Optical glass, press-molding preform and optical element

摘要

An optical glass having a refractive index (nd) of 1.57 to 1.67, an Abbe's number (nud) of 55 to 65 and a glass transition temperature (Tg) of 560° C. or lower and having a low-temperature softening property and excellent climate resistance or a haze value of 3% or less, or an optical glass comprising, by mol %, 22 to 40% of B₂O₃, 12 to 40% of SiO₂, 2 to 20% of Li₂O, 5 to 15% of CaO, 2 to 14% of ZnO, 0.5 to 4% of La₂O₃, 0 to 3% of Gd₂O₃, 0 to 3% of Y₂O₃, the total content of La₂O₃, Gd₂O₃ and Y₂O₃ being at least 1%, 0 to 5% of Al₂O₃, 0 to 3% of ZrO₂ and 0 to 5% of BaO, the total content of the above components being more than 96%, and having a refractive index (nd) of 1.57 to 1.67 and an Abbe's number (nud) of 55 to 65.