JP7096648B2 - Optical glass, preforms and optical elements - Google Patents

Description

The present invention relates to optical glass, preforms and optical elements.

In recent years, optical elements incorporated in in-vehicle optical devices such as in-vehicle cameras and optical elements incorporated in optical devices that generate a lot of heat such as projectors, copiers, laser printers, and broadcasting equipment have higher temperatures. Increased use in the environment. In such a high temperature environment, the temperature at the time of use of the optical element constituting the optical system tends to fluctuate greatly, and the temperature often reaches 100 ° C. or higher. At this time, since the adverse effect on the imaging characteristics of the optical system due to the temperature fluctuation becomes so large that it cannot be ignored, it is required to construct an optical system in which the imaging characteristics and the like are unlikely to be affected by the temperature fluctuation.

As a material for optical elements constituting an optical system, there is a great demand for high refractive index low dispersion glass having a refractive index ( _{nd) of 1.65 or more and an Abbe number (ν d )} of 40 or more and 62 or less. .. As such a high-refractive index low-dispersion glass, for example, glass compositions represented by Patent Documents 1 to 3 are known.

Japanese Unexamined Patent Publication No. 60-221338 Japanese Unexamined Patent Publication No. 05-201743 Japanese Unexamined Patent Publication No. 2005-179142

In constructing an optical system in which the image quality is unlikely to be affected by temperature fluctuations, an optical element made of glass whose refractive index decreases when the temperature rises and whose relative refractive index has a negative temperature coefficient. By using an optical element made of glass, which has a high refractive index when the temperature rises and the temperature coefficient of the relative refractive index is positive, the effect of temperature changes on imaging characteristics, etc. is corrected. It is preferable in that it can be done.

In particular, a high refractive index low-dispersion glass having a refractive index ( _{nd) of 1.65 or more and an Abbe number (ν d )} of 40 or more and 62 or less can contribute to the correction of the influence of temperature changes on the imaging characteristics. From the viewpoint, glass having a low relative refractive index temperature coefficient is desired, and more specifically, glass having a negative relative refractive index temperature coefficient and glass having a small absolute value of the relative refractive index temperature coefficient are used. It is desired.

The present invention has been made in view of the above problems, and an object thereof is to have optical characteristics of high refractive index and low dispersion, and to have a low temperature coefficient of relative refractive index. It is an object of the present invention to provide an optical glass that can contribute to the correction of the influence of a temperature change on the imaging characteristics, and a preform and an optical element using the optical glass.

As a result of intensive test and research to solve the above problems, the present inventors have used at least one of the SiO ₂ component, the B ₂ O ₃ component and the BaO component, and the Ln ₂ O ₃ component in combination. By adjusting the content of each component, it was found that the temperature coefficient of the relative refractive index is low while having a desired refractive index and Abbe number, and the present invention has been completed. Specifically, the present invention provides the following.

(1) By mass%,
SiO ₂ component 5.0% or more and 30.0% or less,
B ₂ O ₃ component is more than 0% and 25.0% or less,
Contains 38.0% or more and 63.0% or less of BaO component,
It contains a total of 10.0% or more and 35.0% or less of Ln ₂ O ₃ components (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb).
It has a refractive index (nd) of 1.65 or more, and has an Abbe number (ν _d ) of 40 or more and 62 or less _.
An optical glass having a temperature coefficient (40 to 60 ° C.) of relative refractive index (589.29 nm) in the range of +2.0 × 10 ^-6 to -10.0 × ^10-6 (° C. ^-1 ).

(2) By mass%,
MgO component 0-5.0%
CaO component 0 to 10.0%
SrO component 0 to 10.0%
K ₂ O component 0 to 10.0%
TiO ₂ component 0 to 10.0%
Nb ₂ O ₅ component 0 to 10.0%
WO ₃ component 0 to 10.0%
ZrO ₂ component 0 to 10.0%
ZnO component 0 to 10.0%
La ₂ O ₃ component 0-35.0%
Gd ₂ O ₃ component 0-20.0%
Y ₂ O ₃ component 0-20.0%
Yb ₂ O ₃ component 0 to 10.0%
Li ₂ O component 0-3.0%
Na ₂ O component 0-5.0%
Al ₂ O ₃ component 0 to 15.0%
Ga ₂ O ₃ component 0 to 10.0%
P ₂ O ₅ component 0 to 10.0%
GeO ₂ component 0 to 10.0%
Ta ₂ O ₅ component 0-5.0%
Bi ₂ O ₃ component 0 to 10.0%
TeO ₂ component 0 to 10.0%
SnO ₂ component 0-3.0%
Sb ₂ O ₃ component 0-1.0%
And
The optical glass according to (1), wherein the content of fluoride as F, which is substituted with a part or all of one or more oxides of each of the above elements, is 0 to 10.0% by mass.

(3) The optical glass according to (1) or (2), wherein the sum of the contents of the RO components is 40.0% or more and 65.0% or less in mass% (R is Mg, Ca, Sr, in the formula). One or more selected from the group consisting of Ba).

