JP6893749B2 - Optical glass, lens preforms and optics - Google Patents

Description

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

In recent years, the digitization and high definition of devices that use optical systems have been rapidly advancing, and the precision of optical elements such as lenses used in various optical devices, including photography devices such as digital cameras and video cameras, has been improved. The demand for light weight and miniaturization is increasing more and more.

Among the optical glasses for which optical elements are manufactured, glass having a high refractive index ( _nd ) but a lower Abbe number (ν _d ), which can reduce the weight and size of the optical element. Demand is very high. The glass having a high refractive index and low Abbe number, for example, the refractive index (n _d) is not less than 1.70, as an optical glass having an Abbe number of 35 or less, as disclosed in Patent Documents 1 to 4 Glass is known.

Japanese Unexamined Patent Publication No. 2011-001259 Japanese Unexamined Patent Publication No. 08-104537 Japanese Unexamined Patent Publication No. 05-270853 Japanese Unexamined Patent Publication No. 2006-11149

When manufacturing an optical element using such glass, a method of grinding and polishing a glass molded product obtained by heating and softening the glass and press molding (reheat press molding), or cutting and polishing a gob or a glass block. A method (precision press molding) is used in which a preform material obtained by heating or a preform material formed by a known levitation molding or the like is heat-softened and press-molded with a mold having a high-precision molding surface.

However, in the glass disclosed in Patent Documents 1 to 4, the glass is colored yellow or orange because the transmittance for light on the short wavelength side of visible light is low. Further, the glasses disclosed in Patent Documents 1 to 4 are not sufficiently stable. Therefore, the glass disclosed in Patent Documents 1 to 4 is not suitable for the application of transmitting light in the visible region.

The present invention has been made in view of the above problems, and an object of the present invention is to have a high refractive index ( _nd ) and a low Abbe number (ν _d ), but to have devitrification resistance. An object of the present invention is to provide an optical glass having a high visible light transmittance and a lens preform and an optical element using the optical glass.

The present inventors have found that in order to solve the above problems, the results of extensive _research, containing P 2 _{O 5} component, _Nb 2 _{O 5} component, and ZnO ingredients, these and SnO ₂ component, _Sb 2 _{O 3} We have found that by using at least one of a component, an F component, and an S component in combination, the transmittance for visible light can be increased and the stability of the glass can be enhanced while increasing the refractive index of the glass. Has been completed. Specifically, the present invention provides the following.

(1) In terms of mass%, P ₂ O ₅ component is 5.0% or more and 40.0% or less, Nb ₂ O ₅ component is 20.0% or more and 60.0% or less, and Zn O component is more than 0.5% 35. containing 2.0% or less, SnO ₂ component, _Sb 2 _{O 3} component, it contains at least one of F component and S component, 1.70 or more refractive index _{(n d)} and 35 following an Abbe number ([nu _d ) With optical glass.

(2) _{The optical glass according to (1), wherein the total amount of the SnO 2} component, the Sb ₂ O ₃ component, the F component and the S component is more than 0% and 10.0% or less.

(3) By the external division mass% with respect to the oxide-based mass
F component 0-5.0%
S component 0-5.0%
The optical glass according to (1) or (2).

(4) By mass%
SnO ₂ component 0 to 10.0%
Sb ₂ O ₃ component 0-3.0%
The optical glass according to any one of (1) to (3).

(5) By mass%
TiO ₂ component 0 to 25.0%
Bi ₂ O ₃ component 0 to 10.0%
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 sum of mass (TiO ₂ + Nb ₂ O ₅ + Bi ₂ O _{3) is 30.0% or more and 70.0% or less.}

(7) The optical glass according to any one of (1) to (6), wherein the mass ratio ZnO / (TiO ₂ + Nb ₂ O ₅ + Bi ₂ O _{3) is 0.05 or more.}

(8) By mass%
SiO ₂ component 0 to 10.0%
B ₂ O ₃ component 0 to 10.0%
Al ₂ O ₃ component 0 to 10.0%
The optical glass according to any one of (1) to (7).

(9) The optical glass according to any one of (1) to (8), wherein the sum of mass (SiO ₂ + B ₂ O ₃ + Al ₂ O _{3) is 0.1% or more and 20.0% or less.}

(10) By mass%
Li ₂ O component 0 to 10.0%
Na ₂ O component 0 to 15.0%
K ₂ O component 0 to 15.0%
The optical glass according to any one of (1) to (9).

(11) The optical glass according to any one of (1) to (10), wherein the mass ratio (SnO + Sb ₂ O ₃ + F + S) / (SiO ₂ + B ₂ O ₃ + Al ₂ O _{3) is 0.01 or more.}

(12) in mass%, _{R 2} O component is an optical glass (R according to any of the sum of the contents is not more than 20.0% (1) to (11) of Li, from the group consisting of Na and K One or more selected).

(13) MgO component 0 to 15.0% by mass%
CaO component 0 to 15.0%
SrO component 0 to 15.0%
BaO component 0-30.0%
The optical glass according to any one of (1) to (12).

(14) The optical glass according to any one of (1) to (13), wherein the sum of the contents of the MO components is 30.0% or less (M is selected from the group consisting of Mg, Ca, Sr and Ba1). More than a seed).

(15) The optical glass according to any one of (1) to (14) (R is a group consisting of Li, Na and K) containing 0.1% or more and 40.0% or less of _{R 2 O component and MO component in total.} One or more selected from the group, and M is one or more selected from the group consisting of Mg, Ca, Sr and Ba).

(16) The optical glass according to any one of (1) to (15) having a mass ratio ZnO / (R ₂ O + MO) of 0.10 or more (R is one selected from the group consisting of Li, Na and K). As described above, M is one or more selected from the group consisting of Mg, Ca, Sr and Ba).

(17) The optical glass according to any one of (1) to (16), wherein the content of _{WO 3 component is 15.0% or less in mass%.}

(18)% by weight _Y 2 _{O 3} component from 0 to 10.0%
La ₂ O ₃ component 0 to 10.0%
Gd ₂ O ₃ component 0 to 10.0%
Yb ₂ O ₃ component 0 to 10.0%
The optical glass according to any one of (1) to (17).

