Patent ID: 7638449

Claim:
An optical glass comprising, by mass %: 30 to 40% of B 2 O 3 ; 2.5 to 6% of Li 2 O; 10 to 17% of ZnO; 12 to 22% of La 2 O 3 ; 15 to 25% of Gd 2 O 3 ; 0 to 5% of SiO 2 ; 0 to 5% of Bi 2 O 3 ; 0 to 15% of Al 2 O 3 ; 0 to 3% of ZrO 2 ; 0 to 5% of WO 3 ; 0 to 5% of Ta 2 O 5 ; 0 to 3% of TiO 2 ; 0 to 5% of Y 2 O 3 ; and 0 to 5% of MgO+CaO+SrO+BaO, wherein an average linear thermal expansion coefficient (α) from 50 to 350° C. is 85×10 −7 /° C. or less.