| 摘要 |
A glass having a refractive index /- 1.880, an Abbe number of <= 30.4 and a density /} 4.1; contains, by oxide wt., 6-9% silicon, 15-19% boron, 12-20.5% niobium, 8-10% zirconium, 7-11% titanium, 23-32% lanthanum, 0-5% yttrium, 0-5% tungsten, 8-13% calcium, 0-2% strontium, 0-2% barium, 0-2% magnesium, 0-5% zinc and 0-2% alkali metal oxides. The total amount (i) silicon and boron oxides, is <= 26%, (ii) zirconium, titanium and lanthanum oxides is <= 44% and (iii) calcium, strontium, barium, magnesium and zirconium oxides is <= 9%. |
