| 摘要 |
PROBLEM TO BE SOLVED: To provide optical glass having desired, advantageous optical characteristics (optical position using nand &ngr;, and internal transmittance τ).SOLUTION: Optical glass includes LaO, SiO, BO, TiO, and TaO, of which the BO/SiOratio in terms of weight percentage is less than 1, and has a following composition (mass% based on oxides): 40.0 to 60.0 LaO, 5.0 to 18.0 SiO, 4.0 to <10.0 BO, 0.1 to 10.0 TiO, 0.1 to 10.0 TaO, 0 to 15.0 ZrO, 0 to 15.0 NbO, 0 to 5.0 YO, and 0 to 15.0 GdO. |
