US Patent 7989377 Optical glass and optical element

Provided is an optical glasses that has high refractivity and low dispersion and anomalous partial dispersion capability and that has excellent processability and devitrification resistance and ensures that the occurrence of striae can be inhibited, the optical glass including an optical glass having a refractive index (nd) of 1.54 to 1.60, an Abbe's number (vd) of 65 to 78, a partial dispersion ratio of 0.530 or more, a specific gravity of 4.0 or less and a viscosity, measured at its liquidus temperature, of 4 dPa·s or more and an optical glass comprising as cationic components, by cationic %, 20 to 50% of p5+, 0.1 to 20% of Al3+, 0.1 to 20% of Mg2+, 0 to 20% of Ca2+, 0 to 20% of Sr2+, 0.1 to 30% of Ba2+ and 0 to 10% of Y3+, and further comprising, as anionic components, F− and O2−, wherein the ratio of the content of Mg2+ to the content of Al3+, Mg2+/Al3+, based on cationic %, is 1.2 or less.