JP6900110B2 - Optical glass, preforms and optics - Google Patents

Description

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

In recent years, the digitization and high definition of devices that use optical systems have been rapidly advancing, and various optical devices such as imaging devices such as digital cameras and video cameras, and image reproduction (projection) devices such as projectors and projection televisions. In this field, there is an increasing demand for reducing the number of optical elements such as lenses and prisms used in an optical system, and reducing the weight and size of the entire optical system.

Among the optical glasses for which optical elements are manufactured, it has a high refractive index ( _nd ) of 1.85 or more and a low Abbe of 25 or more and 35 or less, which can reduce the weight and size of the entire optical system. The demand for high refractive index and highly dispersed glass having a number (ν _{d) is very high.} As such a high refractive index low dispersion glass, a glass composition as represented by Patent Document 1 is known.

Japanese Unexamined Patent Publication No. 2015-02913

In order to reduce the material cost of the optical glass, it is desired that the raw material cost of the optical glass is as low as possible. However, it cannot be said that the glass described in Patent Document 1 sufficiently meets such a demand.

The present invention has been made in view of the above problems, and an object of the present invention is to make _{an optical glass having a refractive index (nd} ) and an Abbe number (ν _d ) within desired ranges at a lower cost. To get to.

As a result of intensive test and research to solve the above problems, the present inventors have used the TiO ₂ component, the ZnO component and the BaO component in combination in _{addition to the B 2} O ₃ component and the La ₂ O _{3 component.} In addition, they have found that a glass can be obtained in which the material cost is suppressed while obtaining a desired high refractive index and high dispersion, and have completed the present invention.
Specifically, the present invention provides the following.

(1) By mass%
B ₂ O ₃ component 6.0% or more and 30.0% or less,
La ₂ O ₃ component is 25.0% or more and 50.0% or less,
TiO ₂ component is 6.0% or more and 25.0% or less,
ZnO component is 2.0% or more and 23.0% or less,
Contains 4.0% or more and 22.0% or less of BaO component,
An optical glass having a refractive index ( _{nd ) of 1.85 or more and an Abbe number (ν d} ) of 25 or more and 35 or less.

(2) By mass%
SiO ₂ component 0 to 13.0%,
Gd ₂ O ₃ component 0 to 10.0%
Y ₂ O ₃ component 0 to 20.0%
Yb ₂ O ₃ component 0 to 10.0%
Nb ₂ O ₅ component 0 to 15.0%
WO ₃ component 0-20.0%
ZrO ₂ component 0 to 15.0%
Ta ₂ O ₅ component 0-5.0%
MgO component 0-5.0%
CaO component 0-10.0%
SrO component 0-10.0%
Li ₂ O component 0-5.0%
Na ₂ O component 0 to 10.0%
K ₂ O component 0 to 10.0%
P ₂ O ₅ component 0 to 10.0%
GeO ₂ component 0-10.0%
Al ₂ O ₃ component 0 to 10.0%
Ga ₂ O ₃ component 0 to 10.0%
Bi ₂ O ₃ component 0 to 10.0%
TeO ₂ component 0-10.0%
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 the above elements, is 0 to 10.0% by mass.

(3) The optical glass according to (1) or (2), wherein the sum of mass (SiO ₂ + B ₂ O _{3) is 10.0% or more and 30.0% or less.}

(4) The optical glass according to any one of (1) to (3), wherein the sum of mass (TiO _{2 + ZnO) is 10.0% or more and 45.0% or less.}

(5) The sum of mass (BaO + ZnO) is 10.0% or more and 40.0% or less (the optical glass according to any one of 1 to (4).

(6) The optical glass according to any one of (1) to (5), wherein the _{mass ratio TiO 2} / SiO _{2 is 1.00 or more.}

(7) The optical glass according to any one of (1) to (6), wherein the mass ratio (TiO ₂ + ZnO + BaO) / La ₂ O _{3 is 0.50 or more and 1.50 or less.}

(8) The optical glass according to any one of (1) to (7), wherein the mass ratio BaO / Ln ₂ O _{3 is 0.0400 or more and 0.5000 or less.}

(9) The optical glass according to any one of (1) to (8), wherein the mass ratio (SiO _{2 + BaO) / ZnO is 8.00 or less.}

(10) The optical glass according to any one of (1) to (9), wherein the sum of mass (TiO ₂ + Nb ₂ O ₅ + WO _{3) is 7.0% or more and 25.0% or less.}

(11) The optical glass according to any one of (1) to (10), wherein the _{mass ratio TiO 2} / (TiO ₂ + Nb ₂ O ₅ + WO _{3) is 0.600 or more and 1.000 or less.}

(12) The optical glass according to any one of (1) to (11), wherein the sum of mass (Ta ₂ O ₅ + Gd ₂ O ₃ + Nb ₂ O _{5) is 10.0% or less.}

(13) The optical glass according to any one of (1) to (12), wherein the mass ratio (Ta ₂ O ₅ + Gd ₂ O ₃ + Nb ₂ O ₅ ) / (TiO _{2 + ZnO) is 0.500 or less.}

(14) The optical glass according to any one of (1) to (13), wherein the sum of mass (CaO + SrO) is 10.0% or less.

(15) By mass%
The sum of the contents of the RO component (R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, Zn) is 10.0% or more and 40.0% or less of the Rn ₂ O component (formula). Among them, Rn is the sum of the contents of one or more selected from the group consisting of Li, Na, and K) of 10.0% or less. The sum of the contents of the Ln ₂ O ₃ components (in the formula, Ln is La, Gd). , Y, Yb) is 27.0% or more and 52.0% or less (one or more selected from the group) according to any one of (1) to (14).

(16) A preform material made of the optical glass according to any one of (1) to (15).

(17) An optical element made of the optical glass according to any one of (1) to (15).

(18) An optical device including the optical element according to (17).

According to the present invention, it is possible to obtain an optical glass having a _{refractive index (nd} ) and an Abbe number (ν _{d) within desired ranges at a lower cost.}
Further, according to the present invention, although the refractive index ( _nd ) and the Abbe number (ν _d ) are within the desired ranges, the optics have high stability, high transmittance for visible light, and low specific gravity. You can also get glass.

