +0.72070).

Description

Optical glass, preform and optical element

The invention relates to an optical glass, a preform and an optical element.

Optical systems such as digital cameras and video cameras include blurs called aberrations, although their sizes are different. This aberration is a monochromatic aberration and a chromatic aberration. In particular, the chromatic aberration strongly depends on the material characteristics of the lens used in the optical system.

Generally, chromatic aberration is corrected by combining a low-dispersion convex lens and a high-dispersion concave lens, but this combination can only correct the aberrations of the red and green regions, leaving the aberrations of the blue region. The aberration of the blue region that cannot be removed is called a secondary spectrum. In order to correct the secondary spectrum, an optical design with reference to the movement of the g-ray (435.835nm) in the blue region is necessary. At this time, the partial dispersion ratio (θg, F) is used as an index of the optical characteristics that are of interest in optical design. In the above-mentioned optical system combining a low-dispersion lens and a high-dispersion lens, since the lens on the low-dispersion side uses an optical material with a relatively large dispersion, the lens on the high-dispersion side uses an optical material with a relatively small dispersion. Good correction of the secondary spectrum.

The partial dispersion ratio (θg, F) is represented by the following formula (1).

θg, F = (n _g -n _F ) / (n _F -n _C ) (1)

In optical glass, there is a substantially linear relationship between the partial dispersion ratio (θg, F) indicating the partial dispersion in the short wavelength region and the Abbe number (ν _d ). The straight line representing the relationship is two points obtained by plotting the partial dispersion ratio and Abbe number of NSL7 and PBM2 on the orthogonal coordinates using the partial dispersion ratio as the vertical axis and Abbe number as the horizontal axis. It is indicated by a straight line and is called a normal line (see FIG. 1). The regular glass that becomes the benchmark of the regular line also varies from one optical glass manufacturer to another, but each company defines it with approximately the same slope and intercept. (NSL7 and PBM2 are optical glass manufactured by Ohara Co., Ltd., the Abbe number (ν _d ) of PBM2 is 36.3, the partial dispersion ratio (θg, F) is 0.5828, and the Abbe number (ν _d ) of NSL7 is 60.5, part The dispersion ratio (θg, F) was 0.5436).

Here, as a glass with a relatively small partial dispersion, for example, optical glasses as shown in Patent Documents 1 to 3 are known.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2008-297198

[Patent Document 2] International Publication No. 2001/072650

[Patent Document 3] Japanese Patent Laid-Open No. 10-265238

However, the glass disclosed in Patent Documents 1 to 3 has a low refractive index (n _d ) and a high Abbe number (ν _d ), so it has a low dispersion, so it is not suitable for use as a lens for the above-mentioned modified secondary spectrum . That is, an optical glass having both a small partial dispersion ratio and high refractive index and high dispersion optical characteristics is sought.

In addition, in order to reduce the material cost of the optical glass, it is desirable that the raw material cost of various components constituting the optical glass is as cheap as possible. In addition, in order to reduce the manufacturing cost of the optical glass, it is more desirable that the raw material has a higher melting property, that is, melting at a lower temperature. However, it is difficult to believe that the glass composition described in Patent Documents 1 to 3 satisfies these various requirements sufficiently.

The present invention has been made in view of the problems described above, and an object thereof is to more inexpensively obtain optical glass having a refractive index and an Abbe number within a desired range and having a relatively small partial dispersion, or a preform and an optical element using the same.

The present inventors repeatedly carried out intensive experiments to solve the above-mentioned problems. As a result, they found that by using the SiO ₂ component and the Ta ₂ O ₅ component in combination and adjusting the content thereof, the partial dispersion ratio (θg, F) of the glass was reduced to It has a desired relationship with the Abbe number (ν _d ), and reduces the material cost of glass by reducing the content of the Ta ₂ O ₅ component, thereby completing the present invention. Specifically, the present invention provides the following.

(1) An optical glass containing 5.0 to 60.0% of SiO ₂ component in terms of mass%, a content of Ta ₂ O ₅ component of 20.0% or less, and a partial dispersion ratio (θg, F) equal to the Abbe number (ν _d ), satisfy the relationship of (-0.00160 × ν _d +0.63460) ≦ (θg, F) ≦ (-0.00421 × ν _d +0.72070) within the range of ν _d ≦ 25, and within the range of ν _d > 25 A relationship of (-0.00250 × ν _d +0.65710) ≦ (θg, F) ≦ (-0.00421 × ν _d +0.72070) is satisfied.

(2) The optical glass according to (1), wherein the ZrO ₂ component is 0 to 25.0% and the Nb ₂ O ₅ component is 0 to 60.0% in terms of mass%.

(3) The optical glass according to (1) or (2), wherein the mass ratio ZrO ₂ / Nb ₂ O ₅ is 0.01 or more.

(4) The optical glass according to any one of (1) to (3), wherein the mass and ZrO ₂ + Nb ₂ O ₅ are 25.0 to 65.0%.

(5) The optical glass according to any one of (1) to (4), wherein the mass ratio Nb ₂ O ₅ / (Ta ₂ O ₅ + SiO ₂ ) is 0.30 or more and 3.00 or less.

(6) The optical glass according to any one of (1) to (5), wherein the TiO ₂ component is 0 to 20.0% and the Li ₂ O component is 0 to 25.0% in terms of mass%.

(7) The optical glass according to any one of (1) to (6), wherein the mass ratio (Nb ₂ O ₅ + TiO ₂ ) / (Ta ₂ O ₅ + ZrO ₂ + Li ₂ O) is 10.00 or less.

(8) The optical glass according to any one of (1) to (7), wherein the mass ratio ZrO ₂ / (Nb ₂ O ₅ + TiO ₂ ) is 0.05 or more.

(9) The optical glass according to any one of (1) to (8), wherein the mass ratio TiO ₂ / (Nb ₂ O ₅ + Ta ₂ O ₅ ) is 0.01 or more.

(10) The optical glass according to any one of (1) to (9), wherein the mass and ZrO ₂ + Li ₂ O are 5.0% or more and 35.0% or less.

(11) The optical glass according to any one of (1) to (10), wherein a Na ₂ O component is 0 to 30.0% and a K ₂ O component is 0 to 15.0% in terms of mass%.

(12) The optical glass according to any one of (1) to (11), wherein the mass of Rn ₂ O component (where Rn is one or more selected from the group consisting of Li, Na, and K) The sum is 30.0% or less.

(13) The optical glass according to any one of (1) to (12), wherein the MgO component is 0 to 20.0%, the CaO component is 0 to 20.0%, and the SrO component is 0 to 20.0% by mass%. The BaO composition is 0 to 20.0%, and the ZnO composition is 0 to 30.0%.

(14) The optical glass according to any one of (1) to (13), wherein the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, and Zn) The mass sum is below 20.0%.

