JP2018090474A - Optical glass, preform material and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical glass having high refractive index and high dispersion optical characteristics, a high partial dispersion ratio, and a low glass production cost. SOLUTION: The optical glass contains more than 0% to 35.0% of La2O3 component, more than 0% to 45.0% of TiO2 component, and more than 0% to 45.0% of BaO component in mass%. , The total amount of the SiO2 component and the B2O3 component is 5.0% or more and 30.0% or less, the mass ratio of TiO2 / (TiO2 + BaO) is 0.10 or more and 0.90 or less, and the refractive index (nd) is 1. It has an optical constant in the range of .80 or more, the Abbe number (νd) is 35.0 or less, and the partial dispersion ratio (θg, F) is 0.57 or more. [Selection diagram] Fig. 1

Description

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

  In recent years, digitalization of devices using optical systems and high definition of images / videos are rapidly progressing. In particular, high-definition images and videos are prominent in optical devices such as digital cameras, video cameras, and projectors. At the same time, the optical system built in these optical devices is reduced in weight and size by reducing the number of optical elements such as lenses and prisms.

Among optical glasses for producing optical elements, it has a high refractive index (n _d ) of 1.80 or more and can reduce the weight and size of the entire optical system, and is 15.0 or more and 35.0. The demand for high refractive index and high dispersion glass having the following low Abbe number (ν _d ) is greatly increasing. As such a high refractive index and high dispersion glass, a glass composition represented by Patent Document 1 is known.

JP 2010-215503 A JP 2011-178571 A

However, the glass described in Patent Document 1 contains a large amount of rare earths such as Nb ₂ O ₅ component and La ₂ O ₃ component in order to achieve high refractive index and high dispersion, resulting in high production cost. there were. Therefore, there has been a demand for an optical glass that has a high refractive index and a high dispersion, but has a low production cost.

On the other hand, the partial dispersion ratio (θg, F) is used as an index of optical characteristics to be noticed in optical design in correcting the aberration (secondary spectrum) in the blue region of chromatic aberration. The partial dispersion ratio (θg, F) is expressed by the following equation (1).
θg, F = (n _g −n _F ) / (n _F −n _C ) (1)

  Here, in an optical system that corrects chromatic aberration by combining a low-dispersion convex lens and a high-dispersion concave lens, an optical material having a small partial dispersion ratio (θg, F) is used for the low-dispersion lens, and a high-dispersion lens is used. The secondary spectrum can be corrected by using an optical material having a large partial dispersion ratio (θg, F) for the lens and combining them.

However, in the glass described in Patent Document 2, even if it has a high refractive index and a high dispersion, the Ta ₂ O ₅ component is essential, so the production cost is large, and in addition, the partial dispersion ratio is small, so that the secondary dispersion is small. It was not sufficient for use as a lens for correcting the spectrum. That is, there has been a demand for an optical glass having a high partial dispersion ratio (θg, F) while having a high refractive index (n _d ) and a low Abbe number (ν _d ).

The present invention has been made in view of the above-mentioned problems, and the object thereof is an optical glass having a high refractive index and high dispersion and low production cost, and a preform using the same. It is to provide an optical element.
Another object of the present invention is to provide an optical glass that has a high refractive index and high dispersion and is preferably used for correcting chromatic aberration, 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 studies and research. As a result, while using the La ₂ O ₃ component, the TiO ₂ component, and the BaO component together, the total of the SiO ₂ component and the B ₂ O ₃ component. By adjusting the amount and the mass ratio of TiO ₂ / (TiO ₂ + BaO), the desired partial dispersion ratio can be obtained while suppressing the production cost while obtaining the desired high refractive index and high dispersion. The headline and the present invention were completed.
Specifically, the present invention provides the following.

(1)% by mass based on oxide,
La ₂ O ₃ component more than 0% to 35.0%,
TiO ₂ component exceeds 0% to 45.0%, and BaO component exceeds 0% to 45.0%
Contains,
The total amount of SiO ₂ component and B ₂ O ₃ component is 5.0% or more and 30.0% or less,
The mass ratio of TiO ₂ / (TiO ₂ + BaO) is 0.10 or more and 0.90 or less,
An optical glass having an optical constant having a refractive index (nd) of 1.80 or more, an Abbe number (νd) of 35 or less, and a partial dispersion ratio (θg, F) of 0.57 or more.

(2)% by mass based on oxide,
SiO ₂ component 0 to 30.0% and B ₂ O ₃ component 0 to 30.0%
The optical glass according to (1).

(3)% by mass based on oxide,
ZnO component 0 to 30.0%,
Y ₂ O ₃ component 0 to 15.0%,
Nb ₂ O ₅ component 0 to 25.0%,
Yb ₂ O ₃ component 0 to 15.0%,
Gd ₂ O ₃ component 0 to 15.0%, and Bi ₂ O ₃ component 0 to 10.0%,
The optical glass according to (1) or (2).

(4)% by mass based on oxide,
The optical glass according to any one of (1) to (3), wherein the mass sum of (La ₂ O ₃ + Nb ₂ O ₅ + Gd ₂ O ₃ + Yb ₂ O ₃ ) is more than 0 and 40.0% or less.

(5)% by mass based on oxide,
The total of Ln ₂ O ₃ components (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb) is more than 0% and not more than 50.0% (1) to (4) Any one of the optical glasses.