(4) The optical glass according to any one of (1) to (3), wherein the sum of mass (RO + K ₂ O) is 40.0% or more and 65.0% or less (in the formula, R is Mg, Ca, Sr, Ba). One or more selected from the group consisting of).

(5) The optical glass according to any one of (1) to (4), wherein the sum of mass (SiO ₂ + B ₂ O ₃ ) is 15.0% or more and 40.0% or less.

(6) The optical glass according to any one of (1) to (5), wherein the mass sum TiO ₂ + Nb ₂ O ₅ + WO ₃ + ZrO ₂ is 10.0% or less.

(7) Any one of (1) to (6) in which the mass ratio (RO + K ₂ O) / (TIO ₂ + Nb ₂ O ₅ + WO ₃ + ZrO ₂ + ZnO + SiO ₂ + B ₂ O ₃ ) is 1.00 or more and 3.00 or less. The optical glass according to the description (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba).

(8) The optical glass according to any one of (1) to (7), wherein the sum of the contents of the Rn ₂ O components is 10.0% or less in mass% (in the formula, Rn is from Li, Na, K). One or more selected from the group of

(9) A preform material made of the optical glass according to any one of (1) to (8).

(10) An optical element made of the optical glass according to any one of (1) to (8).

(11) An optical device including the optical element according to (10).

According to the present invention, it has optical characteristics of high refractive index and low dispersion, and has a low temperature coefficient of relative refractive index, which can contribute to correction of the influence of temperature change on imaging characteristics. Optical glass and preforms and optical elements using the same can be obtained.

The optical glass of the present invention has a SiO ₂ component of 5.0% or more and 30.0% or less _{, a B2 O 3 component} of more than 0% and 25.0% or less, and a BaO component of 38.0% or more and 63% by mass. It contains 0.0% or less and contains 10.0% or more and 35.0% or less of Ln ₂ O ₃ components in total (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, Yb). ), A refractive index (nd) of 1.65 or more, an Abbe number (ν _{d )} of 40 or more and 62 or less, and a temperature coefficient (40 to 60 ° C.) of a relative refractive index (589.29 nm). It is in the range of +2.0 × ^10-6 to -10.0 × ^10-6 (° C ^-1 ). By using at least one of the SiO ₂ component, the B ₂ O ₃ component and the BaO component, and the Ln ₂ O ₃ component in combination and adjusting the content of each component, the desired refractive index and Abbe number can be obtained. However, the temperature coefficient of the relative refractive index takes a low value. Therefore, an optical glass having high refractive index and low dispersion optical characteristics and having a low temperature coefficient of relative refractive index, which can contribute to the correction of the influence on the imaging characteristics due to the temperature change, is obtained. be able to.

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 carried out with appropriate modifications within the scope of the object of the present invention. It should be noted that the description may be omitted as appropriate for the parts where the explanations are duplicated, but the gist of the invention is not limited.

[Glass component]
The composition range of each component constituting the optical glass of the present invention is described below. In the present specification, the content of each component shall be expressed in mass% with respect to the total mass of the oxide equivalent composition, unless otherwise specified. Here, the "oxide-equivalent composition" is used when it is assumed that the oxides, composite salts, metal fluorides, etc. used as raw materials for the glass constituents of the present invention are all decomposed at the time of melting and changed to oxides. It is a composition which describes each component contained in a glass, assuming that the total mass number of the produced oxide is 100 mass%.

<About essential and optional ingredients>
The SiO ₂ component is an essential component as a glass-forming oxide. In particular, by containing 5.0% or more of the SiO ₂ component, the chemical durability can be enhanced, the viscosity of the molten glass can be increased, and the coloring of the glass can be reduced. In addition, the stability of the glass can be improved to facilitate the acquisition of glass that can withstand mass production. Therefore, the content of the SiO ₂ component is preferably 5.0% or more, more preferably more than 6.0%, still more preferably more than 8.0%, still more preferably more than 10.0%.
On the other hand, by setting the content of the SiO ₂ component to 30.0% or less, the temperature coefficient of the relative refractive index can be reduced, the increase in the glass transition point can be suppressed, and the decrease in the refractive index can be suppressed. Therefore, the content of the SiO ₂ component is preferably 30.0% or less, more preferably less than 27.0%, still more preferably less than 24.0%, still more preferably less than 20.0%, still more preferably 18. It shall be less than 0%.

The B ₂ O ₃ component is an essential component as a glass-forming oxide. In particular, by containing more than ₀ % of the _B2O3 component, the devitrification of the glass can be reduced and the Abbe number of the glass can be increased. Therefore, the content of the _B2O3 component is preferably _more than 0%, more preferably 3.0% or more, still more preferably more than 5.0%, still more preferably more than 7.0%, still more preferably 10. It shall be over 0%.
On the other hand, by setting the content of the B ₂ O ₃ component to 25.0% or less, a larger refractive index can be easily obtained, the temperature coefficient of the relative refractive index can be reduced, and deterioration of chemical durability can be suppressed. Be done. Therefore, the content of the _B2O3 component is preferably 25.0% or less, _more preferably less than 22.0%, still more preferably less than 20.0%, still more preferably less than 17.0%.