(19) From _{(1), the sum of the contents of the Ln 2} O ₃ component (Ln is one or more selected from the group consisting of Y, La, Gd and Yb) is 15.0% or less (1). 18) The optical glass according to any one of.

(20) By mass%
GeO ₂ component 0-10.0%
TeO ₂ component 0 to 15.0%
ZrO ₂ component 0-10.0%
Ta ₂ O ₅ component 0 to 10.0%
Ga ₂ O ₃ component 0 to 10.0%
The optical glass according to any one of (1) to (19).

(21) The optical glass according to any one of (1) to (20), wherein the _{wavelength (λ 70} ) showing a spectral transmittance of 70% is 490 nm or less.

(22) The optical glass according to any one of (1) to (21), wherein the glass transition point is 680 ° C. or lower.

(23) An optical element made of the optical glass according to any one of (1) to (22).

(24) A preform for polishing and / or precision press molding made of the optical glass according to any one of (1) to (22).

(25) An optical element obtained by precision pressing the preform according to (24).

According to the present invention, _{an optical glass having a high refractive index (nd} ) and a low Abbe number (ν _d ), yet having high devitrification resistance and high visible light transmittance, and a lens using the same. Preforms and optical elements can be provided.

The optical glass of the present invention, in _mass%, P 2 _{O 5} ingredient 40.0% 5.0% or more or less, _Nb 2 _{O 5} ingredient 60.0% 20.0% or more of the following, the ZnO component 0. containing more than 5% 35.0% or less, SnO ₂ component, _Sb 2 _{O 3} component, it contains at least one of F component and S component, 1.70 or more refractive index _{(n d)} and 35 following Abbe It has a number (ν _d ). By containing the P ₂ O ₅ component and the Nb ₂ O ₅ component and containing a ZnO component of a predetermined value or more, the transmittance for visible light can be increased while increasing the refractive index of the glass. It _{contains P 2} O ₅ component, Nb ₂ O ₅ component and Zn O _{component, and by using at least one of SnO 2} component, Sb _{2 O 3} component, F component and S component in combination with these, the internal transmittance of the glass And even if the content of the ZnO component and other components is increased, the devitrification of the glass can be reduced. Therefore, an optical glass having a high refractive index ( _nd ) and a low Abbe number (ν _d ), but having high devitrification resistance and high visible light transmittance, a lens preform using the optical glass, and a lens preform using the optical glass. Optical elements can be provided.

_{In particular, the present invention has conventionally contained only a small amount, and the ZnO component and SnO 2} which have only been described in the literature based on speculation such as "if the content is too large, the devitrification resistance decreases" and the like. It was newly found that a stable glass having a high refractive index and a high visible light transmittance can be obtained by using at least one of a component, an Sb ₂ O _{3 component, an F component and an S component in combination.} Is.

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. Unless otherwise specified in the present specification, the content of each component shall be expressed as a mass% of the total mass of the 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 at the time of melting and changed to oxides. The composition is such that each component contained in the glass is described with the total mass of the produced oxide as 100% by mass.

<About essential ingredients and optional ingredients>
The P ₂ O ₅ component is a glass forming component and an essential component that lowers the melting temperature of the glass raw material. In particular, by _{setting the content of the P 2} O ₅ component to 5.0% or more, the stability of the glass and the transmittance in the visible region can be improved. Therefore, the _{lower limit of the content of the P 2} O ₅ component is preferably 5.0%, more preferably 13.0%, still more preferably 18.0%, still more preferably 22.0%.
On the other hand, a high refractive index can be obtained by setting the content _{of the P 2} O _{5 component to 40.0% or less.} Therefore, _{the content of the P 2} O ₅ component is preferably 40.0%, more preferably 35.0%, and even more preferably 32.0%.
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 Nb ₂ O ₅ component is an essential component that increases the devitrification resistance, chemical durability and refractive index of glass and lowers the Abbe number. In particular, by _{containing 20.0% or more of the Nb 2} O ₅ component, a high refractive index can be obtained and a desired low Abbe number can be obtained. Further, by _{containing 20.0% or more of the Nb 2} O ₅ component, a lower coefficient of thermal expansion can be easily obtained, and there is an effect of preventing glass breakage in a processing process accompanied by a temperature change such as a precision press. Therefore, _{the content of the Nb 2} O ₅ component is preferably 20.0%, more preferably 26.0%, still more preferably 31.0%, still more preferably 36.0% as the lower limit, still more preferably 38. It should be over 0.0%.
On the other hand, by reducing _{the content of the Nb 2} O ₅ component to 60.0% or less, the devitrification resistance of the glass can be enhanced. Therefore, _{the content of the Nb 2} O ₅ component is preferably 60.0%, more preferably 55.0%, and even more preferably 52.0%.
As the Nb ₂ O _{5 component, Nb 2} O ₅ or the like can be used as a raw material.

The ZnO component is an essential component that enhances the devitrification resistance of glass. In particular, by containing more than 0.5% of the ZnO component, the meltability and devitrification resistance of the glass raw material can be enhanced, the glass transition point can be lowered, the transmittance of the glass for visible light can be enhanced, and the specific gravity can be increased. Can be reduced and the refractive index can be increased. Further, since the ZnO component is a component that lowers the coefficient of thermal expansion, it has an effect of preventing glass breakage in a processing process accompanied by a temperature change such as a precision press. Therefore, the content of the ZnO component is preferably more than 0.5%, more preferably more than 1.0%, still more preferably more than 2.0%, still more preferably more than 3.0%, still more preferably 4.0. %. Here, the content of the ZnO component may be more than 8.0% or more than 10.0%.
On the other hand, the upper limit of the content of the ZnO component is preferably 35.0%, more preferably 30.0%, still more preferably 25.0%, still more preferably 21.0%.
As the ZnO component, ZnO, Zn (PO ₃ ) ₂ , ZnSO ₄ , ZnF _2, or the like can be used as a raw material.