(6) On the oxide basis,
The optical glass according to any one of (1) to (5), wherein a mass ratio of TiO ₂ / (La ₂ O ₃ + Nb ₂ O ₅ + Gd ₂ O ₃ + Yb ₂ O ₃ ) is more than 0 and 5.00 or less.

(7)% by mass based on oxide,
The optical component according to any one of (1) to (6), wherein the mass sum of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 15.0% or less. Glass.

(8)% by mass based on oxide,
Any of (1) to (7), wherein the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is greater than 0% and not greater than 45.0% The optical glass described.

(9)% by mass based on oxide,
ZrO ₂ component 0 to 20.0%,
WO ₃ component 0-10.0%,
Ta ₂ O ₅ component 0 to 10.0%,
MgO component 0 to 15.0%,
CaO component 0 to 30.0%,
SrO component 0 to 30.0%,
Li ₂ O component 0 to 15.0%,
Na ₂ O component 0 to 15.0%,
K ₂ O component 0 to 15.0%,
P ₂ O ₅ component 0 to 10.0%,
GeO ₂ component 0 to 10.0%,
Al ₂ O ₃ component 0 to 15.0%,
Ga ₂ O ₃ component 0 to 15.0%,
TeO ₂ component 0 to 10.0%,
SnO ₂ component 0-3.0% and Sb ₂ O ₃ component 0-1.0%
(1) The optical glass in any one of (8) containing.

  (10) A preform material comprising the optical glass according to any one of (1) to (9)

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

  (12) An optical apparatus comprising the optical element according to (11).

According to the present invention, it is possible to provide an optical glass having a high refractive index and a high dispersion and a low production cost, and a preform and an optical element using the optical glass.
In addition, according to the present invention, it is possible to provide an optical glass having a high refractive index and a high dispersion and preferably used for correcting chromatic aberration, and a preform and an optical element using the optical glass.

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.

The optical glass of the present invention is, in mass%, La ₂ O ₃ component more than 0% to 35.0%, TiO ₂ component more than 0% to 45.0%, and BaO component more than 0% to 45.0%. The total amount of SiO ₂ component and B ₂ O ₃ component is 5.0% or more and 30.0% or less, and the mass ratio of TiO ₂ / (TiO ₂ + BaO) is 0.10 or more and 0.90 or less. And an optical glass having an optical constant having a refractive index (nd) of 1.80 or more, an Abbe number (νd) of 35.0 or less, and a partial dispersion ratio (θg, F) of 0.57 or more.
According to the present invention, while using La ₂ O ₃ component, TiO ₂ component and BaO component in combination, by adjusting the content of each component, it is possible to achieve high refractive index and high dispersion in glass. Stability is improved. For this reason, it is possible to provide an optical glass having a high refractive index and a high dispersion and a low production cost, and a preform and an optical element using the optical glass.
Further, by adjusting the content of each component, the partial dispersion ratio of the glass can be further increased while achieving a high refractive index and high dispersion. Therefore, it is possible to provide an optical glass having a high refractive index and a high dispersion, and preferably used for correcting chromatic aberration, and a preform and an optical element using the optical glass.

[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 contents of the respective components are all expressed in mass% with respect to the total mass of the glass based on the oxide. Here, the “oxide standard” is based on the assumption that oxides, composite salts, metal fluorides, etc. used as raw materials for the glass constituents of the present invention are all decomposed and changed to oxides during melting. It is the composition which described each component contained in glass by making the total mass of an oxide into 100 mass%.

<About essential and optional components>
The La ₂ O ₃ component is a component that increases the refractive index of the glass and decreases dispersion. In particular, it is an essential component capable of obtaining a desired high refractive index by containing more than 0% of La ₂ O ₃ component. Therefore, the content of the La ₂ O ₃ component is preferably more than 0%, more preferably 1.0%, still more preferably 2.0%, still more preferably 3.0%, still more preferably 4.5%. Is the lower limit.
On the other hand, by setting the content of La ₂ O ₃ component to 35.0% or less, the devitrification resistance of the glass can be increased, the Abbe number can be reduced, the increase in the specific gravity of the glass can be suppressed, and the production cost can be reduced. can do. Therefore, the content of the La ₂ O ₃ component is preferably 35.0%, more preferably 24.0%, still more preferably 21.0%, and further preferably 18.0%.
As the La ₂ O ₃ component, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer) or the like can be used as a raw material.

The TiO ₂ component is an essential component that, when contained in excess of 0%, can increase the refractive index of the glass, adjust the Abbe number low, increase the partial dispersion ratio, and increase the devitrification resistance. Therefore, the content of the TiO ₂ component is preferably more than 0%, preferably 10.0%, more preferably more than 17.0%, more preferably 21.5%, and even more preferably 23.5%. To do.
On the other hand, when the content of the TiO ₂ component is 45.0% or less, the coloring of the glass is reduced and the visible light transmittance can be increased. Further, devitrification due to excessive inclusion of the TiO ₂ component can be suppressed. Accordingly, the content of the TiO ₂ component is preferably 45.0%, more preferably 38.0%, further preferably 35.0%, and further preferably 32.0%.
As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

The BaO component is an essential component that can increase the refractive index and devitrification resistance of the glass and increase the meltability of the glass raw material when it contains more than 0%. Therefore, the content of the BaO component is preferably more than 0%, more preferably 5.0%, still more preferably 8.0%, and still more preferably 10.0%.
On the other hand, when the content of the BaO component is 45.0% or less, the refractive index of the glass is hardly lowered and the devitrification of the glass can be reduced. Accordingly, the content of the BaO component is preferably 45.0%, more preferably 35.0%, further preferably 32.0%, and further preferably 30.0%.
As the BaO component, BaCO ₃ , Ba (NO ₃ ) ₂ or the like can be used as a raw material.

