Patent ID: 8575049

Claim:
An optical glass comprising, by mass %, 12 to 30% of total of B 2 O 3 and SiO 2 , 0 to 17% B 2 O 3 , 55 to 80% of total of La 2 O 3 , Gd 2 O 3 , Y 2 O 3 , Yb 2 O 3 , ZrO 2 , Nb 2 O 5 and WO 3 , 2 to 10% of ZrO 2 , 0 to 15% of Nb 2 O 5 , 0 to 12% of ZnO, 0% or more but less than 13% of Ta 2 O 5 , and 0 to 0.2% Li 2 O, 0 to 5% BaO, the optical glass containing no Pb, wherein the ratio of the content of Ta 2 O 5 to the total content of La 2 O 3 , Gd 2 O 3 , Y 2 O 3 , Yb 2 O 3 , ZrO 2 , Nb 2 O 5 and WO 3 is 0.23 or less, the ratio of the total content of La 2 O 3 , Gd 2 O 3 , Y 2 O 3 and Yb 2 O 3 to the total content of B 2 O 3 and SiO 2 is from 2 to 3.6, the optical glass having a refractive index nd of 1.86 or more and an Abbe's number νd of 38 or more.