| 摘要 |
PROBLEM TO BE SOLVED: To provide a glass having a refractive index nd ranging from 1.790 to 1.830, an Abbe number νd ranging from 45 to 48, excellent thermal stability, and absorption characteristics suitable for manufacturing a cemented lens.SOLUTION: The glass has, in terms of mass%, a total content of 20 to 35% of SiOand BO, a total content of 50 to 70% of LaO, GdO, YOand YbO, a content of 37 to 69% of LaO, a content of 0 to 3% of GdO, a content of 3 to 30% of YO, a content of 0% or more and less than 2% of YbO, a content of 2 to 15% of ZrO, a total content of 1 to 6% of TiO, NbOand TaO, a content of 0 to 4% of ZnO, a content of 0 to 2% of WO, in which a mass ratio ZnO/NbOranges from 0 to 1.0; and the glass contains NbOas an essential component and has a refractive index nd ranging from 1.790 to 1.830 and an Abbe number νd ranging from 45 to 48.SELECTED DRAWING: None |