(15) The optical glass according to any one of (1) to (14), wherein the Y ₂ O ₃ component is 0 to 10.0%, the La ₂ O ₃ component is 0 to 10.0%, and Gd ₂ The O ₃ component is 0 to 10.0%, and the Yb ₂ O ₃ component is 0 to 10.0%.

(16) The optical glass according to any one of (1) to (15), wherein the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of Y, La, Gd, and Yb The mass of) is less than 20.0%.

(17) The optical glass according to any one of (1) to (16), wherein the B ₂ O ₃ component is 0 to 30.0%, the P ₂ O ₅ component is 0 to 10.0%, and the GeO ₂ The composition is 0 to 10.0%, the Al ₂ O ₃ composition is 0 to 15.0%, the Ga ₂ O ₃ composition is 0 to 15.0%, the WO ₃ composition is 0 to 20.0%, the Bi ₂ O ₃ composition is 0 to 20.0%, and TeO _{The 2} component is 0 to 20.0%, and the Sb ₂ O ₃ component is 0 to 3.0%.

(18) The optical glass according to any one of (1) to (17), wherein the content of the ZrO ₂ component, the ZnO component, and the Nb ₂ O ₅ component in mass% satisfies ZrO ₂ + (ZnO / Nb ₂ O ₅ ) The relationship of ≧ 3.00.

(19) The optical glass according to any one of (1) to (18), wherein the mass ratio (Ta ₂ O ₅ + SiO ₂ + ZnO) / Nb ₂ O ₅ is 0.30 or more.

(20) The optical glass according to any one of (1) to (19), which has a refractive index (nd) of 1.75 or more and 2.00 or less and an Abbe number (νd) of 20 or more and 40 or less.

(21) The optical glass according to any one of (1) to (20), wherein the wavelength (λ ₇₀ ) at which the spectral transmittance shows 70% is 500 nm or less.

(22) A preform comprising the optical glass according to any one of (1) to (21) and used for polishing processing and / or precision pressure molding.

(23) An optical element obtained by grinding and / or grinding the optical glass according to any one of (1) to (21).

(24) An optical element, which is formed by precision press molding the optical glass according to any one of (1) to (21).

According to the present invention, it is possible to more inexpensively obtain optical glass having a refractive index and an Abbe number within a desired range and a relatively small partial dispersion, or a preform and an optical element using the same.

FIG. 1 is a diagram showing a normal line represented by orthogonal coordinates in which the partial dispersion ratio (θg, F) is the vertical axis and the Abbe number (ν _d ) is the horizontal axis.

FIG. 2 is a graph showing the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) of the glass in the example of the present case.

The optical glass of the present invention contains 5.0 to 60.0% of the SiO ₂ component in terms of mass%, the content of the Ta ₂ O ₅ component is 20.0% or less, and the partial dispersion ratio (θg, F) is equal to the Abbe number (ν _d ). room, in relation ν _d ≦ ≦ (θg, F) ≦ ( -0.00421 × ν d +0.72070) within the range of 25 to satisfy (-0.00160 × ν _d +0.63460), in ν _d> 25 as to satisfy the range of (- 0.00250 × ν _d +0.65710) ≦ (θg, F) ≦ (-0.00421 × ν _d +0.72070). By using the SiO ₂ component and the Ta ₂ O ₅ component together and adjusting the content thereof, the partial dispersion ratio (θg, F) of the glass has a desired relationship with the Abbe number (ν _d ). In addition, the material cost of glass is reduced by reducing the content of the Ta ₂ O ₅ component. Therefore, it is possible to more inexpensively obtain optical glass having a refractive index and an Abbe number within a desired range and a relatively small partial dispersion, or a preform and an optical element using the same.

Hereinafter, embodiments of the optical glass of the present invention will be described in detail, but the present invention is not limited in any way by the following embodiments, and may be appropriately modified and implemented within the scope of the object of the present invention. In addition, there are cases where the description is appropriately omitted, but the purpose of the invention is not limited.

[Glass composition]

The composition range of each component which comprises the optical glass of this invention is demonstrated below. Unless otherwise specified in this specification, the content of each component is all set as relative to oxidation. The mass% of the total mass of the glass in terms of composition is expressed. Here, the "oxide conversion composition" refers to the case where the oxides, complex salts, and metal fluorides used as the raw materials of the glass constituents of the present invention are all decomposed and converted into oxides when melted. The total mass of the produced oxide is 100% by mass, and represents the composition of each component contained in the glass.

<About essential ingredients and optional ingredients>

The SiO ₂ component is a glass-forming oxide and is a useful component for forming a skeleton of glass. That is, by containing 5.0% or more of the SiO ₂ component, the network structure of the glass can be increased to the extent that a stable glass can be obtained, and therefore, devitrification resistance can be improved. Therefore, the content of the SiO ₂ component is preferably 5.0% as the lower limit, more preferably 7.0% as the lower limit, still more preferably 9.0% as the lower limit, still more preferably 11.0% as the lower limit, and still more preferably 14.0% is the lower limit.

On the other hand, when the content of the SiO ₂ component is set to 60.0% or less, a decrease in the refractive index of the glass can be suppressed. Therefore, the content of the SiO ₂ component is preferably 60.0% as the upper limit, more preferably 45.0% as the upper limit, still more preferably 35.0% as the upper limit, and even more preferably 29.5% as the upper limit.

As the SiO ₂ component, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF _6, or the like can be used as a raw material.

When the content of Ta ₂ O ₅ exceeds 0%, it is an arbitrary component that can increase the refractive index of glass, reduce the partial dispersion ratio, increase the visible light transmittance, and lower the liquidus temperature.

On the other hand, by setting the content of the Ta ₂ O ₅ component to 20.0% or less, it is possible to suppress an increase in material cost caused by excessively containing the Ta ₂ O ₅ component, and to reduce devitrification or streaks. Therefore, the content of the Ta ₂ O ₅ component is preferably 20.0% as the upper limit, more preferably 18.0% as the upper limit, and even more preferably 17.0% as the upper limit.

As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

When the ZrO ₂ component contains more than 0%, it is an arbitrary component that can increase the refractive index of glass and reduce the partial dispersion ratio. Moreover, the ZrO ₂ component may not be contained, but in order to easily obtain a glass having a high refractive index and a low partial dispersion ratio, the content of the ZrO ₂ component may preferably be more than 0%, more preferably more than 1.0%, It is more preferably more than 2.5%, still more preferably more than 4.0%, still more preferably more than 5.0%, still more preferably more than 6.5%, and still more preferably more than 8.0%.

