Patent ID: 8647996

Claim:
An optical glass in the form of an oxide glass comprising, denoted as cation percentages, 15 to 35 percent of Si 4+ , 0 to 20 percent of B 3+ , 15 to 25 percent of Nb 5+ , 0 to 9 percent of Ti 4+ , 0 to 3 percent of Zr 4+ , 0.25 to 2.5 percent of W 6+ , 0 to 19 percent of Li + , 3 to 19 percent of Na + , 0 to 18 percent of K + , 0 to 9 percent of Zn 2+ , 0 to 2 percent of Ba 2+ , and 0 to 3 percent of Ca 2+ ; wherein the cation ratio of the Nb 5+ content to the combined content of Nb 5+ and Ti 4+ (Nb 5+ /(Nb 5+ +Ti 4+ )) falls within a range of 0.71 to 1; H/L falls within a range of 1.15 to 2.55, where H denotes the sum of 20 times the Si 4+ content and twice the Nb 5+ content (20Si 4+ +2Nb 5+ ), and L denotes the sum of eight times the B 3+ content, six times the Li + content, five times the Na + content, three times the K + content, three times the Zn + content, and seven times the W 6+ content (8B 3+ +6Li + +5Na + +3K + +3Zn 2+ +7W 6+ ); the combined content of Ti 4+ , Nb 5+ , and Zr 4+ falls within a range of 20 to 30.78 percent; the combined content of Ba 2+ , Ca 2+ , and Zr 4+ falls within a range of 0 to 3.79 percent; the combined content of Ti 4+ , Nb 5+ , W 6+ , Ba 2+ , Ca 2+ , Zr 4+ , and Li + is 50 percent or less; the refractive index nd falls within a range of 1.75 to 1.86; and the Abbé number v(nu)d falls within a range of 24 to 30.