Patent ID: 7538051
Filing Date: 2009-05-26
Classification: C03B,C03C,Y10S

Abstract:
1. A press-moldable preform which is formed of an optical glass having a refractive index (nd) of 1.46 to 1.58 and an Abbe's number (νd) of 65 to 74, and comprising, by mol %, 45 to 65% of P 2 O 5 , 12 to 19% of Al 2 O 3 , 5 to 30% of MgO, 1 to 25% of a total of Li 2 O, Na 2 O and K 2 O, 0.5 to 16% of B 2 O 3 , 0 to 25% of ZnO, 0 to 25% of CaO, 0 to 25% of SrO, 0 to 30% of BaO, 0 to 10% of La 2 O 3 , 0 to 10% of Gd 2 O 3 , 0 to 10% of Y 2 O 3 , 0 to 10% of Yb 2 O 3 and 0 to 10% of Lu 2 O 3 , the total content of said components being at least 95% and contains no SiO 2 .