The optical glass of the present invention _{contains at least one of SnO 2} component, Sb ₂ O ₃ component, F component and S component in an amount of more than 0%. As a result, defoaming of the glass can be promoted, and the internal transmittance can be increased by reducing the coloring of the glass. _{Therefore, the total of the contents of the SnO 2} component and the Sb ₂ O ₃ component with respect to the total mass of the oxide conversion composition and the contents of the F component and the S component in the external division with respect to the oxide-based mass is preferably 0. The lower limit may be more than%, more preferably 0.1%, and even more preferably 0.2%.
On the other hand, by setting the total content to 10.0% or less, it is possible to easily suppress the occurrence of veins on the glass, the decrease in devitrification resistance, and the coloring. It is possible to prevent excessive foaming when the glass is melted. Therefore, the total content of the F component and the S component in the external division with respect to the oxide-based mass is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, still more preferably 1. The upper limit is 0.0%.

The F component is an optional component that can enhance the meltability and devitrification resistance of the glass, promote defoaming of the glass, reduce the coloring of the glass, and increase the internal transmittance by containing more than 0%. ..
On the other hand, by setting the content of the F component to 5.0% or less, it is possible to reduce the occurrence of veins in the glass and make it difficult for the glass to be devitrified. Therefore, the content of the F component in the external division with respect to the mass based on the oxide is preferably 5.0%, more preferably 3.0%, and further preferably 1.0%.
As the F component, ZrF ₄ , AlF ₃ , NaF, CaF ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ , LaF _{3, and the} like can be used as raw materials.

The S (sulfur) component is an optional component that can promote defoaming of glass, reduce coloration of glass, and increase internal transmittance by containing more than 0%.
On the other hand, by setting the content of the S component to 5.0% or less, it is possible to reduce the occurrence and coloring of veins on the glass and make it difficult for the glass to be devitrified. Therefore, the content of the S component in the external division with respect to the mass based on the oxide is preferably 5.0%, more preferably 3.0%, and further preferably 1.0%.
S component, it is preferable to use a sulfate as a starting material, for example, _{Li 2 SO 4 · H 2 O} , Na 2 SO 4, K 2 SO 4, MgSO 4, CaSO 4 · 1 / 2H 2 O, SrSO 4, BaSO _{4, ZnSO 4 · 7H 2 O} , can be used _{ZnSO 4, La 2 (SO 4} ) 3 · 9H 2 O and the like.

The total content of the F component and the S component is preferably more than 0% and 5.0% or less.
By setting the total content to more than 0%, defoaming of the glass can be promoted, and by reducing the coloring of the glass, the internal transmittance can be increased. Therefore, the total content of the F component and the S component in the external division with respect to the oxide-based mass may be preferably more than 0%, more preferably 0.1%, and further preferably 0.2% as the lower limit.
On the other hand, by setting the total content to 5.0% or less, the occurrence of veins and coloring on the glass can be reduced, and the glass can be made less likely to be devitrified. Therefore, the total content of the F component and the S component in the external division with respect to the mass based on the oxide is preferably 5.0%, more preferably 3.0%, and further preferably 1.0%.

The contents of the F component and the S component in the present specification assume that all the cation components constituting the glass are made of oxides bonded to oxygen having a balance of electric charges, and the whole glass made of these oxides is made of oxides. The masses of the F component and the S component when the mass is 100% are shown in units of mass% (externally divided mass% with respect to the oxide-based mass. Hereinafter, it may be simply referred to as "externally divided mass%"). It was done.

When the SnO ₂ component is contained in excess of 0%, the defoaming of the glass can be promoted, and at the same time, _{the reduction of the Nb 2} O ₅ component, the TiO ₂ component, etc. is suppressed, thereby increasing the transmittance of the glass for visible light. Is an optional ingredient. Therefore, _{the content of the SnO 2} component may be preferably more than 0%, more preferably 0.05% or more, still more preferably 0.1% or more.
On the other hand, when _{the content of the SnO 2} component exceeds 10.0%, the glass tends to be devitrified, the transmittance in visible light also tends to decrease, and the SnO ₂ component and melting equipment (particularly precious metals such as Pt) are likely to decrease. ) Is likely to occur. Therefore, _{the content of the SnO 2} component is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%.
As the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , and SnF ₄ can be used as raw materials.

When the Sb ₂ O ₃ component is contained in excess of 0%, the defoaming of the glass can be promoted, and at the same time, _{the reduction of the Nb 2} O ₅ component, the TiO ₂ component, etc. is suppressed, so that the transmittance of the glass with respect to visible light It is an optional ingredient that can enhance. Therefore, _{the content of the Sb 2} O ₃ component may be preferably more than 0%, more preferably 0.1% or more, still more preferably 0.2% or more.
On the other hand, when _{the content of the Sb 2} O ₃ component exceeds 3.0%, the transmittance in visible light tends to decrease, and the Sb ₂ O ₃ component and the melting equipment (particularly noble metal such as Pt) Alloying is likely to occur. Therefore, _{the content of the Sb 2} O ₃ component is preferably 3.0%, more preferably 1.0%, still more preferably 0.8%, still more preferably 0.5%.
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 components that clarify and defoam the _{glass are not limited to the above-mentioned SnO 2} component, Sb ₂ O ₃ component, F component, and S component, and are known in the field of glass production as a clarifying agent and a defoaming agent. Alternatively, a combination thereof can be used.

When the TiO ₂ component is contained in excess of 0%, the meltability, devitrification resistance and refractive index of the glass can be enhanced, the Abbe number can be reduced, and the chemical durability can be enhanced. Further, since the TiO ₂ component is a component that lowers the coefficient of thermal expansion, it has an effect of preventing glass breakage in a processing process accompanied by a temperature change such as a precision press.
On the other hand, by _{setting the content of the TiO 2} component to 25.0% or less, the decrease in the transmittance for visible light can be suppressed, and the decrease in the devitrification resistance can be suppressed. Therefore, _{the content of the TiO 2} component is preferably 25.0%, more preferably 20.0%, further preferably 15.0%, still more preferably 12.0%, still more preferably 6.0%. And.
As the TiO _{2 component, TiO 2} 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 of glass and the meltability of the glass raw material and lower the glass transition point when the content exceeds 0%.
On the other hand, by _{setting the content of the Bi 2} O ₃ component to 10.0% or less, it is possible to suppress a decrease in devitrification resistance and a decrease in the transmittance for visible light. In addition, the problem that the pot is invaded by the reduction of _{the Bi 2} O _{3 component can be suppressed.} Therefore, _{the content of the Bi 2} O ₃ component is preferably 10.0%, more preferably less than 5.0%, still more preferably less than 3.0%.

