Phosphate optical glasses, for precision press molding precast, and the optical element

摘要

PROBLEM TO BE SOLVED: To provide a phosphate optical glass suitable for precise press molding having a refractive index of 1.57 to 1.62, an Abbe number of 65 to 70 and a small thermal expansion coefficient.;SOLUTION: There is provided a phosphate optical glass which contains 32 to 50 mol% of P₂O₅, 3 to 20 mol% of B₂O₃, 12 to 25 mol% of BaO, 0 to 20 mol% of SrO, 0 to 8 mol% of Al₂O₃, more than 0 mol% and 15 mol% or less of Li₂O, more than 0 mol% and 11 mol% or less of MgO, 0 to 15 mol% of CaO, 0 to 5 mol% of Gd₂O₃, 0 to 5 mol% of La₂O₃ and 0 to 0.5 mol% of Sb₂O₃ and no ZnO. There can be provided a phosphate optical glass having a thermal expansion coefficient at 20 to 300°C of less than 110×10^-7/°C and a transition temperature of less than 520°C by rationally distributing the content of each component.;COPYRIGHT: (C)2015,JPO&INPIT