The sum (mass sum) of the contents of the Ln ₂ O ₃ component (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, Yb) is 10.0% or more and 35.0% or less. Is.
In particular, when the sum is 10.0% or more, the refractive index and Abbe number of the glass are increased, so that it is possible to easily obtain a glass having a desired refractive index and Abbe number. Therefore, the mass sum of the Ln ₂ O ₃ components is preferably 10.0% or more, more preferably more than 13.0%, still more preferably more than 15.0%, still more preferably more than 18.0%.
On the other hand, when the sum is 35.0% or less, the liquidus temperature of the glass is lowered, so that the devitrification of the glass can be reduced. In addition, it is possible to suppress an increase in the Abbe number more than necessary. Therefore, the mass sum of the Ln ₂ O ₃ components is preferably 35.0% or less, more preferably less than 30.0%, still more preferably less than 25.0%, still more preferably less than 23.0%.

The BaO component is an essential component that can enhance the meltability of the glass raw material, reduce the devitrification of the glass, increase the refractive index, and reduce the temperature coefficient of the relative refractive index. Therefore, the content of the BaO component is preferably 38.0% or more, more preferably more than 39.0%, still more preferably more than 40.0%, still more preferably more than 42.0%, still more preferably 45.0. %, More preferably more than 48.0%.
On the other hand, by setting the content of the BaO component to 63.0% or less, it is possible to reduce the decrease in the refractive index of the glass due to the excessive content, the decrease in the chemical durability, and the devitrification. Therefore, the content of the BaO component is preferably 63.0% or less, more preferably 60.0% or less, still more preferably less than 58.0%, still more preferably less than 55.0%.

The MgO component, CaO component and SrO component are optional components that can adjust the refractive index, meltability and devitrification resistance of the glass when the content exceeds 0%.
On the other hand, by setting the content of the MgO component to 5.0% or less, or the content of the CaO component or the SrO component to 10.0% or less, the decrease in the refractive index can be suppressed, and these It is possible to reduce devitrification due to excessive inclusion of components. Therefore, the content of the MgO component is preferably 5.0% or less, more preferably less than 4.0%, still more preferably less than 3.0%, still more preferably less than 1.0%. The contents of the CaO component and the SrO component are preferably 10.0% or less, more preferably less than 7.0%, still more preferably less than 4.0%, still more preferably less than 1.0%.

The Li ₂ O component, Na ₂ O component, and K ₂ O component are optional components that can improve the meltability of the glass and lower the glass transition point when the content exceeds 0%. _In particular, when the K2O component is contained in excess of 0%, the temperature coefficient of the relative refractive index can be reduced.
On the other hand, by reducing the contents of the Li ₂ O component, the Na ₂ O component and the K ₂ O component, it is difficult to lower the refractive index of the glass and the devitrification of the glass can be reduced. Further, in particular, by reducing the content of the Li ₂ O component, the viscosity of the glass is increased, so that the veins of the glass can be reduced. Therefore, the content of the Li ₂ O component is preferably 3.0% or less, more preferably less than 2.0%, still more preferably less than 1.1%, still more preferably less than 0.6%, still more preferably 0. It may be less than 0.3%. The content of the Na ₂ O component may be preferably 5.0% or less, more preferably less than 3.0%, still more preferably less than 2.0%, still more preferably less than 1.0%. _The content of the K2O component may be preferably 10.0% or less, more preferably less than 7.0%, still more preferably less than 4.0%, still more preferably less than 2.0%.

The TiO ₂ component is an optional component that can increase the refractive index of the glass and reduce the devitrification of the glass when it is contained in an amount of more than 0%.
On the other hand, by reducing the content of the TiO ₂ component to 10.0% or less, the temperature coefficient of the relative refractive index can be reduced, devitrification due to the excessive content of the TiO ₂ component can be reduced, and visible light of glass (particularly). It is possible to suppress a decrease in transmittance for a wavelength of 500 nm or less). Further, this can suppress a decrease in the Abbe number. Therefore, the content of the TiO ₂ component may be preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.5%, still more preferably less than 2.0%.

The Nb ₂ O ₅ component is an optional component whose devitrification resistance can be enhanced by increasing the refractive index of the glass and lowering the liquidus temperature of the glass when the content exceeds 0%.
On the other hand, by setting the content of the Nb ₂ O ₅ component to 10.0% or less, the temperature coefficient of the relative refractive index can be reduced, the devitrification due to the excessive content of the Nb ₂ O ₅ component can be reduced, and the devitrification can be reduced. It is possible to suppress a decrease in the transmittance of glass with respect to visible light (particularly, a wavelength of 500 nm or less). Further, this can suppress a decrease in the Abbe number. Therefore, the content of the Nb ₂ O ₅ component may be 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%.