The total content (sum of mass) of the TiO ₂ component, the Nb ₂ O ₅ component, and the Bi ₂ O ₃ component is preferably 30.0% or more and 70.0% or less.
In particular, by setting the total amount to 30.0% or more, the refractive index of the glass can be increased and the Abbe number can be reduced. Therefore, the lower limit of the mass sum (TiO ₂ + Nb ₂ O ₅ + Bi ₂ O ₃ ) is preferably 30.0%, more preferably 35.0%, and even more preferably 41.0%.
On the other hand, by setting the total amount to 70.0% or less, the transmittance for visible light can be increased and coloring can be reduced. Further, since this makes it possible to obtain a stable glass with less coloring, it is possible to obtain a glass useful for mold pressing. Therefore, the sum of mass (TiO ₂ + Nb ₂ O ₅ + Bi ₂ O ₃ ) is preferably up to 70.0%, more preferably 63.0%, still more preferably 58.0%, still more preferably 54.0%. And.

The ratio (mass ratio) of the content of the ZnO component to the total content of the TiO ₂ component, the Nb ₂ O ₅ component, and the Bi ₂ O _{3 component is preferably 0.05 or more.} As a result, the decrease in devitrification resistance can be suppressed, and the transmittance for visible light can be increased. Therefore, the mass ratio ZnO / (TiO ₂ + Nb ₂ O ₅ + Bi ₂ O ₃ ) is preferably 0.05 or more, more preferably more than 0.065, and further preferably more than 0.08.
On the other hand, this ratio may be preferably up to 1.00, more preferably 0.80, even more preferably 0.60, still more preferably 0.45.

When the SiO ₂ component is contained in excess of 0%, it is an optional component that can increase the transmittance of glass for visible light and reduce coloration, and can enhance the devitrification resistance of glass by promoting stable glass formation. is there. In particular, by allowing the content of the SiO ₂ component, since the SiO ₂ component permits the use of the quartz crucible eluting molten glass, a higher transmittance glass is obtained. Of the SiO ₂ component and the B ₂ O ₃ component and Al ₂ O ₃ component described later, the SiO ₂ component has a particularly high effect of improving the devitrification resistance, and therefore, the B ₂ O ₃ component or the Al ₂ O ₃ component By using them in combination, the effect can be made more remarkable. Therefore, _{the content of the SiO 2} component may be preferably more than 0%, more preferably 0.2%, and even more preferably 0.3% as the lower limit.
On the other hand, by _{setting the content of the SiO 2} component to 10.0% or less, _{the decrease in devitrification resistance due to the SiO 2} component can be suppressed, so that it is possible to easily obtain a glass having high stability. Therefore, _{the content of the SiO 2} component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 2.5%, still more preferably less than 2.0%, still more preferably 1. It shall be less than 5%.
As the SiO _{2 component, SiO 2} , K ₂ SiF ₆ , Na ₂ SiF _6, or the like can be used as a raw material.

The B ₂ O ₃ component is a component that enhances the meltability of the glass raw material and promotes the formation of stable glass when the content exceeds 0%, thereby enhancing the devitrification resistance, and is an optional component in the glass. ..
On the other hand, by _{setting the content of the B 2} O ₃ component to 10.0% or less, the decrease in devitrification resistance can be suppressed and the transmittance for visible light can be increased. Therefore, _{the content of the B 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 2.7% or less.
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.

When the Al ₂ O ₃ component is contained in excess of 0%, the meltability, devitrification resistance and chemical durability of the glass can be enhanced, and the viscosity at the time of glass melting can be enhanced.
In particular, by _{setting the content of the Al 2} O ₃ component to 10.0% or less, the meltability of the glass raw material can be enhanced and the devitrification resistance can be enhanced. Therefore, _{the content of the Al 2} O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%.
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 total content (sum of mass) of the SiO ₂ component, the B ₂ O ₃ component and the Al ₂ O ₃ component is preferably 0.1% or more and 20.0% or less.
In particular, when the total amount is 0.1% or more, the stability of the glass is enhanced and the devitrification resistance is enhanced. Therefore, the mass sum (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) is preferably 0.1%, more preferably 0.5%, still more preferably 1.0%, still more preferably 1.3% as the lower limit. And.
On the other hand, by setting the total amount to 20.0% or less, it is possible to suppress a decrease in the refractive index and devitrification resistance of the glass. Therefore, the sum of mass (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) is preferably 20.0% or less, more preferably less than 15.0%, still more preferably less than 10.0%, still more preferably 7.5. It is less than%, more preferably less than 4.0%.

The _{content of SnO 2} component and Sb ₂ O ₃ component with respect to the total mass of the oxide conversion composition with respect to the total content of _{SiO 2} component, B ₂ O ₃ component and Al ₂ O ₃ component, and the outside of the oxide standard mass. The total ratio of the F component and the S component in the split is preferably 0.01 or more. As a result, the ratio of the component having a defoaming action to the glass forming component is increased, so that the defoaming effect on the molten glass can be further enhanced. Therefore, the mass ratio (SnO + Sb ₂ O ₃ + F + S) / (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) may be preferably 0.01, more preferably 0.03, and further preferably 0.05 as the lower limit. ..
On the other hand, this ratio may be preferably 0.50, more preferably 0.40, still more preferably 0.30 as the upper limit from the viewpoint of suppressing excessive foaming.

The Li ₂ O component is an optional component that can lower the melting temperature of the glass raw material and the glass transition point when the content exceeds 0%.
On the other hand, by _{reducing the content of the Li 2} O component to 10.0% or less, a decrease in the refractive index and an increase in the Abbe number can be suppressed, and the devitrification resistance can be enhanced. Therefore, _{the content of the Li 2} O component is preferably 10.0%, more preferably 5.0%, still more preferably 2.3%, still more preferably 1.5%.
As the Li ₂ O component, Li ₂ CO ₃ , LiPO ₃ , LiNO ₃ , LiF and the like can be used as raw materials.

