JP7410634B2 - Optical glass, preforms and optical elements - Google Patents

Description

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

In recent years, the digitalization of devices that use optical systems and the increase in the definition of images and videos have progressed rapidly. In particular, the increase in the definition of images and videos is noticeable in optical devices such as digital cameras, video cameras, and projectors. At the same time, the optical systems built into these optical devices are being made lighter and smaller by reducing the number of optical elements such as lenses and prisms.

Among the optical glasses used to make optical elements, glass with a high refractive index (n _d ) of 1.90 or more and a low Abbe's index of 15 or more and 30 or less, which can reduce the weight and size of the entire optical system, is particularly preferred. The demand for high refractive index, high dispersion glass having a high refractive index (v _d ) is increasing significantly. As such a high refractive index low dispersion glass, a glass composition typified by Patent Document 1 is known.

Japanese Patent Application Publication No. 2011-178571

However, the glass described in Patent Document 1 has a high refractive index and high dispersion, so it contains many components with high material unit costs, such as GeO ₂ components, Nb ₂ O ₅ components, and Ta ₂ O ₅ components, and the production cost is high. The problem was that it was expensive. Therefore, there has been a demand for an optical glass that has a high refractive index and high dispersion, has a short wavelength (λ ₅ ) at which the spectral transmittance is 5%, and is inexpensive to produce.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide an optical system that has a short wavelength (λ ₅ ) exhibiting a high refractive index and spectral transmittance of 5%, and is inexpensive to produce. An object of the present invention is to provide glass, a preform using the glass, and an optical element.

In order to solve the above-mentioned problems, the present inventors have carried out extensive research and testing, and found that while using the La ₂ O ₃ components, TiO ₂ components, and BaO components together, the SiO ₂ components and the B ₂ O ₃ components were combined. By adjusting the total amount and the mass ratio of TiO ₂ /(TiO ₂ +BaO), it is possible to obtain the desired high refractive index and high dispersion, while suppressing production costs, and at the same time achieving a wavelength at which the spectral transmittance is 5%. (λ ₅ ) was found to be shorter, and the present invention was completed.
Specifically, the present invention provides the following.

(1) Mass% based on oxide,
La ₂ O ₃ components more than 0% to 45.0%,
_TiO component more than 0% to 45.0% and BaO component more than 0% to 40.0%
Contains
The total amount of SiO ₂ components and B ₂ O ₃ components 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 a refractive index (nd) of 1.90 or more, an Abbe number (ν _d ) of 30.0 or less, and a wavelength (λ ₅ ) at which spectral transmittance is 5% of 400 nm or less.

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

(3) Mass% based on oxide,
ZnO component 0-20.0%,
Y ₂ O ₃ components 0-15.0%,
Nb ₂ O ₅ components 0 to 25.0%,
Yb ₂ O ₃ components 0 to 15.0%, and Gd ₂ O ₃ components 0 to 15.0%
The optical glass according to (1) or (2).

(4) Mass% based on oxide,
The optical glass according to any one of (1) to (3), wherein the sum of the masses of (La ₂ O ₃ +Nb ₂ O ₅ +Gd ₂ O ₃ +Yb ₂ O ₃ ) is more than 0% and 60.0% or less.

(5) Mass% based on oxide,
(1) to (4), in which the total of the _three Ln ₂ O components (in the formula, 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; Any of the optical glasses described above.

(6) The optical glass according to any one of (1) to (5), wherein TiO ₂ /BaO is greater than 0 and less than 3.00 on an oxide basis.

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

(8) Mass% based on oxide,
(1) to (7), wherein the mass sum of the RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, and Zn) is more than 0% and 35.0% or less; Optical glass as described in any of the above.

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

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

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

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

According to the present invention, an optical glass that has a high refractive index and high dispersion, has a short wavelength (λ ₅ ) showing a spectral transmittance of 5%, and has a low production cost, and a preform and an optical glass using the same. We can provide elements.

FIG. 3 is a diagram showing a normal line in which the partial dispersion ratio (θg, F) is expressed on the vertical axis and the Abbe number (ν _d ) is expressed on the orthogonal coordinates on the horizontal axis. FIG. 3 is a diagram showing the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) for the glass of the example of the present application.

The optical glass of the present invention contains La ₂ O ₃ components in an amount of over 0% to 45.0%, TiO ₂ components in an amount of over 0% to 45.0%, and BaO component in an amount of over 0% to 40.0% by mass. %, 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 The refractive index (nd) is 1.90 or more, the Abbe number (νd) is 30.0 or less, and the wavelength (λ ₅ ) at which the spectral transmittance is 5% is 400 nm or less.
According to the present invention, a high refractive index and high dispersion can be achieved in the glass by using _three La ₂ O components, _two TiO components, and a BaO component in combination and adjusting the content of each component. The stability of the glass is increased. For this reason, we are developing an optical glass that has a high refractive index and high dispersion, has a short wavelength (λ ₅ ) showing a spectral transmittance of 5%, and is low in production cost, as well as preforms and optical elements using this glass. Can be provided.

[Glass component]
The composition range of each component constituting the optical glass of the present invention will be described below. In this specification, unless otherwise specified, the content of each component is expressed in mass % based on the total mass of the glass on an oxide basis. Here, the "oxide standard" refers to the oxides, composite salts, metal fluorides, etc. used as raw materials for the glass components of the present invention, assuming that they are all decomposed and converted into oxides when melted. The composition shows each component contained in the glass, with the total mass of oxides being 100% by mass.