It is a figure which shows the relationship between the refractive index (nd) and the Abbe number (ν _{d) about the glass of the Example of this application.}

The optical glass of the present invention, in _mass%, B 2 _{O 3} component 30.0% 6.0% or more of the following, _La 2 _{O 3} ingredient 25.0% or more 50.0% or less, the TiO ₂ component 6 It contains 0.0% or more and 25.0% or less, ZnO component is 2.0% or more and 23.0% or less, and BaO component is 4.0% or more and 22.0% or less, and has a refractive index of 1.85 or more (nd _). ), And has an Abbe number (ν _d ) of 25 or more and 35 or less. According to the present invention, when the TiO ₂ component, the ZnO component and the BaO component are used in combination in _{addition to the B 2} O ₃ component and the La ₂ O _{3 component, the desired high refractive index and high dispersion can be obtained.} It is possible to obtain glass with reduced material cost.

Hereinafter, embodiments of the optical glass of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and the present invention is carried out with appropriate modifications within the scope of the object of the present invention. be able to. 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, unless otherwise specified, the content of each component shall be indicated by mass% of the total amount of substance of glass in the oxide conversion composition. Here, the "oxide-equivalent composition" is based on the assumption that the oxides, composite salts, metal fluorides, etc. used as raw materials for the glass constituents of the present invention are all decomposed into oxides at the time of melting. It is a composition which describes each component contained in a glass, assuming that the total amount of substance of the produced oxide is 100% by mass.

<About essential ingredients and optional ingredients>
The B ₂ O ₃ component is an essential component that is indispensable as a glass-forming oxide in the optical glass of the present invention containing a large amount of rare earth oxides.
In particular, by _{containing 6.0% or more of the B 2} O ₃ component, the devitrification resistance of the glass can be enhanced and the specific gravity can be reduced. Therefore, _{the content of the B 2} O ₃ component is preferably 6.0% or more, more preferably more than 8.5%, still more preferably more than 10.0%, still more preferably more than 10.5%, still more preferably. It shall be over 12.0%.
On the other hand, by _{reducing the content of the B 2} O ₃ component to 30.0% or less, a decrease in the refractive index and an increase in the Abbe number can be suppressed, and a deterioration in chemical durability can be suppressed. Therefore, _{the content of the B 2} O ₃ component is preferably 30.0% or less, more preferably 27.0% or less, still more preferably 24.0% or less, still more preferably less than 20.0%, still more preferably. It is less than 18.0%, more preferably less than 15.5%, still more preferably less than 15.0%.
B ₂ O ₃ component can be used _H 3 _BO 3 as a starting _{material, Na 2 B 4 O 7,} Na 2 B 4 O 7 · 10H 2 O, the BPO ₄ and the like.

The La ₂ O ₃ component is an essential component whose refractive index can be increased by containing 25.0% or more. Further, _{by containing the La 2} O ₃ component, the content of other rare earth elements that increase the specific gravity is reduced, so that glass having a small specific density can be obtained more easily. Therefore, _{the content of the La 2} O ₃ component is preferably 25.0% or more, more preferably more than 28.0%, still more preferably more than 31.0%, still more preferably more than 34.0%, still more preferably. It shall be over 36.0%.
On the other hand, _{by reducing the content of the La 2} O ₃ component to 50.0% or less, the stability of the glass can be improved, devitrification can be reduced, and an increase in the Abbe number can be suppressed. Therefore, _{the content of the La 2} O ₃ component is preferably 50.0% or less, more preferably less than 46.0%, still more preferably less than 43.0%, still more preferably less than 40.0%.
As the La ₂ O _{3 component, La 2} O ₃ , La (NO ₃ ) ₃ , XH ₂ O (X is an arbitrary integer) or the like can be used as a raw material.

When the TiO ₂ component is contained in an amount of 6.0% or more, the refractive index can be increased, the Abbe number can be reduced, the specific gravity can be reduced, and the devitrification resistance can be improved. Therefore, _{the content of the TiO 2} component is preferably 6.0% or more, more preferably more than 7.0%, still more preferably more than 8.0%, still more preferably more than 11.0%, still more preferably 13. It shall be over 0%.
On the other hand, _{by reducing the content of the TiO 2} component to 25.0% or less, the coloring of the glass can be reduced, the visible light transmittance can be increased, and the Abbe number can be suppressed from being lowered more than necessary. In addition, devitrification due to excessive inclusion of _{the TiO 2 component can be suppressed.} Therefore, _{the content of the TiO 2} component is preferably 25.0% or less, more preferably less than 20.0%, still more preferably less than 18.0%, still more preferably less than 16.0%.
As the TiO _{2 component, TiO 2} or the like can be used as a raw material.

When the ZnO component is contained in an amount of 2.0% or more, the glass transition point can be lowered, the specific gravity can be reduced, and the chemical durability can be enhanced. Therefore, the content of the ZnO component may be preferably 2.0% or more, more preferably more than 3.0%, still more preferably more than 5.0%, still more preferably more than 6.5%.
On the other hand, by setting the content of the ZnO component to 23.0% or less, the decrease in the refractive index and the devitrification can be reduced. Further, since the viscosity of the molten glass is increased by this, the occurrence of veins on the glass can be reduced. Therefore, the content of the ZnO component is preferably 23.0% or less, more preferably less than 20.0%, still more preferably less than 15.0%, still more preferably less than 13.0%, still more preferably 11.0. It shall be less than%.
As the ZnO component, ZnO, ZnF _2, or the like can be used as a raw material.

By containing 4.0% or more of the BaO component, the material cost can be suppressed while increasing the refractive index of the glass, the meltability and devitrification resistance of the glass raw material can be enhanced, and the glass transition point can be lowered. It is an essential ingredient that can be made. Therefore, the content of the BaO component is preferably 4.0% or more, more preferably more than 5.0%, still more preferably more than 6.6%, still more preferably more than 7.0%, still more preferably 8.0. %.
On the other hand, by reducing the content of the BaO component to 22.0% or less, devitrification due to excessive content and an increase in specific gravity can be suppressed. Therefore, the content of the BaO component is preferably 22.0% or less, more preferably less than 18.0%, still more preferably less than 15.0%, still more preferably less than 13.0%.
As the BaO component, BaCO ₃ , Ba (NO ₃ ) ₂ , BaF _2, or the like can be used as a raw material.

