Patent ID: 6816319
Filing Date: 2004-11-09
Classification: C03C,G02B

Abstract:
A planar lens in which a refractive index distribution is formed by diffusing a refractive index-increasing component into a flat glass substrate in a substantially hemispherical form or semicylinder form,wherein the refractive index-increasing component is silver, and the flat glass substrate comprises Li as an alkali metal that is subject to an ion exchange with the silver, and the flat glass substrate comprises: 0 to 80 mol % SiO2; 0 to 80 mol % B2O2; 0 to 80 mol % P2O5; 3 to 45 mol % Li2O; 0 to 20 mol % Na2O: 0 to 30 mol % MgO; 0 to 30 mol % CaO; 0 to 30 mol % SrO; 0 to 30 mol % BaO; 0 to 30 mol % ZrO2; 0 to 30 mol % Y2O2; 0 to 20 mol % La2O3; 0 to 40 mol % Al2O3; and 0 to 20 mol % Sm2O3, wherein the sum of SiO2, B2O3 and P2O5 is 30 to 80 mol %, and the sum of Li2O and Na2O is 3 to 65 mol %.