<About essential ingredients and optional ingredients>
The La ₂ O ₃ component is a component that increases the refractive index of glass and reduces dispersion. In particular, by containing more than 0% of the La ₂ O ₃ component, it is an essential component that can obtain a desired high refractive index. Therefore, the content of _{the three} La ₂ O components is preferably more than 0%, more preferably 3.0%, even more preferably 15.0%, even more preferably 20.0%, even more preferably 25.0%, More preferably, the lower limit is 27.0%.
On the other hand, by setting the content of the La ₂ O ₃ component to 45.0% or less, the devitrification resistance of the glass can be improved, an increase in the specific gravity of the glass can be suppressed, and the production cost can be lowered. Therefore, the upper limit of the content of the _three La ₂ O components is preferably 45.0%, more preferably 40.0%, still more preferably 38.0%, and still more preferably 37.0%.
For the La ₂ O ₃ component, La ₂ O ₃ , La(NO ₃ ) _{3.XH 2} O (X is any integer), etc. can be used as a raw material.

The TiO ₂ component is an essential component that, when contained in an amount exceeding 0%, can increase the refractive index of the glass, adjust the Abbe number to a low value, increase the partial dispersion ratio, and improve the devitrification resistance. Therefore, the content of the _two TiO components is preferably more than 0%, preferably more than 5.0%, more preferably more than 10.0%, even more preferably 15.0%, still more preferably 18.0%, even more preferably The lower limit is more than 20.0%.
On the other hand, by setting the content of the TiO ₂ component to 45.0% or less, coloring of the glass can be reduced and visible light transmittance can be increased. Furthermore, devitrification due to excessive inclusion of _two TiO components can be suppressed. Therefore, the content of _{the two} TiO components is preferably 45.0%, more preferably 38.0%, even more preferably 32.0%, even more preferably 27.0%, and even more preferably 25.0%. shall be.
For the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

The BaO component is an essential component that, when contained in an amount exceeding 0%, can improve the refractive index and devitrification resistance of the glass, as well as the meltability of the glass raw material. Therefore, the lower limit of the BaO component content is preferably more than 0%, more preferably 5.0%, even more preferably 8.0%, and even more preferably 10.0%.
On the other hand, by setting the content of the BaO component to 40.0% or less, the refractive index of the glass can be made difficult to decrease and devitrification of the glass can be reduced. Therefore, the upper limit of the BaO component content is preferably 40.0%, more preferably 35.0%, still more preferably 28.0%, even more preferably 23.0%, and even more preferably 20.0%. do.
For the BaO component, BaCO ₃ , Ba(NO ₃ ) ₂ , etc. can be used as a raw material.

The sum of the contents (mass sum) of the _three B ₂ O components and the _two SiO components is preferably 5.0% or more and 30.0% or less.
In particular, by setting this sum to 5.0% or more, it is possible to suppress a decrease in devitrification resistance due to the deficiency of the B ₂ O ₃ component and the SiO ₂ component. Therefore, the lower limit of the mass sum (B ₂ O ₃ +SiO ₂ ) is preferably 5.0%, more preferably 7.0%, and even more preferably 9.0%.
On the other hand, by setting this sum to 30.0% or less, a decrease in the refractive index due to excessive inclusion of these components can be suppressed, making it easier to obtain a desired high refractive index. Therefore, the upper limit of the mass sum (B ₂ O ₃ +SiO ₂ ) is preferably 30.0%, more preferably 23.0%, even more preferably 18.0%, and even more preferably 16.50%.

Here, the ratio (mass ratio) of the content of the _two TiO components to the sum of the contents of the _two TiO components and the BaO component is preferably 0.1 or more. Thereby, a high partial dispersion ratio can be obtained while maintaining a high refractive index and high dispersion. Therefore, the lower limit of the mass ratio TiO ₂ /(TiO ₂ +BaO) is preferably 0.10, more preferably 0.30, even more preferably 0.40, and still more preferably 0.45.
On the other hand, by setting this mass ratio to 0.90 or less, coloring of the glass can be reduced, 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, still more preferably 0.73, and even more preferably 0.68.

The SiO ₂ component is an optional component that can improve devitrification resistance when contained in an amount exceeding 0%. Therefore, the lower limit of the content of the two SiO ₂ components is preferably more than 0%, more preferably more than 0.5%, even more preferably more than 1.0%, and 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 into the molten glass, and melting at high temperatures can be avoided. The upper limit of the content of the _two SiO components is preferably 30.0%, more preferably 23.0%, even more preferably 16.0%, even more preferably 11.0%, and even more preferably 9.0%. .
For the SiO ₂ component, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ , etc. can be used as a raw material.

