JP2020079187A - Optical glass, optical element, and preform - Google Patents

Abstract

To provide an optical glass that has optical properties of a high refractive index and a low dispersion, and can be heated and molded more stably.SOLUTION: An optical glass contains, in terms of cation% (mol%), Pof 22.0% or more and 47.0% or less, Alof 1.0% or more and 25.0% or less, Mgof more than 0% and 25.0% or less, Caof 0% or more and 25.0% or less, Srof more than 0% and 24.0% or less, Baof more than 0% and 22.0% or less, Znof more than 0% and 24.0% or less, and in terms of anion% (mol%), Fof 25.0% or more and 60.0% or less, Oof 40.0% or more and 75.0% or less, and has a refractive index (n) of 1.50 or more and 1.60 or less, an Abbe number (ν) of 65 or more and 75 or less, a mean coefficient of linear expansion α of 145×10°Cor less.SELECTED DRAWING: None

Description

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

  In recent years, digitalization and high definition of devices using an optical system are rapidly progressing, and various optical devices such as photographing devices such as digital cameras and video cameras, and image reproducing (projection) devices such as projectors and projection TVs. In the field, there is an increasing demand for reducing the number of optical elements such as lenses and prisms used in the optical system and reducing the weight and size of the entire optical system.

As the material of the optical elements constituting the optical system, emergency demand for high refractive index and low dispersion glass having a 1.50 to 1.60 of the refractive index (n _d) and 65 or more 75 or less Abbe number ([nu _d) Is rising. As such a high refractive index and low dispersion glass, for example, glass compositions represented by Patent Documents 1 to 3 are known.

JP, 2009-256169, A JP, 2012-001422, A JP 2012-126608 A

  High-refractive-index, low-dispersion glass is used together with other glasses having different optical characteristics, such as glass having high dispersion (low Abbe number), for the purpose of reducing aberrations in the optical system and achieving high imaging characteristics. It is often incorporated in a unit, and in recent years, it is often incorporated in a lens configuration as an aspherical lens. However, since a fluorophosphate glass as described in Patent Document 1 generally has a higher linear expansion coefficient than other glasses, reheat press molding at the time of manufacturing an optical element or an aspherical lens is used. There was a great concern that defects such as cracks and chips would be easily received in the heat molding such as precision mold press molding during the production, due to thermal shock. Under such circumstances, there is a demand for a high-refractive-index, low-dispersion glass that has a small expansion during heating and can perform precision mold press molding and reheat press molding more stably.

  The present invention has been made in view of the above problems, and an object of the present invention is to have an optical property of high refractive index and low dispersion, and an optical that can be more stably heat-molded. It is intended to provide glass, a preform and an optical element using the glass.

In order to solve the above-mentioned problems, the inventors of the present invention have conducted earnest test research and as a result, as a cation component, P ⁵⁺ , Al ³⁺ , Mg ^2+, and Ba ²⁺ are contained in the glass, and Zn ²⁺ is contained in the glass. By adjusting the content, it was found that a glass having a desired average refractive index and Abbe number and a small average linear expansion coefficient at 100 to 300° C. can be obtained, and the present invention has been completed. Specifically, the present invention provides the following.

(1) In terms of cation% (mol %), P ⁵⁺ content is 22.0% or more and 47.0% or less, Al ³⁺ content is 1.0% or more and 25.0% or less, and Mg ²⁺ content is included. Rate is more than 0% and 25.0% or less, Ca ²⁺ content is 0% or more and 25.0% or less, Sr ²⁺ content is more than 0% and 24.0% or less, and Ba ²⁺ content is 0. %, 22.0% or less, the Zn ²⁺ content is more than 0% and 24.0% or less, and the F ⁻ content is 25.0% or more and 60.0% in terms of anion% (mol %). % or ^{less, O 2-is} a content of less 75.0% or more 40.0% of a refractive index _{(n d)} of 1.50 or more 1.60 or less, the Abbe number ([nu _d) is 65 or more 75 or less And an optical glass having an average linear expansion coefficient α of 145×10 ⁻⁷ ° C. ⁻¹ or less at 100 to 300° C. defined by the Japan Optical Glass Industry Association standard JOGIS08-2003.

(2) The total content of at least one selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ^2+, and Ba ²⁺ (R ²⁺ : cation %) is 27.0 to 59.0%. Optical glass.

⁽³⁾ the ratio of the content of ^{Zn 2+} for the content of ^{P 5+ (Zn} 2+ ^{/ P 5+)} is 0.050 than (1) or (2), wherein the optical glass.

(4) The content of La ³⁺ is 0 to 15.0%, the content of Gd ³⁺ is 0 to 12.0%, and the content of Y ³⁺ is 0 to 12.0% in terms of cation% (mol %). , Yb ³⁺ content is 0 to 10.0%, the optical glass according to any one of (1) to (3).

(5) The total content of one or more kinds selected from the group consisting of Y ³⁺ , La ³⁺ , Gd ³⁺ , Yb ³⁺ and Lu ³⁺ (Ln ³⁺ : cation %) is 0 to 15.0% (1) The optical glass according to any one of (4) to (4).