When the Na ₂ O component is contained in excess of 0%, the melting temperature of the glass raw material and the glass transition point can be lowered, and the devitrification resistance can be enhanced.
On the other hand, by _{reducing the content of the Na 2} O component to 15.0% or less, it is possible to suppress a decrease in the refractive index and an increase in the Abbe number. Therefore, _{the content of the Na 2} O component is preferably 15.0%, more preferably 10.0%, further preferably 7.0%, and further preferably less than 5.0%.
As the Na ₂ O component, Na ₂ CO ₃ , NaH ₂ PO ₄ , Na NO ₃ , NaF, Na ₂ SiF _{6, and the} like can be used as raw materials.

The K ₂ O component is a component that can lower the melting temperature and glass transition point of the glass raw material when it is contained in excess of 0%, and is an optional component that can further enhance the devitrification resistance than the _{above-mentioned Na 2 O component.} ..
On the other hand, by the content of K 2 _O component below 15.0%, suppressed the decrease or increase of the Abbe number of the refractive index. Therefore, the content of _{K 2} O component is preferably 15.0%, more preferably 10.0%, more preferably 7.0%, more preferably the upper limit of 5.0%.
As the K ₂ O component, K ₂ CO ₃ , KH ₂ PO ₄ , KNO ₃ , KF, KHF ₂ , K ₂ SiF _{6, and the} like can be used as raw materials.

The total content (sum of mass) of the R ₂ O component (R is one or more selected from the group consisting of Li, Na and K) is preferably 20.0% or less. As a result, it is possible to suppress a decrease in the refractive index of the glass and an increase in the Abbe number. In addition, the devitrification resistance of glass is also enhanced. Therefore, _{the mass sum of the R 2} O components (for example, _{the total content of the Li 2} O component, the Na ₂ O component, and the K ₂ O component) is preferably 20.0%, more preferably 15.0% as the upper limit. , More preferably less than 12.0%, even more preferably less than 10.0%, still more preferably less than 6.0%.
On the other hand, this total amount may exceed 0%. As a result, the glass transition point (Tg) can be lowered and the transmittance for light in the visible region can be increased. Therefore, the mass sum of _{R 2} O component is preferably 0 percent, more preferably 0.5%, more preferably 1.0%, more preferably may be a lower limit of 2.0%.

The MgO component, CaO component and SrO component are optional components that can enhance the meltability and devitrification resistance of the glass raw material when the content exceeds 0%. In particular, the MgO component is a component that can reduce the coefficient of thermal expansion of glass and can reduce the specific gravity as compared with other alkaline earth components, particularly the BaO component.
On the other hand, by reducing the content of the MgO component to 15.0% or less, it is possible to suppress a decrease in devitrification resistance and an increase in the glass transition point. Therefore, the content of the MgO component is preferably 15.0%, more preferably 10.0%, still more preferably 5.0%, still more preferably 3.0%.
Further, by setting the content of each of the CaO component and the SrO component to 15.0% or less, the decrease in devitrification resistance and the increase in the glass transition point can be suppressed, and the thermal stability of the glass can be enhanced. Therefore, the content of each of the CaO component and the SrO component is preferably 15.0%, more preferably 10.0% as the upper limit, still more preferably less than 7.0%, still more preferably less than 4.0%. To do.
The MgO component, CaO component and SrO component are raw materials such as MgO, MgCO ₃ , Mg (PO ₃ ) ₂ , MgF ₂ , CaCO ₃ , Ca (PO ₃ ) ₂ , CaF ₂ , SrCO ₃ , Sr (NO ₃ ) ₂ , SrF _{2 and the} like can be used.

The BaO component is an optional component that, when it contains more than 0%, can further enhance the refractive index and the transmittance for visible light and enhance the devitrification resistance of glass when used in combination with the ZnO component.
On the other hand, by setting the content of the BaO component to 30.0% or less, an increase in the glass transition point and a specific gravity can be suppressed, and a decrease in devitrification resistance due to an excessive content can be suppressed. Therefore, the content of the BaO component is preferably 30.0%, more preferably 25.0%, further preferably 20.0%, further preferably 17.0%, still more preferably 11.0% as the upper limit. To do.
As the BaO component, BaCO ₃ , Ba (PO ₃ ) ₂ , BaSO ₄ , Ba (NO ₃ ) ₂ , BaF _2, etc. can be used as raw materials.

The total content (sum of mass) of the MgO component and the ZnO component is preferably more than 0.5% and 35.0% or less.
In particular, by setting the total content to more than 0.5%, the devitrification resistance, the refractive index, and the transmittance for visible light can be increased, the increase in the glass transition point can be suppressed, and the coefficient of thermal expansion of the glass can be reduced. And the specific gravity can be reduced. Therefore, the mass sum (MgO + ZnO) is preferably more than 0.5%, more preferably more than 1.0%, still more preferably more than 3.0%, still more preferably 4.5% or more, still more preferably 6.5. % Or more.
On the other hand, the total content may be preferably up to 35.0%, more preferably 30.0%, even more preferably 25.0%, even more preferably 22.0%.

The sum of the contents of the MO component (M is one or more selected from the group consisting of Mg, Ca, Sr and Ba) is preferably 30.0% or less. As a result, it is possible to suppress an increase in the glass transition point and a decrease in devitrification resistance due to excessive content. Therefore, the mass sum of the MO components (for example, the total content of the MgO component, the CaO component, the SrO component and the BaO component) is preferably 30.0%, more preferably 25.0%, still more preferably 20.0%. Is the upper limit. Here, the total content of MO components may be less than 15.0%.

The total content of R ₂ O component and the MO components (wt sum) is preferably not more than 40.0% or more 0.1% (R is Li, 1 or more selected from the group consisting of Na and K And M is one or more selected from the group consisting of Mg, Ca, Sr and Ba).
In particular, by setting the total content to 0.1% or more, the melting temperature of the glass raw material can be lowered, the glass transition point can be lowered, and the devitrification resistance of the glass and the transmittance for light in the visible region can be improved. Can be enhanced. Therefore, the lower limit of the mass sum (R ₂ O + MO) is preferably 0.1%, more preferably 1.0%, still more preferably 1.5%, still more preferably 2.0%.
On the other hand, by setting the total content to 40.0% or less, it is possible to suppress a decrease in the refractive index and an increase in the Abbe number. Therefore, the mass sum (R ₂ O + MO) is preferably up to 40.0%, more preferably 30.0%, still more preferably 25.0%, still more preferably 22.0%.