The B ₂ O ₃ component is an optional component that, when contained in an amount exceeding 0%, forms a network structure inside the glass, promotes stable glass formation, and improves devitrification resistance. Therefore, the lower limit of the content of the _three B ₂ O components is preferably more than 0%, more preferably more than 0.5%, even more preferably more than 1.0%, and still more preferably more than 2.0%.
On the other hand, by setting the content of the _three B ₂ O components to 30.0% or less, it is possible to suppress a decrease in the refractive index, reduce the Abbe number, and suppress deterioration of chemical durability. Therefore, the content of the _three B ₂ O components is preferably 30.0% or less, more preferably 20.0%, even more preferably less than 15.0%, even more preferably 12.0%, even more preferably 10.0%. The upper limit is less than 0%.
For the _{three B2O} components, _H3BO3 , _Na2B4O7 , _{Na2B4O7.10H2O} , _{BPO4 , etc.} can _be used as _{raw materials .}

The ZnO component is an optional component that can improve the meltability of glass, lower the glass transition point, and reduce devitrification when contained in an amount exceeding 0%. Therefore, the lower limit of the content of the ZnO component is preferably more than 0%, more preferably more than 0.5%, still more preferably more than 1.0%, and even more preferably more than 1.5%.
On the other hand, by controlling the content of the ZnO component to 20.0% or less, a decrease in refractive index and devitrification can be reduced. Moreover, since the viscosity of the molten glass is increased thereby, the occurrence of striae in the glass can be reduced. Therefore, the upper limit of the content of the ZnO component is preferably 20.0%, more preferably 15.0%, even more preferably 11.0%, and even more preferably 8.0%.
For the ZnO component, ZnO, _ZnF2 , etc. can be used as a raw material.

The Y ₂ O ₃ component is an optional component that can suppress an increase in glass material cost when contained in an amount exceeding 0%.
By controlling the content of the _three Y ₂ O components to 15.0% or less, it is possible to suppress a decrease in the refractive index of the glass, reduce the Abbe number, and improve the devitrification resistance of the glass. Therefore, the upper limit of the content of the _three Y ₂ O components is preferably 15.0%, more preferably 10.0%, and even more preferably 5.0%.
For the _{three Y2O} components, _Y2O3 , _{YF3 ,} etc. can be used as raw materials.

The Nb ₂ O ₅ component is an optional component that, when contained in an amount exceeding 0%, can increase the refractive index of the glass and improve the devitrification resistance. Therefore, the lower limit of the content of the Nb ₂ O ₅ component is preferably more than 0%, more preferably 2.0%, and still more preferably 4.0%.
On the other hand, by reducing the content of the Nb ₂ O ₅ component to 25.0% or less, the decrease in devitrification resistance of the glass and the decrease in visible light transmittance due to excessive content of the Nb ₂ O ₅ component can be prevented. It is possible to suppress the increase in the glass material cost. Therefore, the upper limit of the content of the Nb ₂ O ₅ component is preferably 25.0%, more preferably 20.0%, even more preferably 16.0%, and even more preferably 13.0%.
For 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 glass when contained in an amount exceeding 0%.
On the other hand, by controlling the content of the Yb ₂ O ₃ component to 15.0% or less, the devitrification resistance of the glass can be improved and the Abbe number can be reduced. Therefore, the upper limit of the content of the _three Yb ₂ O components is preferably 15.0%, more preferably 10.0%, and even more preferably 5.0%.
For 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 the Abbe number when contained in an amount exceeding 0%.
On the other hand, by reducing the Gd ₂ O ₃ component, which is particularly expensive among 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 prevent the Abbe number of the glass from increasing more than necessary. Therefore, the upper limit of the content of the _three Gd ₂ O components is preferably 15.0%, more preferably 10.0%, and even more preferably 5.0%.
For the Gd ₂ O ₃ component, Gd ₂ O ₃ , GdF ₃ , etc. can be used as a raw material.

In addition, in the optical glass of the present invention, the sum of the contents (sum of mass) of ₃ components of La ₂ O, ₅ components of Nb ₂ O, ₃ components of Gd ₂ O, and Yb ₂ O ₃ should be 60.0% or less. is preferred. As a result, the content of these expensive components is reduced, so that the cost of glass materials can be suppressed and the Abbe number can be reduced. Therefore, the mass sum (La ₂ O ₃ + Nb ₂ O ₅ + Gd ₂ O ₃ + Yb ₂ O ₃ ) is preferably 60.0%, more preferably 57.0%, still more preferably 53.0%, even more preferably 49 The upper limit is .0%, more preferably 47.0%.
On the other hand, by containing more than 0%, a desired high refractive index can be obtained. Therefore, the lower limit is preferably more than 0%, more preferably 10.0%, still more preferably 20.0%, even more preferably 25.0%, even more preferably 30.0%, and even more preferably 35.0%. .

The sum of the contents (sum of mass) of the _three Ln ₂ O components (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is more than 0% to 50.0%. .
In particular, by making this mass sum more than 0%, the refractive index of the glass can be increased, making it easier to obtain high refractive index glass. Moreover, coloring can be reduced thereby. Therefore, the lower limit of the mass sum of the contents of the _three Ln ₂ O components is preferably more than 0%, more preferably 1.0%, even more preferably 3.0%, and even more preferably 5.0%.
On the other hand, by setting this mass sum to 50.0% or less, devitrification resistance can be improved and the Abbe number can be reduced. Therefore, the upper limit of the mass sum of the contents of the _three Ln ₂ O components is preferably 50.0%, more preferably less than 40.0%, even more preferably 30.0%, and still more preferably 25.0%. .