(6) In terms of cation% (mol %), the content of Li ⁺ is 0 to 10.0%, the content of Na ⁺ is 0 to 10.0%, and the content of K ⁺ is 0 to 10.0%. The optical glass according to any one of (1) to (5).

(7) Any one of (1) to (6), wherein the total content of one or more kinds (Rn ⁺ : cation %) selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ is 10.0% or less. The optical glass described.

(8) In terms of cation% (mol %), the content of Si ⁴⁺ is 0 to 10.0%, the content of B ³⁺ is 0 to 10.0%, and the content of Ti ⁴⁺ is 0 to 10.0%. , Nb ⁵⁺ content 0 to 10.0%, W ⁶⁺ content 0 to 10.0%, Zr ⁴⁺ content 0 to 10.0%, Ta ⁵⁺ content 0 to 10. 0%, Ge ⁴⁺ content 0 to 10.0%, Bi ³⁺ content 0 to 10.0%, Te ⁴⁺ content 0 to 10.0%
The optical glass according to any one of (1) to (7).

  (9) An optical element comprising the optical glass according to any one of (1) to (8).

  (10) A preform for polishing and/or precision mold press molding, which is made of the optical glass according to any one of (1) to (8).

  According to the present invention, it is possible to obtain an optical glass having optical characteristics of high refractive index and low dispersion, which can be more stably heat-molded, and a preform and an optical element using the same. ..

  Further, according to the present invention, it is possible to obtain an optical glass which is characteristic in that it has a large anomalous dispersion (Δθg, F), a preform and an optical element using the optical glass.

The optical glass of the present invention has a P ⁵⁺ content of 22.0% or more and 47.0% or less and an Al ³⁺ content of 1.0% or more and 25.0% or less in ^terms of cation% (mol %). The content of Mg ²⁺ is more than 0% and 25.0% or less, the content of Ca ²⁺ is 0% or more and 25.0% or less, the content of Sr ²⁺ is more than 0% and 24.0% or less, Ba ²⁺ The content is more than 0% and 22.0% or less, the content of Zn ²⁺ is more than 0% and 24.0% or less, and the content of F ⁻ is 25.0% in terms of anion% (mol %). or 60.0% ^{less, O 2-is} a content of less 75.0% or more 40.0% of a refractive index _{(n d)} of 1.50 or more 1.60 or less, the Abbe number ([nu _d) is It is 65 or more and 75 or less, and the average linear expansion coefficient α at 100 to 300° C. defined by the Japan Optical Glass Industry Association standard JOGIS08-2003 is 145×10 ⁻⁷ ° C. ⁻¹ or less. As a cation component, Zn ²⁺ is contained in the glass together with P ⁵⁺ , Al ³⁺ , Mg ²⁺ and Ba ²⁺ , and by adjusting the content of each component, it has optical characteristics of high refractive index and low dispersion, and Since an optical glass having a small linear expansion coefficient can be obtained, it is possible to obtain an optical glass that can be more stably heat-molded.

  Hereinafter, embodiments of the optical glass of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. It should be noted that, although description may be omitted as appropriate for portions where description is duplicated, this does not limit the gist of the invention.

<Glass component>
Each component constituting the optical glass of the present invention will be described.
In the present specification, unless otherwise specified, the content of each component is expressed as cation% or anion% based on the molar ratio. Here, "cation%" and "anion%" (hereinafter sometimes referred to as "cation% (mol%)" and "anion% (mol%)" are the glass constituent components of the optical glass of the present invention. Is separated into a cation component and an anion component, and the total proportion of each is 100 mol %, and the content of each component contained in the glass is shown.
It should be noted that the ionic valences of the respective components are merely representative values for convenience, and are not distinguished from other ionic valences. The ionic valence of each component present in the optical glass may be other than the representative value. For example, P is usually present in the glass in a state where the ionic valency is 5, so it is expressed as “P ⁵⁺ ”in the present specification, but it may exist in a state of another ionic valence. As described above, strictly speaking, each component is treated as being present in the glass with a representative ionic valence even if it exists in a state of another ionic valence.

[Cation component]
P ⁵⁺ is a glass-forming component, and has the properties of increasing the anomalous dispersion of glass, suppressing devitrification, and increasing the refractive index. Therefore, the P ⁵⁺ content is preferably 22.0%, more preferably 25.0%, further preferably 28.0% as the lower limit, and further preferably more than 30.0%.
On the other hand, by reducing the P ⁵⁺ content within the range of 47.0% or less, a desired high Abbe number can be easily obtained, and the linear expansion coefficient can be lowered. Therefore, the upper limit of the P ⁵⁺ content is preferably 47.0%, more preferably 45.0%, further preferably 42.0%, further preferably 40.0%, further preferably 38.0%. To do.

Al ³⁺ has the properties of increasing the anomalous dispersion of glass, increasing the devitrification resistance, reducing the degree of wear, and decreasing the coefficient of linear expansion. Therefore, the Al ³⁺ content is preferably 1.0% or more, more preferably more than 3.0%, further preferably more than 5.0%, further preferably more than 8.0%, further preferably 10.0. % Over.
On the other hand, by reducing the content of Al ³⁺ within the range of 25.0% or less, it is possible to easily obtain a desired high refractive index. Therefore, the content of Al ³⁺ is preferably 25.0%, more preferably 23.0%, further preferably 20.0% as an upper limit, further preferably less than 18.0%, further preferably 15.0%. Less than %.

