Optical glass, press-molding glass material, and optical element and method of manufacturing the same
An optical glass, comprising, denoted as cation percentages: a content of Si 4+ and B 3+ (35 to 55); a combined content of La 3+ , Gd 3+ , and Y 3+ (30 to 55), wherein Gd 3+ is 5 to 20%; a content of Ti 4+ , Nb 5+ , Ta 5+ and W 6+ (7 to 20); Zr 4+ (2 to 8); and Zn 2+ (0 to 10); wherein a cation ratio of Zn 2+ to Gd 3+ is 0 to 0.80; a cation ratio of Gd 3+ to Ti 4+ , Nb 5+ , Ta 5+ , and W 6+ combined is 0.65 to 2.00; a cation ratio of Ta 5+ to Ti 4+ , Nb 5+ , Ta 5+ , and W 6+ combined is 0 to 0.30; a cation ratio of Ti 4+ to Ti 4+ , Nb 5+ , Ta 5+ , and W 6+ combined is 0.30 to 0.90; and a refractive index nd is 1.890 to 1.950, and an Abbé number νd of equal to or lower than 39.0, the Abbé number νd satisfying a relation of νd≧(2.334−nd)/0.012 relative to nd.
1. An optical glass, which is an oxide glass comprising, denoted as cation percentages:
a combined content of Si 4+ and B 3+ of 35 to 55 percent;
a combined content of La 3+ , Gd 3+ , and Y 3+ of 30 to 55, wherein a content of Gd 3+ ranging from 5 to 20 percent;
a combined content of Ti 4+ , Nb 5+ , Ta 5+ and W 6+ of 7 to 20 percent;
2 to 8 percent of Zr 4+ ; and
0 to 10 percent of Zn 2+ ;
wherein a cation ratio of a content of Zn 2+ to a content of Gd 3+ (Zn 2+ /Gd 3+ ) ranges from 0 to 0.80;
a cation ratio of the content of Gd 3+ to the combined content of Ti 4+ , Nb 5+ , Ta 5+ , and W 6+ (Gd 3+ /(Ti 4+ +Nb 5+ +Ta 5+ +W 6+ )) ranges from 0.65 to 2.00;
a cation ratio of a content of Ta 5+ to the combined content of Ti 4+ , Nb 5+ , Ta 5+ , and W 6+ (Ta 5+ /(Ti 4+ +Nb 5+ +Ta 5+ +W 6+ )) ranges from 0 to 0.30;
a cation ratio of a content of Ti 4+ to the combined content of Ti 4+ , Nb 5+ , Ta 5+ , and W 6+ (Ti 4+ /(Ti 4+ +Nb 5+ +Ta 5+ +W 6+ )) ranges from 0.30 to 0.90; and
which has a refractive index ranging from 1.890 to 1.950, and an Abbé number νd of equal to or lower than 39.0, the Abbé number νd satisfying a relation of νd≧(2.334−nd)/0.012 relative to the refractive index nd.
2. The optical glass according to claim 1 , wherein a content of Ta 5+ ranges from 0 to 4 cation percent.
3. The optical glass according to claim 1 , wherein a content of Si 4+ ranges from 6 to 15 cation percent, and a content of B 3+ ranges from 25 to 45 cation percent.
4. The optical glass according to claim 1 , wherein a content of La 3+ ranges from 15 to 30 cation percent.
5. The optical glass according to claim 1 , wherein a content of Ti 4+ ranges from 1 to 10 cation percent.
6. The optical glass according to claim 1 , which has a liquidus temperature of equal to or lower than 1,300° C.
7. The optical glass according to claim 1 , which has a glass transition temperature of equal to or greater than 650° C.
8. The optical glass according to claim 1 , which has a specific gravity ranging from 4.50 to 5.50.
9. A press-molding glass material, which is comprised of the optical glass according to claim 1 .
10. An optical element, which is comprised of the optical glass according to claim 1 .
11. A method of manufacturing an optical element, which comprises steps of:
preparing a molded glass article by heating and press molding with a pressing mold the press-molding glass material according to claim 9 ; and
processing the molded glass article that has been prepared to provide an optical element.