On the other hand, by setting the content of the ZrO ₂ component to 25.0% or less, the liquidus temperature of the glass can be lowered and devitrification resistance can be improved. In addition, it is possible to suppress an increase in the glass transition point. Therefore, the content of the ZrO ₂ component is preferably 25.0% as the upper limit, more preferably 22.0% as the upper limit, still more preferably 18.0% as the upper limit, still more preferably 15.0% as the upper limit, and still more preferably The upper limit is 12.0%, and further preferably the upper limit is 9.3%.

For the ZrO ₂ component, ZrO ₂ , ZrF _4, or the like can be used as a raw material.

When the Nb ₂ O ₅ component contains more than 0%, it is an arbitrary component that can increase the refractive index of glass, reduce the Abbe number, and reduce the partial dispersion ratio. Therefore, the Nb ₂ O ₅ component may preferably contain more than 0%, more preferably more than 5.0%, still more preferably more than 10.0%, and still more preferably more than 21.0%.

On the other hand, by setting the content of the Nb ₂ O ₅ component to 60.0% or less, the liquidus temperature of the glass is lowered, and thus an optical glass having high devitrification resistance can be obtained. In addition, by this, the visible light transmittance of the glass is not easily deteriorated, and solarization can be reduced. Therefore, the content of the Nb ₂ O ₅ component is preferably 60.0% as the upper limit, more preferably 55.0% as the upper limit, and even more preferably 52.0% as the upper limit.

As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

The ratio (mass ratio) of the content of the ZrO ₂ component to the content of the Nb ₂ O ₅ component is preferably 0.01 or more. By increasing this ratio, the partial dispersion ratio can be reduced, and the exposure effect can be reduced. Therefore, the mass ratio ZrO ₂ / Nb ₂ O ₅ preferably uses 0.01 as the lower limit, more preferably 0.05 as the lower limit, still more preferably 0.09 as the lower limit, and even more preferably 0.15 as the lower limit.

On the other hand, from the viewpoint of further improving the devitrification resistance and the melting property of the glass raw material, the upper limit of the ratio may be preferably 1.00 as the upper limit, more preferably 0.50 as the upper limit, and more preferably The upper limit is preferably 0.30.

The sum of the contents of the ZrO ₂ component and the Nb ₂ O ₅ component is preferably 25.0 to 65.0%.

In particular, by setting the sum to 25.0% or more, the partial dispersion ratio of glass can be reduced, and the Abbe number can be reduced. Therefore, the mass sum (ZrO ₂ + Nb ₂ O ₅ ) is preferably 25.0% as the lower limit, more preferably 30.0% as the lower limit, still more preferably 35.0% as the lower limit, and even more preferably 40.0% as the lower limit. It is more preferable to use 46.0% as the lower limit.

On the other hand, by setting the sum to 65.0%, the devitrification resistance of the glass can be improved, and the exposure effect can be reduced. Therefore, the mass sum (ZrO ₂ + Nb ₂ O ₅ ) is preferably 65.0% as the upper limit, more preferably 62.0% as the upper limit, and even more preferably 60.0% as the upper limit.

The ratio (mass ratio) of the content of the Nb ₂ O ₅ component to the sum of the contents of the Ta ₂ O ₅ component and the SiO ₂ component is preferably 0.30 or more and 3.00 or less.

In particular, by setting the ratio to 0.30 or more and increasing the content of the Nb ₂ O ₅ component, which is a component that lowers the partial dispersion ratio, the partial dispersion ratio can be further reduced. Therefore, the mass ratio of Nb ₂ O ₅ / (Ta ₂ O ₅ + SiO ₂ ) is preferably 0.30 as the lower limit, more preferably 0.55 as the lower limit, even more preferably 0.75 as the lower limit, and even more preferably 1.00 as the lower limit. It is more preferable to set 1.20 as the lower limit.

On the other hand, by setting the ratio to 3.00 or less, the devitrification resistance of the glass can be further improved. Therefore, the mass ratio Nb ₂ O ₅ / (Ta ₂ O ₅ + SiO ₂ ) is preferably 3.00 as the upper limit, more preferably 2.80 as the upper limit, and even more preferably 2.50 as the upper limit.

When the content of TiO ₂ exceeds 0%, it is an arbitrary component that can increase the refractive index of glass, reduce the Abbe number, and improve devitrification resistance. Therefore, the TiO ₂ component may preferably be contained with more than 0% as the lower limit, more preferably 0.5% as the lower limit, still more preferably 0.7% as the lower limit, and still more preferably 1.0% as the lower limit.

On the other hand, by setting the content of the TiO ₂ component to 20.0% or less, the coloration of the glass can be reduced, so that the visible light transmittance is not easily deteriorated. In addition, this can suppress an increase in the partial dispersion ratio. Therefore, the content of the TiO ₂ component is preferably 20.0% as the upper limit, more preferably 15.0% as the upper limit, still more preferably 13.0% as the upper limit, still more preferably 10.0% as the upper limit, and still more preferably 7.5% is the upper limit, further preferably 4.5% as the upper limit, and still more preferably 3.3% as the upper limit.

As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

When the Li ₂ O content exceeds 0%, it is an arbitrary component that can reduce the partial dispersion ratio of glass, lower the liquidus temperature, and lower the glass transition point. Therefore, the Li ₂ O component may preferably be contained in an amount of more than 0%, more preferably more than 1.0%, more preferably more than 2.5%, still more preferably more than 3.0%, and still more preferably 5.8%.

On the other hand, by setting the content of the Li ₂ O component to 25.0% or less, devitrification of glass caused by excessively containing the Li ₂ O component can be reduced. Moreover, since devitrification resistance at the time of reheating can be improved, the press-moldability of glass can be improved. Therefore, the content of the Li ₂ O component is preferably 25.0% as the upper limit, more preferably 20.0% as the upper limit, still more preferably 15.0% as the upper limit, and even more preferably 11.0% as the upper limit.

As a Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , LiF, or the like can be used as a raw material.

The ratio (mass ratio) of the total content of the Nb ₂ O ₅ component and the TiO ₂ component to the total content of the Ta ₂ O ₅ component, the ZrO ₂ component, and the Li ₂ O component is preferably 10.00 or less. Thereby, a partial dispersion ratio can be reduced. Therefore, the mass ratio (Nb ₂ O ₅ + TiO ₂ ) / (Ta ₂ O ₅ + ZrO ₂ + Li ₂ O) is preferably 10.00 as the upper limit, more preferably 8.00 as the upper limit, and even more preferably 6.00 as the upper limit. The upper limit is more preferably 4.00 as the upper limit, and further preferably 3.10 as the upper limit.

On the other hand, from the viewpoint of increasing the refractive index of glass and reducing the Abbe number, the ratio may preferably be more than 0 as the lower limit, more preferably 0.50 as the lower limit, and still more preferably 0.80 as the lower limit.