The WO ₃ component is an optional component capable of increasing the refractive index, lowering the glass transition point, and reducing devitrification while reducing the coloring of the glass due to other high refractive index components when the content exceeds 0%. ..
On the other hand, by setting the content of the WO ₃ component to 10.0% or less, the temperature coefficient of the relative refractive index can be reduced and the material cost can be suppressed. _In addition, the coloring of the glass due to the WO3 component can be reduced and the visible light transmittance can be increased. Therefore, the content of the WO ₃ component 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%, still more preferably 0. It may be less than 5%.

_The ZrO2 component is an optional component capable of increasing the refractive index and Abbe number of the glass and reducing devitrification when the content exceeds 0%.
_On the other hand, by setting the content of the ZrO2 component to 10.0% or less, the temperature coefficient of the relative refractive index can be reduced, and the devitrification due to the excessive content of the _ZrO2 component can be reduced. Therefore, the content of the ZrO2 component may be preferably 10.0% or less, _more preferably less than 8.0%, still more preferably less than 5.0%, still more preferably 3.0% or less.

The ZnO component is an optional component that, when contained in excess of 0%, enhances the meltability of the raw material, promotes defoaming from the melted glass, and enhances the stability of the glass. It is also a component that can lower the glass transition point and improve the chemical durability.
On the other hand, by setting the content of the ZnO component to 10.0% or less, the temperature coefficient of the relative refractive index can be reduced, the expansion due to heat can be reduced, the decrease in the refractive index can be suppressed, and the excessive viscosity can be achieved. It is possible to reduce devitrification due to the decrease. Therefore, the content of the ZnO component is preferably 10.0% or less, more preferably less than 6.0%, still more preferably less than 4.5%, still more preferably less than 3.0%, still more preferably 2.5. It may be less than%, more preferably less than 1.0%.

_When the _Y2O3 component is contained in excess of 0%, the material cost of glass can be suppressed as compared with other rare earth elements while maintaining a high refractive index and a high Abbe number, and the Y2O3 component is higher than other rare earth components. Is also an optional component that can reduce the specific gravity of glass.
_On the other hand, by setting the content of the _Y2O3 component to 20.0% or less, the decrease in the refractive index of the glass can be suppressed and the stability of the glass can be enhanced. In addition, deterioration of the meltability of the glass raw material can be suppressed. Therefore, the content of the _Y2O3 component may be preferably 20.0% or less, _more preferably less than 15.0%, still more preferably less than 10.0%, still more preferably less than 5.0%.

The La ₂ O ₃ component is an optional component that can increase the refractive index and Abbe number of the glass when it is contained in excess of 0%. Therefore, the content of the La ₂ O ₃ component is preferably more than 0%, more preferably 5.0% or more, still more preferably more than 8.0%, still more preferably more than 10.0%, still more preferably 13. It may be more than 0%, more preferably more than 15.0%, still more preferably more than 17.0%.
On the other hand, by reducing the content of the La ₂ O ₃ component to 35.0% or less, devitrification can be reduced by increasing the stability of the glass, and an increase in the Abbe number more than necessary can be suppressed. In addition, the meltability of the glass raw material can be improved. Therefore, the content of the La ₂ O ₃ component is preferably 35.0% or less, more preferably less than 30.0%, still more preferably less than 26.0%, still more preferably less than 23.0%.

The Gd ₂ O ₃ component and the Yb ₂ O ₃ component are optional components that can increase the refractive index of the glass when the content exceeds 0%.
On the other hand, the Gd ₂ O ₃ component and the Yb ₂ O ₃ component have a high raw material price among rare earths, and the higher the content, the higher the production cost. Further, by reducing the content of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component, an increase in the Abbe number of the glass can be suppressed. Therefore, the content of the Gd ₂ O ₃ component is preferably 20.0% or less, more preferably less than 15.0%, still more preferably less than 10.0%, still more preferably less than 7.0%, still more preferably. It may be less than 4.0%. The content of the Yb ₂ O ₃ component may be 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%.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are optional components that can improve the chemical durability of the glass and the devitrification resistance of the molten glass when the content exceeds 0%. Therefore, in particular, the content of the Al ₂ O ₃ component may be preferably more than 0%, more preferably more than 0.5%, and even more preferably more than 1.0%.
On the other hand, by reducing the content of the Al ₂ O ₃ component to 15.0% or less, or by setting the content of the Ga ₂ O ₃ component to 10.0% or less, the liquid phase temperature of the glass is lowered to withstand the resistance. The devitrification can be increased. Therefore, the content of the Al ₂ O ₃ component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 6.0%, still more preferably less than 3.0%, still more preferably. It may be less than 1.0%. The content of the Ga ₂ O ₃ component may be 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%.

The P ₂ O ₅ component is an optional component capable of lowering the liquidus temperature of the glass and increasing the devitrification resistance when the content exceeds 0%.
_On the other hand, by setting the content of the _P2O5 component to 10.0% or less, it is possible to suppress a decrease in the chemical durability of the glass, particularly the water resistance. Therefore, the content of the P ₂ O ₅ component may be 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%.

