JP2012206892A - Optical glass, perform, and optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical glass whose refractive index (n) is in a desired range, but whose Abbe number (ν) and partial dispersion ratio (θg, F) are small, and whose transparency to visible light is enhanced.SOLUTION: The optical glass contains, with respect to the whole glass mass in terms of oxide composition, in mol%, ≥20.0% and ≤60.0% of component SiO, >20.0% and ≤50.0% of component CaO, and >0% and ≤20.0% of the total of components BaO and KO, and ≤30.0% of component NbO, and has a relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν) in the range of ν≤31 satisfying (-0.00162×νd+0.63822)≤(θg, F)≤(-0.00275×νd+0.68125), and a relationship therebetween in the range of ν>31 satisfying (-0.00162×νd+0.63822)≤(θg, F)≤(-0.00162×νd+0.64622).

Description

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

  Optical systems such as digital cameras and video cameras, although large and small, contain blurs called aberrations. This aberration is classified into monochromatic aberration and chromatic aberration. In particular, the chromatic aberration is strongly dependent on the material characteristics of the lens used in the optical system.

  In general, chromatic aberration is corrected by combining a low-dispersion convex lens and a high-dispersion concave lens. However, this combination can only correct aberrations in the red region and the green region, and remains in the blue region. This blue region aberration that cannot be removed is called a secondary spectrum. In order to correct the secondary spectrum, it is necessary to perform an optical design in consideration of the trend of the g-line (435.835 nm) in the blue region. At this time, the partial dispersion ratio (θg, F) is used as an index of the optical characteristics to be noticed in the optical design. In the optical system combining the low dispersion lens and the high dispersion lens, an optical material having a large partial dispersion ratio (θg, F) is used for the low dispersion side lens, and the partial dispersion ratio ( By using an optical material having a small θg, F), the secondary spectrum is corrected well.

The partial dispersion ratio (θg, F) is expressed by the following equation (1).
θg, F = (n _g −n _F ) / (n _F −n _C ) (1)

In optical glass, there is an approximately linear relationship between a partial dispersion ratio (θg, F) representing partial dispersion in a short wavelength region and an Abbe number (ν _d ). The straight line representing this relationship plots the partial dispersion ratio and Abbe number of NSL7 and PBM2 on the Cartesian coordinates employing the partial dispersion ratio (θg, F) on the vertical axis and the Abbe number (ν _d ) on the horizontal axis. It is represented by a straight line connecting two points and is called a normal line (see FIG. 1). Normal glass, which is the standard for normal lines, differs depending on the optical glass manufacturer, but each company defines it with almost the same slope and intercept. (NSL7 and PBM2 are optical glasses manufactured by OHARA, Inc., and 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, and the partial dispersion ratio (θg, F) is 0.5436.)

  Here, as glass having high dispersion, for example, optical glasses as shown in Patent Documents 1 to 3 are known.

Japanese Patent Laid-Open No. 03-005340 JP 2006-219365 A JP-A 61-168551

However, the glasses disclosed in Patent Documents 1 to 3 have a small partial dispersion ratio and are not sufficient for use as a lens for correcting the secondary spectrum. Further, the glasses disclosed in Patent Documents 1 to 3 are not sufficiently transparent to visible light, and are not sufficient for use in applications that transmit visible light. That is, there is a demand for an optical glass having a small Abbe number (ν _d ), high dispersion, a small partial dispersion ratio (θg, F), and high transparency to visible light.

The present invention has been made in view of the above problems, and the object of the present invention is to have a small Abbe number (ν _d ) and a partial dispersion while the refractive index (n _d ) is within a desired range. The object is to obtain an optical glass having a small ratio (θg, F) and enhanced transparency to visible light, and a preform and an optical element using the optical glass.

In order to solve the above-mentioned problems, the present inventors have conducted intensive test research, and as a result, by combining the SiO ₂ component and the CaO component, and making these contents within a predetermined range, a stable glass can be obtained. It was found that the Abbe number (ν _d ) was lowered while being formed, and the coloration of the glass was reduced. Further, by making the content of the Nb ₂ O ₅ component within a predetermined range, it has been found that devitrification of the glass is reduced while obtaining a high refractive index, a low Abbe number, and a low partial dispersion ratio, The present invention has been completed. Specifically, the present invention provides the following.

(1) Containing 20.0% or more and 60.0% or less of SiO ₂ component in mol%, and more than 20.0 and 50.0% or less of CaO component with respect to the total amount of glass of oxide conversion composition Nb ₂ O ₅ content is 30.0% or less, and the partial dispersion ratio (θg, F) is in the range of νd ≦ 31 (−0.00162 × νd + 0) with the Abbe number (νd). .63822) ≦ (θg, F) ≦ (−0.00275 × νd + 0.68125), and in the range of νd> 31, (−0.00162 × νd + 0.63822) ≦ (θg, F) ≦ (− 0.00162 × νd + 0.64622).

(2) The optical glass according to (1), which contains 0 to 20.0% of a TiO ₂ component in mol% with respect to the total amount of the glass having an oxide equivalent composition.

(3) The optical element according to (1) or (2), wherein the sum of the contents of the Nb ₂ O ₅ component and the TiO ₂ component is 10.0% or more and 40.0% or less with respect to the total amount of glass having an oxide equivalent composition. Glass.

  (4) The optical glass according to any one of (1) to (3), which contains 0 to 25.0% of a BaO component in mol% with respect to the total amount of glass having an oxide equivalent composition.

(5) the molar ratio of the oxide composition in terms of _{(Nb 2 O 5 + BaO)} / (TiO 2 + CaO) is 0.100 or more (1) to (4) any description of the optical glass.

(6) any description of the optical glass of the molar ratio _TiO 2 / _Nb 2 _{O 5} in terms of oxide composition is 3.00 or less (1) (5).

(7) the glass the total amount of substance of the oxide composition in terms of, from 0 to 25.0% Li ₂ O component in mol% and / or Na ₂ O component from 0 to 25.0% and / or _{K 2} O ingredient 0 ˜25.0% and / or Cs ₂ O component 0 to 10.0%
The optical glass according to any one of (1) to (6).

(8) The molar sum of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) with respect to the total amount of glass in the oxide equivalent composition is 30.0% or less The optical glass according to (7).

(9) 0 to 20.0% of MgO component and / or 0 to 20.0% of SrO component and / or 0 to 30.0% of ZnO component in mol% with respect to the total amount of glass in the oxide conversion composition
The optical glass according to any one of (1) to (8).

  (10) The molar sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, and Zn) with respect to the total amount of glass in the oxide equivalent composition is 20.0% or more The optical glass according to (9), which is 60.0% or less.

