OPTICAL GLASS

摘要

Provided is optical glass which has low glass transition temperature (Tg) and specific optical constants that are a refractive index (nd) of 1.60-1.80 and an Abbe number (?d) within the range of 30-60, while containing less rare earth elements. The optical glass has a refractive index (nd) within the range of 1.60-1.80, an Abbe number (?d) within the range of 30-60 and a glass transition temperature (Tg) of 600°C or less, while containing, in mass% based on oxides, 20% or less of Ln2O3 (wherein Ln represents one or more elements selected from among La, Y, Yb and Gd), Bi2O3, Ta2O5, GeO2 and WO3 in total and 20% or less of Nb2O5. Preferably, the optical glass additionally contains, in mass% based on oxides, 10-50% of SiO2, 30% or less of B2O3, more than 0% but 20% or less of TiO2 and 10-60% (inclusive) of RO (wherein R represents one or more elements selected from among Mg, Ca, Zn, Sr and Ba).