| 摘要 |
<p>This invention is directed to the production of glasses especially suitable for use as ophthalmic lenses which exhibit indices of refraction between about 1.699-1.703, Abbe numbers equal to or greater than 41.0, densities less than 3.25 g/cm3, and good resistance to attack by acids. The glasses are essentially free of Al2O3 and consist essentially, in weight percent on the oxide basis, of: -SiO2 33-37 CaO 8-9.5 -B2O3 7.5-13 SrO 2-4 -SiO2 + B2O3 44-48 La2O3 12.3-14.5 -Li2O 5-8 ZrO2 4-6 -Na2O 0-2.5 Nb2O5 8-10.5 -K2O 0-2 TiO2 5-7 -Li2O + Na2O + K2O 5-8 As2O3 0-0.8. -</p> |