Mg ²⁺ has the properties of increasing the devitrification resistance of glass, reducing the degree of wear, and decreasing the coefficient of linear expansion. Therefore, the lower limit of the Mg ²⁺ content is preferably more than 0%, more preferably more than 1.0%, even more preferably more than 3.0%, further preferably more than 5.0%.
On the other hand, by reducing the Mg ²⁺ content within the range of 25.0% or less, it is possible to easily obtain a desired high refractive index. Therefore, the upper limit of the Mg ²⁺ content is preferably 25.0%, more preferably 22.0%, further preferably 20.0%, and further preferably 17.0%.

Ca ²⁺ is an optional component having the properties of increasing the devitrification resistance of the glass, suppressing the decrease of the refractive index, lowering the degree of abrasion, and decreasing the coefficient of linear expansion when the content exceeds 0%. Therefore, the lower limit of the Ca ²⁺ content is preferably more than 0%, more preferably more than 2.0%, further preferably more than 5.0%, further preferably more than 7.0%, further preferably 10.0. It may be more than %.
On the other hand, by reducing the Ca ²⁺ content within the range of 25.0% or less, it is possible to enhance the devitrification resistance of the glass and easily obtain a desired high refractive index. Therefore, the upper limit of the Ca ²⁺ content is preferably 25.0%, more preferably 22.0%, further preferably 19.0%, and further preferably 16.0%.

Sr ²⁺ is an optional component having a property of increasing the devitrification resistance of the glass and suppressing the decrease of the refractive index when the content thereof exceeds 0%. Therefore, the Sr ²⁺ content is preferably more than 0%, more preferably more than 1.0%, further preferably more than 3.0%, further preferably more than 5.0%, further preferably more than 8.0%. May be
On the other hand, by reducing the Sr ²⁺ content within the range of 24.0% or less, it is possible to enhance the devitrification resistance of the glass and easily obtain a desired high refractive index. Therefore, the Sr ²⁺ content is preferably 24.0%, more preferably 22.0%, further preferably 20.0%, further preferably 17.0%, further preferably 15.0%, further preferably Up to 13.0%.

Ba ²⁺ has the properties of increasing the devitrification resistance of glass, maintaining low dispersibility, and increasing the refractive index. Therefore, the Ba ²⁺ content is preferably more than 0%, more preferably more than 1.0%, further preferably more than 2.0%, further preferably more than 4.0%, further preferably more than 6.0%. May be
On the other hand, by reducing the Ba ²⁺ content within the range of 22.0% or less, the devitrification resistance of the glass can be increased, the specific gravity can be reduced, and the linear expansion coefficient can be reduced. Therefore, the Ba ²⁺ content is preferably 22.0% or less, more preferably less than 20.0%, further preferably less than 17.0%, further preferably less than 15.0%, further preferably 13.0%. Less than %.

Zn ²⁺ has the properties of reducing the linear expansion coefficient of glass, lowering the glass transition point, and increasing the devitrification resistance of glass. Therefore, the Zn ²⁺ content is preferably more than 0%, more preferably more than 1.0%, further preferably more than 2.0%, further preferably more than 3.0%, further preferably more than 5.0%. , More preferably more than 7.0%, further preferably more than 10.0%.
On the other hand, by reducing the Zn ²⁺ content within the range of 24.0% or less, it is possible to easily obtain a desired low Abbe number. Therefore, the upper limit of the Zn ²⁺ content is preferably 24.0%, more preferably 21.0%, further preferably 18.0%, and further preferably 15.0%.

R ²⁺ is one or more selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ . The total content of R ^{2+ is} the sum of at least one selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ .
Here, by setting the total content of R ²⁺ within the range of 27.0 to 59.0%, glass with higher devitrification resistance can be obtained.
Therefore, the lower limit of the total content of R ²⁺ is preferably 27.0%, more preferably 30.0%, further preferably 32.0%, further preferably 35.0%, further preferably 37.0%. And Further, the upper limit of the total content of R ²⁺ is preferably 59.0%, more preferably 55.0%, further preferably 52.0%, further preferably 48.0%, further preferably 45.0%. And more preferably 42.0%.

In the optical glass of the present invention, the ratio (Zn ²⁺ /P ⁵⁺ ) of the Zn ²⁺ content (cation %) to the P ⁵⁺ content (cation %) is preferably more than 0.010. By increasing the ratio (Zn ²⁺ /P ⁵⁺ ), the linear expansion coefficient of glass can be reduced. Therefore, this (Zn ²⁺ /P ⁵⁺ ) ratio is preferably more than 0.010, more preferably more than 0.050, even more preferably more than 0.100, even more preferably more than 0.200, still more preferably 0.300. It may be super.
On the other hand, the upper limit of the (Zn ²⁺ /P ⁵⁺ ) ratio may be preferably 0.800, more preferably 0.600, still more preferably 0.500.

