Optical glass, preform for precision press molding, and optical element

摘要

Provided is a medium-refractive-index low-dispersion optical glass that may be precision press-molded, that has a high water resistance, and that has a low specific gravity, as well as a preform for precision press molding and an optical element which use such an optical glass. The optical glass has a composition including, in % by mass, SiO2: 35 to 55%, B2O3: 12 to 27%, Al2O3: 6 to 16%, Li2O: 5 to 12%, MgO: 0 to 10%, CaO: 5 to 17%, ZrO2: 0 to 7%, La2O3: 0 to 7%, ZnO: 0 to 5%, TiO2: 0 to 5%, Nb2O5: 0 to 5%, and Ta2O5: 0 to 5%. SrO and BaO are not included.

主权项

1. An optical glass having a refractive index (nd) of 1.575 to 1.605 and an Abbe number (νd) of 58 to 62, comprising a composition including,
in % by mass, SiO2 in an amount of 35 to 55%, B2O3 in an amount of 12 to 27%, Al2O3 in an amount of 6 to 16%, Li2O in an amount of 5 to 12%, MgO in an amount of 0 to 10%, CaO in an amount of 5 to 17%, ZrO2 in an amount of 0 to 7%, La2O3 in an amount of 0 to 7%, ZnO in an amount of 0 to 5%, TiO2 in an amount of 0 to 5%, Nb2O5 in an amount of 0 to 5%, and Ta2O5 in an amount of 0 to 5%, wherein SrO and BaO are not included.