The ratio (mass ratio) of the content of the ZrO ₂ component to the total content of the TiO ₂ component and the Nb ₂ O ₅ component is preferably 0.05 or more. Thereby, the ratio of the content of ZrO ₂ to the content of Nb ₂ O ₅ or TiO _{2 which} leads to high dispersion is within a specific range, so that a lower Abbe number and a lower partial dispersion ratio can be taken into consideration. Therefore, the mass ratio ZrO ₂ / (Nb ₂ O ₅ + TiO ₂ ) is preferably 0.05 as the lower limit, more preferably 0.08 as the lower limit, still more preferably 0.10 as the lower limit, and still more preferably 0.15 as the lower limit.

On the other hand, from the viewpoint of improving the devitrification resistance of glass, the ratio may preferably be 0.30 as the upper limit, more preferably 0.20 as the upper limit, and even more preferably 0.15 as the upper limit.

The ratio (mass ratio) of the content of the TiO ₂ component to the total content of the Nb ₂ O ₅ component and the Ta ₂ O ₅ component is preferably 0.01 or more. Especially in a state containing a large amount of ZrO ₂ components, by including a TiO ₂ component in a specific amount or more with respect to the Nb ₂ O ₅ component and the Ta ₂ O ₅ component, the devitrification resistance of the glass can be improved, and Reduce the Abbe number. Therefore, the mass ratio TiO ₂ / (Nb ₂ O ₅ + Ta ₂ O ₅ ) is preferably 0.01 as the lower limit, more preferably 0.05 as the lower limit, still more preferably 0.08 as the lower limit, and even more preferably 0.10 as the lower limit. The lower limit is more preferably 0.13 as the lower limit.

On the other hand, from the viewpoint of improving the visible light transmittance or partial dispersion ratio of glass, the ratio may preferably be 0.30 as the upper limit, more preferably 0.25 as the upper limit, and still more preferably 0.20 as the upper limit.

The sum of the contents of the ZrO ₂ component and the Li ₂ O component is preferably 5.0% or more and 35.0% or less.

In particular, by setting the sum to be 5.0% or more, the partial dispersion ratio can be reduced even in a state where the content of the Ta ₂ O ₅ component is small, so that it can disperse a small portion having a required amount. It is easier to reduce the material cost than glass. Therefore, the mass sum (ZrO ₂ + Li ₂ O) is preferably 5.0% as the lower limit, more preferably 8.0% as the lower limit, still more preferably 10.0% as the lower limit, and even more preferably 12.0% as the lower limit.

On the other hand, by making this sum 35.0%, the devitrification resistance of glass can be improved. Therefore, the mass sum (ZrO ₂ + Li ₂ O) is preferably 35.0% as the upper limit, more preferably 30.0% as the upper limit, still more preferably 25.0% as the upper limit, and even more preferably 20.0% as the upper limit.

When the content of Na ₂ O exceeds 0%, it is an optional component that can reduce the partial dispersion ratio of glass, improve chemical durability, especially water resistance, and reduce the glass transition point. Therefore, the content of the Na ₂ O component may preferably exceed 0% as the lower limit, more preferably 1.0% as the lower limit, and even more preferably 2.1% as the lower limit.

On the other hand, by setting the content of the Na ₂ O component to 30.0% or less, an increase in the partial dispersion ratio of the glass can be suppressed. In addition, it is possible to reduce devitrification of the glass caused by excessively containing a Na ₂ O component, improve the press formability of the glass, and improve chemical durability. Therefore, the content of the Na ₂ O component is preferably 30.0% as the upper limit, more preferably 25.0% as the upper limit, still more preferably 20.0% as the upper limit, still more preferably 18.0% as the upper limit, and even more preferably Use 15.0% as the upper limit.

As the Na ₂ O component, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ and the like can be used as raw materials.

When the K ₂ O component contains more than 0%, it is an arbitrary component that can reduce the glass transition point.

On the other hand, by setting the content of the K ₂ O component to 15.0% or less, devitrification of glass caused by excessively containing the K ₂ O component can be reduced. Moreover, since devitrification resistance at the time of reheating can be improved, the press-moldability of glass can be improved. Therefore, the content of the K ₂ O component is preferably 15.0% as the upper limit, more preferably 10.0% as the upper limit, and even more preferably 5.0% as the upper limit.

As the K ₂ O component, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like can be used as a raw material.

The total content (mass) of the Rn ₂ O component (where Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 30.0% or less. Thereby, the devitrification resistance of the glass can be improved, the chemical durability can be improved, and the fogging under high humidity can be reduced. Therefore, the total content of the Rn ₂ O component is preferably 30.0% as the upper limit, more preferably 20.0% as the upper limit, and even more preferably 16.0% as the upper limit.

On the other hand, from the viewpoint of further improving the devitrification resistance during reheating, the total content of the Rn ₂ O component may preferably be more than 0% as the lower limit, and more preferably be 5.0% as the lower limit. The lower limit is preferably 8.0%.

The MgO component is an arbitrary component which can reduce the melting temperature of glass when it contains more than 0%. CaO component, SrO component, and BaO component are arbitrary components which can reduce the liquidus temperature of glass, and improve devitrification resistance when it contains more than 0%. Among them, the BaO component is also a component that can reduce the partial dispersion ratio of glass when it contains more than 0%.

On the other hand, by setting the contents of the MgO component, the CaO component, the SrO component, and BaO to 20.0% or less, respectively, it is possible to suppress the decrease in the refractive index and improve the devitrification resistance of the glass. Further, by setting the content of the MgO component and the CaO component to 20.0% or less, the chemical durability of the glass can also be improved.

Therefore, the contents of the MgO component, the CaO component, the SrO component, and the BaO are preferably 20.0% as the upper limit, more preferably 10.0% as the upper limit, and even more preferably 5.0% as the upper limit.

MgO component, CaO component, SrO component and BaO components may be used _{MgO, MgCO 3, MgF 2,} CaCO 3, CaF 2, Sr (NO 3) 2, SrF 2, BaCO 3, Ba (NO 3) 2 and the like as a raw material.

When the ZnO component contains more than 0%, it is an arbitrary component that can lower the liquidus temperature of the glass and lower the glass transition point.

On the other hand, by setting the content of the ZnO component to 30.0% or less, the required high refractive index can be obtained and the chemical durability of the glass can be improved. Therefore, the content of the ZnO component is preferably 30.0% as the upper limit, more preferably 20.0% as the upper limit, and even more preferably 10.0% as the upper limit.

As the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

The total content (mass) of the RO component (R is one or more selected from Mg, Ca, Sr, Ba, and Zn) is preferably 40.0% or less. Thereby, deterioration of devitrification resistance of the glass can be suppressed, and Reduction in refractive index can be suppressed. Therefore, the total content of the RO component is preferably 20.0% as the upper limit, more preferably 10.0% as the upper limit, still more preferably 5.0% as the upper limit, and even more preferably 2.0% as the upper limit. .

