Patent ID: 7955998

Claim:
An optical glass comprising, by mass %, 13 to 30% of B 2 O 3 , 0.1 to 4% of Li 2 O, 17 to 35% of ZnO, 15 to 45% of La 2 O 3 , 4 to 15% of Ta 2 O 5 exclusive of 15%, 0 to 10% of ZrO 2 , 0 to 10% of Nb 2 O 5 provided that Ta 2 O 5 /(Ta 2 O 5 +ZrO 2 +Nb 2 O 5 )≧0.57, 0 to 20% of WO 3 , 0 to 1% of Sb 2 O 3 , 0 to 1% of GeO 2 and 0 to 1% of Gd 2 O 3 and having a refractive index (n d ) of 1.80 to 1.84 and an Abbe's number (ν d ) of 40.0 to 45.0.