Patent ID: 6645894
Filing Date: 2003-11-11
Classification: C03C,Y10S

Abstract:
An optical glass having a glass composition containing no Ta2O5 and comprising, by weight %, 0 to 7% of SiO2, 18 to 30% of B2O3, provided that the total content of SiO2 and B23 is 23 to 35%, 2 to 10% of ZnO, 30 to less than 45% of La9O3, 1 to 20% of Gd2O3, 0 to 20% of Y2O3, provided that the total content of La2O3, Gd2O3 and Y2O3 is 45 to 60%, 3 to 8% of ZrO2 and 3 to 12% of Nb2O5, the weight ratio of the total content of La2O3, Gd2O3 and Y2O3: the content of ZnO being 9.5:1 to 25:1, the weight ratio of the content of ZnO: the content of Nb2O5 being 1:1.30 to 1:4.2, the total content of these components being at least 95% by weight, the optical glass having a refractive index [nd] and an Abbe's number [&ngr;d] which satisfy all of the following relational expressions,1.820<nd&lE;1.850 42.0&lE;&ngr;nd&lE;44.0.