Further, in the optical glass of the present invention, the ratio (Mg ²⁺ /P ⁵⁺ ) of the Mg ²⁺ content (cation %) to the P ⁵⁺ content (cation %) is preferably 1.00 or less.
By reducing the ratio of the content of Mg ^{2+ to} the content of the glass-forming component P ⁵⁺ , the devitrification resistance of the glass is enhanced, and the devitrification when press-molding by softening the glass by heating is reduced. You can do it. Therefore, this (Mg ²⁺ /P ⁵⁺ ) ratio is preferably 1.00, more preferably 0.80, still more preferably 0.60, still more preferably 0.46, still more preferably 0.41 and even more preferably. The upper limit is 0.37.
On the other hand, the lower limit of the (Mg ²⁺ /P ⁵⁺ ) ratio is preferably 0.01, more preferably 0.05, further preferably 0.10, and more preferably from the viewpoint of obtaining glass having a desired small linear expansion coefficient. It may be preferably 0.15.

In addition, the optical glass of the present invention has a ratio (Zn%) of the total of Ca ²⁺ content, Sr ²⁺ content and Ba ²⁺ content (cation %) to the total of Zn ²⁺ content and Mg ²⁺ content (cation %). ²⁺ +Mg ²⁺ )/(Ca ²⁺ +Sr ²⁺ +Ba ²⁺ ) is preferably 0.20 or more. As a result, the content ratio of Zn ²⁺ and Mg ²⁺ , which has a strong effect of decreasing the linear expansion coefficient, is low, and the content ratio of Ca ²⁺ , Sr ²⁺ , and Ba ²⁺ , which has a large effect of increasing the linear expansion coefficient, is high. It is possible to easily obtain a glass having a smaller linear expansion coefficient because the glass has a larger linear expansion coefficient. Therefore, the lower limit of this (Zn ²⁺ +Mg ²⁺ )/(Ca ²⁺ +Sr ²⁺ +Ba ²⁺ ) ratio is preferably 0.20, more preferably 0.30, and further preferably 0.40.
On the other hand, the upper limit of the (Zn ²⁺ +Mg ²⁺ )/(Ca ²⁺ +Sr ²⁺ +Ba ²⁺ ) ratio is preferably 2.00, more preferably 1.80, and even more preferably 1.50 from the viewpoint of obtaining stable glass. , And more preferably 1.20.

La ³⁺ , Gd ³⁺ , Y ³⁺ , Yb ³⁺ and Lu ³⁺ have the property of maintaining low dispersibility, increasing the refractive index and further increasing the devitrification resistance when at least one of them ^exceeds 0%. It is an optional component.
On the other hand, the La ³⁺ content is reduced to 15.0% or less, and the content of at least one of Gd ³⁺ and Y ³⁺ is reduced to 12.0% or less, or Yb ^3+. By reducing the content of at least one of ^Ru and Lu ³⁺ within the range of 10.0% or less, it is difficult to reduce the abnormal dispersion of the glass, and the stability of the glass is increased to make it difficult to devitrify. be able to. Therefore, the upper limit of the La ³⁺ content is preferably 15.0%, more preferably less than 10.0%, and further preferably less than 7.0%. The content of Gd ³⁺ and Y ³⁺ is preferably 12.0% as the upper limit, more preferably less than 8.0%, further preferably less than 5.0%, and further preferably less than 3.0%. To do. The content of Yb ³⁺ and Lu ³⁺ is preferably 10.0% as an upper limit, more preferably less than 5.0%, further preferably less than 3.0%, and further preferably less than 1.0%. To do.

Ln ³⁺ is one or more selected from the group consisting of Y ³⁺ , La ³⁺ , Gd ³⁺ , Yb ³⁺ and Lu ³⁺ . The total content of Ln ^{3+ is} the total of one or more selected from the group consisting of Y ³⁺ , La ³⁺ , Gd ³⁺ , Yb ³⁺ and Lu ³⁺ .
Here, by reducing the total content of Ln ³⁺ within the range of 15.0% or less, it is possible to make it difficult to reduce the anomalous dispersibility of the glass, to make it difficult to devitrify the glass, and to have a high refractive index. It is possible to easily obtain a glass having a high rate and a low dispersion. Therefore, the total content of Ln ³⁺ preferably has an upper limit of 15.0%, more preferably less than 10.0%, further preferably less than 7.0%, further preferably less than 5.0%, and further preferably It is less than 3.0%, more preferably less than 1.0%.

Li ⁺ , Na ⁺ and K ⁺ are optional components having a property of lowering the glass transition point (Tg) while maintaining devitrification resistance during glass formation when at least one of them is contained in an amount of more than 0%. ..
On the other hand, by reducing the content of at least one of Li ⁺ , Na ⁺ and K ⁺ within the range of 10.0% or less, the abrasion degree of glass is reduced and the chemical durability is enhanced. You can Therefore, the content of Li ⁺ , Na ^+, and K ⁺ is preferably 10.0% as an upper limit, more preferably less than 5.0%, and further preferably less than 3.0%.

Rn ⁺ is at least one selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ . The total content of Rn ^{+ is} a total of one or more kinds selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ .
Here, by reducing the total content of Rn ⁺ within the range of 10.0% or less, it is possible to reduce the abrasion degree of the glass and enhance the chemical durability. Therefore, the total content of Rn ⁺ is preferably 10.0% as an upper limit, more preferably less than 5.0%, and further preferably less than 3.0%.