When the content of Y ₂ O ₃ component, La ₂ O ₃ component, Gd ₂ O ₃ component, and Yb ₂ O ₃ component exceeds 0%, it is any component that can increase the refractive index of glass and improve devitrification resistance. .

On the other hand, by setting the contents of each of the Y ₂ O ₃ component, the La ₂ O ₃ component, the Gd ₂ O ₃ component, and the Yb ₂ O ₃ component to 10.0% or less, the devitrification resistance of the glass can be improved, and It is difficult to reduce the dispersion of glass. Therefore, the content of each of the Y ₂ O ₃ component, the La ₂ O ₃ component, the Gd ₂ O ₃ component, and the Yb ₂ O ₃ component is preferably 10.0% as the upper limit, more preferably 5.0% as the upper limit, and even more preferably Use 3.0% as the upper limit.

Y ₂ O ₃ component, La ₂ O ₃ component, Gd ₂ O ₃ component and Yb ₂ O ₃ component can use Y ₂ O ₃ , YF ₃ , La ₂ O ₃ , La (NO ₃ ) ₃ ‧ XH ₂ O (X It is an arbitrary integer), Gd ₂ O ₃ , GdF ₃ , Yb ₂ O ₃ and the like as raw materials.

The total content (sum of mass) of the Ln ₂ O ₃ component (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is preferably 20.0% or less. Thereby, the reduction in dispersion of the glass can be suppressed, and the devitrification resistance of the glass can be improved. Therefore, the sum of the contents of the Ln ₂ O ₃ components is preferably 20.0% as the upper limit, more preferably 10.0% as the upper limit, and even more preferably 4.0% as the upper limit.

When the B ₂ O ₃ component contains more than 0%, it is an arbitrary component that can form a skeleton of more glass.

On the other hand, by reducing the content of the B ₂ O ₃ component to 30.0% or less, it is possible to suppress a decrease in the refractive index of the glass and to suppress the deterioration of the visible light transmittance. Moreover, the press-moldability of glass can be improved. Therefore, the content of the B ₂ O ₃ component is preferably 30.0% as the upper limit, more preferably 15.0% as the upper limit, still more preferably 8.0% as the upper limit, and still more preferably 4.0% as the upper limit.

For the B ₂ O ₃ component, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ ‧ 10H ₂ O, BPO ₄ and the like can be used as raw materials.

When the content of the P ₂ O ₅ component exceeds 0%, it is an arbitrary component that can improve the stability of the glass.

On the other hand, by setting the content of the P ₂ O ₅ component to 10.0% or less, devitrification caused by excessively containing the P ₂ O ₅ component can be reduced. Therefore, the content of the P ₂ O ₅ component is preferably 10.0% as the upper limit, more preferably 5.0% as the upper limit, and even more preferably 3.0% as the upper limit.

For the P ₂ O ₅ component, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ and the like can be used as raw materials.

When the GeO ₂ component contains more than 0%, it is an arbitrary component that can increase the refractive index of glass and reduce devitrification during molding.

On the other hand, by setting the content of the GeO ₂ component to 10.0% or less, the amount of expensive GeO ₂ components can be reduced, and thus the material cost of glass can be reduced. Therefore, the content of the GeO ₂ component is preferably 10.0% as the upper limit, more preferably 5.0% as the upper limit, and even more preferably 3.0% as the upper limit.

As the GeO ₂ component, GeO ₂ or the like can be used as a raw material.

When the content of the Al ₂ O ₃ component and the Ga ₂ O ₃ component exceeds 0%, they are arbitrary components that can improve the chemical durability of the glass.

On the other hand, devitrification resistance of glass can be improved by setting the content of these components to 15.0% or less, respectively. Therefore, the content of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 15.0% as the upper limit, more preferably 10.0% as the upper limit, and even more preferably 5.0% as the upper limit.

As the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga (OH) ₃ and the like can be used as raw materials.

When the content of WO ₃ exceeds 0%, it is an arbitrary component that can increase the refractive index of glass, reduce the Abbe number, and lower the liquidus temperature.

On the other hand, by setting the content of the WO ₃ component to 20.0% or less, the partial dispersion ratio of the glass can be made difficult to increase, and the visible light transmittance can be improved. Therefore, the content of the WO ₃ component is preferably 20.0% as the upper limit, more preferably 10.0% as the upper limit, and even more preferably 5.0% as the upper limit.

As the WO ₃ component, WO ₃ and the like can be used as a raw material.

When the content of the Bi ₂ O ₃ component and the TeO ₂ component exceeds 0%, it is an arbitrary component that can increase the refractive index of the glass and reduce the glass transition point.

On the other hand, by setting the content of each of the Bi ₂ O ₃ component and the TeO ₂ component to 20.0% or less, the coloration of the glass can be reduced, and deterioration in visible light transmittance can be suppressed. In particular, by setting the content of the Bi ₂ O ₃ component to 20.0% or less, it is possible to make it difficult for the partial dispersion ratio of the glass to increase. Therefore, the content of each of the Bi ₂ O ₃ component and the TeO ₂ component is preferably 20.0% as the upper limit, more preferably 10.0% as the upper limit, and even more preferably 5.0% as the upper limit.

As the Bi ₂ O ₃ component and the TeO ₂ component, Bi ₂ O ₃ , TeO _2, or the like can be used as a raw material.

When the Sb ₂ O ₃ component contains more than 0%, it is an arbitrary component that can promote defoaming of the glass and can clarify the glass.

On the other hand, by setting the content of the Sb ₂ O ₃ component to 3.0% or less, excessive foaming is unlikely to occur when the glass is melted, and the Sb ₂ O ₃ component and melting equipment (especially noble metals such as Pt) can be suppressed. Of alloying. Therefore, the content of the Sb ₂ O ₃ component is preferably 3.0% as the upper limit, more preferably 2.0% as the upper limit, and even more preferably 1.0% as the upper limit. But in the case where emphasis on the environmental impact of the optical glass, preferably not containing Sb ₂ O ₃ component.

As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O _7, 5H ₂ O, or the like can be used as a raw material.

In addition, the component which clarifies and defoams glass is not limited to the above-mentioned Sb ₂ O ₃ component, and a clarifying agent, a defoaming agent, or a combination thereof known in the glass manufacturing field may be used.

The content of the ZrO ₂ component, the ZnO component, and the Nb ₂ O ₅ component in the optical glass of the present invention preferably satisfies the relationship of ZrO ₂ + (ZnO / Nb ₂ O ₅ ) ≧ 3.00. This can further reduce the partial dispersion ratio. Therefore, the value of ZrO ₂ + (ZnO / Nb ₂ O ₅ ) is preferably 3.00 as the lower limit, more preferably 5.00 as the lower limit, and even more preferably 6.00 as the lower limit.

