Patent ID: 7670974

Claim:
An optical glass comprising, given as molar percentages, 28 to 50 percent of P 2 O 5 ; more than 20 percent but not more than 50 percent of BaO; 1 to 20 percent MgO; a sum of Li 2 O, Na 2 O, and K 2 O exceeding 3 percent (with 0 to 25 percent of Li 2 O, greater than or equal to 0 percent and less than 10 percent of Na 2 O, and 0 to 12 percent of K 20 ); more than 0 percent but not more than 15 percent of ZnO; 0 to 25 percent of B 2 O 3 ; 0 to 5 percent of Al 2 O 3 ; 0 to 8 percent of Gd 2 O 3 ; 0 to 20 percent of CaO; 0 to 15 percent of SrO; and 0 to 1 percent of Sb 2 O 3 ; with a sum of oxide contents of P, Ba, Mg, Li, Na, K, Zn, B, Al, Gd, Ca, Sr, and Sb being greater than or equal to 98 percent, and wherein the optical glass contains no La 2 O 3 .