| 摘要 |
PROBLEM TO BE SOLVED: To provide high-refractive index low-dispersion optical glass which can be stably supplied and has excellent glass stability.SOLUTION: Optical glass is characterized by including, in mol%, 0.1-40% of SiO, 10-50% of BO, 0.5-22% of ZnO, 5-50% of LaO, 0.1-25% of GdO, 0.1-20% of YO, 0-25% of ZrO, 0-25% of TiO, 0-20% of NbO, 0-7% of TaO, above 0.1% and below 20% of WO, the mass ratio SiO/BOof the content of SiOto the content of BOis ≤1, the refractive index nd is 1.86-1.95, the abbe number &ngr;d is ≥(2.36-nd)/0.014 and <38, and the glass transition temperature is 640°C or higher. |