To the total content of R ₂ O component and the MO components, the ratio of the content of ZnO component (mass ratio) is preferably 0.10 or more. As a result, the devitrification resistance, the refractive index, and the transmittance for visible light can be increased, and the average linear expansion coefficient α can be reduced. Therefore, the mass ratio ZnO / (R ₂ O + MO) is preferably 0.10, more preferably 0.12, still more preferably 0.17, still more preferably 0.22, still more preferably 0.25, still more preferably. The lower limit is 0.27.
On the other hand, this ratio may be preferably up to 20.00, more preferably 15.00, even more preferably 10.00.

The WO ₃ component is an optional component that can increase the refractive index and devitrification resistance of glass, reduce the Abbe number, and increase the meltability of the glass raw material when the content exceeds 0%. Further, since the WO ₃ component is a component that lowers the coefficient of thermal expansion, it has an effect of preventing glass breakage in a processing process accompanied by a temperature change such as a precision press.
On the other hand, _{by reducing the content of the WO 3} component to 15.0% or less, the devitrification resistance can be enhanced and the decrease in the transmittance for visible light can be suppressed. Therefore, _{the content of the WO 3} component is preferably 15.0%, more preferably 10.0%, still more preferably 7.5%, still more preferably 6.5%, still more preferably 5.0%, and further. The upper limit is preferably 4.0%.
As the WO _{3 component, WO 3} or the like can be used as a raw material.

The Y ₂ O ₃ component is an optional component that can increase the devitrification resistance, the refractive index and the transmittance of the glass when it is contained in excess of 0%.
On the other hand, by the content of Y ₂ O ₃ component to 10.0% or less, it is possible to suppress the devitrification resistance decreases and the rise of the glass transition point. _Accordingly, the content of Y 2 _{O 3} component is preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, more preferably less than 1.0%.
As the Y ₂ O _{3 component, Y 2} O ₃ , YF _3, or the like can be used as a raw material.

The La ₂ O ₃ component, the Gd ₂ O ₃ component, and the Yb ₂ O ₃ component are optional components that can increase the devitrification resistance, the refractive index, and the transmittance of the glass when each of them contains more than 0%.
On the other hand, _{by reducing the contents of the La 2} O ₃ component, the Gd ₂ O ₃ component, and the Yb ₂ O ₃ component to 10.0% or less, the increase in the glass transition point can be suppressed and the devitrification resistance can be achieved. The decrease can be suppressed. Therefore, _{the content of each of the La 2} O ₃ component, the Gd ₂ O ₃ component and the Yb ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably 3.0%. Less than, more preferably less than 1.0%.
The La ₂ O ₃ component, Gd ₂ O ₃ component, and Yb ₂ O ₃ component are used as raw materials for La ₂ O ₃ , La (NO ₃ ) ₃ , XH ₂ O (X is an arbitrary integer), Gd ₂ O ₃ , and GdF. ₃ , Yb ₂ O _3, etc. can be used.

The sum (mass sum) of the contents of the Ln ₂ O ₃ component (Ln is one or more selected from the group consisting of Y, La, Gd and Yb) is preferably 15.0% or less. As a result, it is possible to suppress a decrease in the devitrification resistance of the glass and an increase in the glass transition point. Therefore, _{the mass sum of the Ln 2} O ₃ components (for example, _{the total content of the Y 2} O ₃ component, the La ₂ O ₃ component, the Gd ₂ O ₃ component and the Yb ₂ O ₃ component) is preferably 15.0% or less. , More preferably 10.0% or less, still more preferably less than 5.0%, still more preferably less than 3.0%.

The GeO ₂ component is an optional component that can enhance the refractive index and devitrification resistance of glass when it is contained in excess of 0%.
On the other hand, _{by reducing the content of the GeO 2} component to 10.0% or less, the material cost of glass can be reduced. Therefore, _{the content of the GeO 2} component is preferably 10.0% or less, more preferably 5.0% or less, still more preferably less than 3.0%, still more preferably less than 1.0%.
As the GeO _{2 component, GeO 2} or the like can be used as a raw material.

The TeO ₂ component is an optional component that can increase the meltability of the glass raw material, increase the refractive index of the glass, 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 TeO 2} component to 15.0% or less, the devitrification resistance of the glass can be enhanced, and the problem that the pot is invaded by the reduction of _{the TeO 2 component can be suppressed.} Therefore, _{the content of the TeO 2} 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%.
As the TeO _{2 component, TeO 2} or the like can be used as a raw material.

ZrO ₂ component, when ultra containing 0%, an elevated refractive index and devitrification resistance of the glass, and is an optional component that enhances the transmission for visible light. Further, since the ZrO ₂ component is a component that lowers the coefficient of thermal expansion, it has an effect of preventing glass breakage in a processing process accompanied by a temperature change such as a precision press.
On the other hand, by the content of the ZrO ₂ component to 10.0% or less, it is suppressed deterioration of devitrification resistance. Therefore, the content of the ZrO ₂ component is preferably 10.0%, more preferably 5.0%, more preferably the upper limit of 3.0%.
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 of 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 10.0% or less, the devitrification resistance of the glass can be enhanced. Therefore, _{the content of the Ta 2} O ₅ component is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%.
As the Ta ₂ O _{5 component, Ta 2} O ₅ or the like can be used as a raw material.

The Ga ₂ O ₃ component is an optional component that can increase the refractive index of glass when it is contained in excess of 0%.
On the other hand, by _{setting the content of the Ga 2} O ₃ component to 10.0% or less, it is possible to increase the degree of wear of the glass and facilitate the polishing process while increasing the devitrification resistance of the glass. Therefore, _{the content of the Ga 2} O ₃ component is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%.
As the Ga ₂ O ₃ component, Ga ₂ O ₃ and _{Ga F 3} can be used as raw materials.

<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 not described above can be added, if necessary, as long as the characteristics of the glass of the present invention are not impaired. However, even when each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo is contained alone or in a small amount, the glass is colored and a specific wavelength in the visible region is used. Since it has a property of diminishing the effect of increasing the visible light transmittance of the present invention by causing absorption, it is preferable that the optical glass that transmits wavelengths in the visible region is substantially not contained.