Here, the ratio (mass ratio) of the content of the _two TiO components to the sum of the contents of _the three components La ₂ O, the ₅ Nb ₂ O components, the ₃ Gd ₂ O components, and the Yb ₂ O ₃ is greater than 0. It is preferable. Thereby, a high partial dispersion ratio can be obtained while maintaining a high refractive index and high dispersion, and production costs can be reduced. Therefore, the mass ratio TiO ₂ /(La ₂ O ₃ +Nb ₂ O ₅ +Gd ₂ O ₃ +Yb ₂ O ₃ ) is preferably greater than 0, more preferably 0.10, still more preferably 0.20, even more preferably 0. The lower limit is .40.
On the other hand, by setting this mass ratio to 2.00 or less, coloring of the glass can be reduced, 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 2.00, more preferably 1.00, still more preferably 0.80, even more preferably The upper limit is 0.66.

Here, the ratio (mass ratio) of the content of the _two TiO components to the content of the BaO component is preferably greater than zero. Thereby, a high partial dispersion ratio can be obtained while maintaining a high refractive index and high dispersion. The lower limit of the mass ratio TiO ₂ /BaO is preferably greater than 0, more preferably 0.10, still more preferably 0.40, and even more preferably 0.60.
On the other hand, by setting this mass ratio to 3.00 or less, coloring of the glass can be reduced, visible light transmittance can be increased, and devitrification can be suppressed. Therefore, the upper limit of the mass ratio TiO ₂ /BaO is preferably 3.00, more preferably 2.00, and even more preferably 1.60.

Here, the ratio (mass ratio) of the sum of the contents of the _two TiO components and the _three components of WO to the sum of the contents of the BaO components is preferably greater than zero. Thereby, a high partial dispersion ratio can be obtained while maintaining a high refractive index and high dispersion, and devitrification resistance can be improved. Therefore, the lower limit of the mass ratio (TiO ₂ +WO ₃ )/BaO is preferably more than 0, more preferably 0.30, even more preferably 0.60, even more preferably 0.80, and still more preferably 1.00. .
On the other hand, by setting this mass ratio to 3.00 or less, coloring of the glass can be reduced, visible light transmittance can be increased, and devitrification can be suppressed. Therefore, the upper limit of the mass ratio (TiO ₂ +WO ₃ )/BaO is preferably 3.00, more preferably 2.50, and even more preferably 1.90.

The sum of the contents (mass sum) of the _two TiO components and the _five Nb ₂ O components is preferably more than 0%. Thereby, the refractive index and dispersion can be increased, and the devitrification resistance can be improved. Therefore, the mass sum (TiO ₂ +Nb ₂ O ₅ ) is preferably more than 0%, more preferably more than 10.0%, even more preferably more than 15.0%, even more preferably more than 20.0%, even more preferably 25%. The lower limit is more than .0%.
On the other hand, by containing 60.0% or less, coloring of the glass can be reduced, visible light transmittance can be increased, and devitrification can be suppressed. Therefore, the upper limit is preferably 60.0%, more preferably 50.0%, still more preferably 45.0%, even more preferably 40.0%, even more preferably 35.0%, and even more preferably 33.0%. shall be.

The total amount of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) is preferably 15.0% or less. This suppresses a decrease in the refractive index of the glass and improves devitrification resistance. Therefore, the upper limit of the sum of the Rn ₂ O components is preferably 15.0%, more preferably 10.0%, still more preferably less than 5.0%, and still more preferably less than 1.0%.

The sum of the contents (sum of mass) of the RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 35.0% or less. Thereby, devitrification due to excessive inclusion of the RO component can be reduced, and a decrease in the refractive index can be suppressed. Therefore, the mass sum of the contents of the RO components is preferably 35.0%, more preferably 30.0%, even more preferably 27.0%, even more preferably less than 23.0%, even more preferably 20.0%. The upper limit is %.
On the other hand, by making this sum more than 0%, the meltability of the glass raw materials and the stability of the glass can be improved. Therefore, the lower limit of the total content of RO components is preferably more than 0%, more preferably 4.0%, even more preferably 7.0%, and still more preferably more than 9.0%.

When the ZrO ₂ component is contained in an amount exceeding 0%, it can contribute to increasing the refractive index and lowering the dispersion of the glass, and can improve the devitrification resistance of the glass. Therefore, the lower limit of the content of the _two ZrO components is preferably more than 0%, more preferably 0.5%, and even more preferably 1.0%.
On the other hand, by controlling the ZrO ₂ component to 20.0% or less, it is possible to suppress a decrease in the devitrification resistance of the glass and an unnecessary increase in the Abbe number due to excessive inclusion of the ZrO ₂ component. Therefore, the content of _{the two} ZrO components is preferably 20.0%, more preferably 16.0%, even more preferably 12.0%, even more preferably 9.0%, and even more preferably less than 6.5%. Upper limit.
For the ZrO ₂ component, ZrO ₂ , ZrF ₄ , etc. can be used as a raw material.

