Optical glass, glass gob for press-molding, optical part, process for producing glass shaped material and process for producing optical part

Abstract

An optical glass having a high light transmittance, a high refractive index and excellent production stability, which contains at least one of CaO and SrO together with SiO2, B2O3, La2O3, Nb2O5, TiO2 and BaO, having a composition that substantially contains, by weight %, 1 to 18% of SiO2, 3 to 24% of B2O3, provided that the ratio of content of B2O3 to the content of SiO2 (B2O3/SiO2) is over 1, 10 to 50% of La2O3, 1 to 30% of Nb2O5, 1 to 30% of TiO2, over 6% but not more than 25% of BaO, less than 7% of CaO, 6% or less of SrO, 0 to 13% of MgO, provided that the total content of BaO, CaO, SrO and MgO is 40% or less, 0 to 15% of ZnO, 0 to 15% of ZrO2, 0 to 10% of Al2O3, 0 to 20% of Gd2O3, 0% or more but less than 2% of Y2O3, 0 to 5% of Yb2O3, 0 to 18% of Ta2O5, 0 to 20% of Bi2O3, 0 to 10% of GeO2, 0% or more but less than 2% of Sb2O3, and 0% or more but less than 2% of SnO2, and having a refractive index (nd) of over 1.8, Abbe's number (νd) of 28 to 40 and a density of 4.2 g/cm3 or more.

Dependencies are inferred from the claim text.