(11) the glass the total amount of substance of the oxide composition in terms of, 0~30.0% _P 2 _{O 5} component in mol% and / or _B 2 _{O 3} component from 0 to 40.0% and / or GeO ₂ component 0 to 20.0% and / or _Y 2 _{O 3} component from 0 to 15.0% and / or _La 2 _{O 3} component from 0 to 15.0% and / or _Gd 2 _{O 3} component from 0 to 15.0% and / or _Yb 2 _{O 3} component from 0 to 15.0% and / or _Ta 2 _{O 5} component from 0 to 15.0% and / or _Bi 2 _{O 3} component from 0 to 15.0% and / or WO ₃ components 0-20. 0% and / or TeO ₂ component from 0 to 30.0% and / or ZrO ₂ component from 0 to 15.0% and / or _Al 2 _{O 3} component from 0 to 15.0% and / or _Sb 2 _{O 3} component 0 1.0%
The optical glass according to any one of (1) to (10), further comprising:

  (12) The optical glass according to any one of (1) to (11), having a refractive index (nd) of 1.70 to 2.20 and an Abbe number (νd) of 20 to 40.

(13) The optical glass according to any one of (1) to (12), wherein a wavelength (λ ₇₀ ) having a spectral transmittance of 70% is 500 nm or less.

  (14) A preform for polishing and / or precision press molding comprising the optical glass according to any one of (1) to (13).

  (15) An optical element obtained by grinding and / or polishing the optical glass according to any one of (1) to (13).

  (16) An optical element formed by precision press-molding the optical glass according to any one of (1) to (13).

According to the present invention, the SiO ₂ component and the CaO component are used in combination with one or more of the BaO component and the K ₂ O component, and the content thereof is within a predetermined range. While achieving high dispersion, the partial dispersion ratio (θg, F) of the glass has a desired relationship with the Abbe number (ν _d ), and the coloration of the glass is reduced. Therefore, an optical glass having a high refractive index (n _d ), a small Abbe number (ν _d ), a small partial dispersion ratio (θg, F) and high transparency to visible light, and The preform and optical element used can be obtained.

It is a figure which shows the normal line by which partial dispersion ratio ((theta) g, F) is represented on the orthogonal coordinate of a vertical axis | shaft and Abbe number ((nu) _d ) on a horizontal axis. It is a figure which shows the relationship between the partial dispersion ratio ((theta) g, F) and the Abbe number ((nu) _d ) about the glass of the Example of this application.

In the optical glass of the present invention, the SiO ₂ component is 20.0% or more and 60.0% or less and the CaO component is more than 20.0 and 50.0% by mol% with respect to the total amount of the glass having an oxide conversion composition. %, Nb ₂ O ₅ component content is 30.0% or less, and the partial dispersion ratio (θg, F) is within the range of νd ≦ 31 (−0) with respect to the Abbe number (νd). .00162 × νd + 0.63822) ≦ (θg, F) ≦ (−0.00275 × νd + 0.68125), and in the range of νd> 31, (−0.00162 × νd + 0.63822) ≦ (θg, F ) ≦ (−0.00162 × νd + 0.64622). By using both the SiO ₂ component and the CaO component and keeping their contents within a predetermined range, the Abbe number (ν _d ) can be reduced while the glass is stable, and the coloring of the glass is reduced. Is done. In addition, by setting the content of the Nb ₂ O ₅ component within a predetermined range, glass devitrification is reduced while a high refractive index, a low Abbe number, and a low partial dispersion ratio are obtained. Therefore, an optical glass having a low Abbe number (ν _d ), a small partial dispersion ratio (θg, F), and a high transparency to visible light, while the refractive index (n _d ) is within a desired range, A preform and an optical element using can be obtained.

  Hereinafter, embodiments of the optical glass of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. be able to. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the meaning of invention is not limited.

[Glass component]
The composition range of each component constituting the optical glass of the present invention is described below. In the present specification, unless otherwise specified, the content of each component is expressed in mol% with respect to the total amount of glass in the oxide equivalent composition. Here, the “oxide equivalent composition” means that the oxide, composite salt, metal fluoride, etc. used as the raw material of the glass component of the present invention are all decomposed and changed into oxides when melted. It is the composition which described each component contained in glass by making the total substance amount of the said production | generation oxide into 100 mol%.

<About essential and optional components>
The SiO ₂ component is a component that promotes stable glass formation and reduces devitrification (generation of crystalline substances), which is undesirable as an optical glass. In particular, when the content of the SiO ₂ component is 20.0% or more, a glass having excellent devitrification resistance can be obtained without significantly increasing the partial dispersion ratio of the glass. Moreover, devitrification and coloring at the time of reheating can be reduced thereby. On the other hand, by making the content of the SiO ₂ component 60.0% or less, it is possible to easily obtain a desired high refractive index by making it difficult for the refractive index of the glass to decrease, and partial dispersion of the glass An increase in the ratio can be suppressed. Further, by setting the content of SiO ₂ component below 60.0%, it is possible to maintain a good meltability. Therefore, the content of the SiO ₂ component is preferably 20.0%, more preferably 21.0%, still more preferably 24.0%, and even more preferably 27.0% with respect to the total amount of glass in the oxide conversion composition. Most preferably, the lower limit is 30.0%. Further, the content of this SiO ₂ component is preferably 60.0%, more preferably 50.0%, and most preferably 45.0%. SiO ₂ component may be contained in the glass by using as a raw material such as _{SiO 2, K 2 SiF 6,} Na 2 SiF 6 or the like.

The CaO component is a component necessary for obtaining a glass having a low Abbe number and high devitrification resistance. In particular, when the content of the CaO component is more than 20.0%, an optical glass having a low Abbe number and high devitrification resistance can be obtained, and the solubility of the glass can be increased. On the other hand, by making the content of the CaO component 50.0% or less, while suppressing the decrease in the refractive index of the glass and the increase in the partial dispersion ratio, the devitrification resistance of the glass due to the excessive content of the CaO component. Deterioration can be suppressed. Moreover, devitrification and coloring at the time of reheating can be reduced thereby. Therefore, the content of the CaO component with respect to the total amount of glass in the oxide conversion composition is preferably more than 20.0%, more preferably 24.0% as an upper limit, and even more preferably more than 30.0%. More preferably, the upper limit is 32.0%, and most preferably the lower limit is 33.5%. In addition, the content of the CaO component is preferably 50.0%, more preferably 45.0%, and most preferably 40.0%. The CaO component can be contained in the glass using, for example, CaCO ₃ , CaF ₂ or the like as a raw material.