The WO ₃ component is an optional component that, when contained in an amount exceeding 0%, can increase the refractive index while reducing the coloring of the glass caused by other high refractive index components, increase the partial dispersion ratio, and increase the devitrification resistance of the glass. It is. Further, the WO ₃ component is also a component that can lower the glass transition point. Therefore, the lower limit of the content of the _three WO components is preferably more than 0%, more preferably 0.1%, even more preferably 0.2%, and still more preferably 0.3%.
On the other hand, by controlling the content of the WO ₃ components to 10.0% or less, it is possible to reduce the coloring of the glass due to the WO ₃ components and increase the visible light transmittance. Therefore, the upper limit of the content of the _three WO components is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%.
For 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, when contained in an amount exceeding 0%, can increase the refractive index of the glass and improve the devitrification resistance.
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. In addition, by reducing the content of the Ta ₂ O ₅ component to 10.0% or less, the melting temperature of the raw material is lowered and the energy required to melt the raw material is reduced, so the manufacturing cost of optical glass can also be reduced. . Therefore, the upper limit of the content of the _five Ta ₂ O components is preferably 10.0%, more preferably 8.0%, and still more preferably 5.0%. In particular, from the viewpoint of producing cheaper optical glass, the content of the _five Ta ₂ O components is preferably 4.0%, more preferably 3.0%, and even more preferably less than 1.0%. Most preferably, it does not contain.
For 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 improve 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 controlling 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 upper limit of the content of the MgO component is preferably 15.0%, more preferably 10.0%, and even more preferably 5.0%.
For the MgO component, MgCO ₃ , MgF ₂ , etc. can be used as a raw material.

The CaO component is an optional component that, when contained in an amount exceeding 0%, can improve the refractive index and devitrification resistance of the glass, as well as the meltability of the glass raw material. Therefore, the lower limit of the content of the CaO component is preferably more than 0%, more preferably 0.5%, even more preferably 1.5%, and still more preferably 3.0%.
On the other hand, by setting the content of the CaO component to 15.0% or less, the refractive index of the glass can be made difficult to decrease and devitrification of the glass can be reduced. Therefore, the upper limit of the content of the CaO component is preferably 15.0%, more preferably 10.0%, and even more preferably 5.0%.
For the CaO component, CaCO ₃ , CaF ₂ , etc. can be used as a raw material.

The SrO component is an optional component that, when contained in an amount exceeding 0%, can improve the refractive index and devitrification resistance of the glass, as well as the meltability of the glass raw material. Therefore, the lower limit of the content of the SrO component is preferably more than 0%, more preferably 0.5%, even more preferably 1.5%, and still more preferably 3.0%.
On the other hand, by setting the content of the SrO component to 15.0% or less, the refractive index of the glass can be made difficult to decrease and devitrification of the glass can be reduced. Therefore, the upper limit of the content of the SrO component is preferably 15.0%, more preferably 10.0%, and even more preferably 5.0%.
For the SrO component, SrCO ₃ , SrF ₂ , etc. can be used as a raw material.

The Li ₂ O component, the Na ₂ O component, and the K ₂ O component are optional components that can improve the meltability of glass when at least one of them is contained in an amount exceeding 0%. In particular, the K ₂ O component is also 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, Na ₂ O component, or K ₂ O component, it is possible to suppress a decrease in the refractive index of the glass and to reduce devitrification. In particular, by reducing the content of the Li ₂ O component, it is possible to suppress a decrease in the partial dispersion ratio of the glass. Therefore, the content of at least one of the Li ₂ O component, Na ₂ O component, and K ₂ O component is preferably 15.0%, more preferably less than 10.0%, and even more preferably less than 5.0%. The upper limit is more preferably less than 1.0%.
_Li2O component, _Na2O component, and _K2O component _{are Li2CO3} , _{LiNO3 ,} LiF, _Na2CO3 , _{NaNO3 ,} NaF, _Na2SiF6 , _K2CO3 , _KNO3 as raw materials _. , KF, _KHF2 , _K2SiF6 , _etc. can be used.

The P ₂ O ₅ component is an optional component that can improve the devitrification resistance of the glass when it is contained in an amount exceeding 0%. In particular, by controlling the content of the P ₂ O ₅ component to 10.0% or less, it is possible to suppress a decrease in the chemical durability of the glass, especially the water resistance. Therefore, the upper limit of the content of the P ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%.
For _{the P2O5} component, Al( _PO3 ) ₃ , Ca( _PO3 ) ₂ , Ba( _PO3 ) ₂ , _BPO4 , _{H3PO4 ,} etc. can be used as raw materials.

The GeO ₂ component is an optional component that can increase the refractive index of the glass and improve the devitrification resistance when it is contained in an amount exceeding 0%. However, since the raw material price of GeO ₂ is high, if the amount thereof is large, the material cost increases, and the cost reduction effect by reducing the Gd ₂ O ₃ component and the Ta ₂ O ₅ component is canceled out. Therefore, the content of _{the two} GeO components is preferably 10.0%, more preferably 5.0%, still more preferably 1.0%, and most preferably not contained.
For 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, when contained in an amount exceeding 0%, can improve the chemical durability of the glass and the devitrification resistance of the glass.
On the other hand, by controlling the content of each of the _three Al ₂ O components and the _three Ga ₂ O components to 15.0% or less, it is possible to suppress a decrease in the devitrification resistance of the glass due to their excessive content. Therefore, the upper limit of the content of each of the _three Al ₂ O components and the _three Ga ₂ O components is preferably 15.0%, more preferably 8.0%, and even more preferably 3.0%.
For the Al ₂ O ₃ component and the Ga ₂ O ₃ component, materials such as Al ₂ O ₃ , Al(OH) ₃ , AlF ₃ , Ga ₂ O ₃ , and Ga(OH) ₃ can be used.

