Phototropic glass with a refractive index greater than or equal to 1.59, an abbe number greater than or equal to 44 and a density less than or equal to 3.0 g/cm3

摘要

A phototropic glass with the optical characteristics of nd greater than to or equal to 1.59 and vd greater than or equal to 44, and with a density less than or equal to 3.0 g/cm-3 is provided having a composition comprising: -SiO2 42-56 -B2O3 11-18 -Al2O3 0-5 -sum of SiO2, B2O3, and Al2O3 55-75 -Li2O 3-9 -Na2O 0-7.98 -K2O 0-8.22 -sum of alkaki metal oxides 7-15 -MgO 3-12 -CaO 0-3 -SrO 0-3 -BaO 0-6 -ZnO 0-2 -sum of alkali earth metal 3-12 -oxides amd ZnO -TiO2 3.06-6.74 -ZrO2 2-11 -Nb2O5 2.28-8 - La2O3 0-3 -Er2O3 0-1 -