The Nb ₂ O ₅ component is a component that increases the devitrification resistance of the glass, and is a component that decreases the Abbe number and the partial dispersion ratio while increasing the refractive index of the glass, and is an optional component in the optical glass of the present invention. It is. In particular, by setting the content of the Nb ₂ O ₅ component to 30.0% or less, an increase in the melting temperature during glass production can be suppressed, and devitrification due to excessive content of the Nb ₂ O ₅ component can be reduced. Therefore, the content of the Nb ₂ O ₅ component is preferably 30.0%, more preferably 20.0%, and most preferably 15.0% with respect to the total amount of glass in the oxide equivalent composition. The Nb ₂ O ₅ component may not be contained, but by containing more than 0% of the Nb ₂ O ₅ component, the Abbe number should be lowered while increasing the refractive index of the glass. And the partial dispersion ratio of the glass can be reduced. Further, the content of Nb ₂ O ₅ component that contains more than 0%, increasing the devitrification resistance of the glass, it is possible to improve the press formability of the glass. Therefore, the content of the Nb ₂ O ₅ component with respect to the total amount of glass in the oxide conversion composition is preferably more than 0%, more preferably 3.0%, more preferably 4.0%, and even more preferably 5%. 0.0%, most preferably 6.0% is the lower limit. The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

The TiO ₂ component is a component that lowers the Abbe number while increasing the refractive index of the glass, and is an optional component in the optical glass of the present invention. In particular, when the content of the TiO ₂ component is 20.0% or less, the coloration of the glass can be reduced and the internal transmittance of the glass can be increased. Further, by setting the content of the TiO ₂ component in 10.0% or less, the partial dispersion ratio is hard to rise, it is possible to easily obtain a low partial dispersion ratio close to normal line. Accordingly, the content of the TiO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 15.0%, and even more preferably less than 12.0%, most preferably The upper limit is 9.0%. On the other hand, it is preferable not to contain a TiO ₂ component from the viewpoint of obtaining a lower partial dispersion ratio or reducing coloring, but a higher refractive index or a lower Abbe number can be obtained, or devitrification resistance can be increased. In view of this, the content of the TiO ₂ component is preferably more than 0%, more preferably 1.0%, still more preferably 3.0%, and most preferably 4.5%. TiO ₂ component may be contained in the glass by using as the starting material for example TiO ₂ or the like.

In the optical glass of the present invention, the sum of the contents of the Nb ₂ O ₅ component and the TiO ₂ component is preferably 10.0% or more and 40.0% or less. In particular, when the sum is 10.0% or more, the contents of the Nb ₂ O ₅ component and the TiO ₂ component that increase the refractive index and lower the Abbe number increase, so that the desired high refractive index and low Abbe An optical glass having a number can be obtained. On the other hand, when this sum is 40.0% or less, devitrification due to these components is reduced, and thus a glass having higher devitrification resistance and stability can be obtained. Therefore, the molar sum (Nb ₂ O ₅ + TiO ₂ ) with respect to the total amount of glass in the oxide conversion composition is preferably 10.0%, more preferably 12.0%, still more preferably 14.0%, most preferably The lower limit is 15.0%. On the other hand, the molar sum (Nb ₂ O ₅ + TiO ₂ ) with respect to the total amount of glass in the oxide conversion composition is preferably 40.0%, more preferably 30.0%, still more preferably 25.0%, most preferably. Has an upper limit of 20.0%.

A BaO component is a component which raises the refractive index of glass, makes the partial dispersion ratio of glass low, and improves the devitrification resistance of glass. In particular, by setting the content of the BaO component to 25.0% or less, deterioration of devitrification resistance and chemical durability due to excessive inclusion of the BaO component can be suppressed. Therefore, the content of the BaO component is preferably 25.0%, more preferably 20.0%, still more preferably 15.0%, and most preferably 10.0% with respect to the total amount of glass in the oxide conversion composition. The upper limit. Although the BaO component is an optional component, it does not have to be contained. However, by containing more than 0% of the BaO component, the desired high refractive index and low portion can be obtained while improving solubility and devitrification resistance. The dispersion ratio can be easily realized. Moreover, devitrification and coloring at the time of reheating can be reduced thereby. Therefore, the content of the BaO component with respect to the total amount of glass in the oxide conversion composition is preferably more than 0%, more preferably 0.5%, and even more preferably 1.0%. On the other hand, the BaO component can be contained in the glass using, for example, BaCO ₃ , Ba (NO ₃ ) ₂ or the like as a raw material.

In the optical glass of the present invention, the sum of the contents of the Nb ₂ O ₅ component and the BaO component with respect to the sum of the contents of the TiO ₂ component and the CaO component is preferably 0.100 or more. As a result, the contents of the Nb ₂ O ₅ component and the BaO component, which are components that lower the partial dispersion ratio, increase with respect to the contents of the TiO ₂ component and the CaO component, which are components that increase the partial dispersion ratio. An optical glass having a low partial dispersion ratio can be obtained. Therefore, the molar ratio (Nb ₂ O ₅ + BaO) / (TiO ₂ + CaO) of the oxide conversion composition is preferably 0.100, more preferably 0.120, still more preferably 0.130, and most preferably 0.140. Is the lower limit. On the other hand, the upper limit of the molar ratio (Nb ₂ O ₅ + BaO) / (TiO ₂ + CaO) is not particularly limited, but the optical glass of the present invention has this molar ratio (Nb ₂ O ₅ + BaO) / (TiO ₂ + CaO). It is often 1.000 or less, more specifically 0.700 or less, and more specifically 0.400 or less.

Further, the optical glass of the present invention, it is preferred molar ratio _TiO 2 / _Nb 2 _{O 5} in terms of oxide composition is 3.00 or less. Thereby, the partial dispersion ratio is lowered while the Abbe number of the glass is adjusted within a desired range, so that an optical glass having a relationship between the desired Abbe number and the partial dispersion ratio can be obtained. At the same time, an optical glass with little coloring can be obtained. Therefore, the molar ratio TiO ₂ / Nb ₂ O ₅ of the oxide conversion composition is preferably 3.00, more preferably 2.00, and still more preferably 2.50.

Li 2 _O component improves the meltability of the glass is a component and to lower the partial dispersion ratio of the glass, an optional component of the optical glass of the present invention. In particular, by reducing the content of the Li ₂ O component to 25.0% or less, a decrease in the refractive index is suppressed, and at the time of forming the glass or reheating the glass due to excessive inclusion of the Li ₂ O component, crystals The chemical durability of the glass can be increased while reducing precipitation. Accordingly, the content of the Li ₂ O component with respect to the total amount of glass having an oxide conversion composition is preferably 25.0%, more preferably 17.0%, still more preferably 12.0%, and even more preferably 9.5. %, Most preferably 5.0%. The Li ₂ O component can be contained in the glass using, for example, Li ₂ CO ₃ , LiNO ₃ , LiF or the like as a raw material.

Na 2 _O component, with a component for improving the meltability of the glass is a component for lowering the glass transition point, which is an optional component of the optical glass of the present invention. In particular, by making the content of the Na ₂ O component 25.0% or less, it is possible to make it difficult for the refractive index to decrease and to make it difficult to deteriorate the chemical durability. Moreover, devitrification resistance at the time of glass formation can be improved, and devitrification and coloring at the time of reheating can be reduced. Therefore, the content of the Na ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 25.0%, more preferably 15.0%, still more preferably 10.0%, and most preferably 5.0. % Is the upper limit. The Na ₂ O component can be contained in the glass using, for example, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ or the like as a raw material.

