Optical glass, press-molding glass material, and optical element and method of the same

1. Optical glass, which is oxide glass comprising, denoted as cation percentages:

Si 4+ 0 to 30%;

B 3+ 15 to 60%;

Li + 0 to 10%;

Na + 0 to 10%;

K + 0 to 15%;

Mg 2+ 0 to 20%;

Ca 2+ 0 to 15%;

Sr 2+ 0 to 20%;

Ba 2+ 0 to 20%;

Zn 2+ 13 to 40%;

La 3+ 0 to 11%;

Gd 3+ 0 to 10%;

Y 3+ 0 to 6%;

Yb 3+ 0 to 6%;

Zr 4+ 0 to 5%;

Ti 4+ 0 to 7%;

Nb 5+ 2 to 20%;

Ta 5+ 0 to 5%;

W 6+ 0 to 10%;

Te 4+ 0 to 5%;

Ge 4+ 0 to 5%;

Bi 3+ 0 to 5%; and

Al 3+ 0 to 5%;

wherein

a combined content of Si 4+ and B 3+ ranges from 35 to 65%;

a cation ratio of a content of B 3+ to the combined content of Si 4+ and B 3+ , B 3+ /(Si 4+ +B 3+ ), ranges from 0.3 to 1;

a combined content of Li + , Na + , and K + ranges from 0 to 20%;

a cation ratio of a content of Zn 2+ to a combined content of Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ , and Zn 2+ , Zn 2+ /(Mg 2+ +Ca 2+ Sr 2+ +Ba 2+ +Zn 2+ ), ranges from 0.30 to 1;

a combined content of La 3+ , Gd 3+ , and Y 3+ ranges from 0 to 20%;

a combined content of Ti 4+ , Nb 5+ , Ta 5+ , and W 6+ ranges from 10 to 20%;

a cation ratio of the content of Ti 4+ to the combined content of Ti 4+ and Nb 5+ (Ti 4+ /(Ti 4+ +Nb 5+ )) ranges from 0 to 0.20; and

a cation ratio of the combined content of Ti 4+ and W 6+ to the combined content of Ti 4+ , Nb 5+ , Ta 5+ , and W 6+ ((Ti 4+ +W 6+ )/(Ti 4+ +Nb 5+ +Ta 5+ +W 6+ )) ranges from 0 to 0.20, and

comprising no Pb, with a refractive index nd ranging from 1.750 to 1.850, an Abbé number νd ranging from 29.0 to 40.0, and a glass transition temperature of less than 630° C.

2. The optical glass according to claim 1 , which has a partial dispersion ratio, Pg,F, of equal to or lower than 0.600, the partial dispersion ratio being denoted as (ng−nF)/(nFnc) with a refractive index ng at a g line, nF at an F line, and nc at a c line.

3. The optical glass according to claim 1 , which has a deviation, ΔPg,F, of a partial dispersion ratio, Pg,F, of equal to or lower than 0.02, wherein the ΔPg,F is calculated by the following equation:

ΔPg,F=Pg,F + (0.0018 ×νd )−0.6483

and in the equation, Pg,F is a partial dispersion ratio denoted as (ng−nF)/(nF−nc) with a refractive index ng at a g line, nF at an F line, and nc at a c line, and vd is an Abbú´ number.

4. The optical glass according to claim 1 , which has a specific gravity of equal to or lower than 4.5.

5. The optical glass according to claim 1 , which has a liquidus temperature of lower than 1,100° C.

6. The optical glass according to claim 1 , the wavelength λ70 of which is equal to or lower than 450 nm, the λ70 being a wavelength at which light transmittance over a wavelength range of 280 to 700 nm is 70%.

7. The optical glass according to claim 1 , the wavelength λ5 of which is equal to or lower than 370 nm, the λ5 being a wavelength at which light transmittance over a wavelength range of 280 to 700 nm is 5%.

8. A press-molding glass material, which is comprised of the optical glass according to claim 1 .

9. An optical element, which is comprised of the optical glass according to claim 1 .

10. A method of manufacturing an optical element, which comprises:

heating and precision press molding with a pressing mold the press-molding glass material according to claim 8 .