Patent ID: 7855158

Claim:
An optical glass comprising, denoted as molar percentages: 0 to 20 percent SiO 2 , 5 to 40 percent B 2 O 3 , SiO 2 +B 2 O 3 =15 to 50 percent, 0.5 to 10 percent Li 2 O, 12 to 36 percent ZnO, where 3×Li 2 O+ZnO≧18 percent, 5 to 30 percent La 2 O 3 , 0 to 20 percent Gd 2 O 3 , 0 to 10 percent Y 2 O 3 , La 2 O 3 +Gd 2 O 3 =10 to 30 percent, La 2 O 3 /SIGMA(Σ)RE 2 O 3 =0.67 to 0.95 (where SIGMA(Σ)RE 2 O 3 =La 2 O 3 +Gd 2 O 3 +Y 2 O 3 +Yb 2 O 3 +Sc 2 O 3 +Lu 2 O 3 ), 0.5 to 10 percent ZrO 2 , 1 to 15 percent Ta 2 O 5 , 1 to 20 percent WO 3 , Ta 2 O 5 /WO 3 ≦2.5 (molar ratio), 0 to 8 percent Nb 2 O 5 , 0 to 8 percent TiO 2 , and no Te; and having a refractive index nd of not less than 1.87 and an Abbé number nu(v)d of not less than 35 but less then 40.