K 2 _O component is a component to lower the glass transition point while adjusting the meltability of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the K ₂ O component to 25.0% or less, devitrification resistance at the time of glass formation can be increased, and devitrification and coloring at the time of reheating can be reduced. Therefore, the content of the K ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 25.0%, more preferably 20.0%, still more preferably 15.0%, and most preferably 10.0. % Is the upper limit. The K ₂ O component may not be contained from the viewpoint of obtaining a glass with higher press formability, but is preferably more than 0% and more preferably 0 because of the effect of lowering the partial dispersion ratio. It may be contained at a lower limit of 0.5%, more preferably 1.0%. The K ₂ O component can be contained in the glass using, for example, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like as a raw material.

Cs 2 _O component is a component to lower the glass transition point, which is an optional component of the optical glass of the present invention. In particular, by setting the content of the Cs ₂ O component to 10.0% or less, devitrification of the glass due to excessive inclusion of the Cs ₂ O component can be reduced. Therefore, the upper limit of the content of the Cs ₂ O component with respect to the total amount of the glass having an oxide conversion composition is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%. Cs ₂ O component may be contained in the glass by using as the starting material for example _Cs 2 _{CO 3,} CsNO 3, and the like.

In the optical glass of the present invention, the sum of the contents of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K and Cs) is 30.0% or less. Is preferred. In particular, by setting the molar sum to 30.0% or less, it is possible to easily obtain a desired high refractive index and reduce devitrification of the glass. Therefore, the molar sum of the content of the Rn ₂ O component with respect to the total amount of glass in the oxide conversion composition is preferably 30.0%, more preferably 20.0%, even more preferably 10.0%, most preferably The upper limit is 5.0%.

The MgO component is a component that lowers the melting temperature of the glass and is an optional component in the optical glass of the present invention. In particular, by setting the content of the MgO component to 20.0% or less, it is possible to improve the devitrification resistance of the glass while suppressing a decrease in the refractive index of the glass. Moreover, devitrification and coloring at the time of reheating can be reduced thereby. Therefore, the content of the MgO component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 10.0%, and most preferably 5.0%. The MgO component can be contained in the glass using, for example, MgO, MgCO ₃ , MgF ₂ or the like as a raw material.

A SrO component is a component which raises the refractive index of glass and improves the devitrification resistance of glass, and is an arbitrary component in the optical glass of this invention. In particular, the deterioration of the chemical durability of the glass can be suppressed by setting the content of the SrO component to 20.0% or less. Accordingly, the SrO component content is preferably 20.0%, more preferably 15.0%, and most preferably 10.0% with respect to the total amount of glass in the oxide equivalent composition. The SrO component can be contained in the glass using, for example, Sr (NO ₃ ) ₂ , SrF ₂ or the like as a raw material.

The ZnO component is a component that increases the devitrification resistance of the glass and lowers the glass transition point, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the ZnO component to 30.0% or less, it is possible to increase the chemical durability of the glass while reducing devitrification during reheating of the glass. Moreover, devitrification and coloring at the time of reheating can be reduced thereby. Accordingly, the ZnO component content is preferably 30.0%, more preferably 20.0%, still more preferably 16.0%, and most preferably 10.0% with respect to the total amount of glass in the oxide equivalent composition. The upper limit. Although the ZnO component is an optional component, it does not have to be contained. However, from the viewpoint of obtaining particularly high devitrification resistance and a low glass transition point, the content of this ZnO component is preferably more than 0%, more The lower limit is preferably 0.5%, and more preferably 1.0%. The ZnO component can be contained in the glass using, for example, ZnO, ZnF ₂ or the like as a raw material.

  In the optical glass of the present invention, the RO component (wherein R is one or more selected from the group consisting of Zn, Mg, Ca, Sr, and Ba) increases the refractive index while increasing the devitrification resistance of the glass. It is a useful component for adjusting. In particular, the devitrification resistance of the glass can be improved by setting the content of the RO component to 20.0% or more. On the other hand, if the total content of these RO components is too large, the devitrification resistance of the glass tends to deteriorate, and the chemical durability of the glass tends to deteriorate. Therefore, the total content of the RO component with respect to the total glass material amount of the oxide conversion composition is preferably 20.0%, more preferably 25.0%, still more preferably 30.0%, and most preferably 35. More than 0%. Further, the total content of this RO component is preferably 60.0%, more preferably 55.0%, and most preferably 50.0%.

P ₂ O ₅ component is a component which enhances the stability of the glass, an optional component of the optical glass of the present invention. In particular, by setting the content of the P ₂ O ₅ component to 30.0% or less, devitrification due to excessive inclusion of the P ₂ O ₅ component is reduced, so that the stability of the glass can be enhanced. Therefore, the content of the P ₂ O ₅ component with respect to the total amount of glass in the oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 10.0%. The P ₂ O ₅ component can be contained in the glass using, for example, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ or the like as a raw material. .

The B ₂ O ₃ component is a component that promotes stable glass formation, increases devitrification resistance, and increases the solubility of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the B ₂ O ₃ component to 40.0% or less, a desired high refractive index can be obtained by suppressing a decrease in the refractive index, and an increase in the partial dispersion ratio of the glass is suppressed. be able to. Moreover, devitrification at the time of reheating of glass can be reduced thereby. Therefore, the content of the B ₂ O ₃ component is preferably 40.0%, more preferably 30.0%, still more preferably 20.0%, and even more preferably 15.5% with respect to the total amount of glass in the oxide conversion composition. The upper limit is 0%, most preferably 10.0%. The B ₂ O ₃ component is an optional component and may not be contained. However, by containing more than 0% of the B ₂ O ₃ component, the devitrification resistance and solubility of the glass can be improved. . Therefore, the content of this B ₂ O ₃ component is preferably more than 0%, more preferably 1.0%, and most preferably 2.0%. The B ₂ O ₃ component can be contained in the glass using, for example, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ .10H ₂ O, BPO ₄ or the like as a raw material.

The GeO ₂ component is a component that increases the refractive index of the glass and stabilizes the glass to reduce devitrification during molding, and is an optional component in the optical glass of the present invention. In particular, when the content of the GeO ₂ component is 20.0% or less, the amount of expensive GeO ₂ component used is reduced, so that the material cost of the glass can be reduced. Accordingly, the content of the GeO ₂ component with respect to the total amount of the glass having an oxide conversion composition is preferably 20.0%, more preferably 10.0%, still more preferably 5.0%, and most preferably 3.0%. Is the upper limit. The GeO ₂ component can be contained in the glass using, for example, GeO ₂ as a raw material.