On the other hand, the value may be preferably 15.00 as the upper limit, more preferably 12.00 as the upper limit, and even more preferably 10.00 as the upper limit.

The ratio (mass ratio) of the total content of the Ta ₂ O ₅ component, the SiO ₂ component, and the ZnO component to the content of the Nb ₂ O ₅ component is preferably 0.30 or more. Thereby, devitrification resistance can be improved, and the partial dispersion ratio can be further reduced. Therefore, the mass ratio (Ta ₂ O ₅ + SiO ₂ + ZnO) / Nb ₂ O _{5 is} preferably 0.30 as the lower limit, more preferably 0.40 as the lower limit, still more preferably 0.50 as the lower limit, and still more preferably 0.567 is the lower limit.

On the other hand, the mass ratio may preferably be 1.50 as the upper limit, more preferably 1.20 as the upper limit, and even more preferably 1.00 as the upper limit.

<About ingredients that should not be contained>

Next, components which should not be contained in the optical glass of the present invention, and components which are not preferable to be contained will be described.

As long as the characteristics of the glass of the present invention are not impaired, other components not described above may be added as necessary. However, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, Lu, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo has a separate or composite When it is contained in a small amount, the glass may be colored to absorb a specific wavelength in the visible light region, thereby reducing the visible light transmittance. Therefore, it is preferable that the optical glass, which transmits the wavelength in the visible light region, does not substantially change. Contains these.

In addition, since lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components having a high environmental load, they are preferably substantially not contained, that is, they are not contained except for inevitable mixing.

Furthermore, the components of Th, Cd, Tl, Os, Be, and Se have tended to be restrained and used as harmful chemical substances in recent years. When used, not only glass manufacturing steps It is necessary to take measures on environmental countermeasures to the processing steps and the finished products. Therefore, when it is important to take environmental impact into consideration, it is preferable not to include these substances in substance.

Since the glass composition of the present invention is expressed in terms of mass% relative to the total mass of the glass in terms of oxide conversion, it cannot be directly expressed as Moire%. However, in the present invention, it exists in various types that satisfy the requirements. The composition represented by Moire% of each component in the characteristic glass composition is roughly the following value in terms of oxide conversion composition.

SiO ₂ composition 10.0 ~ 70.0 mole%

And Ta ₂ O ₅ composition 0 ~ 10.0 mole%

ZrO ₂ composition 0 ~ 30.0 mole%

Nb ₂ O ₅ composition 0 ~ 30.0 mole%

TiO ₂ composition 0 ~ 35.0 mole%

Li ₂ O composition 0 ~ 50.0 mole%

Na ₂ O composition 0 ~ 40.0 mole%

K ₂ O composition 0 ~ 25.0 mole%

MgO composition 0 ~ 50.0 mole%

CaO composition 0 ~ 40.0 mole%

SrO composition 0 ~ 25.0 mole%

BaO composition 0 ~ 20.0 mole%

ZnO composition 0 ~ 40.0 mole%

Y ₂ O ₃ composition 0 ~ 8.0 mol%

La ₂ O ₃ composition 0 ~ 5.0 mol%

Gd ₂ O ₃ composition 0 ~ 5.0 mole%

Yb ₂ O ₃ composition 0 ~ 5.0 mol%

B ₂ O ₃ composition 0 ~ 50.0 mole%

P ₂ O ₅ composition 0 ~ 10.0 mole%

GeO ₂ composition 0 ~ 10.0 mole%

Al ₂ O ₃ composition 0 ~ 25.0 mole%

Ga ₂ O ₃ composition 0 ~ 7.0 mol%

WO ₃ composition 0 ~ 15.0 mole%

Bi ₂ O ₃ composition 0 ~ 7.0 mol%

TeO ₂ composition 0 ~ 20.0 mole%

Sb ₂ O ₃ composition 0 ~ 2.0 mol%

[Production method]

The optical glass of the present invention is produced in the following manner, for example. That is, the above-mentioned raw materials are uniformly mixed so that each component falls within a specific content range, and the prepared mixture is put into a platinum crucible, a quartz crucible, or an alumina crucible, and after rough melting, the gold crucible, platinum crucible, and platinum Alloy crucibles or iridium crucibles are melted in a temperature range of 1100 to 1400 ° C for 3 to 5 hours, stirred and homogenized, and defoamed. After the temperature is reduced to 1000 to 1300 ° C, the final stirring is performed to remove streaks. It is produced by casting into a mold and slow cooling.

<Physical properties>

The optical glass of the present invention has a low partial dispersion ratio (θg, F). More specifically, the partial dispersion ratio (θg, F) of the optical glass of the present invention is in a range between ν _d ≦ 25 and Abbe number (ν _d ) (−0.00160 × ν _d +0.63460) ≦ (θg, F) ≦ (-0.00421 × ν d +0.72070) of the relationship, in ν _d> 25 as to satisfy the range of _{(-0.00250 × ν d +0.65710) ≦} (θg, F) ≦ (-0.00421 × ν d + 0.72070). Thereby, an optical glass having high dispersion and a low partial dispersion ratio can be obtained, and therefore, chromatic aberration of an optical element formed of the optical glass can be reduced.

Here, the lower limit of the partial dispersion ratio (θg, F) of the optical glass with ν _d ≦ 25 is preferably (-0.00160 × ν _d +0.63460), more preferably (-0.00160 × ν _d +0.63660), and further preferably It is (-0.00160 × ν _d +0.63860).

In addition, the lower limit of the partial dispersion ratio (θg, F) of optical glass with ν _d > 25 is preferably (-0.00250 × ν _d +0.65710), more preferably (-0.00250 × ν _d +0.65910), and even more preferably (-0.00250 × ν _d +0.66110).

On the other hand, the upper limit of the partial dispersion ratio (θg, F) of the optical glass is preferably (-0.00421 × ν _d +0.72070) for both the optical glass of ν _d > 25 and ν _d ≦ 25. It is more preferably (-0.00421 × ν _d +0.71970), and still more preferably (-0.00421 × ν _d +0.71870).

Moreover, especially in the area with a small Abbe number (ν _d ), the partial dispersion ratio of glass is usually higher than the normal line, and the normal partial dispersion ratio of glass and Abbe number (ν _d ) The relationship is represented by a curve. However, it is difficult to approximate this curve. Therefore, in the present invention, a straight line having a different slope with ν _d = 25 as a boundary is used to indicate that the partial dispersion ratio is lower than that of ordinary glass.