The GeO ₂ component is an optional component capable of increasing the refractive index of the glass and improving the devitrification resistance when it is contained in an amount of more than 0%.
However, the raw material price of GeO ₂ is high, and if the content of GeO 2 is high, the production cost is high. Therefore, the content of the GeO ₂ component 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%, still more preferably 0. It may be less than 1%.

The Ta ₂ O ₅ component is an optional component that can increase the refractive index of the glass and enhance the devitrification resistance when it is contained in an amount of more than 0%.
On the other hand, by reducing the content of the Ta ₂ O ₅ component to 5.0% or less, the raw material cost of the optical glass can be reduced, the melting temperature of the raw material is lowered, and the energy required for melting the raw material is reduced. Therefore, the manufacturing cost of the optical glass can be reduced. Therefore, the content of the Ta ₂ O ₅ component is preferably 5.0% or less, more preferably less than 3.0%, still more preferably less than 1.0%, still more preferably less than 0.5%, still more preferably. It may be less than 0.1%. In particular, from the viewpoint of reducing the material cost, it is most preferable that the Ta ₂ O ₅ component is not contained.

The Bi ₂ O ₃ component is an optional component that can increase the refractive index and lower the glass transition point when it contains more than 0%.
On the other hand, by setting the content of the Bi ₂ O ₃ component to 10.0% or less, the liquidus temperature of the glass can be lowered and the devitrification resistance can be improved. Therefore, the content of the Bi ₂ O ₃ component may be 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%.

The TeO ₂ component is an optional component that can increase the refractive index and lower the glass transition point when the content exceeds 0%.
On the other hand, TeO ₂ has a problem that it can be alloyed with platinum when the glass raw material is melted in a platinum crucible or a melting tank in which a portion in contact with the molten glass is made of platinum. Therefore, the content of the TeO ₂ component may be 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%.

The SnO ₂ component is an optional component that can reduce the oxidation of the molten glass to make it clear and increase the visible light transmittance of the glass when it is contained in an amount of more than 0%.
On the other hand, by setting the content of the SnO ₂ component to 3.0% or less, it is possible to reduce the coloring of the glass and the devitrification of the glass due to the reduction of the molten glass. Further, since the alloying of the SnO ₂ component and the melting equipment (particularly noble metal such as Pt) is reduced, the life of the melting equipment can be extended. Therefore, the content of the SnO ₂ component may be preferably 3.0% or less, more preferably less than 1.0%, still more preferably less than 0.5%, still more preferably less than 0.1%.

The Sb ₂ O ₃ component is an optional component capable of defoaming 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, it is possible to suppress a decrease in transmittance in the short wavelength region of the visible light region, solarization of glass, and deterioration of internal quality. Therefore, the content of the Sb ₂ O ₃ component may be preferably 1.0% or less, more preferably less than 0.5%, and further preferably less than 0.2%.

The component that clarifies and defoams the glass is not limited to the above Sb ₂ O ₃ component, and a clarifying agent, a defoaming agent, or a combination thereof known in the field of glass production can be used.

The F component is an optional component capable of increasing the Abbe number of the glass, lowering the glass transition point, and improving the devitrification resistance when the content exceeds 0%.
However, when the content of the F component, that is, the total amount of fluoride substituted with a part or all of one or more oxides of each of the above-mentioned metal elements exceeds 10.0%, F Since the amount of volatilization of the components increases, it becomes difficult to obtain a stable optical constant, and it becomes difficult to obtain a uniform glass. In addition, the Abbe number rises more than necessary.
Therefore, the content of the F component may be 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%.

The sum (mass sum) of the contents of the RO component (R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba in the formula) is preferably 40.0% or more and 65.0% or less.
In particular, by setting the mass sum of the RO components to 40.0% or more, devitrification of the glass can be reduced and the temperature coefficient of the relative refractive index can be reduced. Therefore, the mass sum of the RO components is preferably 40.0% or more, more preferably more than 41.0%, still more preferably more than 42.0%, still more preferably more than 45.0%, still more preferably 48.0. %.
On the other hand, by setting the mass sum of the RO components to 65.0% or less, the decrease in the refractive index can be suppressed and the stability of the glass can be improved. Therefore, the mass sum of the RO components is preferably 65.0% or less, more preferably less than 60.0%, still more preferably less than 57.0%.

The sum (mass sum) of the RO component (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) and the content of the K2O component is 40.0% or _more 65. 0% or less is preferable.
In particular, by setting the mass sum of the mass sum (RO + K ₂ O) to 40.0% or more, the devitrification of the glass can be reduced and the temperature coefficient of the relative refractive index can be reduced. Therefore, the mass sum (RO + K ₂ O) is preferably 40.0% or more, more preferably more than 41.0%, still more preferably more than 42.0%, still more preferably more than 45.0%, still more preferably 48. It should be over 0.0%.
On the other hand, by setting the sum of mass (RO + K ₂ O) to 65.0% or less, the decrease in the refractive index can be suppressed and the stability of the glass can be improved. Therefore, the sum of mass (RO + K ₂ O) is preferably 65.0% or less, more preferably less than 60.0%, still more preferably less than 57.0%.