The sum (mass sum) of the contents of the B ₂ O ₃ component and the SiO ₂ component is preferably 5.0% or more and 30.0% or less.
In particular, by making this sum 5.0% or more, it is possible to suppress a decrease in devitrification resistance due to the lack of the B ₂ O ₃ component or the SiO ₂ component. Therefore, the mass sum (B ₂ O ₃ + SiO ₂ ) is preferably 5.0%, more preferably 10.0%, still more preferably 13.0%, and further preferably 15.0%.
On the other hand, by making this sum 30.0% or less, a decrease in the refractive index due to excessive inclusion of these components can be suppressed, so that a desired high refractive index can be easily obtained. Therefore, the upper limit of the mass sum (B ₂ O ₃ + SiO ₂ ) is preferably 30.0%, more preferably 24.0%, and still more preferably 22.0%.

Here, the ratio (mass ratio) of the content of TiO _{2 to} the sum of the contents of the TiO ₂ component and the BaO component is preferably 0.10 or more. Thereby, the partial dispersion ratio can be increased while maintaining a high refractive index and high dispersion. Therefore, the mass ratio TiO ₂ / (TiO ₂ + BaO) is preferably 0.10, more preferably 0.30, still more preferably 0.40, and still more preferably 0.45.
On the other hand, by setting the mass ratio to 0.90 or less, the coloring of the glass can be reduced, the visible light transmittance can be increased, and devitrification can be suppressed. Therefore, the upper limit of the mass ratio TiO ₂ / (TiO ₂ + BaO) is preferably 0.90, more preferably 0.80, and even more preferably 0.75.

The SiO ₂ component is an optional component that can enhance devitrification resistance when it is contained in an amount of more than 0%. Therefore, the content of the SiO ₂ component is preferably more than 0%, more preferably more than 0.5%, still more preferably more than 1.0%, still more preferably more than 2.0%.
On the other hand, by setting the content of the SiO ₂ component to 30.0% or less, the SiO ₂ component can be easily melted in the molten glass, and melting at a high temperature can be avoided. Accordingly, the upper limit of the content of the SiO ₂ component is preferably 30.0%, more preferably 28.0%, still more preferably 23.0%, still more preferably 18.0%, still more preferably 16.0%. And
As the SiO ₂ component, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ or the like can be used as a raw material.

The B ₂ O ₃ component is an optional component that, when contained in excess of 0%, forms a network structure inside the glass, promotes stable glass formation, and increases devitrification resistance. Therefore, the content of the B ₂ O ₃ component is preferably more than 0%, more preferably more than 0.5%, still more preferably more than 1.0%, still more preferably more than 2.0%.
On the other hand, by setting the content of the B ₂ O ₃ component to 30.0% or less, a decrease in refractive index can be suppressed, the Abbe number can be reduced, and deterioration in chemical durability can be suppressed. Therefore, the content of the B ₂ O ₃ component is preferably 30.0%, more preferably 28.0%, still more preferably 25.0%, still more preferably 23.0%, still more preferably 20.0%. Is the upper limit.
As the B ₂ O ₃ component, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ .10H ₂ O, BPO ₄ or the like can be used as a raw material.

The ZnO component is an optional component that can improve the meltability of the glass, lower the glass transition point, and reduce devitrification when it contains more than 0%. Accordingly, the content of the ZnO component is preferably more than 0%, more preferably more than 0.5%, still more preferably more than 1.0%, still more preferably more than 2.0%.
On the other hand, by making the content of the ZnO component 30.0% or less, it is possible to reduce the refractive index and devitrification. Moreover, since the viscosity of molten glass is raised by this, generation | occurrence | production of the striae to glass can be reduced. Accordingly, the upper limit of the content of the ZnO component is preferably 30.0%, more preferably 23.0%, still more preferably 17.0%, and still more preferably 14.0%.
As the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

The Y ₂ O ₃ component is an optional component that suppresses an increase in the material cost of the glass and increases the refractive index when it is contained in an amount of more than 0%.
Y ₂ O ₃ by the content of the component is below 15.0%, suppressed the decrease in the refractive index of the glass, it is possible to reduce the Abbe number is and enhance devitrification resistance of the glass. Therefore, the content of the Y ₂ O ₃ component is preferably 15.0%, more preferably 10.0%, and still more preferably 5.0%.
As the Y ₂ O ₃ component, Y ₂ O ₃ , YF ₃ or the like can be used as a raw material.

The Nb ₂ O ₅ component is an optional component that can increase the refractive index of the glass, increase the partial dispersion ratio of the glass, and increase the devitrification resistance when it contains more than 0%. Therefore, the content of the Nb ₂ O ₅ component is preferably more than 0%, more preferably 0.5%, and still more preferably 1.0%.
On the other hand, by making the content of the Nb ₂ O ₅ component 25.0% or less, it is possible to reduce the devitrification resistance of the glass due to the excessive content of the Nb ₂ O ₅ component and the transmittance of visible light. In addition, the Abbe number can be reduced. Therefore, the content of the Nb ₂ O ₅ component is preferably 25.0%, more preferably 18.0%, still more preferably 13.0%, and further preferably 10.0%.
As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

The Yb ₂ O ₃ component is an optional component that can increase the refractive index of the glass and reduce the dispersion when it exceeds 0%.
On the other hand, by setting the content of the Yb ₂ O ₃ component to 15.0% or less, the devitrification resistance of the glass can be increased and the production cost can be suppressed. Therefore, the content of the Yb ₂ O ₃ component is preferably 15.0%, more preferably 10.0%, and still more preferably 5.0%.
As the Yb ₂ O ₃ component, Yb ₂ O ₃ or the like can be used as a raw material.