The optical glass of the present invention preferably has a specific refractive index and dispersion (Abbe number). More specifically, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.75 as the lower limit, more preferably 1.77 as the lower limit, and even more preferably 1.78 as the lower limit. On the other hand, the upper limit of the refractive index (n _d ) of the optical glass of the present invention may be preferably 2.00 or less, more preferably 1.95 or less, and even more preferably 1.90 or less. The Abbe number (ν _d ) of the optical glass of the present invention is preferably 40 as the upper limit, more preferably 35 as the upper limit, and even more preferably 30 as the upper limit. On the other hand, the lower limit of the Abbe number (ν _d ) of the optical glass of the present invention is not particularly limited, but may be preferably 20 or more, more preferably 23 or more, and even more preferably 25 or more. As a result, the degree of freedom in optical design is expanded, and even if the thickness of the device is reduced, a large amount of light refraction can be obtained.

The optical glass of the present invention preferably has less coloration and high visible light transmittance. In particular, if the optical glass of the present invention is expressed in terms of the transmittance of glass, a wavelength (λ ₇₀ ) showing a spectral transmittance of 70% in a sample having a thickness of 10 mm is 500 nm or less, more preferably 460 nm or less, and even more preferably 420 nm or less. . In the optical glass of the present invention, the wavelength (λ ₅ ) at which a sample having a thickness of 10 mm exhibits a spectral transmittance of 5% is 440 nm or less, more preferably 400 nm or less, and even more preferably 380 nm or less. As a result, the absorption end of the glass becomes near the ultraviolet region, which can improve the transmittance of the glass to light with a wider range of wavelengths than the visible light region, thereby reducing coloration, so the optical glass can be used better Material for optical elements that transmit visible light and modify the secondary spectrum.

The exposure effect of the optical glass of the present invention is preferably 5.0% or less. Therefore, even if the machine equipped with optical glass is used for a long time, it will not easily cause the color balance to deteriorate. Therefore, the correction of the high-precision secondary spectrum can be continued for a longer time. In particular, the higher the use temperature, the greater the exposure effect. Therefore, the optical glass of the present invention is particularly effective when the vehicle is used at a high temperature. Therefore, the exposure effect of the optical glass of the present invention is preferably 5.0% as the upper limit, more preferably 4.5% as the upper limit, and even more preferably 4.0% as the upper limit. In addition, the "exposure effect" in this specification refers to the amount of degradation of the spectral transmittance at 450 nm when the glass is irradiated with ultraviolet rays. Specifically, it is based on the standard of Japan Optical Glass Industry Association JOGIS04-1994. The "method for measuring the exposure effect of optical glass" is obtained by measuring the spectral transmittance before and after irradiating light from a high-pressure mercury lamp.

[Preforms and Optical Elements]

The glass molded body can be produced from the produced optical glass by a method such as reheat press molding or precision press molding. That is, a preform for press molding of a mold can be made from an optical glass, the preform is reheated and press-molded, and then a grinding process is performed to produce a glass formed body, or a preform to be produced by grinding processing, or A preform formed by a known float-forming process or the like is subjected to precision press molding to produce a glass formed body. In addition, the method of manufacturing a glass forming body is not limited to the said method.

The glass formed body manufactured in the above manner can be used for various optical elements and optical designs. In particular, the optical glass of the present invention is preferably used for an optical element such as a lens or a lens. This can reduce the halo caused by chromatic aberration of the transmitted light of the optical system provided with the optical element. Therefore, when the optical element is used in a camera, it is possible to capture more accurately. When capturing the shooting object, when the optical element is used in a projector, the required image can be projected in higher definition.

[Example]

Compositions of Examples (No. 1 to No. 27) and Comparative Examples (No. A), refractive index (n _d ), Abbe number (ν _d ), and partial dispersion ratio (θg, F) of the present invention The wavelengths (λ ₅ , λ ₇₀ ) showing the effects of exposure, and spectral transmission of 5% and 70% are shown in Tables 1 to 4. In addition, the following examples are for illustration purposes only, and the present invention is not limited to these examples.

The glasses of the examples and comparative examples of the present invention are oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphoric acid compounds and other general optical glasses selected as the raw materials for each component. The high-purity raw materials used were weighed so as to have the composition ratios of the respective examples and comparative examples shown in the table, and after being mixed uniformly, they were put into a platinum crucible and placed in an electric furnace according to the ease of melting of the glass composition. It is melted in the temperature range of 1100 ~ 1400 ℃ for 3 ~ 5 hours. After stirring and homogenizing and defoaming, the temperature is reduced to 1000 ~ 1300 ℃. After stirring and homogenizing, it is cast into a mold and slowly cooled to make it. glass.

The refractive index, Abbe number, and partial dispersion ratio of the glass of the examples and comparative examples were measured based on the Japan Optical Glass Industry Standard JOGIS01-2003. Then, for the values of the obtained Abbe number and partial dispersion ratio, the intercept b when the slope a is 0.00160, 0.00250, and 0.00421 in the relational expression (θg, F) =-a × ν _d + b is obtained. In addition, the glass used for this measurement is a thing with the slow cooling temperature reduction rate set to -25 degreeC / hr, and processed by the slow cooling furnace.

Based embodiment and the visible light transmittance of the glass of Example Comparative Example was measured according to Japan Optical Glass Industry Society criteria JOGIS02- ^2003. Furthermore, in the present invention, the presence or absence of the tint of the glass is determined by measuring the visible light transmittance of the glass. Specifically, for a parallel polished product having a thickness of 10 ± 0.1 mm, the spectral transmittance of 200 to 800 nm is measured in accordance with JISZ8722, and λ ₅ (wavelength at 5% transmittance) and λ ₇₀ (at 70% transmittance) are obtained. Wavelength).

Effect of exposure-based glass and Comparative Examples of the embodiment according to Example JOGIS04- ¹⁹⁹⁴ "Determination of the effect of the exposure method of optical glass" Japanese Optical Glass Industrial Standards, measuring changes in the wavelength of 450nm light transmittance before and after light irradiation (%). Here, the irradiation of light was performed by heating an optical glass sample to 150 ° C. and irradiating light with a wavelength of 450 nm for 3 hours using an ultra-high pressure mercury lamp.

As shown in the table, the Abbe number (ν _d ) of the optical glass of the example exceeds 25, and the partial dispersion ratio (θg, F) is (-0.00421 × ν _d +0.72070) or less, more specifically, ( -0.00421 × ν _d +0.71769) or less.

On the one hand, the lower limit of the partial dispersion ratio (θg, F) of the optical glass obtained in the examples is (-0.00250 × ν _d +0.65710) or more. Therefore, it can be seen that the partial dispersion ratio (θg, F) of the optical glass according to the embodiment of the present invention is within a desired range.

On the other hand, although the glass of Comparative Example (No. A) had ν _d > 25, the partial dispersion ratio (θg, F) exceeded (-0.00421 × ν _d +0.72070).