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 are components that increase the refractive index of the glass and reduce the partial dispersion ratio. In the optical glass of the present invention, It is an optional component. In particular, the devitrification resistance of the glass can be improved by setting the contents of the Y ₂ O ₃ component, La ₂ O ₃ component, Gd ₂ O ₃ component, and Yb ₂ O ₃ component to 15.0% or less, respectively. And an increase in the Abbe number of the glass can be suppressed. 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 with respect to the total glass material amount of the oxide conversion composition is preferably 15.0%, The upper limit is preferably 10.0%, more preferably 7.0%, and most preferably 4.2%. Y ₂ O ₃ component, La ₂ O ₃ component, Gd ₂ O ₃ component and Yb ₂ O ₃ component are, for example, Y ₂ O ₃ , YF ₃ , La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ as raw materials. O (X is an arbitrary integer), Gd ₂ O ₃ , GdF ₃ , Yb ₂ O _{3 and the} like can be used.

The Ta ₂ O ₅ component is a component that increases the refractive index of the glass, decreases the Abbe number and partial dispersion ratio of the glass, and increases the devitrification resistance of the glass, and is an optional component in the optical glass of the present invention. In particular, by making the content of Ta ₂ O ₅ component 15.0% or less, the amount of Ta ₂ O ₅ component, which is a rare mineral resource, is reduced, and the glass is more easily melted at a lower temperature. The production cost can be reduced. Further, by setting the content of _Ta 2 _{O 5} component below 15.0%, can be reduced devitrification of the glass due to excessive content of _Ta 2 _{O 5} component. Therefore, the content of the Ta ₂ O ₅ component with respect to the total amount of glass in the oxide conversion composition is preferably 15.0%, more preferably 10.0%, and most preferably 5.0%. The Ta ₂ O ₅ component can be contained in the glass using, for example, Ta ₂ O ₅ as a raw material.

Bi ₂ O ₃ component, low Abbe number by increasing the refractive index of the glass is a component and to lower the glass transition point, which is an optional component of the optical glass of the present invention. In particular, by setting the content of the Bi ₂ O ₃ component to 15.0% or less, it is possible to make it difficult to raise the partial dispersion ratio of the glass. Further, by setting the content of Bi ₂ O ₃ component below 15.0%, it is possible to reduce the coloring of the glass, it is possible to increase the internal transmittance of the glass. Therefore, the content of the Bi ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 15.0%, more preferably 10.0%, and most preferably 5.0%. The Bi ₂ O ₃ component can be contained in the glass using, for example, Bi ₂ O ₃ as a raw material.

The WO ₃ component is a component that increases the refractive index of the glass to lower the Abbe number, increases the devitrification resistance of the glass, and increases the solubility of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the WO ₃ component to 20.0% or less, it is possible to make it difficult to increase the partial dispersion ratio of the glass. Further, by setting the content of WO ₃ components below 20.0%, to reduce the coloration of the glass, it is possible to increase the internal transmittance of the glass. Therefore, the upper limit of the content of the WO ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 20.0%, more preferably 10.0%, and most preferably 5.0%. The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

The TeO ₂ component is a component that raises the refractive index of the glass, lowers the partial dispersion ratio of the glass, and lowers the glass transition point, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the TeO ₂ component to 30.0% or less, it is possible to reduce the coloration of the glass and increase the transmittance of the glass with respect to visible light. Moreover, glass with lower material costs can be obtained by reducing the use of expensive TeO ₂ components. Therefore, the content of the TeO ₂ component with respect to the total glass substance amount of the oxide conversion composition is preferably 30.0%, more preferably 20.0%, and most preferably 10.0%. The TeO ₂ component can be contained in the glass using, for example, TeO ₂ as a raw material.

The ZrO ₂ component is a component that increases the refractive index and Abbe number of the glass, lowers the partial dispersion ratio, and increases the devitrification resistance, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the ZrO ₂ component to 15.0% or less, devitrification of the glass can be reduced, and more uniform glass can be easily obtained. Therefore, the content of the ZrO ₂ component is preferably 15.0%, more preferably 12.0%, and most preferably 10.0% with respect to the total amount of glass in the oxide conversion composition. The ZrO ₂ component may not be contained, but by containing more than 0% of the ZrO ₂ component, the partial dispersion ratio of the glass can be easily lowered while increasing the refractive index and Abbe number of the glass. Moreover, devitrification and coloring at the time of reheating can be reduced thereby. Therefore, the content of the ZrO ₂ component with respect to the total amount of glass in the oxide conversion composition is preferably more than 0%, more preferably 1.0%, and even more preferably 2.0%. The ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ , ZrF ₄ or the like as a raw material.

The Al ₂ O ₃ component is a component that improves the chemical durability of the glass and improves the devitrification resistance of the glass, and is an optional component in the optical glass of the present invention. In particular, by setting the content of the Al ₂ O ₃ component to 15.0% or less, devitrification due to excessive inclusion of the Al ₂ O ₃ component can be reduced. Moreover, devitrification and coloring at the time of reheating can be reduced thereby. Therefore, the upper limit of the content of the Al ₂ O ₃ component with respect to the total amount of glass in the oxide conversion composition is preferably 15.0%, more preferably 10.0%, and most preferably 5.0%. The Al ₂ O ₃ component can be contained in the glass using, for example, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ or the like as a raw material.

The Sb ₂ O ₃ component is a component that accelerates defoaming of the glass and clarifies the glass, and is an optional component in the optical glass of the present invention. Sb ₂ O ₃ component, by a content relative to the glass the total amount of substance 1.0% or less, can be hardly caused excessive foaming during glass melting, Sb ₂ O ₃ ingredient is dissolved facilities (especially Alloying with noble metals such as Pt). Accordingly, the Sb ₂ O ₃ component content is preferably 1.0%, more preferably 0.8%, and even more preferably 0.6% with respect to the total amount of glass in the oxide equivalent composition. However, when importance is attached to the environmental impact of the optical glass, it is preferable not to contain the Sb ₂ O ₃ component. The Sb ₂ O ₃ component can be contained in the glass using, for example, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ · 5H ₂ O, or the like as a raw material.

Incidentally, components of the fining defoaming of glass is not limited to the above Sb ₂ O ₃ ingredients may be used known refining agents and defoamers in the field of glass production, or a combination thereof .

<About ingredients that should not be included>
Next, components that should not be contained in the optical glass of the present invention and components that are not preferably contained will be described.

  If necessary, other components can be added to the optical glass of the present invention as long as the properties of the glass are not impaired.

  However, the transition metal components such as V, Cr, Mn, Co, Ni, Cu, Ag, and Mo, excluding Ti, Zr, and Nb, are colored by the glass even when each of them is contained alone or in combination. Since it has a property of causing absorption at a specific wavelength in the visible range, it is preferable that the optical glass using the wavelength in the visible range does not substantially contain.

Furthermore, lead compounds such as PbO, arsenic compounds such as As ₂ O ₃ , and components of Th, Cd, Tl, Os, Be, and Se have been refraining from being used as harmful chemical substances in recent years. Environmental measures are required not only in the manufacturing process but also in the processing process and disposal after commercialization. Therefore, when importance is placed on the environmental impact, it is preferable not to substantially contain them except for inevitable mixing. As a result, the optical glass is substantially free of substances that pollute the environment. Therefore, the optical glass can be manufactured, processed, and discarded without taking any special environmental measures.