When the SiO ₂ component is contained in excess of 0%, the viscosity of the molten glass can be increased, the coloring of the glass can be reduced, and the devitrification resistance can be increased. Therefore, _{the content of the SiO 2} component is preferably more than 0%, more preferably more than 1.0%, still more preferably more than 3.0%, still more preferably more than 4.5%, still more preferably 6.3%. Above, more preferably, it may be 6.6% or more.
On the other hand, by _{setting the content of the SiO 2} component to 13.0% or less, the decrease in the refractive index can be suppressed, the increase in the glass transition point can be suppressed, and the specific gravity can be reduced. Therefore, _{the content of the SiO 2} component is preferably 13.0% or less, more preferably less than 10.0%, and further preferably less than 8.0%.
As the SiO _{2 component, SiO 2} , K ₂ SiF ₆ , Na ₂ SiF _6, or the like can be used as a raw material.

The Gd ₂ O ₃ component, the Y ₂ O ₃ component, and the Yb ₂ O ₃ component are optional components that can increase the refractive index of the glass and enhance the devitrification resistance when at least one of them is contained in an amount of more than 0%. is there.
On the other hand, _{by reducing the content of each of the Gd 2} O ₃ component and the Yb ₂ O ₃ component to 10.0% or less, devitrification due to excessive content of these components can be reduced and the Abbe number can be increased. It can be suppressed and the material cost of glass can be suppressed. Therefore, _{the contents of the Gd 2} O ₃ component and the Yb ₂ O ₃ component are preferably 10.0% or less, more preferably less than 7.0%, still more preferably less than 4.0%, still more preferably 2. It is less than 0%, more preferably less than 1.0%.
Further, by _{setting the content of the Y 2} O ₃ component to 20.0% or less, devitrification due to excessive content of these components can be reduced, and an increase in the Abbe number can be suppressed. _Accordingly, the content of Y 2 _{O 3} component is preferably 20.0% or less, more preferably less than 10.0%, more preferably less than 5.0%.
As the Gd ₂ O ₃ component, the Y ₂ O ₃ component, and the Yb ₂ O ₃ component, Gd ₂ O ₃ , GdF ₃ , Y ₂ O ₃ , YF ₃ , Yb ₂ O _{3, and the} like can be used as raw materials.

The Nb ₂ O ₅ component is an optional component capable of increasing the refractive index and lowering the Abbe number and increasing the devitrification resistance when the content exceeds 0%.
On the other hand, _{by reducing the content of the Nb 2} O ₅ component to 15.0% or less, it is possible to suppress a decrease in devitrification resistance and a decrease in visible light transmittance due to an excessive content _{of the Nb 2} O _{5 component.} Be done. Further, as a result, the specific gravity of the glass can be reduced and the material cost can be suppressed. Therefore, _{the content of the Nb 2} O ₅ component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably. It shall be less than 1.0%.
As the Nb ₂ O _{5 component, Nb 2} O ₅ or the like can be used as a raw material.

The WO ₃ component is an optional component capable of increasing the refractive index, lowering the Abbe number, lowering the glass transition point, and increasing the devitrification resistance when the content exceeds 0%. Therefore, _{the content of the WO 3} component may be preferably more than 0%, more preferably more than 0.3%, and even more preferably more than 0.5%.
On the other hand, by _{setting the content of the WO 3} component to 20.0% or less, it is possible to make it difficult to reduce the transmittance of glass with respect to visible light, and it is possible to suppress the material cost. Therefore, _{the content of the WO 3} component is preferably 20.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably 1. It shall be less than 5%.
As the WO _{3 component, WO 3} or the like can be used as a raw material.

ZrO ₂ component, when ultra containing 0%, can contribute to a high refractive index of the glass, and is an optional component that enhances devitrification resistance. Therefore, the content of the ZrO ₂ component is preferably 0 percent, more preferably 0.5 percent, more preferably 2.0 percent, and more preferably be 4.0% greater.
On the other hand, _{by reducing the ZrO 2} component to 15.0% or less, it is possible to suppress an increase in the Abbe number and a decrease in devitrification resistance due to an excessive content _{of the ZrO 2 component.} Therefore, the content of the ZrO ₂ component is preferably 15.0% or less, more preferably less than 10.0%, more preferably less than 8.0%.
As the ZrO _{2 component, ZrO 2} , ZrF _4, or the like can be used as a raw material.

The Ta ₂ O ₅ component is an optional component that can increase the refractive index, the devitrification resistance, and the viscosity of the molten glass when it is contained in excess of 0%.
On the other hand, _{by reducing the content of the Ta 2} O ₅ component to 5.0% or less, the amount of the Ta ₂ O ₅ component used, which is a rare mineral resource, is reduced, so that the material cost of glass can be reduced. In addition, this makes it possible to reduce the specific gravity. Therefore, _{the content of the Ta 2} O ₅ component is preferably 5.0% or less, more preferably less than 5.0%, further preferably less than 3.0%, still more preferably less than 1.0%, and most preferably. Does not contain.
As the Ta ₂ O _{5 component, Ta 2} O ₅ or the like can be used as a raw material.

The MgO component, CaO component and SrO component are optional components that can enhance the meltability of the glass raw material and the devitrification resistance of the glass when at least one of them is contained in excess of 0%. In particular, the MgO component and the CaO component are also components whose specific gravity can be reduced by containing them.
On the other hand, by setting the content of the MgO component to 5.0% or less, it is possible to reduce the decrease in the refractive index and the devitrification due to the excessive content of these components. Further, by setting the content of each of the CaO component and the SrO component to 10.0% or less, it is possible to reduce the decrease in the refractive index and the devitrification due to the excessive content of these components. Therefore, the content of the MgO component is preferably 5.0% or less, more preferably less than 3.0%, still more preferably less than 1.0%. The content of each of the CaO component and the SrO component is preferably 10.0% or less, more preferably less than 5.0%, further preferably less than 3.0%, still more preferably less than 1.0%. ..
As the MgO component, CaO component and SrO component, MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF _{2 and the} like can be used as raw materials.

