| 摘要 |
An optical glass in includes SiO2, B2O3, Al2O3, BaO, CaO, ZnO, La2O3, Gd2O3, and Y2O3, each in a specific ratio. Further, the optical glass satisfies the following conditional expressions (1) and (2), taking the content of SiO2 as A, the content of B2O3 as B, the content in total of La2O3, Gd2O3 and Y2O3 as C, and the content in total of SiO2 and B2O3 as D. 0.35<A/B<0.70  (1) 0.80<C/D<1.0  (2) By the above constitution, a high refractive index and low dispersibility are secured and at the same time deformation temperature (and glass transition temperature) lowers. By containing Al2O3, the glass structure is stabilized and a failure in appearance such as cloudiness in press molding is difficult to occur. |
