| 摘要 |
The optical glass of the present invention has optical constants of a refractive index (nd) within a range from 1.74 to 1.80 and an Abbe number (nu d) within a range from 47 to 51, contains, as essential components, SiO2, B2O3. La2O3, Gd2O3, ZrO2, Ta2O5, ZnO and Li2O, is substantially free of Pb, As and F, and contains ZrO2 in an amount of 6 mass % or less. The optical glass has ratio of ZnO/(ZrO2 + Ta2O5) within a range from 0.45 to 1.5 and glass transition temperature (Tg) within a range from 530 °C to 630 °C. |