The Li ₂ O component is an optional component that can improve the meltability of the glass and lower the glass transition point when it is contained in excess of 0%.
On the other hand, _{by reducing the content of the Li 2} O component to 5.0% or less, a decrease in the refractive index and devitrification can be reduced, and the chemical durability can be improved. Further, since the viscosity of the molten glass is increased by this, the occurrence of veins on the glass can be reduced. Therefore, _{the content of the Li 2} O 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%.
As the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , LiF or the like can be used as a raw material.

The Na ₂ O component and the K ₂ O component are optional components that can improve the meltability of the glass raw material, increase the devitrification resistance, and lower the glass transition point when at least one of them is contained in excess of 0%. is there.
On the other hand, by _{setting the respective contents of the Na 2} O component and the K ₂ O component to 10.0% or less, it is possible to make it difficult to reduce the refractive index, and it is possible to reduce devitrification due to excessive content. Therefore, _{the respective contents of the Na 2} O component and the K ₂ O component are preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably 1.0. It shall be less than%.
As the Na ₂ O component and the K ₂ O component, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF _6, etc. can be used as raw materials. it can.

The P ₂ O ₅ component is an optional component that can enhance devitrification resistance when it is contained in excess of 0%.
On the other hand, by _{setting 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, particularly the water resistance. Therefore, _{the content of the P 2} O ₅ 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%.
As the P ₂ O ₅ component, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO _{4, and the} like can be used as raw materials.

The GeO ₂ component is an optional component that can increase the refractive index of glass and increase the devitrification resistance when it is contained in excess of 0%.
However, _{since the raw material price of GeO 2} is high, if the amount is large, the material cost is high, _{and the effect of cost reduction due to the inclusion of the TiO 2} component, the ZnO component, the BaO component, and the like is diminished. Therefore, _{the content of the GeO 2} component is preferably 10.0% or less, more preferably less than 5.0%, further preferably less than 3.0%, still more preferably less than 1.0%, and most preferably contained. do not.
As the GeO _{2 component, GeO 2} or the like can be used as a raw material.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are optional components that can enhance chemical durability and devitrification resistance when at least one of them is contained in an amount of more than 0%.
On the other hand, by _{setting the contents of the Al 2} O ₃ component and the Ga ₂ O ₃ component to 10.0% or less, respectively, devitrification due to excessive content can be reduced. Therefore, _{the contents of the Al 2} O ₃ component and the Ga ₂ O ₃ component are preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably 1. It shall be less than 0%.
As the Al ₂ O _{3 component, Al 2} O ₃ , Al (OH) ₃ , AlF _3, or the like can be used as a raw material.

The Bi ₂ O ₃ component is an optional component that can increase the refractive index, reduce the Abbe number, and lower the glass transition point when the content exceeds 0%.
On the other hand, _{by reducing the content of the Bi 2} O ₃ component to 10.0% or less, the devitrification resistance of the glass can be enhanced, and the coloring of the glass can be reduced to increase the visible light transmittance. Therefore, _{the content of the Bi 2} O 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%.
As the Bi ₂ O _{3 component, Bi 2} O ₃ or the like can be used as a raw material.

The TeO ₂ component is an optional component that can increase the refractive index and lower the glass transition point when the content exceeds 0%.
On the other hand, _{by reducing the content of the TeO 2} component to 10.0% or less, the coloring of the glass can be reduced and the visible light transmittance can be increased. Further, 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 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%.
As 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 can increase the visible light transmittance of the glass while reducing the oxidation of the molten glass and clarifying it when the content exceeds 0%.
On the other hand, _{by reducing 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 is preferably 3.0% or less, more preferably less than 1.0%, and further preferably less than 0.5%.
As the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , SnF _4, or the like can be used as a raw material.

The Sb ₂ O ₃ component is an optional component capable of defoaming the molten glass when it contains more than 0%.
On the other hand, _{if the amount of Sb 2} O ₃ is too large, the transmittance in the short wavelength region of the visible light region becomes poor. Therefore, _{the content of the Sb 2} O ₃ component is preferably 1.0% or less, more preferably less than 0.5%, still more preferably less than 0.1%.
Sb ₂ O ₃ component can be used _{Sb 2 O 3, Sb 2 O} 5, Na 2 H 2 Sb 2 O 7 · 5H 2 O and the like as raw materials.

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 the fluoride substituted with a part or all of one or more oxides of the above-mentioned elements as F exceeds 10.0%, the F component Since the amount of volatile matter increases, it becomes difficult to obtain a stable optical constant, and it becomes difficult to obtain a homogeneous glass. In addition, the Abbe number rises more than necessary.
Therefore, the content of the F 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%.
The F component can be contained in glass by using, for example, ZrF ₄ , AlF ₃ , NaF, CaF _{2, etc. as a raw material.}

The sum (mass sum) of the contents of the B ₂ O ₃ component and the SiO ₂ component is preferably 10.0% or more and 30.0% or less.
In particular, by setting this sum to 10.0% or more, _{devitrification due to deficiency of the B 2} O ₃ component and the SiO ₂ component can be suppressed. Therefore, the sum of mass (B ₂ O ₃ + SiO ₂ ) is preferably 10.0% or more, more preferably more than 12.0%, still more preferably more than 15.0%, still more preferably more than 17.0%, and further. It is preferably more than 18.0%.
On the other hand, by setting the sum to 30.0% or less, it is possible to suppress a decrease in the refractive index due to excessive inclusion of these components. Therefore, the mass sum (B ₂ O ₃ + SiO ₂ ) is preferably 30.0% or less, more preferably less than 28.0%, still more preferably less than 25.0%, still more preferably less than 22.0%. ..