The Bi ₂ O ₃ component is an optional component that can increase the refractive index and lower the glass transition point when contained in an amount exceeding 0%.
On the other hand, by controlling the content of the _three Bi ₂ O components to 10.0% or less, the devitrification resistance of the glass can be improved, and the coloring of the glass can be reduced and the visible light transmittance can be increased. Therefore, the upper limit of the content of the _three Bi ₂ O components is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%.
For the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

The _TeO2 component is an optional component that can increase the refractive index and lower the glass transition point when contained in an amount exceeding 0%.
However, TeO ₂ has the problem of being alloyed with platinum when a glass raw material is melted in a platinum crucible or a melting tank in which the portion in contact with molten glass is made of platinum. Therefore, the content of _{the two} TeO components is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, and even more preferably not contained.
For the TeO ₂ component, TeO ₂ or the like can be used as a raw material.

The SnO ₂ component is an optional component that, when contained in an amount exceeding 0%, can reduce oxidation of the molten glass, clarify the molten glass, and make it difficult to 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, coloring of the glass due to reduction of the molten glass and devitrification of the glass can be made less likely to occur. Furthermore, since alloying between the SnO ₂ components and the melting equipment (particularly noble metals 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%, even more preferably less than 1.0%, and still more preferably not contained.
For the _SnO2 component, SnO, _SnO2 , _SnF2 , _SnF4 , etc. can be used as raw materials.

The Sb ₂ O ₃ component is an optional component capable of defoaming the molten glass when contained in an amount exceeding 0%. On the other hand, by controlling the content of the Sb ₂ O ₃ components to 1.0% or less, excessive foaming can be prevented and alloying with melting equipment (especially noble metals such as Pt) can be reduced. Therefore, the content of the _three Sb ₂ O components is preferably 1.0% or less, more preferably less than 0.5%, still more preferably less than 0.3%, even more preferably less than 0.1%.
For the _three Sb ₂ O components, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O _{7.5H 2} O, etc. can be used as raw materials.

Note that the component for clarifying and defoaming the glass is not limited to the above-mentioned _three Sb ₂ O components, and a known clarifying agent, defoaming agent, or a combination thereof in the field of glass manufacturing can be used.

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 contained in an amount exceeding 0%.
However, if the content of the F component, that is, the total amount of fluoride substituted for part or all of the oxides of one or more of the above-mentioned metal elements as F exceeds 10.0%, Since the amount of component volatilization increases, it becomes difficult to obtain stable optical constants and it becomes difficult to obtain homogeneous glass. Moreover, the Abbe number increases more than necessary.
Therefore, the content of component F is preferably 10.0%, more preferably less than 5.0%, even more preferably less than 3.0%, even more preferably less than 1.0%, and still more preferably not contained.
<About ingredients that should not be included>
Next, components that should not be included in the optical glass of the present invention and components that are not preferably included will be explained.

Other components can be added to the optical glass of the present invention, as necessary, within a range that does not impair the properties of the glass of the present invention. However, since the GeO ₂ component increases the dispersibility of the glass, it is preferable that it is not substantially included.

In addition, each transition metal component other than Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, such as Hf, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, Mo, Ce, Nd Even if a small amount of each of these substances is contained alone or in combination, the glass will be colored and have the property of absorbing light of a specific wavelength in the visible range. Preferably, it does not substantially contain.

Furthermore, lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ , as well as components such as Th, Cd, Tl, Os, Be, and Se, have recently been avoided as harmful chemicals, and are Environmental measures are required not only in the manufacturing process, but also in the processing process and even the disposal after productization. Therefore, when considering the environmental impact, it is preferable that these substances are not substantially contained except for unavoidable contamination. As a result, the optical glass is substantially free from substances that pollute the environment. Therefore, this optical glass can be manufactured, processed, and disposed of 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, the prepared mixture is put into a platinum crucible, a quartz crucible, or an alumina crucible and roughly melted. , put in a platinum alloy crucible or iridium crucible and melt at a temperature range of 900 to 1400°C for 1 to 5 hours, stir to homogenize and remove bubbles, then lower the temperature to 1300°C or less and perform final stirring. It is manufactured by removing striae and molding using a mold. Here, as means for obtaining molded glass using a mold, there is a method for flowing molten glass into one end of the mold and at the same time pulling out the molded glass from the other end of the mold, and a method for obtaining molded glass using a mold. An example of this method is to cast the material into a mold and slowly cool it.

[Physical properties]
The optical glass of the present invention preferably has a high refractive index and high dispersion. In particular, the lower limit of the refractive index (nd) of the optical glass of the present invention is preferably 1.90, more preferably 1.95, and still more preferably 1.98. The upper limit of this refractive index may be preferably 2.20, more preferably 2.15, and still more preferably 2.10. Further, the lower limit of the Abbe number (νd) of the optical glass of the present invention is preferably 15.0, more preferably 18.0, even more preferably 20.0, and preferably 30.0, more preferably 28.0. , more preferably the upper limit is 27.0.
By having such a high refractive index, a large amount of light refraction can be obtained even if the optical element is made thinner. Further, by having such high dispersion, high imaging characteristics etc. can be achieved, for example, when combined with an optical element having low dispersion (high Abbe number).
Therefore, the optical glass of the present invention is useful in terms of optical design, and while achieving particularly high imaging characteristics, it is possible to downsize the optical system and expand the degree of freedom in optical design.