The total amount of the SiO ₂ component and B ₂ O ₃ is preferably 15.0% or more and 40.0% or less.
In particular, by setting the total amount to 15.0% or more, stable glass can be easily obtained. Therefore, the sum of mass (SiO ₂ + B ₂ O ₃ ) is preferably 15.0% or more, more preferably more than 18.0%, still more preferably more than 20.0%, still more preferably more than 23.0%, and further. It is preferably more than 25.0%.
On the other hand, by setting the total amount to 40.0% or less, the temperature coefficient of the relative refractive index can be reduced. Therefore, the sum of mass (SiO ₂ + B ₂ O ₃ ) is preferably 40.0% or less, more preferably less than 35.0%, still more preferably less than 33.0%, still more preferably less than 30.0%. ..

The total amount (mass sum) of the TiO ₂ component, the Nb ₂ O ₅ component, the WO ₃ component and the ZrO ₂ component is preferably 10.0% or less. As a result, the temperature coefficient of the relative refractive index can be reduced. Therefore, the mass sum of TiO ₂ + Nb ₂ O ₅ + WO ₃ + ZrO ₂ is preferably 10.0% or less, more preferably less than 7.0%, and further preferably 5.0% or less.

The ratio (mass ratio) of the total contents of the TiO ₂ component, the Nb ₂ O ₅ component, the WO ₃ component, the ZrO ₂ component and the ZnO component to the total content of the SiO ₂ component and the B ₂ O ₃ component is more than 0. It is preferable to have.
By increasing this ratio, the temperature coefficient of relative refractive index can be reduced. Therefore, the mass ratio (TiO ₂ + Nb ₂ O ₅ + WO ₃ + ZrO ₂ + ZnO) / (SiO ₂ + B ₂ O ₃ ) is preferably more than 0, more preferably more than 0.05, still more preferably more than 0.10. ..
On the other hand, this mass ratio may be preferably less than 0.50, more preferably less than 0.40, still more preferably less than 0.30, still more preferably less than 0.20, from the viewpoint of obtaining stable glass.

RO component (in the formula, R is Mg, Ca, Sr, R is Mg, Ca, Sr, with respect to the total content of TiO ₂ component, Nb ₂ O ₅ component, WO ₃ component, ZrO ₂ component, ZnO component, SiO ₂ component and B ₂ O ₃ component. The ratio (mass ratio) of the total content (mass ratio) of one or more selected from the group consisting of Ba) and the K2O component is preferably 1.00 or _more and 3.00 or less.
By increasing this ratio, the temperature coefficient of relative refractive index can be reduced. Therefore, the mass ratio (RO + K ₂ O) / (TiO ₂ + Nb ₂ O ₅ + WO ₃ + ZrO ₂ + ZnO + SiO ₂ + B ₂ O ₃ ) is preferably 1.00 or more, more preferably more than 1.10, and further preferably 1. It is more than 20, more preferably more than 1.30, still more preferably more than 1.40, still more preferably 1.53 or more.
On the other hand, this mass ratio may be preferably less than 3.00, more preferably less than 2.80, and even more preferably less than 2.50 from the viewpoint of obtaining stable glass.

The sum (mass sum) of the contents of the Rn ₂ O component (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 10.0% or less. As a result, it is possible to suppress a decrease in the viscosity of the molten glass, make it difficult to decrease the refractive index of the glass, and reduce devitrification of the glass. Therefore, the mass sum of the Rn ₂ O components is preferably 10.0% or less, more preferably less than 7.0%, still more preferably less than 4.0%, still more preferably less than 2.0%.

<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.

Other components can be added as needed within a range that does not impair the characteristics of the glass of the present invention. However, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb and Lu, is used alone. Alternatively, even if it is compounded and contained in a small amount, the glass is colored and has a property of causing absorption at a specific wavelength in the visible region. ..

Further, since lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components having a high environmental load, it is desirable that they are not substantially contained, that is, they are not contained at all except for unavoidable contamination.

Furthermore, each component of Th, Cd, Tl, Os, Be, and Se has tended to refrain from being used as a harmful chemical substance in recent years, and is used not only in the glass manufacturing process but also in the processing process and disposal after commercialization. Environmental measures are required up to this point. Therefore, when the environmental impact is emphasized, it is preferable that these are not substantially contained.

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, as a raw material for each of the above components, each component prescribes a high-purity raw material used for ordinary optical glass such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphate compounds. The mixture is uniformly mixed so as to be within the range of the content of the glass, and the prepared mixture is put into a platinum pit and melted in an electric furnace in a temperature range of 900 to 1500 ° C. for 2 to 5 hours depending on the difficulty of melting the glass raw material. It is produced by stirring and homogenizing it, lowering it to an appropriate temperature, casting it into a mold, and slowly cooling it.