The glass that is preferably used as the optical glass of the present invention cannot be expressed directly in the description of mass% because the composition is expressed in mol% with respect to the total amount of glass of oxide conversion composition. The composition expressed by mass% of each component present in the glass composition satisfying various required properties generally takes the following values in terms of oxide composition.
SiO ₂ component 15.0-45.0 mass% and CaO component 15.0-35.0 mass%
Nb ₂ O ₅ component 0 to 55.0 mass% and / or TiO ₂ component 0 to 20.0 mass% and / or BaO component 0 to 45.0 mass% and / or Li ₂ O component 0 to 10.0 Mass% and / or Na ₂ O component 0 to 20.0 mass% and / or K ₂ O component 0 to 30.0 mass% and / or Cs ₂ O component 0 to 25.0 mass% and / or MgO component 0 5.0 wt% and / or SrO component from 0 to 25.0% by weight and / or ZnO component from 0 to 25.0% by weight and / or _P 2 _{O 5} component from 0 to 30.0% by weight and / or _{B 2} O ₃ component 0 to 30.0 mass% and / or GeO ₂ component 0 to 20.0 mass% and / or Y ₂ O ₃ component 0 to 30.0 mass% and / or La ₂ O ₃ component 0 to 40. 0% by weight and / or _Gd 2 _{O 3} component from 0 to 40.0% by weight and / The _Yb 2 _{O 3} component from 0 to 40.0% by weight and / or _Ta 2 _{O 5} component from 0 to 50.0% by weight and / or _Bi 2 _{O 3} component from 0 to 50.0% by weight and / or WO ₃ ingredient 0 30.0% by weight and / or TeO ₂ component from 0 to 45.0% by weight and / or ZrO ₂ component 0 to 20.0% by weight and / or _Al 2 _{O 3} component 0 to 20.0% by weight and / or Sb ₂ O ₃ component 0-3.0 mass%

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, the above raw materials are uniformly mixed so that each component is within a predetermined content range, and the prepared mixture is put into a platinum crucible, a quartz crucible or an alumina crucible and roughly melted, then a gold crucible, a platinum crucible In a platinum alloy crucible or iridium crucible, melt in a temperature range of 1100 to 1400 ° C. for 3 to 5 hours, stir to homogenize, blow out bubbles, etc., then lower the temperature to 1000 to 1300 ° C. and then finish stirring This is done by removing the striae, casting into a mold and slow cooling.

<Physical properties>
The optical glass of the present invention preferably has a predetermined refractive index and dispersion (Abbe number). More specifically, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.70, more preferably 1.75, and most preferably 1.78. On the other hand, the upper limit of the refractive index (n _d ) of the optical glass of the present invention is not particularly limited, but is generally 2.20 or less, more specifically 2.10 or less, more specifically 2.00 or less, and more specifically. Specifically, it is often 1.95 or less. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 40, more preferably 38, and most preferably 35. 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 is generally 20 or more, more specifically 25 or more, and more specifically 27 or more. As a result, the degree of freedom in optical design is increased, and a large amount of light refraction can be obtained even if the device is made thinner.

Moreover, 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 (−0.00162 × νd + 0.63822) in the range of ν _d ≦ 31 with respect to the Abbe number (ν _d ). ≦ (θg, F) ≦ (−0.00275 × νd + 0.68125) is satisfied, and (−0.00162 × νd + 0.63822) ≦ (θg, F) ≦ (− in the range of ν _d > 31 0.00162 × νd + 0.64622). As a result, an optical glass having a partial dispersion ratio (θg, F) close to the normal line can be obtained, so that chromatic aberration of an optical element formed from the optical glass can be reduced. Here, the lower limit of the partial dispersion ratio (θg, F) of the optical glass at ν _d ≦ 31 is preferably (−0.00162 × νd + 0.63822), more preferably (−0.00162 × νd + 0.63922), Most preferably (−0.00162 × νd + 0.64022). On the other hand, the upper limit of the partial dispersion ratio (θg, F) of the optical glass at ν _d ≦ 31 is preferably (−0.00275 × νd + 0.68125), more preferably (−0.00275 × νd + 0.68025). Most preferred is (−0.00275 × νd + 0.67925). Further, the lower limit of the partial dispersion ratio (θg, F) of the optical glass at ν _d > 31 is preferably (−0.00162 × νd + 0.63822), more preferably (−0.00162 × νd + 0.63922), most preferably Preferably, it is (−0.00162 × νd + 0.64022). On the other hand, the upper limit of the partial dispersion ratio (θg, F) of the optical glass at ν _d > 31 is preferably (−0.00162 × νd + 0.64622), more preferably (−0.00162 × νd + 0.64522). Most preferred is (−0.00162 × νd + 0.64422). In particular, in a region where the Abbe number (ν _d ) is small, the partial dispersion ratio (θg, F) of general glass is higher than that of the normal line, and the partial dispersion ratio (θg, F) of general glass is high. And the Abbe number (ν _d ) are represented by curves. However, since it is difficult to approximate this curve, the present invention uses a straight line having a different slope from ν _d = 31 as a partial dispersion ratio (θg, F) lower than that of general glass. Expressed.

Moreover, it is preferable that the optical glass of this invention has little coloring. In particular, when the optical glass of the present invention is represented by the transmittance of the glass, the wavelength (λ ₇₀ ) indicating a spectral transmittance of 70% in a sample having a thickness of 10 mm is 500 nm or less, more preferably 470 nm or less, and still more preferably. Is 450 nm or less, and most preferably 430 nm or less. In addition, the optical glass of the present invention has a wavelength (λ ₈₀ ) of 560 nm or less, more preferably 540 nm or less, and most preferably, when the sample has a thickness of 10 mm and exhibits a spectral transmittance of 80%. Is 520 nm or less. In the optical glass of the present invention, a wavelength (λ ₅ ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm is 420 nm or less, more preferably 400 nm or less, and most preferably 380 nm or less. Thereby, the absorption edge of the glass is positioned in the vicinity of the ultraviolet region, and the transparency of the glass in the visible region is enhanced. Therefore, this optical glass can be preferably used as a material for an optical element such as a lens.

The optical glass of the present invention preferably has good press formability. That is, the optical glass of the present invention divides the transmittance of light (d-line) having a wavelength of 587.56 nm of the test piece after the reheating test (ii) by the transmittance of d-line of the test piece before the reheating test. The measured value is preferably 0.95 or more. Also, a lambda ₇₀ is a wavelength at which the transmittance of the reheating test (a) before the specimen is 70% and the difference between the lambda ₇₀ of the test piece after the reheating test is 20nm or less. This makes it difficult for devitrification and coloring to occur even in a reheating test assuming reheat press processing, so that the light transmittance of the glass is less likely to be lost. Processing can be facilitated. That is, since an optical element having a complicated shape can be produced by press molding, it is possible to realize optical element production with low production cost and high productivity.