Si ⁴⁺ is an optional component having the properties of increasing the devitrification resistance of glass, increasing the refractive index, and decreasing the degree of abrasion when it is contained in an amount of more than 0%.
On the other hand, by reducing the content rate of Si ⁴⁺ within the range of 10.0% or less, devitrification of the glass due to excessive content of Si ⁴⁺ can be reduced. Therefore, the upper limit of the Si ⁴⁺ content is preferably 10.0%, more preferably less than 5.0%, and further preferably less than 3.0%.

B ³⁺ is an optional component having the properties of increasing the devitrification resistance of the glass, increasing the refractive index, and decreasing the degree of wear when contained in an amount of more than 0%.
On the other hand, the chemical durability of the glass can be increased by reducing the B ³⁺ content within the range of 10.0% or less. Therefore, the upper limit of the B ³⁺ content is preferably 10.0%, more preferably less than 5.0%, and further preferably less than 3.0%.

Ti ⁴⁺ , Nb ⁵ and W ⁶⁺ are optional components having the property of increasing the refractive index of glass when at least one of them is contained in an amount of more than 0%. In addition, Nb ⁵⁺ has a property of improving chemical durability, and W ⁶⁺ is a component having a property of lowering the glass transition point.
On the other hand, by reducing the content of at least one of Ti ⁴⁺ , Nb ⁵ and W ⁶⁺ within the range of 10.0% or less, it is possible to easily obtain a desired high Abbe number. In addition, coloring of glass can be reduced by reducing the content rates of Ti ⁴⁺ and W ⁶⁺ . Therefore, the content of Ti ⁴⁺ , Nb ⁵ and W ⁶⁺ is preferably the upper limit of 10.0%, more preferably less than 5.0%, further preferably less than 3.0%, and further preferably 1.0%. Less than %.

Zr ⁴⁺ is an optional component having a property of increasing the refractive index of glass when it is contained in an amount of more than 0%.
On the other hand, by reducing the Zr ⁴⁺ content within the range of 10.0% or less, striae due to volatilization of the components in the glass can be reduced. Therefore, the upper limit of the Zr ⁴⁺ content is preferably 10.0%, more preferably less than 5.0%, and further preferably less than 3.0%.

Ta ⁵⁺ is an optional component having a property of increasing the refractive index of glass when it is contained in an amount of more than 0%.
On the other hand, by reducing the content of Ta ⁵⁺ within the range of 10.0% or less, the devitrification of the glass can be reduced. Therefore, the upper limit of the content of Ta ⁵⁺ is preferably 10.0%, more preferably less than 5.0%, and further preferably less than 3.0%.

Ge ⁴⁺ is an optional component having a property of increasing the refractive index of the glass and increasing the devitrification resistance when it is contained in an amount of more than 0%.
On the other hand, by reducing the Ge ⁴⁺ content within the range of 10.0% or less, the material cost of glass can be reduced. Therefore, the upper limit of the Ge ⁴⁺ content is preferably 10.0%, more preferably less than 5.0%, and further preferably less than 3.0%.

Bi ³⁺ and Te ⁴⁺ are optional components having the properties of increasing the refractive index of glass and lowering the glass transition point when contained in an amount of more than 0%.
On the other hand, by reducing the content rate of at least one of Bi ³⁺ and Te ⁴ within the range of 10.0% or less, coloring and devitrification of glass can be reduced. Therefore, the content of Bi ³⁺ and Te ⁴ is preferably 10.0% as an upper limit, more preferably less than 5.0%, and further preferably less than 3.0%.

[About anion component]
F ⁻ has the properties of increasing the anomalous dispersion and Abbe number of glass, lowering the glass transition point, and making it difficult for the glass to devitrify. Therefore, the lower limit of the F ⁻ content is preferably 25.0%, more preferably 28.0%, further preferably 30.0%, and further preferably 33.0%.
On the other hand, when the content of F ⁻ is high, F ⁻ has a property of excessively increasing the Abbe number of glass and decreasing the degree of wear. Therefore, the upper limit of the F ⁻ content is preferably 60.0%, more preferably 55.0%, further preferably 50.0%, and further preferably 47.0%.

O ²⁻ has the property of suppressing devitrification of the glass and suppressing an increase in the degree of wear. Therefore, the lower limit of the O2 ^- content is preferably 40.0%, more preferably 45.0%, further preferably 50.0%, and further preferably 53.0%.
On the other hand, the content of O ²⁻ is preferably 75.0%, more preferably 72.0%, further preferably 70.0%, further preferably 67 in order to easily obtain the effect of the other anion component. The upper limit is 0.0%.

Further, from the viewpoint of suppressing devitrification of the glass, the total content of O ^{2 −} and F ⁻ is preferably 98.0%, more preferably 99.0% as a lower limit, and further preferably 100%. %.

[About other ingredients]
Other components may be added to the optical glass of the present invention, if necessary, within a range that does not impair the characteristics of the glass of the present invention.

[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 preferable to be contained will be described.

  Cations of transition metals such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo, except for Ti, Zr, Nb, W, La, Gd, Y, Yb and Lu, may be used alone or in combination. Even if contained in a small amount, the glass has a property of being colored and absorbing at a specific wavelength in the visible range. Therefore, it is preferable that the glass is not substantially contained particularly in an optical glass using a wavelength in the visible range.