Therefore, it can be seen that the optical glass of the example has a smaller partial dispersion in the relationship with the Abbe number than the glass of the comparative example.

The λ ₇₀ (wavelength at 70% transmittance) of the optical glass of the examples was all 500 nm or less, and more specifically, 420 nm or less. The λ ₅ (wavelength at 5% transmittance) of the optical glass according to the embodiment of the present invention is 440 nm or less, and more specifically, 360 nm or less. Therefore, it can be seen that the optical glass of the embodiment of the present invention is not easy to be colored, and has high transmittance of visible light.

In addition, the refractive index (n _d ) of the optical glass of the examples were all 1.75 or more, more specifically, 1.79 or more, and the refractive index (n _d ) was 2.00 or less, and more specifically, 1.90 or less. Within the required range.

The Abbe numbers (ν _d ) of the optical glass of the examples were all 20 or more, more specifically, 25 or more, and the Abbe numbers (ν _d ) were 40 or less, and more specifically, 30 or less. Within the required range.

Therefore, it can be seen that the refractive index (n _d ) and Abbe number (ν _d ) of the optical glass of the embodiment of the present invention are within the required range, and the transmittance of visible light is high, the coloring is less, and the chromatic aberration is Smaller.

Furthermore, the exposure effects of the optical glass in the examples of the present invention are all 5.0% or less, more specifically, 4.5% or less. It can also be seen that the exposure effect of the optical glass due to prolonged ultraviolet irradiation is reduced.

In the above, the present invention has been described in detail for the purpose of illustration, but it should be understood that the purpose of this embodiment is only for illustration, and the industry can make many changes without departing from the spirit and scope of the present invention. more.

Claims (22)

An optical glass containing 11.0 to 45.0% of SiO ₂ component and 10.0 to 60.0% of Nb ₂ O ₅ component in mass%, the content of Ta ₂ O ₅ component is 17.0% or less, and the content of TiO ₂ component is 5.709 % Or less, the mass ratio TiO ₂ / (Nb ₂ O ₅ + Ta ₂ O ₅ ) is 0.123 or less, the mass ratio (Ta ₂ O ₅ + SiO ₂ + ZnO) / Nb ₂ O ₅ is 0.567 or more, and the partial dispersion ratio ( The relationship between θg, F) and Abbe number (ν _d ) satisfies (-0.00160 × ν _d +0.63460) ≦ (θg, F) ≦ (-0.00421 × ν _d +0.72070) in the range of ν _d ≦ 25 In the range of ν _d > 25, the relationship of (-0.00250 × ν _d +0.65710) ≦ (θg, F) ≦ (-0.00421 × ν _d +0.72070) is satisfied. The optical glass according to claim 1, wherein the mass ratio Nb ₂ O ₅ / (Ta ₂ O ₅ + SiO ₂ ) is 0.30 or more and 3.00 or less. For example, the optical glass of claim 1, wherein the mass ratio TiO ₂ / (Nb ₂ O ₅ + Ta ₂ O ₅ ) is 0.01 or more. For example, the optical glass of claim 1 includes, in terms of mass%, a ZrO ₂ component of 0 to 25.0%, a Li ₂ O component of 0 to 25.0%, and a ZnO component of 0 to 30.0%. The optical glass according to claim 4, wherein the mass ratio ZrO ₂ / Nb ₂ O ₅ is 0.01 or more. For example, the optical glass of claim 4, wherein the mass and ZrO ₂ + Nb ₂ O ₅ are 25.0-65.0%. The optical glass according to claim 4, wherein the mass ratio (Nb ₂ O ₅ + TiO ₂ ) / (Ta ₂ O ₅ + ZrO ₂ + Li ₂ O) is 10.00 or less. The optical glass according to claim 4, wherein the mass ratio ZrO ₂ / (Nb ₂ O ₅ + TiO ₂ ) is 0.05 or more. The optical glass as claimed in claim 4, wherein the mass and ZrO ₂ + Li ₂ O are 5.0% or more and 35.0% or less. For example, the optical glass of claim 4, wherein the content of the ZrO ₂ component, the ZnO component, and the Nb ₂ O ₅ component satisfies the relationship of ZrO ₂ + (ZnO / Nb ₂ O ₅ ) ≧ 3.00 in terms of mass%. For example, the optical glass of claim 1 includes, in terms of mass%, a Li ₂ O component of 0 to 25.0%, a Na ₂ O component of 0 to 30.0%, and a K ₂ O component of 0 to 15.0%. The optical glass according to claim 11, wherein the mass of one or more selected from the group consisting of a Li ₂ O component, a Na ₂ O component, and a K ₂ O component is 30.0% or less. For example, the optical glass of claim 1, in terms of mass%, it also contains MgO component 0 ~ 20.0%, CaO component 0 ~ 20.0%, SrO component 0 ~ 20.0%, BaO component 0 ~ 20.0%, ZnO component 0 ~ 30.0% . The optical glass according to claim 13, wherein the mass of one or more selected from the group consisting of a MgO component, a CaO component, an SrO component, a BaO component, and a ZnO component is 20.0% or less. For example, the optical glass of claim 1, in terms of mass%, it contains Y ₂ O ₃ component 0 ~ 10.0%, La ₂ O ₃ component 0 ~ 10.0%, Gd ₂ O ₃ component 0 ~ 10.0%, Yb ₂ O ₃ Ingredients 0 ~ 10.0%. The optical glass according to claim 15, wherein the mass of one or more selected from the group consisting of a Y ₂ O ₃ component, a La ₂ O ₃ component, a Gd ₂ O ₃ component, and a Yb ₂ O ₃ component is 20.0% or less . For example, the optical glass of claim 1, in which the B ₂ O ₃ component is 0 to 30.0%, the P ₂ O ₅ component is 0 to 10.0%, the GeO ₂ component is 0 to 10.0%, and the Al ₂ O ₃ component is 0. ~ 15.0%, Ga ₂ O ₃ composition 0 ~ 15.0%, WO ₃ composition 0 ~ 20.0%, Bi ₂ O ₃ composition 0 ~ 20.0%, TeO ₂ composition 0 ~ 20.0%, Sb ₂ O ₃ composition 0 ~ 3.0%. For example, the optical glass of claim 1 has a refractive index (nd) of 1.75 or more and 2.00 or less, and an Abbe number (νd) of 20 or more and 40 or less. For example, the optical glass of claim 1, wherein the wavelength (λ ₇₀ ) in which the spectral transmittance shows 70% is 500 nm or less. A preform comprising the optical glass according to any one of claims 1 to 19, and used for polishing and / or precision press forming. An optical element obtained by grinding and / or grinding the optical glass according to any one of claims 1 to 19. An optical element which is formed by precision press forming the optical glass according to any one of claims 1 to 19.