The Gd ₂ O ₃ component is an optional component that can increase the refractive index of the glass and increase the Abbe number when it exceeds 0%.
On the other hand, by reducing the particularly expensive Gd ₂ O ₃ component among the rare earth elements to 15.0% or less, the material cost of the glass is reduced, so that a cheaper optical glass can be produced. Moreover, this can suppress the increase of the Abbe number of the glass more than necessary. Accordingly, the content of the Gd ₂ O ₃ component is preferably 15.0%, more preferably 10.0%, and still more preferably 5.0%.
As the Gd ₂ O ₃ component, Gd ₂ O ₃ , GdF ₃ or the like can be used as a raw material.

A Bi ₂ O ₃ component is an optional component that can increase the refractive index and lower the glass transition point when it exceeds 0%.
On the other hand, by making the content of the Bi ₂ O ₃ component 10.0% or less, the devitrification resistance of the glass can be increased, the production cost can be suppressed, and the coloring of the glass is reduced to reduce the visible light. The transmittance can be increased. Moreover, this can suppress the increase of the Abbe number of the glass more than necessary. Therefore, the content of the Bi ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
As the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

Further, it the optical glass of the present invention, _La 2 _{O 3} component, _Nb 2 _{O 5} component, _Gd 2 _{O 3} component and the sum of the content of _Yb 2 _{O 3} (mass sum) is less 40.0% Is preferred. Thereby, since content of these expensive components is reduced, the material cost of glass can be held down. Therefore, the mass sum (La ₂ O ₃ + Nb ₂ O ₅ + Gd ₂ O ₃ + Yb ₂ O ₃ ) is preferably 40.0%, more preferably 30.0%, still more preferably 25.0%, still more preferably 23 0.0% is the upper limit.
On the other hand, a desired high refractive index can be obtained by containing more than 0%. Accordingly, the lower limit is preferably more than 0%, more preferably 5.0%, and still more preferably 8.0%.

The sum (mass sum) of the contents of Ln ₂ O ₃ components (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb) is more than 0% and not more than 50.0% It is preferable.
In particular, when the mass sum exceeds 0%, the refractive index of the glass can be increased, so that a high refractive index glass can be easily obtained. Moreover, coloring can be reduced by this. Therefore, the mass sum of the contents of the Ln ₂ O ₃ component is preferably more than 0%, more preferably 1.0%, still more preferably 3.0%, and even more preferably 5.0%.
On the other hand, by making this mass sum 50.0% or less, devitrification resistance can be enhanced, production cost can be suppressed, and an increase in the Abbe number of glass more than necessary can be suppressed. Therefore, the mass sum of the contents of the Ln ₂ O ₃ component is preferably 50.0%, more preferably less than 40.0%, still more preferably 31.0%, still more preferably 26.0%, still more preferably The upper limit is 21.0%.

Here, the ratio (mass ratio) of the content of TiO _{2 to} the sum of the contents of La ₂ O ₃ component, Nb ₂ O ₅ component, Gd ₂ O ₃ component and Yb ₂ O ₃ is greater than 0. Is preferred. Thereby, while maintaining a high refractive index and high dispersion, a high partial dispersion ratio can be obtained, and the production cost can be suppressed. Therefore, the mass ratio TiO ₂ / (La ₂ O ₃ + Nb ₂ O ₅ + Gd ₂ O ₃ + Yb ₂ O ₃ ) is preferably more than 0, more preferably 0.50, still more preferably 0.80, and even more preferably 1. 0.00 is the lower limit.
On the other hand, by setting the mass ratio to 5.0 or less, the coloring of the glass can be reduced, the visible light transmittance can be increased, and devitrification can be suppressed. Therefore, the mass ratio TiO ₂ / (La ₂ O ₃ + Nb ₂ O ₅ + Gd ₂ O ₃ + Yb ₂ O ₃ ) is preferably 5.00, more preferably 4.00, still more preferably 3.00, and even more preferably The upper limit is 2.80.

The total amount of Rn ₂ O components (wherein Rn is one or more selected from the group consisting of Li, Na and K) is preferably 15.0% or less. Thereby, the fall of the refractive index of glass can be suppressed and devitrification resistance can be improved. Therefore, the upper limit of the mass sum of the Rn ₂ O component is preferably 15.0%, more preferably 10.0%, and still more preferably 5.0%.

The sum (mass sum) of the contents of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably more than 0% and 45.0% or less. Thereby, devitrification due to excessive inclusion of the RO component can be reduced, and a decrease in refractive index can be suppressed. Therefore, the mass sum of the RO component content is preferably 45.0%, more preferably less than 40.0%, even more preferably 38.0%, still more preferably less than 35.0%, and even more preferably 32.%. The upper limit is 0%.
On the other hand, by making this sum more than 0%, the meltability of the glass raw material and the stability of the glass can be enhanced. Therefore, the total content of RO components is preferably more than 0%, more preferably 5.0%, even more preferably 15.0%, and even more preferably more than 20.0%.