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 use as a harmful chemical substance in recent years, and when used, not only the glass manufacturing process but also the processing process and the processing process, and Environmental measures are required until disposal after commercialization. Therefore, when the environmental impact is emphasized, it is preferable that these are not substantially contained.

The glass composition of the present invention cannot be directly expressed in terms of mol% because its composition is expressed in% by mass of the oxide-equivalent composition with respect to the total mass of glass, but various properties required in the present invention. The composition of each component present in the glass composition satisfying the above conditions in terms of mol% has the following values in terms of oxide composition.
P ₂ O ₅ component 5.0-40.0 mol%,
Nb ₂ O ₅ component 15.0 to 50.0 mol% and ZnO component 1.0 to 45.0 mol%
And SnO ₂ component 0-10.0 mol%
Sb ₂ O ₃ component 0-1.5 mol%
F component 0 to 20.0 mol%
S component 0 to 10.0 mol%
TiO ₂ component 0 to 35.0 mol%
Bi ₂ O ₃ component 0-5.0 mol%
SiO ₂ component 0 to 20.0 mol%
B ₂ O ₃ component 0 to 20.0 mol%
Al ₂ O ₃ component 0 to 15.0 mol%
Li ₂ O component 0-35.0 mol%
Na ₂ O component 0 to 30.0 mol%
K ₂ O component 0 to 20.0 mol%
MgO component 0-35.0 mol%
CaO component 0-30.0 mol%
SrO component 0 to 20.0 mol%
BaO component 0 to 25.0 mol%
WO ₃ component 0-10.0 mol%
Y ₂ O ₃ component 0-5.0 mol%
La ₂ O ₃ component 0-5.0 mol%
Gd ₂ O ₃ component 0-5.0 mol%
Yb ₂ O ₃ component 0-5.0 mol%
GeO ₂ component 0 to 15.0 mol%
TeO ₂ component 0 to 15.0 mol%
ZrO ₂ component 0 to 15.0 mol%
Ta ₂ O ₅ component 0-3.0 mol%
Ga ₂ O ₃ component 0 to 10.0 mol%

[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 quartz crucible or an alumina crucible to be roughly melted, and then a platinum crucible, a platinum alloy crucible or an iridium. Put it in a crucible and melt it in a temperature range of 1000 to 1400 ° C for 2 to 10 hours, homogenize it by stirring to break bubbles, etc., then lower it to a temperature of 1300 ° C or less and then perform finish stirring to remove the veins. , It is manufactured by casting it in a mold and slowly cooling it. Then, by annealing the produced glass in the range of 500 ° C. to 700 ° C. for 1 to 100 hours depending on the composition, a glass having excellent physical properties as described later can be obtained.

[Physical characteristics]
The optical glass of the present invention has a higher dispersion (low Abbe number) while having a high refractive index.
_{The refractive index (nd} ) of the optical glass of the present invention is preferably 1.70, more preferably 1.75, and even more preferably 1.80 as the lower limit. The upper limit of the refractive index ( _nd ) may be preferably 2.20, more preferably 2.00, and even more preferably 1.92. By having such a high refractive index, a large amount of refraction of light can be obtained even if the device is further thinned.
_{The Abbe number (ν d} ) of the optical glass of the present invention is preferably 35, more preferably 30 as the upper limit, still more preferably less than 28, still more preferably less than 26. The lower limit of the Abbe number (ν _d ) may be preferably 10, more preferably 15, still more preferably 17, and even more preferably 20. By having such a low Abbe number, for example, when combined with an optical element having a high Abbe number, high imaging characteristics and the like can be achieved.
Therefore, by using such an optical glass having a high refractive index and a high dispersion for, for example, an optical element, it is possible to expand the degree of freedom in optical design while achieving high imaging characteristics and the like.

The optical glass of the present invention preferably has a high transmittance for visible light, particularly a high transmittance for light on the short wavelength side of visible light, and thus less coloring. In particular, in the optical glass of the present invention, the shortest wavelength (λ ₇₀ ) showing a spectral transmittance of 70% in a sample having a thickness of 10 mm is preferably 490 nm, more preferably 480 nm, still more preferably 460 nm, still more preferably 440 nm. And. As a result, the absorption edge of the glass is located in or near the ultraviolet region, and the transparency of the glass with respect to light in the visible region, especially on the short wavelength side, is further enhanced, so that the glass is colored yellow or orange. This optical glass can be preferably used as a material for an optical element such as a lens that transmits visible light.

The optical glass of the present invention preferably has a glass transition point of 680 ° C. or lower. As a result, the glass softens at a lower temperature, so that the glass can be mold-pressed at a lower temperature. Further, it is possible to extend the life of the die by reducing the oxidation of the die used for mold press molding. Therefore, the glass transition point of the optical glass of the present invention is preferably up to 680 ° C, more preferably 660 ° C, and even more preferably 640 ° C.
The lower limit of the glass transition point of the optical glass of the present invention is not particularly limited, but the glass transition point of the optical glass of the present invention is preferably 460 ° C., more preferably 500 ° C., and even more preferably 520 ° C. as the lower limit. Good.

The optical glass of the present invention preferably has high devitrification resistance at the time of glass production (in the specification, it may be simply referred to as "devitrification resistance"). As a result, a decrease in transmittance due to crystallization of the glass during glass production can be suppressed, so that this optical glass can be preferably used for an optical element such as a lens that transmits visible light. As a measure of high devitrification resistance during glass production, for example, a low liquidus temperature can be mentioned.

[Preforms and optics]
From the produced optical glass, a glass molded body can be produced by using a mold press molding means such as reheat press molding or precision press molding. That is, a preform for mold press molding is produced from optical glass, and after reheat press molding is performed on this preform, a glass molded body is produced by polishing, or a preform is produced by polishing. A glass molded body can be produced by performing precision press molding on a preform or a preform formed by a known levitation molding or the like. The means for producing the glass molded body is not limited to these means.

The glass molded body thus produced is useful for various optical elements and optical designs. In particular, it is preferable to manufacture optical elements such as lenses, prisms, and mirrors from the optical glass of the present invention by using means such as precision press molding. As a result, when used in optical equipment that transmits visible light through optical elements such as cameras and projectors, the optical system in these optical equipment can be miniaturized while achieving high-definition and high-precision imaging characteristics. Can be planned.

