Mother glass composition for gradient-index lens, gradient-index lens, manufacturing method thereof, optical product, and optical device

摘要

The present invention provides a mother glass composition for gradient-index lens, from which a lead-free Li-based gradient-index lens that is excellent in weather resistance, in particular weather resistance in the presence of water, can be manufactured. The mother glass composition includes the following components, indicated by mol %: 40≦SiO₂≦65; 1≦TiO₂≦10; 0.1≦MgO≦22; 0.15≦ZnO≦15; 2≦Li₂O≦18; 2≦Na₂O≦20; 0≦B₂O₃≦20; 0≦Al₂O₃≦10; 0≦K₂O≦3; 0≦Cs₂≦O≦3; 0≦Y₂O₃≦5; 0≦ZrO₂≦2; 0≦Nb₂O₅≦5; 0≦In₂O₃≦5; 0≦La₂O₃≦5; and 0≦Ta₂O₅≦5. The mother glass composition further includes at least two oxides selected from CaO, SrO, and BaO each in a range of 0.1 mol % to 15 mol %. The total of MgO+ZnO is greater than or equal to 2 mol %. The molar ratio of ZnO/(MgO+ZnO) is in a range of 0.07 to 0.93. The total of Li₂O+Na₂O is in a range of 6 mol % to 38 mol %. The total of Y₂O₃+ZrO₂+Nb₂O₅+In₂O₃+La₂O₃+Ta₂O₅ is in a range of 0 mol % to 11 mol %.