Precision press-molding preform, process for the production thereof, optical element and process for the production of the optical element

摘要

A precision press-molding preform for producing an optical element for use in an imaging device using a CCD type or MOS type solid image-sensing device, which is formed of a glass composition containing, by mol %, 25 to 45% of P₂O₅, 0.5 to 10% of CuO, 0 to 10% of B₂O₃, 0 to 10% of Al₂O₃, 2 to 30% of Li₂O, 0 to 25% of Na₂O, 0 to 15% of K₂O, the total content of Li₂O, Na₂O and K₂O being 3 to 40%, 3 to 45% of BaO, 0 to 30% of ZnO, 0 to 20% of MgO, 0 to 20% of CaO, 0 to 20% of SrO, 0 to 10% of Bi₂O₃, 0 to 5% of La₂O₃, 0 to 5% of Gd₂O₃ and 0 to 5% of Y₂O₃, the total content of these components being at least 98%, and a precision press-molding preform, which is formed of a phosphate glass containing CuO, an alkali metal oxide, BaO and ZnO and having a BaO content/ZnO content molar ratio (BaO/ZnO) of greater than 1.