| 摘要 |
An optical glass having optical constants of a refractive index (nd) of 1.78 or over, an Abbe number (nud) of 30 or below, and a partial dispersion ratio (thetag, F) of 0.620 or below comprises SiO2 and Nb2O5 as essential components, wherein an amount of Nb2O5 in mass % is more than 40%. The optical glass further comprising, in mass % on oxide basis, less than 2% of K2O and one or more oxides selected from the group consisting of B2O3, TiO2, ZrO2, WO3, ZnO, SrO, Li2O and Na2O wherein a total amount of SiO2, B2O3, TiO2, ZrO2, Nb2O5, WO3, ZnO, SrO, Li2O and Na2O is more than 90% and TiO2/(ZrO2+Nb2O5) is less than 0.32. |