Here, it is preferable that the optical glass of the present invention does not use sulfate as a raw material. As a result, defoaming from the glass raw material after melting is promoted, so that the residual bubbles in the optical glass can be suppressed.

<Physical characteristics>
The optical glass of the present invention has a high refractive index and a high Abbe number (low dispersion).
In particular, the refractive index ( _nd ) of the optical glass of the present invention is preferably 1.65, more preferably 1.67, and even more preferably 1.68 as the lower limit. The refractive index ( _nd ) may be preferably 2.00, more preferably 1.90, more preferably 1.80, and more preferably 1.75 as the upper limit. Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 40, more preferably 45, still more preferably 47, still more preferably 49 as the lower limit. The Abbe number (ν _d ) may be preferably 62, more preferably 60, still more preferably 57, still more preferably 55, still more preferably 53.
By having such a high refractive index, a large amount of refraction of light can be obtained even if the optical element is made thinner. Further, by having such a low dispersion, it is possible to reduce the focus shift (chromatic aberration) due to the wavelength of light when used as a single lens. Therefore, for example, when an optical system is configured in combination with an optical element having a high dispersion (low Abbe number), aberrations can be reduced as a whole of the optical system to achieve high imaging characteristics and the like.
As described above, the optical glass of the present invention is useful for optical design, and particularly when the optical system is configured, the optical system can be miniaturized while achieving high imaging characteristics and the like, and the optical design can be achieved. The degree of freedom can be expanded.

The optical glass of the present invention has a low temperature coefficient (dn / dT) of the relative refractive index.
More specifically, the temperature coefficient of the relative refractive index of the optical glass of the present invention is preferably +2.0 × 10 ^-6 ° C ^-1 , more preferably +1.0 × ^10-6 ° C ^-1 , and even more preferably. The upper limit is 0, more preferably −1.0 × ^10-6 ° C ^-1 , and a value lower than this upper limit (minus side) can be taken.
On the other hand, the temperature coefficient of the relative refractive index of the optical glass of the present invention is preferably -10.0 × 10 ^-6 ° C ^-1 , more preferably −8.0 × 10 ^-6 ° C ^-1 , and even more preferably −. 5.0 × 10 ^-6 ° C ^-1 is set as the lower limit value, more preferably −3.0 × 10 ^-6 ° C ^-1 , and a value higher than this lower limit value (plus side) can be taken.
Of these, little is known about glass having a negative temperature coefficient of relative refractive index, and the options for correction such as image shift due to temperature changes can be expanded. Further, glass having a small absolute value of the temperature coefficient of the relative refractive index can more easily correct the deviation of the image formation due to the temperature change. Therefore, by setting the temperature coefficient of the relative refractive index in such a range, it is possible to contribute to the correction of the deviation of the image formation due to the temperature change.
The temperature coefficient of the relative refractive index of the optical glass of the present invention is the temperature coefficient of the refractive index for light having a wavelength of 589.29 nm in the air having the same temperature as the optical glass, and the temperature is changed from 40 ° C to 60 ° C. It is expressed as the amount of change per 1 ° C (° C ^-1 ) when changed.

[Preforms and optical elements]
From the produced optical glass, a glass molded body can be produced by using, for example, a means for polishing or a means for mold press molding such as reheat press molding or precision press molding. That is, a glass molded body is produced by machining optical glass such as grinding and polishing, or a preform for mold press molding is produced from optical glass, and reheat press molding is performed on this preform. After that, a glass molded body is produced by polishing, a preform produced by polishing, or a preform formed by a known levitation molding or the like is subjected to precision press molding to produce a glass molded body. Can be made. 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, precision press molding, or the like using this preform to manufacture an optical element such as a lens or a prism. This makes it possible to form a preform having a large diameter, so that it is possible to realize high-definition and high-precision imaging characteristics and projection characteristics when used in an optical instrument while increasing the size of the 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, mirrors, etc., and is typically susceptible to high temperatures in in-vehicle optical devices, projectors, copying machines, etc. It can be used for equipment.

Results of the compositions of Examples (No. 1 to No. 53) of the present invention, and the temperature coefficients (dn / dT) of the refractive index ( _{nd), Abbe number (ν d )} and relative refractive index of these glasses. Are shown in Tables 1 to 8. The following examples are for illustrative purposes only, and are not limited to these examples.

The glass of the embodiment of the present invention is used for ordinary optical glass such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphate compounds corresponding to each as a raw material of each component. Select high-purity raw materials, weigh them so that they have the composition ratio of each example shown in the table, mix them uniformly, put them in a platinum crucible, and use an electric furnace according to the difficulty of melting the glass raw materials. After melting in a temperature range of 900 to 1500 ° C. for 2 to 5 hours, the mixture was stirred and homogenized, cast into a mold or the like, and slowly cooled to prepare the product.

The refractive index (nd _{) and Abbe number (ν d )} of the glass of the examples were measured based on the Japan Optical Glass Industry Association standard JOBIS01-2003. The glass used for this measurement was treated in a slow cooling furnace at a slow cooling rate of -25 ° C / hr.

