US Patent 8008219 Optical glass and optical element

An optical glass includes, based on the total weight of the optical glass: not less than 35 weight percent and less than 45 weight percent of P2O5; not less than 0.5 weight percent and less than 10 weight percent of B2O3; 0 to 16 weight percent of Al2O3; 0 to 2.5 weight percent of SiO2; 0 to 26 weight percent of BaO; 0 to 20 weight percent of SrO; 23 to 49 weight percent of ZnO; more than 6 weight percent and not more than 20 weight percent of CaO; 0 to 16 weight percent of MgO; not less than 0 weight percent and less than 1 weight percent of Li2O; 3 to 19 weight percent of Na2O; and 0 to 20 weight percent of K2O, where the total weight of BaO, SrO, ZnO, CaO, and MgO and the total weight of Li2O, Na2O and K2O are predetermined amounts.