Patent ID: 7622409

Claim:
An optical glass comprising, by mol %, 15-45% B 2 O 3 , 5-20% La 2 O 3 , 1-20% Gd 2 O 3 , 10-45% ZnO, 0-15% WO 3 , 0-10% Ta 2 O 5 , 0-10% Nb 2 O 5 , 0-20% TiO 2 , 0-20% SiO 2 , 0-15% Li 2 O, 0-10% Na 2 O, 0-10% K 2 O, 0-10% MgO, 0-10% CaO, 0-10% SrO, 0-10% BaO 0-8% Y 2 O 3 , 0-8% Yb 2 O 3 , provided that the total content of La 2 O 3 , Gd 2 O 3 , Y 2 O 3 and Yb 2 O 3 is 10 to 30%, 0-less than 0.5% ZrO 2 , 0-10% Bi 2 O 3 , and 0-1% Sb 2 O 3 , and having a refractive index (nd) of over 1.86, an Abbe's number (vd) of 35 to less than 39.5 and a glass transition temperature (Tg) of 630° C. or lower.