It is preferable that the optical glass of the present invention has a high visible light transmittance, particularly a high transmittance of light on the short wavelength side of visible light, and thereby has little coloring.
In particular, the optical glass of the present invention has a wavelength (λ ₇₀ ) at which the spectral transmittance is 70% in a 10 mm thick sample, which is preferably 500 nm, more preferably 490 nm, and still more preferably 480 nm. Upper limit.
Further, in the optical glass of the present invention, the shortest wavelength (λ ₅ ) exhibiting spectral transmittance of 5% in a sample with a thickness of 10 mm is preferably 400 nm, more preferably 390 nm as an upper limit. Due to these, the absorption edge of the glass is in the vicinity of the ultraviolet region, and the transparency of the glass to visible light is enhanced, so that this optical glass can be preferably used for optical elements such as lenses that transmit light.

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, and even more preferably Preferably, the lower limit is 0.612.
Further, the partial dispersion ratio (θg, F) of the optical glass of the present invention is expressed as (-0.00162νd+ _0.645 )≦(θg,F)≦(-0.00162νd+0. 680) is preferably satisfied. As a result, an optical glass having a small partial dispersion ratio (θg, F) can be obtained, so that the optical glass can be used to reduce chromatic aberration of an optical element.
Therefore, the lower limit of the partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably (-0.00162νd+0.645), more preferably (-0.00162νd+0.650).
On the other hand, the upper limit of the partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably (-0.00162νd+0.675), more preferably (-0.00162νd+0.670).

The relational expression between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) described above is expressed using a straight line parallel to the normal line in orthogonal coordinates with the vertical axis of the partial dispersion ratio and the horizontal axis of the Abbe number. expressed. The normal line represents the conventionally known linear relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) of glass, and shows the partial dispersion ratio (θg, F) vertically. It is represented by a straight line connecting two points where the partial dispersion ratio and Abbe number of NSL7 and PBM2 are plotted on orthogonal coordinates with Abbe's number (ν _d ) on the axis and Abbe's number (v d ) on the horizontal axis (see FIG. 1). The relationship between the partial dispersion ratio and the Abbe number of conventionally known glasses generally overlaps with the normal line.
Here, NSL7 and PBM2 are optical glasses manufactured by Ohara Co., Ltd., and the Abbe number (ν _d ) of PBM2 is 36.3, the partial dispersion ratio (θg, F) is 0.5828, and the Abbe number (ν _d ) is 60.5, and the partial dispersion ratio (θg, F) is 0.5436.

[Preform and optical element]
A glass molded body can be produced from the produced optical glass using, for example, a polishing method or a mold press forming method such as reheat press molding or precision press molding. In other words, a glass molded body is produced by performing mechanical processing such as grinding and polishing on optical glass, or a preform made from optical glass is subjected to reheat press molding and then polished to form glass. A glass molded body can be produced by performing precision press molding on a preform produced by producing a body, by performing a polishing process, or by performing precision press molding on a preform produced by known levitation molding or the like. Note that the means for producing the glass molded body are not limited to these means.

As described above, the glass molded article formed from the optical glass of the present invention is useful for various optical elements and optical designs, but it is particularly preferable to use it for optical elements such as lenses and prisms. By increasing the stability of the glass, it becomes possible to form glass molded bodies with large diameters, which allows for the creation of large-sized optical elements while providing high-definition and high-definition properties when used in optical equipment such as cameras and projectors. Accurate imaging characteristics and projection characteristics can be achieved.

Compositions of the glasses of Examples (No. 1 to No. 52 ) of the present invention, as well as refractive index (n _d ), Abbe number (ν _d ), transmittance (λ ₅ , λ ₇₀ ) and fraction of these glasses The values of the dispersion ratio (θg, F) are shown in Tables 1 to 10 . Note that the following examples are for illustrative purposes only, and are not intended to be limiting.

The glasses in the examples are all high-purity materials used in ordinary optical glasses, such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphoric acid compounds, etc., which are the raw materials for each component. After selecting the raw materials, weighing them, and mixing them uniformly, they are placed in a platinum crucible, and melted and stirred into the melted glass raw materials in an electric furnace at a temperature of 1280 to 1340°C for 2.5 hours. After removing bubbles, the temperature was lowered to 1,180 to 1,250°C, the mixture was further stirred to homogenize, and then poured into a mold and slowly cooled to produce glass.

The refractive index (n _d ) and Abbe number (v _d ) of the glass in the example were shown as measured values against the d-line (587.56 nm) of a helium lamp. In addition, the Abbe number (ν _d ) is the refractive index of the above d-line, the refractive index (n _F ) for the F-line (486.13 nm) of the hydrogen lamp, and the refractive index (n _C ) for the C-line (656.27 nm). It was calculated from the formula of Abbe number (ν _d )=[( _nd −1)/(n _F −n _C )] using the value of .
The partial dispersion ratio is determined by measuring the refractive index n _C at the C line (wavelength 656.27 nm), the refractive index n _F at the F line (wavelength 486.13 nm), and the refractive index n _g at the G line (wavelength 435.835 nm), It was calculated using the formula (θg, F)=(n _g −n _F )/(n _F −n _C ).
Note that the glass used in this measurement was treated in a slow cooling furnace at a slow cooling temperature drop rate of -25° C./hr.