  In recent years, cations of Pb, As, Th, Cd, Tl, Os, Be, and Se have tended to be refrained from being used as harmful chemical substances, and not only in the glass manufacturing process but also in the processing process and post-product disposal. Measures for environmental measures are required up to. Therefore, when importance is attached to the influence on the environment, it is preferable not to substantially contain one or more of these.

  The term “substantially free from” in the present specification means that the content is preferably less than 0.1%, and more preferably the content is not included except for those contained as unavoidable impurities.

  Although cations of Sb and Ce are useful as defoaming agents, they tend not to be included in optical glasses in recent years as components that adversely affect the environment. Therefore, it is preferable that the optical glass of the present invention does not substantially contain Sb or Ce from such a point.

[Production method]
The method for producing the optical glass of the present invention is not particularly limited. For example, the above raw materials are uniformly mixed so that each component is within a predetermined content range, and the produced mixture is charged into a quartz crucible, an alumina crucible, or a platinum crucible and roughly melted, and then a platinum crucible or a platinum alloy. Put in a crucible or iridium crucible, melt in a temperature range of 900 to 1200°C for 2 to 10 hours, homogenize by stirring to break bubbles, and then lower to a temperature of 850°C or lower, and then stir to finish and streak. Can be produced by casting, casting in a mold and gradually cooling.

[Physical properties]
The optical glass of the present invention preferably has a small average linear expansion coefficient (α). In particular, the optical glass of the present invention has an average coefficient of linear expansion at 100 to 300° C. defined by the Japan Optical Glass Industry Standard JOGIS08-2003, preferably 145×10 ⁻⁷ ° C. ^-1 , more preferably 140×10 7. ^The upper limit is ⁻⁷ ° C. ⁻¹ , more preferably 137×10 ⁻⁷ ° C. ⁻¹ , and further preferably 135×10 ⁻⁷ ° C. ⁻¹ . As a result, even if heat molding such as precision mold breath molding or reheat press molding is performed, defects due to temperature changes and the like are reduced, so that optical elements such as lenses can be stably manufactured.
The lower limit of the average linear expansion coefficient (α) of the optical glass of the present invention is not particularly limited, but the average linear expansion coefficient (α) of the optical glass of the present invention is, for example, 100×10 ⁻⁷ ° C. ⁻¹ , 110×. The lower limit may be 10 ⁻⁷ ° C. ⁻¹ or 120×10 ⁻⁷ ° C. ⁻¹ .

The optical glass of the present invention has a high refractive index ( _nd ) and low dispersibility (high Abbe number).
The optical glass of the present invention preferably has refractive index _{(n d)} of 1.50 or more 1.60 or less. More specifically, the lower limit of the refractive index of the optical glass of the present invention is preferably 1.50, more preferably 1.52, and even more preferably 1.54. On the other hand, in the optical glass of the present invention, the upper limit of the refractive index ( _nd ) is preferably 1.60, more preferably 1.58, still more preferably 1.57.
The optical glass of the present invention preferably has an Abbe number (ν _d ) of 68 or more and 82 or less. More specifically, in the optical glass of the present invention, the lower limit of the Abbe number (ν _d ) is preferably 65, more preferably 67, and further preferably 68. On the other hand, in the optical glass of the present invention, the upper limit of the Abbe number (ν _d ) is preferably 75, more preferably 73, and further preferably 72.
By having such a high refractive index, a large amount of refraction of light can be obtained even when the optical element is made thin. Further, by having such low dispersion, when used as a single lens, it is possible to reduce the shift of the focus (chromatic aberration) due to the wavelength of light. Therefore, for example, when an optical system is configured by combining it with an optical element having high dispersion (low Abbe number), it is possible to reduce aberration as a whole of the optical system and achieve high imaging characteristics.
As described above, the optical glass of the present invention is useful in optical design, and particularly when the optical system is configured, it is possible to achieve the downsizing of the optical system while achieving high imaging characteristics and the like. The degree of freedom of can be expanded.

  In addition, the optical glass of the present invention preferably has a characteristic partial dispersion ratio (θg, F) and anomalous dispersion (Δθg, F), which makes it possible to correct chromatic aberration with high accuracy. Here, the partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably 0.520 or more, more preferably 0.525 or more, still more preferably 0.530 or more. The upper limit of the partial dispersion ratio (θg, F) is preferably 0.580 or less, more preferably 0.575 or less, and even more preferably 0.570 or less.

Here, the partial dispersion ratio (θg, F) indicates the ratio of the difference in refractive index between two wavelength regions in the wavelength dependence of the refractive index, and is expressed by the following equation (1). It
_{θg, F = (n g -n} F) / (n F -n C) ······ formula (1)
Here, _ng means the refractive index at the g-line (435.83 nm), n _F means the F-line (486.13 nm), and n _C means the refractive index at the C-line (656.27 nm).
When the relation between the partial dispersion ratio (θg, F) and the Abbe's number (ν _d ) is plotted on an XY graph, in the case of general optical glass, it is almost plotted on a straight line called a normal line. become. Normal glass, which is the standard for the normal line, differs depending on the optical glass manufacturer, but each company defines almost the same slope and intercept. Here, the normal line in this specification is a XY graph (orthogonal coordinates) in which the vertical axis is the partial dispersion ratio (θg, F) and the horizontal axis is the Abbe number (ν _d ), and the normal line of NSL7 and PBM2 A straight line rising to the right connecting the two points where the partial dispersion ratio and the Abbe number are plotted. (NSL7 and PBM2 are optical glass manufactured by OHARA CORPORATION, NSL7 has an Abbe number (ν _d ) of 60.5, a partial dispersion ratio (θg, F) of 0.5436, and an Abbe number (ν of PBM2. _d ) is 36.3, and the partial dispersion ratio (θg, F) is 0.5828).