The temperature coefficient (dn / dT) of the relative refractive index of the glass of the example is determined by the interference method among the methods described in the Japan Optical Glass Industry Association standard JOGIS18-1994 "Measuring method of the temperature coefficient of the refractive index of optical glass". , The value of the temperature coefficient of the relative refractive index when the temperature was changed from 40 ° C. to 60 ° C. for light having a wavelength of 589.29 nm was measured.

As shown in the table, all of the optical glasses of the examples have a temperature coefficient of relative refractive index in the range of +2.0 × ^10-6 to -10.0 × ^10-6 (° C ^-1 ). In detail, it was in the range of 0 × 10 ^-6 to −3.0 × 10 ^-6 (° C ^-1 ), which was within the desired range. On the other hand, the temperature coefficient of the relative refractive index of all the glasses of the comparative example exceeded +2.0 × ^10-6 . Therefore, it can be seen that the optical glass of the example has a lower temperature coefficient of relative refractive index (value closer to minus) than the glass of the comparative example.

Further, all of the optical glasses of the examples had a refractive index ( _nd ) of 1.65 or more, more specifically 1.68 or more, which were within a desired range. Further, all of the optical glasses of the examples of the present invention had an Abbe number (ν _d ) in the range of 40 or more and 62 or less, and more specifically, in the range of 44 or more and 54 or less, which was within a desired range. ..

Further, the optical glass of the example formed stable glass, and devitrification was unlikely to occur at the time of glass production.

Therefore, it was clarified that the optical glass of the example had a refractive index ( _{nd) and an Abbe number (ν d )} within desired ranges, and had a low temperature coefficient of relative refractive index. For this reason, the optical glass of the embodiment of the present invention contributes to the miniaturization of optical systems such as in-vehicle optical devices and projectors used in a high temperature environment, and also to correct deviations in imaging characteristics due to temperature changes. It is inferred that it will contribute.

Further, using the optical glass of the embodiment of the present invention, a glass block was formed, and the glass block was ground and polished to be processed into the shape of a lens and a prism. As a result, it was possible to stably process 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 idea and scope of the present invention. Will be understood.

Claims (5)

By mass%,
SiO ₂ component is more than 10.0% and less than 27.0%,
B ₂ O ₃ component more than 0% and less than 20.0%,
BaO component is more than 45.0% and less than 63.0%,
Contains,
It contains a total of 10.0% or more and less than 25.0% of Ln ₂ O ₃ components (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb).
The total amount of SiO ₂ component and B ₂ O ₃ is 15.0% or more and 30.0% or less,
The total amount (mass sum) of TiO ₂ component, Nb ₂ O ₅ component, WO ₃ component and ZrO ₂ component is 5.0% or less.
And
MgO component 0-5.0%
CaO component 0 to 10.0%
SrO component 0 to 10.0%
K ₂ O component 0 to 10.0%
TiO ₂ component 0-less than 5.0%
Nb ₂ O ₅ component 0-less than 5.0%
WO ₃ component 0-less than 5.0%
ZrO ₂ component 0-less than 5.0%
ZnO component 0 to 10.0%
La ₂ O ₃ component 0 to less than 23.0%
Gd ₂ O ₃ component 0-20.0%
Y ₂ O ₃ component 0-20.0%
Yb ₂ O ₃ component 0 to 10.0%
Li ₂ O component 0-3.0%
Na ₂ O component 0-5.0%
Al ₂ O ₃ component 0 to 15.0%
Ga ₂ O ₃ component 0 to 10.0%
P ₂ O ₅ component 0 to 10.0%
GeO ₂ component 0 to 10.0%
Ta ₂ O ₅ component 0-5.0%
Bi ₂ O ₃ component 0 to 10.0%
TeO ₂ component 0 to 10.0%
SnO ₂ component 0-3.0%
Sb ₂ O ₃ component 0-1.0%
And
The content of fluoride as F, which is substituted with a part or all of one or more oxides of each of the above elements, is 0 to 10.0% by mass.
It has a refractive index (nd) of 1.65 or more, and has an Abbe number (ν _d ) of 40 or more and 62 or less _.
An optical glass having a relative refractive index (589.29 nm) with a temperature coefficient (40-60 ° C.) in the range of +2.0 × ^10-6 to -10.0 × ^10-6 (° C ^-1 ). The optical glass according to claim 1 , wherein the sum of mass (RO + K ₂ O) is 40.0% or more and 65.0% or less (in the formula, R is one selected from the group consisting of Mg, Ca, Sr, and Ba). that's all). The optical glass according to any one of claims 1 or 2 , wherein the mass ratio (RO + K ₂ O) / (TiO ₂ + Nb ₂ O ₅ + WO ₃ + ZrO ₂ + ZnO + SiO ₂ + B ₂ O ₃ ) is 1.00 or more and 3.00 or less. In the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba). An optical element made of the optical glass according to any one of claims 1 to 3 . An optical device comprising the optical element according to claim 4 .