Optical glass and optical element

摘要

Optical glass which is suitable for press molding does not substantially contain a compound of lead or arsenic, and has intermediate refractive index, low dispersion properties, low Tg and small gravity. Concretely, the optical glass includes the glass components of SiO₂: 20 to 45%, B₂O₃: 15 to 40%, Al₂O₃: 4 to 15%, MgO: 0 to 10% (including 0), CaO: 13 to 25%, MgO+CaO: 13 to 25%, Li₂O: 12.5 to 25%, Na₂O: 0 to 10% (including 0), K₂O: 0 to 10% (including 0), Li₂O+Na₂O+K₂O: 12.5 to 25%, SrO: 0 to 10% (including 0), BaO: 0 to 5% (including 0), and Sb₂O₃: 0 to 1% (including 0).