The ZrO ₂ component is an optional component that can contribute to high refractive index and low dispersion of the glass and can enhance the devitrification resistance of the glass when it is contained in an amount of more than 0%. Therefore, the content of the ZrO ₂ component is preferably more than 0%, more preferably 0.5%, and still more preferably 1.0%.
On the other hand, by making the ZrO ₂ component 20.0% or less, it is possible to suppress a decrease in the devitrification resistance of the glass due to the excessive inclusion of the ZrO ₂ component. Therefore, the content of the ZrO ₂ component is preferably 20.0%, more preferably 15.0%, and still more preferably 10.0%.
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

The WO ₃ component is an optional component that can increase the refractive index, increase the partial dispersion ratio, and increase the devitrification resistance of the glass when it contains more than 0%. Further, WO ₃ components, it is also a component can be lowered glass transition temperature. Therefore, the content of the WO ₃ component is preferably more than 0%, more preferably 0.1%, even more preferably 0.3%, and even more preferably more than 0.5%.
On the other hand, by setting the content of the WO ₃ component to 10.0% or less, it is possible to reduce the coloring of the glass by the WO ₃ component and increase the visible light transmittance. Accordingly, the content of the WO ₃ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
As the WO ₃ component, WO ₃ or the like can be used as a raw material.

The Ta ₂ O ₅ component is an optional component that can increase the refractive index of the glass and increase the devitrification resistance when it exceeds 0%.
On the other hand, by reducing the expensive Ta ₂ O ₅ component to 10.0% or less, the material cost of the glass is reduced, so that a cheaper optical glass can be produced. Moreover, by making the content of the Ta ₂ O ₅ component 10.0% or less, the melting temperature of the raw material is lowered and the energy required for melting the raw material is reduced, so that the manufacturing cost of the optical glass can also be reduced. . Therefore, the content of the Ta ₂ O ₅ component is preferably 10.0%, more preferably 8.0%, and still more preferably 5.0%. In particular, from the viewpoint of producing a cheaper optical glass, the content of the Ta ₂ O ₅ component is preferably 4.0%, more preferably 3.0%, and even more preferably less than 1.0%. Most preferably, it does not contain.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

The MgO component is an optional component that can enhance the meltability of the glass raw material and the devitrification resistance of the glass when it is contained in an amount exceeding 0%.
On the other hand, by setting the content of the MgO component to 15.0% or less, a decrease in refractive index and a decrease in devitrification resistance due to excessive inclusion of these components can be suppressed. Therefore, the content of the MgO component is preferably 15.0%, more preferably 10.0%, and still more preferably 5.0%.
As the MgO component, MgCO ₃ , MgF ₂ or the like can be used as a raw material.

When the CaO component is contained in an amount of more than 0%, the CaO component is an optional component that can increase the refractive index and devitrification resistance of the glass and increase the meltability of the glass raw material. Therefore, the content of the CaO component is preferably more than 0%, more preferably 0.5%, still more preferably 1.5%, and still more preferably 3.0%.
On the other hand, by making the content of the CaO component 30.0% or less, it is difficult to lower the refractive index of the glass and it is possible to reduce the devitrification of the glass. Therefore, the upper limit of the content of the CaO component is preferably 30.0%, more preferably 25.0%, further preferably 20.0%, further preferably 16.0%, and further preferably 13.0%. To do.
As the CaO component, CaCO ₃ , CaF ₂ or the like can be used as a raw material.

The SrO component is an optional component that can increase the refractive index and devitrification resistance of the glass and increase the meltability of the glass raw material when it contains more than 0%. Therefore, the content of the SrO component is preferably more than 0%, more preferably 0.5%, and still more preferably 1.5%.
On the other hand, by making the content of the SrO component 30.0% or less, it is difficult to lower the refractive index of the glass and it is possible to reduce the devitrification of the glass. Therefore, the content of the SrO component is preferably 30.0%, more preferably 25.0%, further preferably 20.0%, further preferably 17.0%, and further preferably 15.0%. To do.
For the SrO component, SrCO ₃ , SrF ₂ or the like can be used as a raw material.

Li ₂ O component, Na ₂ O component and _{K 2} O component, when at least one of which contains more than 0%, is an optional component which can improve the melting property of the glass. In particular, the K ₂ O component is a component that further increases the partial dispersion ratio of the glass.
On the other hand, by reducing the content of the Li ₂ O component, the Na ₂ O component or the K ₂ O component, it is possible to suppress a decrease in the refractive index of the glass and reduce devitrification. In particular, a reduction in the partial dispersion ratio of the glass can be suppressed by reducing the content of the Li ₂ O component. Accordingly, the content of at least one of the Li ₂ O component, the Na ₂ O component, and the K ₂ O component is preferably 15.0% or less, more preferably less than 10.0%, and even more preferably 5.0%. Less than.
Li ₂ O component, Na ₂ O component, and K ₂ O component are Li ₂ CO ₃ , LiNO ₃ , LiF, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ as raw materials. , KF, KHF ₂ , K ₂ SiF ₆ or the like can be used.

P ₂ O ₅ component, when ultra containing 0%, which is an optional component that enhances devitrification resistance of the glass. In particular, by making the content of the P ₂ O ₅ component 10.0% or less, it is possible to suppress a decrease in chemical durability, particularly water resistance, of the glass. Therefore, the content of the P ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
As the P ₂ O ₅ component, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ or the like can be used as a raw material.