The transmittance of the glass in the example was measured according to the Japan Optical Glass Industry Association standard JOGIS02-2003. In the present invention, the presence or absence and degree of coloring of the glass was determined by measuring the transmittance of the glass. Specifically, the spectral transmittance of 200 to 800 nm of a 10 ± 0.1 mm thick parallel polished product was measured in accordance with JIS Z8722, and λ ₅ (wavelength at 5% transmittance) and λ ₇₀ (transmittance 70% wavelength) was determined.
Note that the glass used in this measurement was treated in a slow cooling furnace at a slow cooling temperature drop rate of -25° C./hr.

As shown in the table, all of the optical glasses of the examples of the present invention have a refractive index (n _d ) of 1.90 or more, and this refractive index (n _d ) of 2.20 or less. was 2.10 or less, which was within the desired range.
Further, all of the optical glasses of the examples of the present invention have an Abbe number (ν _d ) of 30.0 or less, more specifically, 28.0 or less, and this Abbe number (ν _d ) of 15.0. More specifically, it was 20.0 or more, which was within the desired range.

Furthermore, the optical glasses of Examples of the present invention all had a λ ₇₀ (wavelength at 70% transmittance) of 500 nm or less, more specifically, 490 nm or less. In addition, the optical glasses of Examples of the present invention all had a λ ₅ (wavelength at 5% transmittance) of 400 nm or less, more specifically, 390 nm or less.

Furthermore, all of the optical glasses of Examples of the present invention had a partial dispersion ratio (θg, F) of (−0.00162νd+0.645) or more, more specifically, (−0.00162νd+0.650) or more. On the other hand, the partial dispersion ratio of the optical glass of the example of the present invention was below ((-0.00162νd+0.680), more specifically below (-0.00162νd+0.670). Therefore, these partial dispersions It was found that the ratio (θg, F) was within the desired range.

Therefore, it has been revealed that the optical glasses of Examples of the present invention can be manufactured at low cost while having refractive index and Abbe number within desired ranges, and have little coloration.

Further, the optical glasses obtained in the examples of the present invention were subjected to reheat press molding, and then ground and polished to be processed into the shapes of lenses and prisms. Further, a preform for precision press molding was formed using the optical glass of the example of the present invention, and this preform for precision press molding was subjected to precision press molding. In either case, the glass after being heated and softened did not have 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 above 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 (9)

Mass% based on oxide,
La ₂ O ₃ component from 30.08% to 41.27%,
WO ₃ components more than 0% to 10%,
TiO ₂ component more than 20.0% to 45.0%,
BaO component 15.60% to 35.0% ,
SiO ₂ component from 0 to 6.63%,
B ₂ O ₃ component from 6.95% to less than 15.0% and ZnO component from 0 to 2.27%
Contains
The total amount of SiO ₂ component and B ₂ O ₃ component is 5.0% or more and 16.73% or less, Ln ₂ O ₃ component (wherein Ln is 1 selected from the group consisting of La, Gd, Y, and Yb) 30.08% or more and 41.27% or less, and the mass ratio of TiO ₂ /(La ₂ O ₃ + Nb ₂ O ₅ + Gd ₂ O ₃ + Yb ₂ O ₃ ) is 0.501 or more and 0.533 or less. , the mass ratio of TiO ₂ /(TiO ₂ +BaO) is 0.53 or more and 0.58 or less , and the mass ratio of TiO ₂ /BaO is 1.14 or more and 1.39 or less ,
The wavelength (λ ₅ ) is 400 nm or less. Mass% based on oxide,
Y ₂ O ₃ component 0-15.0%,
Nb ₂ O ₅ component 0 to 25.0%,
Yb ₂ O ₃ component 0 to 15.0%, and Gd ₂ O ₃ component 0 to 15.0%
The optical glass according to claim 1. Mass% based on oxide,
The optical glass according to claim 1 or 2, wherein the sum of the masses of (La ₂ O ₃ +Nb ₂ O ₅ +Gd ₂ O ₃ +Yb ₂ O ₃ ) is 35.0% or more and 60.0% or less. Mass% based on oxide,
The optical glass according to any one of claims 1 to 3, wherein the sum of the mass 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. Mass% based on oxide,
Any one of claims 1 to 4, wherein the sum of the masses of the RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 15.60% or more and 35.0% or less. Optical glass as described. Mass% based on oxide,
ZrO ₂ component 0-20.0%,
Ta ₂ O ₅ component 0-10.0%,
MgO component 0-15.0%,
CaO component 0-15.0%,
SrO component 0-15.0%,
Li ₂ O component 0 to 15.0%,
Na ₂ O component 0-15.0%,
K ₂ O component 0-15.0%,
P ₂ O ₅ component 0-10.0%,
_GeO2 component 0-10.0%,
Al ₂ O ₃ component 0-15.0%,
Ga ₂ O ₃ component 0-15.0%,
Bi ₂ O ₃ component 0-10.0%,
_TeO2 component 0-10.0%,
SnO ₂ component 0 to 3.0%, and Sb ₂ O ₃ component 0 to 1.0%
The optical glass according to any one of claims 1 to 5, comprising: A preform material made of the optical glass according to any one of claims 1 to 6. An optical element comprising the optical glass according to claim 1. An optical device comprising the optical element according to claim 8.

Images