_{Wavelengths showing glass composition, refractive index (nd} ), Abbe number (ν _d ), and spectral transmittance of Examples (No. 1 to No. 39) and Comparative Example (No. A) of the present invention are 70%. (Λ ₇₀ ) and the glass transition point (Tg) are shown in Tables 1 to 6. Of these, the glass of Comparative Example (No. A) is the glass of Example 5 of Japanese Patent Application Laid-Open No. 2006-11149. The following examples are for purposes of illustration only, and are not limited to these examples.

The glass of these examples is a high-grade glass used for ordinary optical glass such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphate compounds corresponding to each component as a raw material. Purity Raw materials are selected, weighed so as to have the composition ratio of each example and comparative example shown in the table, and mixed uniformly, and then the prepared mixture is put into a quartz crucible to make the glass composition difficult to melt. According to this, after coarse melting in an electric furnace in a temperature range of 1200 to 1350 ° C., the glass is placed in a platinum crucible and melted in a temperature range of 1200 to 1350 ° C. for 2 to 10 hours, stirred and homogenized to break bubbles, and the like. After lowering the temperature to 1300 ° C. or lower and stirring and homogenizing, the glass was cast into a mold and slowly cooled to prepare glass. Then, the obtained glass was annealed in the range of 550 ° C. to 650 ° C. for 2 to 60 hours depending on the composition.

Here, the refractive index and Abbe number of the glass of the example were measured based on the Japan Optical Glass Industry Association standard JOBIS01-2003.

The visible light transmittance of the glass of the example was measured according to the Japan Optical Glass Industry Association standard JOBIS02. In the present invention, the presence or absence and degree of coloration of the glass were determined by measuring the visible light 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 ₇₀ (wavelength at a transmittance of 70%) was determined.

The glass transition point (Tg) of the glass of the example was obtained by measuring the relationship between the temperature and the elongation of the sample in accordance with the Japan Optical Glass Industry Association standard JOGIS08-2003 "Measuring method of thermal expansion of optical glass". It was obtained from the thermal expansion curve obtained.

As shown in Tables 1 to 6, the λ ₇₀ (wavelength at a transmittance of 70%) was 490 nm or less, more specifically 450 nm or less, which was within the desired range.
On the other hand, in the glass of the comparative example, λ ₇₀ was 498 nm.
Therefore, it was clarified that the optical glass of the example of the present invention has a higher transmittance for visible light than the glass of the comparative example.

The optical glasses of Examples of the present invention are both refractive index (n _d) of 1.70 or more, more particularly 1.80 or more, obviously to have the desired high refractive index became.
Further, since the optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 35 or less, more specifically 26 or less, they may have a _{desired low Abbe number (ν d).} It was revealed.
In addition, the optical glasses of the examples of the present invention were all stable glasses that did not devitrify.

Therefore, the optical glass of the embodiment of the present invention has a high refractive index ( _nd ) but a lower Abbe number (ν _d ), has high devitrification resistance, and is visible light. It was revealed that it has a high transmittance for.

Further, when a lens preform was formed using the optical glass of the embodiment of the present invention and molded by mold press molding on this lens preform, it was possible to stably process various lens shapes.

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 (7)

By mass%
P ₂ O ₅ component 18.0% or more and 35.0% or less,
Nb ₂ O ₅ component 31.0% or more and 52.0% or less,
Containing 5.208% or more and 25.0% or less of ZnO component,
The content of TiO ₂ component is 0 to 12.0%,
The content of WO ₃ component is 0-5.0%,
The content of SiO ₂ component is less than 0 to 2.0%,
Contains SnO ₂ component, Sb ₂ O ₃ component, F component and S component in total of more than 0% and 3.0% or less.
The sum of mass (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) is 0.1% or more and less than 4.0%.
The sum of mass (TiO ₂ + Nb ₂ O ₅ + Bi ₂ O ₃ ) is 35.0% or more and 50.331 % or less,
Mass ratio ZnO / (R ₂ O + MO) is 0.10 or more (R is one or more selected from the group consisting of Li, Na and K, and M is selected from the group consisting of Mg, Ca, Sr and Ba. One or more types),
Mass% in the sum of the content of _{R 2} O component is less than 10.0%,
The mass ratio ZnO / (TiO ₂ + Nb ₂ O ₅ + Bi ₂ O ₃ ) is 0.167 or more .
An optical glass having a refractive index ( _nd ) of 1.70 or more and an Abbe number (ν _{d ) of 35 or less, and a wavelength (λ 70} ) showing a spectral transmittance of 70% of 428 nm or less. By mass%
B ₂ O ₃ component 0 to less than 3.0% Al ₂ O ₃ component 0 to less than 3.0% Li ₂ O component 0 to 5.0%
Na ₂ O component 0-7.0%
K ₂ O component 0-7.0%
MgO component 0 to 15.0%
CaO component 0 to 15.0%
SrO component 0 to 15.0%
BaO component 0-30.0%
Y ₂ O ₃ component 0-10.0%
La ₂ O ₃ component 0-10.0%
Gd ₂ O ₃ component 0-10.0%
Yb ₂ O ₃ component 0-10.0%
Bi ₂ O ₃ component 0-10.0%
GeO ₂ components 0-10.0%
TeO ₂ components 0 to 15.0%
ZrO ₂ components 0-10.0%
Ta ₂ O ₅ component 0-10.0%
Ga ₂ O ₃ component 0-10.0%
SnO ₂ components 0-3.0%
Sb ₂ O ₃ component 0-3.0%
And
By the outer mass% of the oxide-based mass,
F component 0-3.0%
S component 0-3.0%
The optical glass according to claim 1. The mass ratio (SnO + Sb ₂ O ₃ + F + S) / (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) is 0.
The optical glass according to claim 1 or 2, which is 01 or more. The optical glass according to any one of claims 1 to 3, wherein the sum of the contents of the MO components is 30.0% or less (M is one or more selected from the group consisting of Mg, Ca, Sr and Ba). .. The optical glass according to any one of claims 1 to 4, wherein the glass transition point is 680 ° C. or lower. An optical element made of the optical glass according to any one of claims 1 to 5. A preform for polishing and / or precision press molding made of the optical glass according to any one of claims 1 to 5.