The ratio (mass ratio) of the content of the SiO ₂ component to the content of the B ₂ O _{3 component is preferably less than 1.00.} As a result, the rise of the glass transition point can be suppressed, so that molding can be facilitated at a lower temperature. Therefore, the mass ratio SiO ₂ / B ₂ O ₃ is preferably less than 1.00, more preferably less than 0.80, and even more preferably less than 0.55.
On the other hand, the mass ratio SiO ₂ / B ₂ O ₃ may be more than 0. This enhances the stability of the glass. Therefore, the mass ratio SiO ₂ / B ₂ O ₃ may be preferably more than 0, more preferably 0.1 or more, still more preferably 0.35 or more, still more preferably 0.45 or more.

The ratio (mass ratio) of the content of the La ₂ O ₃ component to the content of the B ₂ O _{3 component is preferably more than 0.60.} As a result, the refractive index of the glass can be increased. Therefore, the mass ratio La ₂ O ₃ / B ₂ O ₃ is preferably more than 0.60, more preferably more than 1.10, still more preferably more than 1.50, still more preferably more than 1.70, still more preferably 2. It is more than .00, more preferably more than 2.30, still more preferably more than 2.60.
On the other hand, the mass ratio La ₂ O ₃ / B ₂ O ₃ may be preferably less than 5.00, more preferably less than 4.00, still more preferably less than 3.70, still more preferably less than 3.40. ..

The sum (mass sum) of the contents of the TiO ₂ component and the ZnO component is preferably 10.0% or more and 45.0% or less.
In particular, by setting this sum to 10.0% or more, the stability of the glass can be enhanced and the refractive index can be enhanced. Therefore, the mass sum (TiO ₂ + ZnO) is preferably 10.0% or more, more preferably more than 12.0%, still more preferably more than 16.0%, still more preferably more than 16.5%, still more preferably 17. It is more than 0.0%, more preferably more than 19.0%.
On the other hand, the mass sum (TiO ₂ + ZnO) is preferably 45.0% or less, more preferably 40.0% or less, still more preferably 35.0% or less, still more preferably 30.0% or less. Good.

The sum (mass sum) of the contents of the BaO component and the ZnO component is preferably 10.0% or more and 40.0% or less.
In particular, by setting this sum to 10.0% or more, the stability of the glass can be enhanced and the refractive index can be enhanced. Therefore, the mass sum (BaO + ZnO) is preferably 10.0% or more, more preferably more than 13.0%, still more preferably more than 15.0%, still more preferably more than 16.0%, still more preferably 19.0. %.
On the other hand, the mass sum (BaO + ZnO) is preferably 40.0% or less, more preferably less than 35.0%, still more preferably less than 30.0%, from the viewpoint of reducing devitrification due to their excessive content. , More preferably less than 25.0%, even more preferably less than 23.0%.

The ratio (mass ratio) of the content of the TiO ₂ component to the content of the SiO _{2 component is preferably 1.00 or more.}
In particular, by setting this mass ratio to 1.00 or more, the refractive index of the glass can be increased. Therefore, the mass ratio of TiO ₂ / SiO ₂ is preferably 1.00 or more, more preferably more than 1.41, still more preferably more than 1.70, still more preferably more than 1.90, still more preferably more than 2.00. To do.
On the other hand, the upper limit of this mass ratio may be infinite (that is, _{the content of the SiO 2} component is 0), but in particular, by setting this mass ratio to 3.00 or less, the stability of the glass is improved. Be done. Therefore, the mass ratio TiO ₂ / SiO ₂ may be preferably 3.00 or less, more preferably 2.50 or less, and even more preferably 2.26 or less.

The ratio (mass ratio) of the sum of the contents of the TiO ₂ component, the ZnO component and the BaO component to the content of the La ₂ O _{3 component is preferably 1.50 or less.} As a result, the refractive index can be increased without the Abbe number of the glass becoming too low. Therefore, the mass ratio (TiO ₂ + ZnO + BaO) / La ₂ O ₃ is preferably 1.50 or less, more preferably 1.30 or less, still more preferably 1.08 or less, still more preferably less than 1.00, still more preferably. It shall be less than 0.950.
On the other hand, this ratio may be 0.50 or more. As a result, the refractive index can be increased while maintaining the stability of the glass. Therefore, the mass ratio (TiO ₂ + ZnO + BaO) / La ₂ O ₃ may be preferably 0.50 or more, more preferably 0.60 or more, and further preferably 0.70 or more.

The ratio (mass ratio) of the content of the BaO component to the content of the Ln ₂ O ₃ component (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is 0.0400. More than 0.5000 is preferable.
In particular, by setting this ratio to 0.0400 or more, the stability of the glass can be enhanced and the desired low Abbe number can be easily obtained. Therefore, the mass ratio BaO / Ln ₂ O ₃ is preferably 0.0400 or more, more preferably 0.0600 or more, still more preferably more than 0.1000, still more preferably more than 0.1500, still more preferably more than 0.2000. And.
On the other hand, by setting this ratio to 0.5000 or less, devitrification due to excessive inclusion of the BaO component can be reduced. Therefore, the mass ratio BaO / Ln ₂ O ₃ is preferably 0.5000 or less, more preferably 0.4400 or less, still more preferably 0.3800 or less, still more preferably 0.3433 or less.

The ratio (mass ratio) of the sum of the contents of the _{SiO 2} component and the BaO component to the content of the ZnO component is preferably 8.00 or less. As a result, the stability of the glass can be improved. Therefore, the mass ratio (SiO ₂ + BaO) / ZnO is preferably 8.00 or less, more preferably less than 6.50, still more preferably less than 5.50, still more preferably less than 5.30, still more preferably 4.80. Less than, more preferably less than 4.00, still more preferably less than 3.50.

The ratio (mass ratio) of the sum of the contents of the _{TiO 2} component and the La ₂ O ₃ component to the content of the BaO component is preferably 2.00 or more and 12.00 or less.
In particular, by setting this ratio to 2.00 or more, the refractive index of the glass can be increased. Therefore, the mass ratio (TiO ₂ + La ₂ O ₃ ) / BaO is preferably 2.00 or more, more preferably 3.00 or more, still more preferably 3.50 or more, still more preferably 4.02 or more.
On the other hand, by setting this ratio to 12.00 or less, the stability of the glass can be enhanced and devitrification can be reduced. Therefore, the mass ratio (TiO ₂ + La ₂ O ₃ ) / BaO is preferably 12.00 or less, more preferably 10.00 or less, still more preferably 8.00 or less, still more preferably 7.50 or less, still more preferably. It shall be 7.26 or less.