On the other hand, the anomalous dispersion (Δθg, F) indicates how far the plot of the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) is from the normal line in the vertical axis direction. Is. Since the optical glass of the present invention has a large anomalous dispersion (Δθg, F), it has the property of being able to correct chromatic aberration caused by other lenses in the wavelength range near blue.

The refractive index (n _d ), the Abbe number (ν _d ), and the partial dispersion ratio (θg, F) are values obtained by measurement based on Japan Optical Glass Industry Association Standard JOGIS01-2003.

The optical glass of the present invention preferably has a low specific gravity. More specifically, the specific gravity of the optical glass of the present invention is preferably 4.50 [g/cm ³ ] or less. As a result, the mass of the optical element or the optical device using the same is reduced, which can contribute to weight reduction of the optical device. Therefore, the upper limit of the specific gravity of the optical glass of the present invention is preferably 4.50, more preferably 4.20, and further preferably 4.00. The specific gravity of the optical glass of the present invention is generally 3.00 or more, more specifically 3.20 or more, and more specifically 3.50 or more.
The specific gravity of the optical glass of the present invention is measured based on Japan Optical Glass Industry Association Standard JOGIS05-1975 "Method for measuring specific gravity of optical glass".

[Preform and optical element]
A glass molded product can be produced from the produced optical glass by using, for example, a polishing process means or a heat forming means such as reheat press molding or precision mold press molding. That is, optical glass is subjected to mechanical processing such as grinding and polishing to produce a glass molded body, or a preform for mold press molding is produced from optical glass, and reheat press molding is performed on this preform. After that, polishing process is performed to make a glass molded product, or preform made by polishing process and preform molded by known floating molding etc. are subjected to precision mold press molding and glass molding You can create a body. The means for producing the glass molded body is not limited to these means.

  As described above, the optical glass of the present invention is useful for various optical elements and optical designs. Among them, it is particularly preferable to form a preform from the optical glass of the present invention and perform reheat press molding or precision mold press molding using this preform to manufacture an optical element such as a lens or a prism. As a result, it becomes possible to form a preform having a large diameter, so that it is possible to realize high-definition and high-accuracy imaging characteristics and projection characteristics when used in an optical device while increasing the size of an optical element.

  The glass molded body made of the optical glass of the present invention can be used for applications of optical elements such as lenses, prisms and mirrors, and is typically prone to high temperatures such as vehicle-mounted optical devices, projectors and copy machines. It can be used in equipment.

Compositions (shown by mol% of cation% display or anion% display) of the glass of Examples (No. 1 to No. 38) and Comparative Example (No. A) which are optical glasses of the present invention, refractive index (nd ₎ ), Abbe number (ν _d ), partial dispersion ratio (θg, F), average linear expansion coefficient (α), and specific gravity are shown in Tables 1 and 2. It should be noted that the following embodiments are merely for the purpose of illustration, and the embodiments are not limited thereto.

  The optical glasses of Examples and Comparative Examples are made of high-purity raw materials such as oxides, carbonates, nitrates, fluorides, metaphosphoric acid compounds, etc., which are the corresponding raw materials for the respective components. Selected, weighed and uniformly mixed so as to have the composition ratio of each example shown in the table, charged into a platinum crucible, and heated in an electric furnace at 900 to 1200° C. depending on the melting difficulty of the glass composition. After melting in a temperature range for 2 to 10 hours, stirring and homogenizing to break bubbles, etc., the temperature was lowered to 850° C. or lower, then cast into a mold, and gradually cooled to produce glass.

The refractive index of the glass of the Examples and Comparative Examples _(n d), Abbe number ([nu _d) and partial dispersion ratio ([theta] g, F) is, JIS B 7071-2: Measured in accordance with V-block method specified in 2018 did. Here refractive index _{(n d)} is indicated by the measured value for the helium lamp d line (587.56 nm). The Abbe number (ν _d ) is the refractive index for the d line of the helium lamp, the refractive index (n _F ) for the F line (486.13 nm) of the hydrogen lamp, and the refractive index (n for the C line (656.27 nm). The value of _C ) was used to calculate from the equation of Abbe number (ν _d )=[( _nd −1 )/(n _F −n _C )]. The partial dispersion ratio ([theta] g, F) is the refractive index for the g line _{(435.83nm) (n} g), the refractive index for the F line of hydrogen lamp _(n F), the refractive index for the C line _{(n C)} using the value, the partial dispersion ratio ([theta] _{g, F) =} calculated from _{[(n g -n F) /} (n F -n C)] expression. These refractive index (n _d), Abbe number ([nu _d) and partial dispersion ratio ([theta] g, F) is obtained by making measurements on glass obtained by the annealing cooling rate to -25 ° C. / hr ..