Here, the value obtained by dividing the transmittance of the light beam (d-line) having a wavelength of 587.56 nm of the test piece after the reheating test (ii) by the transmittance of the d-line of the test piece before the reheating test (ii) is The lower limit is preferably 0.95, more preferably 0.96, and most preferably 0.97. Further, the difference between the lambda ₇₀ of the test piece after the reheating test and lambda ₇₀ of reheating test (a) prior to the test piece (b) is preferably 20 nm, more preferably 18 nm, and most preferably a maximum of 16nm To do.

  In the reheating test (A), a test piece 15 mm × 15 mm × 30 mm is reheated, and the temperature is raised from room temperature to a temperature 80 ° C. higher than the transition temperature (Tg) of each sample in 150 minutes. This is carried out by keeping the temperature at 80 ° C. higher than the transition temperature (Tg) for 30 minutes, then naturally cooling to room temperature, and polishing the two opposing surfaces of the test piece to a thickness of 10 mm and visually observing them.

[Preforms and optical elements]
A glass molded body can be produced from the produced optical glass by means of mold press molding such as reheat press molding or precision press molding. That is, a preform for mold press molding is prepared from optical glass, and after performing reheat press molding on the preform, polishing is performed to prepare a glass molded body, or for example, polishing is performed. The preform can be precision press-molded to produce a glass molded body. In addition, the means for producing the glass molded body is not limited to these means.

  The glass molded body thus produced is useful for various optical elements, and among them, it is particularly preferable to use it for applications of optical elements such as lenses and prisms. As a result, color bleeding due to chromatic aberration in the transmitted light of the optical system provided with the optical element is reduced. Therefore, when this optical element is used in a camera, a photographing object can be expressed more accurately, and when this optical element is used in a projector, a desired image can be projected with higher definition.

Composition of Examples (No. 1 to No. 41) and Comparative Examples (No. A to No. C) of the present invention, refractive index (n _d ), Abbe number (ν _d ), partial dispersion ratio (θg) , F), wavelengths (λ ₅ , λ ₇₀ , λ ₈₀ ) exhibiting spectral transmittances of 5%, 70%, and 80%, and transmittance fluctuations before and after the reheating test (a) are shown in Tables 1 to 6. Show. The following examples are merely for illustrative purposes, and are not limited to these examples.

  As for the glass of the Example (No.1-No.41) of this invention, and the comparative example (No.A-No.C), all are the oxide, hydroxide, carbonate, respectively corresponding as a raw material of each component, High-purity raw materials used for ordinary optical glass such as nitrates, fluorides, hydroxides, metaphosphoric acid compounds, etc. are selected, and the composition ratios of the examples and comparative examples shown in Tables 1 to 6 are obtained. So that the mixture is uniformly mixed and then put into a platinum crucible, melted in a temperature range of 1100 to 1400 ° C. for 3 to 5 hours in an electric furnace according to the melting difficulty of the glass composition, and stirred to homogenize to remove bubbles. Then, the temperature was lowered to 1000 to 1300 ° C., and the mixture was stirred and homogenized, cast into a mold, and slowly cooled to produce a glass.

Here a refractive index _(n d) of the glass of Example (No.1~No.41) and Comparative Example (No.A~No.C), Abbe number ([nu _d) and partial dispersion ratio ([theta] g, F ) Was measured based on Japan Optical Glass Industry Association Standard JOGIS01-2003. Then, regarding the values of the obtained Abbe number (ν _d ) and partial dispersion ratio (θg, F), the slope a in the relational expression (θg, F) = − a × ν _d + b is 0.00162 and 0.00275. The intercept b at that time was determined. In addition, the glass used for this measurement used what was processed in the slow cooling furnace by making slow cooling temperature-fall rate into -25 degrees C / hr.

Moreover, the transmittance | permeability of the glass of an Example (No.1-No.41) and a comparative example (No.A-No.C) was measured according to Japan Optical Glass Industry Association standard JOGIS02. In the present invention, the presence / absence and degree of coloration of the glass were determined by measuring the transmittance of the glass. More specifically, a face parallel polished product having a thickness of 10 ± 0.1 mm was measured for a spectral transmittance of 200 to 800 nm in accordance with JISZ8722, and λ ₅ (wavelength when the transmittance was 5%), λ ₇₀ (transmittance). The wavelength at 70%) and λ ₈₀ (wavelength at 80% transmittance) were determined.

Moreover, the fluctuation | variation of the transmittance | permeability before and after the reheating test (ii) of the glass of an Example (No.1-No.41) and a comparative example (No.A-No.C) was measured as follows.
The value obtained by dividing the transmittance of the light beam (d-line) having a wavelength of 587.56 nm of the test piece after the reheating test (b) by the d-line transmittance of the test piece before the reheating test is the reheating test (b). It performed according to Japan Optical Glass Industry Association standard JOGIS02-2003 with respect to front and back glass. Specifically, the d-line spectral transmittance of a face-parallel polished product having a thickness of 10 ± 0.1 mm was measured in accordance with JISZ8722, and (d-line transmittance after reheating test (ii)) / (reheated) The d-line transmittance before the test (A) was determined, and the change in the maximum transmittance before and after the reheating test (A) was evaluated.
On the other hand, the difference between λ ₇₀ , which is the wavelength at which the transmittance of the test piece before the reheating test (A) becomes 70%, and λ ₇₀ of the test piece after the reheating test is the same as before and after the reheating test (A). the glass, calculated lambda _{70 (the} wavelength when the transmittance of 70%) in the above test method, the test piece after the reheating test and lambda ₇₀ of reheating test (a) prior to the test piece (a) lambda The difference from ₇₀ was evaluated.
Here, in the reheating test (A), a test piece of 15 mm × 15 mm × 30 mm is placed on an indented refractory and placed in an electric furnace and reheated, and the transition temperature (Tg) of each sample is 150 minutes from room temperature. The temperature is raised to a temperature higher than 80 ° C. (the temperature falling into the refractory), kept at that temperature for 30 minutes, cooled to room temperature, taken out of the furnace, and the two opposing faces are 10 mm thick so that they can be observed inside Then, the polished glass sample was visually observed.

As shown in Tables 1 to 7, the optical glasses of the examples of the present invention have a partial dispersion ratio (θg, F) of (−0.00275 × νd + 0.68125) or less for those having ν _d ≦ 31, More specifically, it was (−0.00275 × νd + 0.67991) or less. In the case of ν _d > 31, the partial dispersion ratio (θg, F) was (−0.00162 × νd + 0.64622) or less, more specifically, (−0.00162 × νd + 0.64476) or less. On the other hand, the optical glass of the example of the present invention has a partial dispersion ratio (θg, F) of (−0.00162 × νd + 0.63822) or more, more specifically (−0.00162 × νd + 0.64094) or more. Met. That is, the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) for the glass of the example of the present application is as shown in FIG. Therefore, it was found that these partial dispersion ratios (θg, F) are within a desired range. On the other hand, the glasses of the comparative examples (No. B, No. C) of the present invention had ν _d > 31 and the partial dispersion ratio (θg, F) exceeded (−0.00162 × νd + 0.64622). . Therefore, it became clear that the optical glass of the Example of this invention has a small partial dispersion ratio ((theta) g, F) compared with the glass of a comparative example (No.B, No.C).

The optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.70 or more, more specifically 1.79 or more, and this refractive index (n _d ) of 2.20 or less. More specifically, it was 1.85 or less, and was within a desired range.

The optical glasses of the examples of the present invention each have an Abbe number (ν _d ) of 20 or more, more specifically 30 or more, and this Abbe number (ν _d ) of 40 or less, more specifically 34. And within the desired range. On the other hand, the glass of the comparative example of the present invention (No. A) are, [nu _d was more than 34. Therefore, it was revealed that the optical glass of the example of the present invention has a smaller Abbe number (ν _d ) than the glass of the comparative example (No. A).

In addition, in the optical glasses of the examples of the present invention, λ ₇₀ (wavelength at 70% transmittance) was 500 nm or less, and more specifically 407 nm or less. In addition, in the optical glasses of the examples of the present invention, each of λ ₅ (wavelength at 5% transmittance) was 420 nm or less, more specifically 359 nm or less. In addition, in the optical glasses of the examples of the present invention, λ ₈₀ (wavelength at 80% transmittance) was 560 nm or less, more specifically 463 nm or less. For this reason, it became clear that the optical glass of the Example of this invention has the high transmittance | permeability with respect to visible light, and is hard to be colored.

Therefore, it is clear that the optical glass of the example of the present invention has a high transmittance for visible light and a small chromatic aberration while the refractive index (n _d ) and the Abbe number (ν _d ) are within the desired ranges. It was.

Moreover, the optical glass of the Example of this invention is the value which divided | segmented the transmittance | permeability of d line | wire of the test piece after a reheating test (ii) by the d line | wire transmittance | permeability of the test piece before a reheating test. It was 0.95 or more, more specifically 0.97 or more, and was within the desired range. Further, in the optical glass of the example of the present invention, the difference in the transmittance λ ₇₀ between the test pieces before and after the reheating test (ii) was 20 nm or less, more specifically 15 nm or less, and was within a desired range. On the other hand, the glass of the comparative example (No. A) of the present invention is a value obtained by dividing the d-line transmittance of the test piece after the reheating test (ii) by the d-line transmittance of the test piece before the reheating test. Was less than 0.95, and after the reheating test (ii), the transmittance was less than 70% for all wavelengths of visible light. Therefore, it was also clarified that the optical glass of the example of the present invention hardly causes coloring or devitrification due to reheating as compared with the glass of the comparative example (No. A).

  Although the present invention has been described in detail for the purpose of illustration, this embodiment is only for the purpose of illustration, and many modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention. Will be understood.

Claims (16)

Containing 20.0% or more and 60.0% or less of the SiO ₂ component in mol%, and more than 20.0 and 50.0% or less of the CaO component with respect to the total amount of the glass having an oxide conversion composition, Nb ₂ The content of O ₅ component is 30.0% or less, and the partial dispersion ratio (θg, F) is within the range of νd ≦ 31 with respect to the Abbe number (νd) (−0.00162 × νd + 0.63822). ≦ (θg, F) ≦ (−0.00275 × νd + 0.68125) is satisfied, and (−0.00162 × νd + 0.63822) ≦ (θg, F) ≦ (−0.00162) in the range of νd> 31. * Optical glass satisfying the relationship of [nu] d + 0.64622). The optical glass according to claim 1, which contains 0 to 20.0% of a TiO ₂ component in mol% based on the total amount of the glass having an oxide equivalent composition. 3. The optical glass according to claim 1, wherein the sum of the contents of the Nb ₂ O ₅ component and the TiO ₂ component with respect to the total amount of the glass having an oxide conversion composition is 10.0% or more and 40.0% or less.   The optical glass according to any one of claims 1 to 3, comprising 0 to 25.0% of a BaO component in mol% with respect to the total amount of the glass having an oxide conversion composition. The optical glass according to any one of claims 1 to 4, wherein a molar ratio (Nb ₂ O ₅ + BaO) / (TiO ₂ + CaO) of an oxide conversion composition is 0.100 or more. 6. The optical glass according to claim 1, wherein the molar ratio TiO ₂ / Nb ₂ O _{5 of the} oxide-converted composition is 3.00 or less. Li ₂ O component 0-25.0% and / or Na ₂ O component 0-25.0% and / or K ₂ O component 0-25. 0% and / or Cs ₂ O component from 0 to 10.0%
The optical glass according to any one of claims 1 to 6. The molar sum of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) with respect to the total amount of glass in the oxide equivalent composition is 30.0% or less Item 8. The optical glass according to Item 7. MgO component 0 to 20.0% and / or SrO component 0 to 20.0% and / or ZnO component 0 to 30.0% in mol% with respect to the total amount of glass in oxide conversion composition
The optical glass according to any one of claims 1 to 8.   The molar sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, Zn) with respect to the total amount of glass in the oxide equivalent composition is 20.0% or more and 60.0 The optical glass according to claim 9, which is not more than%. P ₂ O ₅ component 0 to 30.0% and / or B ₂ O ₃ component 0 to 40.0% and / or GeO ₂ component 0 to 20 in mol% with respect to the total amount of glass in the oxide conversion composition 0.0% and / or Y ₂ O ₃ component 0 to 15.0% and / or La ₂ O ₃ component 0 to 15.0% and / or Gd ₂ O ₃ component 0 to 15.0% and / or Yb ₂ O ₃ component 0 to 15.0% and / or Ta ₂ O ₅ component 0 to 15.0% and / or Bi ₂ O ₃ component 0 to 15.0% and / or WO ₃ component 0 to 20.0% and Te / O ₂ component 0 to 30.0% and / or ZrO ₂ component 0 to 15.0% and / or Al ₂ O ₃ component 0 to 15.0% and / or Sb ₂ O ₃ component 0 to 1.0 %
The optical glass according to claim 1, further comprising:   The optical glass according to any one of claims 1 to 11, which has a refractive index (nd) of 1.70 or more and 2.20 or less and an Abbe number (νd) of 20 or more and 40 or less. The optical glass according to any one of claims 1 to 12, wherein a wavelength (λ ₇₀ ) at which the spectral transmittance is 70% is 500 nm or less.   A preform for polishing and / or precision press molding comprising the optical glass according to any one of claims 1 to 13.   An optical element obtained by grinding and / or polishing the optical glass according to claim 1.   An optical element formed by precision press-molding the optical glass according to claim 1.

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