The GeO ₂ component is an optional component that can increase the refractive index of the glass and improve the devitrification resistance when it contains more than 0%. However, since the raw material price of GeO ₂ is high, the material cost increases when the amount of GeO ₂ is large, thereby reducing the cost reduction effect by reducing the Gd ₂ O ₃ component and the Ta ₂ O ₅ component. Accordingly, the content of the GeO ₂ component is preferably 10.0%, more preferably 5.0%, still more preferably 1.0%, and most preferably not contained.
As the GeO ₂ component, GeO ₂ or the like can be used as a raw material.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are optional components that can increase the chemical durability of the glass and increase the devitrification resistance of the glass when contained in excess of 0%.
On the other hand, by making each content of the Al ₂ O ₃ component and the Ga ₂ O ₃ component 15.0% or less, a decrease in the devitrification resistance of the glass due to the excessive content thereof can be suppressed. Therefore, the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 15.0%, more preferably 8.0%, and still more preferably 3.0%.
For the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga (OH) ₃ or the like can be used as a raw material.

The TeO ₂ component is an optional component that can increase the refractive index and lower the glass transition point when it is contained in excess of 0%.
However, TeO ₂ has a problem that it can be alloyed with platinum when a glass raw material is melted in a crucible made of platinum or a melting tank in which a portion in contact with molten glass is formed of platinum. Accordingly, the content of the TeO ₂ component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, and even more preferably not contained.
TeO ₂ component can use TeO ₂ or the like as a raw material.

The F component is an optional component that can increase the Abbe number of the glass, lower the glass transition point, and improve the devitrification resistance when it contains more than 0%.
However, when the content of the F component, that is, the total amount of F substituted for a part or all of one or more oxides of each of the above metal elements exceeds 10.0%, F Since the volatilization amount of the component increases, it becomes difficult to obtain a stable optical constant, and it becomes difficult to obtain a homogeneous glass. In addition, the Abbe number rises more than necessary.
Therefore, the content of the component F is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%, and still more preferably not contained.

When the SnO ₂ component is contained in an amount of more than 0%, the SnO ₂ component is an optional component that can clarify the molten glass by reducing the oxidation of the molten glass and hardly deteriorate the light transmittance of the glass.
On the other hand, by setting the content of the SnO ₂ component to 3.0% or less, it is possible to make it difficult to cause coloration of the glass due to the reduction of the molten glass and devitrification of the glass. In addition, since the alloying between the SnO ₂ component and the melting equipment (especially a noble metal such as Pt) is reduced, the life of the melting equipment can be extended. Therefore, the content of the SnO ₂ component is preferably 3.0% or less, more preferably less than 2.0%, further preferably less than 1.0%, and further preferably not contained.
For the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , SnF ₄ or the like can be used as a raw material.

The Sb ₂ O ₃ component is an optional component that can degas the molten glass when it contains more than 0%.
On the other hand, by setting the content of the Sb ₂ O ₃ component to 1.0% or less, excessive foaming can be hardly caused, and alloying with melting equipment (particularly a noble metal such as Pt) can be reduced. Accordingly, the content of the Sb ₂ O ₃ component is preferably 1.0% or less, more preferably less than 0.5%, even more preferably less than 0.3%, and even more preferably less than 0.1%.
As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ .5H ₂ O, or the like can be used as a raw material.

Incidentally, components defoamed fining glass is not limited to the above Sb ₂ O ₃ component, a known refining agents in the field of glass production, it is possible to use a defoamer 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 of the present invention are not impaired. However, it is preferable that the GeO ₂ component is not substantially contained since it increases the dispersibility of the glass.

  Moreover, each transition metal component except Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, for example, Hf, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, Mo, Ce, Nd Etc., even in the case where each of them is contained alone or in combination with a small amount, the glass is colored and has the property of absorbing light of a specific wavelength in the visible range. Is preferably substantially free.

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 tended to refrain 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.

[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. In a platinum alloy crucible or iridium crucible, melt in a temperature range of 900 to 1400 ° C. for 1 to 5 hours, stir and homogenize to blow out bubbles, etc. This is produced by removing the striae and molding using a mold. Here, as means for obtaining glass molded using a molding die, means for drawing molten glass from the other end side of the molding die at the same time as flowing the molten glass to one end of the molding die, or molten glass There is a means of slowly cooling by casting into a mold.

[Physical properties]
The optical glass of the present invention has a high refractive index and high dispersion.
In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.80, more preferably 1.85, and still more preferably 1.90. The upper limit of this refractive index is preferably 2.20 or less, more preferably 2.10 or less, and even more preferably less than 2.05.
Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 15.0 or more, more preferably 20.0 or more, further preferably 21.0 or more, more preferably 22.0 or more, The upper limit is preferably 35.0 or less, more preferably 30.0 or less, and still more preferably less than 27.0.
Since the optical glass of the present invention has such a refractive index and Abbe number, it is useful in optical design, and the optical system can be downsized while achieving particularly high imaging characteristics and the like. The degree of freedom can be expanded.