  The average linear expansion coefficient (α) of the glasses of Examples and Comparative Examples was determined according to the Japan Optical Glass Industry Standard JOGIS08-2003 “Measuring Method of Thermal Expansion of Optical Glass” at 100 to 300° C. ..

  The specific gravities of the glass of Examples and Comparative Examples were measured based on Japan Optical Glass Industry Association Standard JOGIS05-1975 "Method of measuring specific gravity of optical glass".

As shown in the table, each of the optical glasses of the examples of the present invention had an average linear expansion coefficient α of 145×10 ⁻⁷ ° C. ⁻¹ or less, which was within the desired range. On the other hand, in Comparative Example A, which is outside the scope of the present invention, this average coefficient of linear expansion (α) exceeded 145×10 ⁻⁷ ° C. ⁻¹ . Therefore, it was revealed that the optical glass of the example of the present invention has a smaller average linear expansion coefficient (α) than the glass of Comparative Example A.

  Further, the optical glass of each of the examples of the present invention had a refractive index of 1.50 or more, more specifically 1.54 or more, which was within the desired range. Further, the optical glasses of the examples of the present invention each had an Abbe number of 65 or more, more specifically 68 or more, which was within the desired range.

  Therefore, it was revealed that the optical glasses of the examples of the present invention had a refractive index and an Abbe number within desired ranges and a small average linear expansion coefficient. From this, it can be inferred that the optical glass of the example of the present invention can be more stably heat-molded, which can contribute to higher resolution and downsizing of the optical system.

  The optical glasses of the examples of the present invention all had a specific gravity of 4.50 or less, more specifically 3.90 or less, which was within the desired range.

  Furthermore, using the optical glass of the example of the present invention, after forming a preform for polishing, grinding and polishing were performed to process the lens and the prism. Further, a preform for precision mold press molding was formed using the optical glass of the example of the present invention, and this preform was precision mold press molded to be processed into lenses and prisms. In any case, it could be processed into various lens and prism shapes.

  Although the present invention has been described in detail above for the purpose of illustration, the present embodiment is merely 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 (10)

In terms of cation% (mol%),
The content of P ⁵⁺ is 22.0% or more and 47.0% or less,
Al ³⁺ content is 1.0% or more and 25.0% or less,
The content of Mg ²⁺ exceeds 0% and is 25.0% or less,
Ca ²⁺ content is 0% or more and 25.0% or less,
Sr ²⁺ content exceeds 0% and 24.0% or less,
Ba ²⁺ content is more than 0% and 22.0% or less,
Zn ²⁺ content is more than 0% and 24.0% or less,
Anion% (mol%) display,
F ⁻ content is 25.0% or more and 60.0% or less,
O ^{2 −} content is 40.0% or more and 75.0% or less,
Refractive index _{(n d)} of 1.50 or more 1.60 or less, the Abbe number ([nu _d) is at least 65 75 or less,
An optical glass having an average coefficient of linear expansion α of 145×10 ⁻⁷ ° C. ⁻¹ or less at 100 to 300° C. defined by Japan Optical Glass Industry Association standard JOGIS08-2003. The optical glass according to claim 1, wherein the total content (R ²⁺ : cation %) of at least one selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ is 27.0 to 59.0%. The ratio of content of ^{Zn 2+} for the content of ^{P 5+ (Zn 2+ / P 5+} ) is according to claim 1 or 2, wherein the optical glass is 0.050 greater. In terms of cation% (mol%),
La ³⁺ content is 0 to 15.0%,
The content of Gd ³⁺ is 0 to 12.0%,
The content of Y ³⁺ is 0 to 12.0%,
Yb ³⁺ content is 0 to 10.0%
The optical glass according to any one of claims 1 to 3, which is The total content of one or more kinds selected from the group consisting of Y ³⁺ , La ³⁺ , Gd ³⁺ , Yb ³⁺ and Lu ³⁺ (Ln ³⁺ : cation %) is 0 to 15.0%. The optical glass according to any one of the above. In terms of cation% (mol%),
Li ⁺ content is 0 to 10.0%,
The content of Na ⁺ is 0 to 10.0%,
K ⁺ content is 0 to 10.0%
The optical glass according to any one of claims 1 to 5. The optical glass according to any one of claims 1 to 6, wherein a total content of one or more kinds (Rn ⁺ : cation %) selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ is 10.0% or less. In terms of cation% (mol%),
Si ⁴⁺ content is 0 to 10.0%,
The content of B ³⁺ is 0 to 10.0%,
The content of Ti ⁴⁺ is 0 to 10.0%,
Nb ⁵⁺ content is 0 to 10.0%,
W ⁶⁺ content is 0 to 10.0%,
The content of Zr ⁴⁺ is 0 to 10.0%,
Ta ⁵⁺ content is 0 to 10.0%,
Ge ⁴⁺ content is 0 to 10.0%,
Bi ³⁺ content is 0 to 10.0%,
Te ⁴⁺ content is 0 to 10.0%
The optical glass according to any one of claims 1 to 7.   An optical element comprising the optical glass according to claim 1.   A preform for polishing and/or precision mold press molding, which is made of the optical glass according to claim 1.