In the optical glass of the present invention, the refractive index can be increased by keeping _{the mass ratio (TiO 2} + La ₂ O _{3 ) / BaO within the above range while particularly reducing the mass ratio (SiO 2} + BaO) / ZnO. However, more stable glass can be obtained.

The sum (mass sum) of the contents of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is preferably 7.0% or more and 25.0% or less.
In particular, when this sum is 7.0% or more, the refractive index is increased, the Abbe number is decreased, and the stability of the glass is increased, so that it is possible to easily obtain an optical glass having a high refractive index and a high dispersion. Therefore, the sum of mass (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 7.0% or more, more preferably more than 9.0%, still more preferably more than 11.0%, still more preferably more than 14.0%. And.
On the other hand, by setting the sum to 25.0% or less, coloring and devitrification of the glass due to excessive inclusion of these components can be reduced. Therefore, the sum of mass (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 25.0% or less, more preferably less than 22.0%, still more preferably less than 19.0%, still more preferably less than 17.0%. And.

The ratio (mass ratio) of the content of the _{TiO 2} component to the sum of the contents of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO _{3 component is preferably 0.600 or more.} As a result, the material cost of glass can be reduced while obtaining a high refractive index and a low Abbe number. Therefore, the mass ratio TiO ₂ / (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 0.600 or more, more preferably 0.700 or more, still more preferably 0.800 or more, still more preferably 0.900 or more. To do.
On the other hand, the upper limit of this mass ratio may be 1.000.

The sum (mass sum) of the contents of the Ta ₂ O ₅ component, the Gd ₂ O ₃ component and the Nb ₂ O _{5 is preferably 10.0% or less.} As a result, the costly material is reduced, so that the material cost of glass can be reduced. Therefore, the sum of mass (Ta ₂ O ₅ + Gd ₂ O ₃ + Nb ₂ O ₅ ) is preferably 10.0% or less, more preferably less than 7.0%, still more preferably less than 5.0%, still more preferably 2. It is less than 0.0%, more preferably less than 1.0%.

The ratio (mass ratio) of the sum of the contents of the _{Ta 2} O ₅ component, the Gd ₂ O ₃ component and the Nb ₂ O ₅ component to the sum of the contents of the TiO ₂ component and the ZnO component is preferably 0.500 or less. As a result, among the components that increase the refractive index, the components having a high material cost are _{reduced relative to the contents of the TiO 2} component and the ZnO component, which are low in material cost, so that the material cost of glass can be reduced. Therefore, the mass ratio (Ta ₂ O ₅ + Gd ₂ O ₃ + Nb ₂ O ₅ ) / (TiO ₂ + ZnO) is preferably 0.500 or less, more preferably 0.400 or less, still more preferably 0.290 or less, and further. It is preferably 0.230 or less, more preferably 0.190 or less, still more preferably less than 0.100.

The sum (mass sum) of the contents of the CaO component and the SrO component is preferably 10.0% or less. As a result, a decrease in the refractive index can be suppressed. Therefore, the mass sum (CaO + SrO) is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.5%.

The sum (mass sum) of the contents of the RO component (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, Zn) is 10.0% or more and 40.0% or less. preferable.
In particular, by setting this sum to 1.0% or more, the meltability of the glass raw material and the devitrification resistance of the glass can be enhanced. Therefore, the total content of the RO component is preferably 10.0% or more, more preferably more than 13.0%, still more preferably more than 15.0%, still more preferably more than 17.0%, still more preferably 18. It shall be over 0%.
On the other hand, by setting the sum to 40.0% or less, devitrification due to excessive inclusion of these components can be reduced, and a decrease in the refractive index can be suppressed. Therefore, the total content of the RO component is preferably 40.0% or less, more preferably less than 35.0%, still more preferably less than 30.0%, still more preferably less than 25.0%, still more preferably 23. It shall be less than 0%.

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 refractive index of the glass and reduce devitrification. Therefore, _{the mass sum of the contents of the Rn 2} O 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%. ..

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, and Yb) is 27.0% or more and 52.0% or less. Is preferable.
In particular, when the mass sum is 27.0% or more, the refractive index of the glass can be increased, so that a high refractive index glass can be easily obtained. Therefore, _{the mass sum of the contents of the Ln 2} O ₃ components is preferably 27.0% or more, more preferably more than 30.0%, still more preferably more than 35.0%, still more preferably more than 37.0%. To do.
On the other hand, when the mass sum is 52.0% or less, the liquidus temperature of the glass is lowered, so that the devitrification resistance can be improved. Further, as a result, an increase in the Abbe number can be suppressed, and the material cost of glass can be suppressed. Therefore, _{the mass sum of the contents of the Ln 2} O ₃ components is preferably 52.0% or less, more preferably less than 51.0%, still more preferably less than 49.0%, still more preferably less than 45.0%. It is more preferably less than 43.0%, still more preferably less than 40.0%.

<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. Therefore, it is preferable that the glass is substantially not contained, especially in optical glass using a 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, the above raw materials are uniformly mixed so that each component is within a predetermined content range, and the prepared mixture is put into a platinum crucible, a quartz crucible or an alumina crucible to be roughly melted, and then a platinum crucible or a platinum alloy. Place in a crucible or iridium crucible and melt in a temperature range of 1100 to 1400 ° C for 1 to 5 hours, homogenize with stirring to break bubbles, etc., then lower the temperature to 1000 to 1300 ° C and perform finish stirring to pulse. It is produced by removing the crucible, casting it in a mold, and slowly cooling it.

