| 摘要 |
<p>A photochromic glass article which is especially suitable for spectacle lenses having an integral colored surface layer and exhibiting near-zero transmittance of radiations having wavelengths shorter than a selected cutoff wavelength ranging between 440-550 nm, said glass consisting essentially, expressed in weight percent on the oxide basis, of 0-2.5% Li2O, o-9%Na2O,0-17%K2O,0-6%Cs2O,8-20%Li2O + Na2O + K2O + Cs2O, 14-23% B2O3, 5-25% Al2O3, 0-25% P2O5, 20-65% SiO2, 0.004-0.02% CuO, 0.15-0.3% Ag, 0.1-0.25% Cl, and 0.1-2% Br, wherein the molar ratio of alkali metal oxides: B2O3 varies between about 0.55-0.85 and the weight ratio Ag: (Cl+Br) ranges between 0.65-0.95. …<??>Such glasses are suitable for use as spectacle lenses for aphakics or for persons subject to photoretinitis or retinitis pigmentosa. …<??>The integral colored layers is developed on the surface by exposure to a strongly reducing atmosphere at a temperature of 350 to 520 DEG C for at least 12 hours.</p> |