It is preferable that the optical glass of the present invention has high visible light transmittance, in particular, high transmittance of light on the short wavelength side of visible light, and thereby less coloring.
In particular, when the optical glass of the present invention is represented by the transmittance of the glass, the wavelength (λ ₇₀ ) showing a spectral transmittance of 70% in a sample having a thickness of 10 mm is preferably 520 nm, more preferably 510 nm, still more preferably 500 nm, More preferably, the upper limit is 490 nm.
In the optical glass of the present invention, the shortest wavelength (λ ₅ ) having a spectral transmittance of 5% in a 10 mm thick sample is preferably 400 nm, more preferably 390 nm, and still more preferably 380 nm.
As a result, the absorption edge of the glass is in the vicinity of the ultraviolet region, and the transparency of the glass with respect to visible light is enhanced. Therefore, this optical glass can be preferably used for an optical element that transmits light such as a lens.

The optical glass of the present invention preferably has a high partial dispersion ratio (θg, F). More specifically, the partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably 0.570, more preferably 0.580, still more preferably 0.595, still more preferably 0.605, Preferably, the lower limit is 0.612.
The partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably (θg, F) ≧ (−0.00162 × ν _d +0.6450) in relation to the Abbe number (ν _d ). Satisfy the relationship.
Thus, the optical glass of the present invention has a higher partial dispersion ratio (θg, F) than a conventionally known glass containing a large amount of rare earth element components. Therefore, an optical element formed from this optical glass can be preferably used for correcting chromatic aberration while achieving high refractive index and high dispersion of the glass.
Here, the partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably (−0.00162 × ν _d +0.6450), more preferably (−0.00162 × ν _d +0.6470). More preferably, (−0.00162 × ν _d +0.6500) is set as the lower limit. On the other hand, the upper limit of the partial dispersion ratio (θg, F) of the optical glass of the present invention is not particularly limited, but is approximately (−0.00162 × ν _d +0.6800) or less, more specifically (−0. 00162 × ν _d +0.6700) or less, more specifically, (−0.00162 × ν _d +0.6650) or less in many cases. In the glass having the composition specified in the present invention, a stable glass can be obtained even if the partial dispersion ratio (θg, F) and the Abbe number (νd) satisfy this relationship.

The relational expression of the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) described above uses a straight line parallel to the normal line in orthogonal coordinates with the partial dispersion ratio on the vertical axis and the Abbe number on the horizontal axis. expressed. The normal line represents a linear relationship between the conventional glass partial dispersion ratio (θg, F) and the Abbe number (ν _d ), and the partial dispersion ratio (θg, F) is expressed vertically. The axis is represented by a straight line connecting two points plotting the partial dispersion ratio and Abbe number of NSL7 and PBM2 on the orthogonal coordinates adopting the Abbe number (ν _d ) as the horizontal axis (see FIG. 1). And the relationship between the partial dispersion ratio and Abbe number of conventionally known glass generally overlaps with the normal line.
Here, NSL7 and PBM2 are optical glass 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 of NSL7 (ν _d ) is 60.5, and the partial dispersion ratio (θg, F) is 0.5436.

[Preforms and optical elements]
A glass molded body can be produced from the produced optical glass by means of, for example, polishing or molding press molding such as reheat press molding or precision press molding. That is, a glass molded body is manufactured by performing mechanical processing such as grinding and polishing on optical glass, or glass molding is performed by performing a polishing process after performing reheat press molding on a preform manufactured from optical glass. A glass molded body can be produced by producing a body, or by performing precision press molding on a preform produced by polishing or a preform formed by known float forming or the like. In addition, the means for producing the glass molded body is not limited to these means.

As described above, the glass molded body formed from the optical glass of the present invention is useful for various optical elements and optical designs, and among them, it is particularly preferable to use them for optical elements such as lenses and prisms. The increased stability of the glass enables the formation of large-diameter glass moldings, so high-definition and high-precision when used in optical equipment such as cameras, while increasing the size of the optical element Imaging characteristics and projection characteristics can be realized.
In addition, since the partial dispersion ratio is increased, the optical element is usefully used for correcting chromatic aberration in the optical system. For example, when the optical element is used in a camera, the object to be photographed can be expressed more accurately. When used in a projector, a desired image can be projected with higher definition.

Composition of the glass of Examples (No. 1 to No. 55 ) of the present invention, and the refractive index (n _d ), Abbe number (ν _d ), transmittance (λ ₅ , λ ₇₀ ) and parts of these glasses The dispersion ratio (θg, F) values are shown in Tables 1 to 10 . The following examples are merely for illustrative purposes, and are not limited to these examples.

  The glasses of the examples are high purity used in ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphate compounds corresponding to the raw materials of each component. After selecting the raw materials, weighing them and mixing them uniformly, they are put into a platinum crucible and melted in the electric furnace in the temperature range of 1250 to 1300 ° C. for 2 hours, and the bubbles by stirring the molten glass raw materials After cutting, the temperature was lowered to 1080 to 1180 ° C., and the mixture was further stirred and homogenized, then cast into a mold and gradually cooled to produce glass.

The refractive index (n _d ), Abbe number (ν _d ), and partial dispersion ratio (θg, F) of the glass of the example are shown as measured values with respect to the d-line (587.56 nm) of the helium lamp. The Abbe number (ν _d ) is the refractive index of the d line, the refractive index (n _F ) for the F lamp (486.13 nm) of the hydrogen lamp, and the refractive index (n _C ) for the C line (656.27 nm). Was calculated from the equation of Abbe number (ν _d ) = [(n _d −1) / (n _F −n _C )].
Partial dispersion ratio is to measure the refractive index _{n g} of the refractive index _n F, g-line (wavelength 435.835 nm) at the C-line refractive index _n C, F line in (a wavelength 656.27 nm) (wavelength 486.13 nm), _{(θg, F) =} was calculated by the equation of _{(n g -n F) / (} n F -n C).

