| 摘要 |
This invention relates to photochromic glasses exhibiting refractive indices greater than 1.59, densities no higher than 3.1 g/cm<3>, Abbe numbers of at least 40, weight losses no greater than 0.01 mg/cm<2> in the A.O. test, and which, when exposed to actinic radiation at room temperatures, darken to transmittances below 40% and fade at least 15 percentage points of transmittance after five minutes' removal from the actinic radiation. |