<Physical characteristics>
The optical glass of the present invention has a high refractive index and a high Abbe number (low dispersion).
_{In particular, the lower limit of the refractive index (nd} ) of the optical glass of the present invention is preferably 1.85 or more, more preferably 1.87 or more, still more preferably more than 1.88, still more preferably more than 1.90. .. The upper limit of the refractive index may be preferably 2.20 or less, more preferably less than 2.10, still more preferably less than 2.00, still more preferably less than 1.95. _{Further, the lower limit of the Abbe number (ν d} ) of the optical glass of the present invention is preferably 25 or more, more preferably 27 or more, and further preferably more than 30. The upper limit of the Abbe number is preferably 35 or less, more preferably less than 34, and further preferably less than 33.
Since the optical glass of the present invention has such a refractive index and Abbe number, it is useful in optical design, and it is possible to reduce the size of the optical system while achieving particularly high imaging characteristics, and the optical design can be achieved. The degree of freedom can be expanded.

Here, the optical glass of the present invention is a refractive index _{(n d)} and Abbe number ([nu _d) is, - the _{(0.01ν d +2.15) ≦ n d} ≦ (-0.01ν d +2.25) It is preferable to satisfy the relationship. In the glass having the composition specified in the present invention, a more stable glass can be obtained by satisfying this relationship between _{the refractive index (nd} ) and the Abbe number (ν _d).
Accordingly, in the optical glass of the present invention refractive index _{(n d)} and Abbe number ([nu _d) is, it is preferable to satisfy the relation of _{n d ≧ (-0.01ν d +2.15)} , n d ≧ (- it is more preferable to satisfy the relationship 0.01ν _d +2.17), it is more preferable to satisfy the relation of _{n d ≧ (-0.01ν d +2.19)} .
On the other hand, the optical glass of the present invention refractive index _{(n d)} and Abbe number ([nu _d) is, it is preferable to satisfy the relation of _{n d ≦ (-0.01ν d +2.25)} , n d ≦ ( it is more preferable to satisfy the relationship -0.01ν _d +2.24), it is more preferable to satisfy the relation of _{n d ≦ (-0.01ν d +2.23)} .

It is preferable that the optical glass of the present invention has a high visible light transmittance, particularly a light transmittance on the short wavelength side of visible light, and thus less coloring.
In particular, in the optical glass of the present invention, the wavelength (λ ₇₀ ) showing a spectral transmittance of 70% in a sample having a thickness of 10 mm is preferably 450 nm, more preferably 430 nm, and further preferably 420 nm in terms of glass transmittance. The upper limit.
Further, in the optical glass of the present invention, the shortest wavelength (λ ₅ ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm is preferably 400 nm, more preferably 380 nm, and further preferably 370 nm as the upper limit.
As a result, the absorbing edge of the glass becomes near the ultraviolet region, and the transparency of the glass with respect to visible light is enhanced. Therefore, this optical glass can be preferably used for an optical element such as a lens that transmits light.

The optical glass of the present invention preferably has a small specific gravity. More specifically, the specific gravity of the optical glass of the present invention is preferably 5.00 or less. As a result, the mass of the optical element and the optical device using the optical element is reduced, which can contribute to the weight reduction of the optical device. Therefore, the specific gravity of the optical glass of the present invention is preferably 5.00, more preferably 4.80, and even more preferably 4.70. The specific gravity of the optical glass of the present invention is often 3.00 or more, more specifically 3.50 or more, and more specifically 4.00 or more.
The specific gravity of the optical glass of the present invention is measured based on the Japan Optical Glass Industry Association standard JOBIS05-2015 "Method for measuring the specific gravity of optical glass".

The optical glass of the present invention preferably has high devitrification resistance, and more specifically, has a low liquidus temperature. That is, the liquidus temperature of the optical glass of the present invention is preferably 1200 ° C., more preferably 1150 ° C., and even more preferably 1100 ° C. As a result, even if the molten glass flows out at a lower temperature, the crystallization of the produced glass is reduced, so that the devitrification when the glass is formed from the molten state can be reduced, and the optics using the glass can be reduced. The influence on the optical characteristics of the element can be reduced. Further, since the glass can be formed even if the melting temperature of the glass is lowered, the manufacturing cost of the glass can be reduced by suppressing the energy consumed at the time of forming the glass. On the other hand, the lower limit of the liquidus temperature of the optical glass of the present invention is not particularly limited, but the liquidus temperature of the glass obtained by the present invention is approximately 800 ° C. or higher, specifically 850 ° C. or higher, and more specifically 900. Often above ° C. The term "liquid phase temperature" as used herein refers to a 30 cc cullet-shaped glass sample placed in a platinum crucible having a capacity of 50 ml and completely melted at 1250 ° C., and the temperature is lowered to a predetermined temperature. When the temperature is maintained for 1 hour, taken out of the furnace, cooled, and immediately observed on the glass surface and the presence or absence of crystals in the glass, it represents the lowest temperature at which no crystals are observed. Here, the predetermined temperature at the time of lowering the temperature is a temperature in increments of 10 ° C. between 1200 ° C. and 800 ° C.

[Glass molded body and optical element]
From the produced optical glass, a glass molded body can be produced by using, for example, polishing means or mold press molding means such as reheat press molding or precision press molding. That is, a glass molded body is produced by performing machining such as grinding and polishing on optical glass, or reheat press molding is performed on a preform produced from optical glass and then polishing is performed to perform glass molding. A body can be produced, a preform produced by polishing, or a preform formed by a known levitation molding or the like can be subjected to precision press molding to produce a glass molded body. The means for producing the glass molded body is not limited to these means.

As described above, the glass molded body formed from the optical glass of the present invention is useful for various optical elements and optical designs, and among them, it is particularly preferable to use it for optical elements such as lenses and prisms. This makes it possible to form a glass molded body with a large diameter, so that while increasing the size of the optical element, high-definition and highly accurate imaging characteristics and projection when used in optical equipment such as cameras and projectors. The characteristics can be realized.

The composition of Examples (No. 1 to No. 29) of the present invention, _{and the wavelengths (refractive index (nd} ), Abbe number (ν _d ), liquidus temperature, and spectral transmittance showing 5% and 70%). λ ₅ , λ ₇₀ ) and specific gravity are shown in Tables 1 to 4.
The following examples are for purposes of illustration only, and are not limited to these examples.