The transmittance | permeability of the glass of an Example was measured according to Japan Optical Glass Industry Association standard JOGIS02-2003. 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 is measured for a spectral transmittance of 200 to 800 nm in accordance with JISZ8722, and λ ₅ (wavelength when the transmittance is 5%) and λ ₇₀ (transmittance). Wavelength at 70%).
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.

As shown in the table, each of the optical glasses according to the examples of the present invention has a refractive index (n _d ) of 1.80 or more, and the refractive index (n _d ) is 2.20 or less, more specifically. Was 2.10 or less, and was within the desired range.
The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 35.0 or less, more specifically 30.0 or less, and this Abbe number (ν _d ) is 15.0. As mentioned above, it was 20.0 or more in detail, and was in the desired range.

Moreover, the optical glass of the Example of this invention had a partial dispersion ratio ((theta) g, F) of 0.570 or more, more specifically 0.605 or more, and had a high value.
Further, the optical glass of the example of the present invention has a relationship of (θg, F) ≧ (−0.00162ν _d +0.6450) between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ). More specifically, the relationship of (θg, F) ≧ (−0.00162ν _d +0.6500) was satisfied. The relationship between the partial dispersion ratio (θg, F) and the Abbe number (νd) for the glass of the example of the present application is as shown in FIG.
From these facts, it was revealed that the optical glass of the example of the present invention has a large partial dispersion ratio (θg, F), and the optical element obtained by this optical glass is useful for correcting chromatic aberration.

  Therefore, it was revealed that the optical glass of the example of the present invention has a high refractive index and a high dispersion, has a high partial dispersion ratio, and is preferably used for correcting chromatic aberration.

  Furthermore, using the optical glass obtained in the example of the present invention, after performing reheat press molding, grinding and polishing were performed to process into the shape of a lens and a prism. Further, a precision press molding preform was formed using the optical glass of the example of the present invention, and this precision press molding preform was precision press molded. In either case, the glass after heat softening did not cause problems such as opacification and devitrification, and could be stably processed into various lens and prism shapes.

  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 (12)

% By mass based on oxide,
La ₂ O ₃ component more than 0% to 35.0%,
TiO ₂ component exceeds 0% to 45.0%, and BaO component exceeds 0% to 45.0%
Contains,
The total amount of SiO ₂ component and B ₂ O ₃ component is 5.0% or more and 30.0% or less,
The mass ratio of TiO ₂ / (TiO ₂ + BaO) is 0.1 or more and 0.9 or less,
An optical glass having an optical constant having a refractive index (n _d ) of 1.80 or more, an Abbe number (ν _d ) of 35.0 or less, and a partial dispersion ratio (θg, F) of 0.57 or more. % By mass based on oxide,
SiO ₂ component 0 to 30.0% and B ₂ O ₃ component 0 to 30.0%
The optical glass according to claim 1. % By mass based on oxide,
ZnO component 0 to 30.0%,
Y ₂ O ₃ component 0 to 15.0%,
Nb ₂ O ₅ component 0 to 25.0%,
Yb ₂ O ₃ component 0 to 15.0%,
Gd ₂ O ₃ component 0 to 15.0%, and Bi ₂ O ₃ component 0 to 10.0%,
The optical glass according to claim 1 or 2. % By mass based on oxide,
4. The optical glass according to claim 1, wherein a mass sum of (La ₂ O ₃ + Nb ₂ O ₅ + Gd ₂ O ₃ + Yb ₂ O ₃ ) is more than 0 and 40.0% or less. % By mass based on oxide,
The total of Ln ₂ O ₃ components (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is more than 0% and 50.0% or less. The optical glass described. On oxide basis,
6. The optical glass according to claim 1, wherein a mass ratio of TiO ₂ / (La ₂ O ₃ + Nb ₂ O ₅ + Gd ₂ O ₃ + Yb ₂ O ₃ ) is more than 0 and 5.00 or less. % By mass based on oxide,
7. The optical glass according to claim 1, wherein the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) has a mass sum of 15.0% or less. % By mass based on oxide,
8. The mass sum of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is more than 0% and 45.0% or less. Optical glass. % By mass based on oxide,
ZrO ₂ component 0 to 20.0%,
WO ₃ component 0-10.0%,
Ta ₂ O ₅ component 0 to 10.0%,
MgO component 0 to 15.0%,
CaO component 0 to 30.0%,
SrO component 0 to 30.0%,
Li ₂ O component 0 to 15.0%,
Na ₂ O component 0 to 15.0%,
K ₂ O component 0 to 15.0%,
P ₂ O ₅ component 0 to 10.0%,
GeO ₂ component 0 to 10.0%,
Al ₂ O ₃ component 0 to 15.0%,
Ga ₂ O ₃ component 0 to 15.0%,
TeO ₂ component 0 to 10.0%,
SnO ₂ component 0-3.0% and Sb ₂ O ₃ component 0-1.0%
The optical glass according to claim 1, comprising:   A preform material comprising the optical glass according to claim 1.   An optical element made of the optical glass according to claim 1.   An optical apparatus comprising the optical element according to claim 11.

Images