Patent ID: 7897532

Claim:
An optical glass composition comprising, in % by weight, 1.0% or more and 12.0% or less of SiO 2 , 8.0% or more and 18.0% or less of B 2 O 3 , 0% or more and 6.0% or less of ZnO, 1.0% or more and 10.0% or less of ZrO 2 , 25.0% or more and 47.0% or less of La 2 O 3 , 0% or more and 5.0% or less of R 2 O (here, R is at least one of Li, Na and K), 0% or more and 15.0% or less of Nb 2 O 5 , 0% or more and 7.0% or less of TiO 2 , 0% or more and 15.0% or less of Ta 2 O 5 , 1.0% or more of Nb 2 O 5 +TiO 2 +Ta 2 O 5 , 0% or more and 25.5% or less of Gd 2 O 3 , 0.5% or more and 15.0% or less of WO 3 and 0.5% or more and 26.0% or less of Gd 2 O 3 +WO 3 , and substantially not containing Y 2 O 3 , and having a refractive index (nd) to the d-line of 1.88 or higher and 1.92 or lower and an Abbe number (νd) to the d-line of 33 or higher and 37 or lower.