The glass of the example has high purity used for ordinary optical glass such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphate compounds, etc., which correspond to each component as a raw material. The raw materials of the above are selected, weighed so as to have the composition ratio of each Example and Comparative Example shown in the table, mixed uniformly, and then put into a platinum crucible, and an electric furnace is charged according to the melting difficulty of the glass composition. Melt in a temperature range of 1100 to 1400 ° C. for 1 to 5 hours, homogenize with stirring to break bubbles, etc., then lower the temperature to 1000 to 1300 ° C. to homogenize with stirring, cast in a mold, and slowly cool. Glass was made.

_{The refractive index (nd} ) and Abbe number (ν _d ) of the glass of the example were shown by the measured values with respect to the d line (587.56 nm) of the helium lamp. The Abbe number (ν _d ) is the refractive index of the d line, the refractive index of the hydrogen lamp with respect to the F line (486.13 nm) (n _F ), and the refractive index of the hydrogen lamp with respect to the C line (656.27 nm) (n _C ). It was calculated from the formula of Abbe number (ν _d ) = [(n _d -1) / (n _F −n _{C)] using the value of.} Then, from the obtained values of the refractive index ( _nd ) and the Abbe number (ν _d ), the intercept b in the relational expression n _d = −a × ν _d + b when the slope a is 0.01 was obtained. The glass used for this measurement was treated in a slow cooling furnace at a slow cooling rate of −25 ° C./hr.

The liquidus temperature of the glass of the example is such that a 30 cc cullet-shaped glass sample is placed in a platinum crucible having a capacity of 50 ml and completely melted at 1250 ° C. in increments of 10 ° C. from 1200 ° C. to 800 ° C. When the temperature was lowered to one of the set temperatures, held for 1 hour, taken out of the furnace, cooled, and immediately observed for the presence or absence of crystals on the glass surface and in the glass, the lowest temperature at which no crystals were observed was obtained. It was.

The transmittance of the glass of the example was measured according to the Japan Optical Glass Industry Association standard JOBIS02-2003. In the present invention, the presence or absence and degree of coloring of the glass were determined by measuring the transmittance of the glass. Specifically, a face-to-face parallel polished product having a thickness of 10 ± 0.1 mm was measured for a spectral transmittance of 200 to 800 nm according to JISZ8722, and λ ₅ (wavelength at a transmittance of 5%) and λ ₇₀ (transmittance). The wavelength at 70%) was determined.

The specific gravity of the glass of the example was measured based on the Japan Optical Glass Industry Association standard JOBIS05-2015 "Measuring method of the specific gravity of optical glass".

As these tables, the optical glasses of Examples of the present invention are both refractive index (n _d) of 1.85 or more, with more detail is 1.89 or more, the refractive index (n _d) is It was 2.20 or less, more specifically 1.91 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 25 or more, more specifically 30 or more, and this Abbe number (ν _d ) is 35 or less, more specifically 33. It was below and was within the desired range.

The optical glasses of Examples of the present invention is a refractive index _{(n d)} and Abbe number ([nu _{d) is, (- 0.01ν d +2.15) ≦} n d ≦ (-0.01ν d +2.25 ) Was satisfied, and more specifically, the relationship of (−0.02ν _d +2.20) ≦ n _d ≦ (−0.02ν _d +2.23) was satisfied. _{Then, the relationship between the refractive index (nd} ) and the Abbe number (ν _d ) for the glass of the embodiment of the present application is shown in FIG.
Accordingly, the optical glasses of Examples of the present invention is cheap TiO ₂ component and ZnO components of material cost among components contributing to a high refractive index, when incorporated the BaO component refractive index (n _d) and Abbe It has been clarified that an optical glass having a number (ν _d ) within a desired range and having high stability can be obtained.

Further, none of the optical glasses of the examples of the present invention was devitrified, and the liquidus temperature was 1200 ° C. or lower, more specifically 1100 ° C. or lower, which was within a desired range.

Further, all of the optical glasses of the examples of the present invention had a specific gravity of 5.00 or less, more specifically 4.70 or less, which were within a desired range.

Further, in the optical glass of the example of the present invention, λ ₇₀ (wavelength at a transmittance of 70%) was 450 nm or less, and more specifically, 430 nm or less. Further, in the optical glass of the example of the present invention, λ ₅ (wavelength at a transmittance of 5%) was 400 nm or less, and more specifically, 370 nm or less. Therefore, it has been clarified that the optical glass of the embodiment of the present invention has a high transmittance for visible light and is difficult to be colored.

Therefore, the optical glass of the embodiment of the present invention has a refractive index ( _nd ) and an Abbe number (ν _d ) within desired ranges, has high stability, has high transmittance for visible light, and has a specific gravity. It has become clear that small optical glasses can be obtained at a lower cost.

Although the present invention has been described in detail above for the purpose of exemplification, the present embodiment is merely for the purpose of exemplification, 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%
B ₂ O ₃ component 6.0% or more and 24.0% or less ,
La ₂ O ₃ component more than 31.0% and less than 50.0%,
TiO ₂ component is 6.0% or more and less than 20.0% ,
ZnO component is more than 5.0% and less than 23.0%,
BaO component is 4.0% or more and less than 18.0%
Containing mass ratio (TiO ₂ + ZnO + BaO) / La ₂ O ₃ is 0.979 or less,
The sum of mass (Ta ₂ O ₅ + Gd ₂ O ₃ + Nb ₂ O ₅ ) is less than 2.0% ,
The mass ratio BaO / Ln ₂ O ₃ (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is more than 0.2000 and 0.5000 or less, and has a refractive index of 1.85 or more. _{(n d)} has an optical glass having 25 or more 35 or less Abbe number (ν _d). The optical glass according to claim 1, wherein the mass ratio (SiO _{2 + BaO) / ZnO is 8.00 or less.} A preform material made of optical glass according to any one of claims 1 to 2. An optical element made of the optical glass according to any one of claims 1 to 2. An optical device including the optical element according to claim 4.

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