Patent ID: 8030233

Claim:
An optical glass, and comprising SiO 2 of 10% or over and 40% or below, Nb 2 O 5 of more than 40% and 65% or below, and ZrO 2 of 1% or over and 15% or below in ratios of amounts in mass % on oxide basis as essential components, wherein an amount of K 2 O is less than 2%, TiO 2 /(ZrO 2 +Nb 2 O 5 ) is 0.2 or below, and a total amount of SiO 2 , B 2 O 3 , TiO 2 , ZrO 2 , Nb 2 O 5 , WO 3 , ZnO, SrO, Li 2 O and Na 2 O is more than 90% wherein the optical glass has optical constants of a refractive index (nd) of 1.78 or over, an Abbe number (νd) of 27 or below, and a partial dispersion ratio (θg, F) of 0.620 or below.