| 摘要 |
The invention provides a novel optical glass which has a refractive index (nd) of 1.78 to 2.2 and an Abbe value (&ngr;d) of 16 to less than 40 and is suitable for precision mold press molding by virtue of its having a low glass transition temperature, namely, an optical glass which contains by mole in terms of oxides 25 to 60% B2O3, 2 to 45% (in total) TiO2 and Nb2O5 and 1 to 25% WO3 and has a refractive index (nd) of 1.78 to 2.2 and an Abbe value (&ngr;d) of 16 to less than 40. Further, the glass contains 5 to 35% La2O3 and 1 to 40% ZnO and has a glass transition temperature (Tg) of 700° C. or below. The optical glass is excellent in meltability, stability and devitrification resistance and has a high refractive index, high light-dispersive power and excellent precision press moldability. |
