| 摘要 |
1498296 Coating with glass AMERICAN OPTICAL COR 21 Feb 1975 [29 Nov 1974] 7460/75 Heading C1M [Also in Division C4] A method of forming a phototropic layer on an optical element comprises (a) applying to a clear surface of the element a solution comprising a silver nitrate and a material which is convertible to a glass comprising SiO 2 optionally together with P 2 O 5 or B 2 O 3 and (b) treating the surface in a halogen containing atmosphere in darkness under conditions to form a layer of glass containing silver halide. The layer may contain 5 to 60 mole per cent of Ag ions and 8 to 85 mole per cent of Cl and/or Br ions and may be <20 Á thick. The solution may contain a sensitizer such as copper nitrate, and the convertible compound may be tetra-ethyl-orthosilicate, alternatives being specified by trade names. A detailed example is disclosed. Step (a) may be by dipping or spin casting. The substrate may contain an optically polarizing layer and may be a polymer of diallyl glycol carbonate, polymethylmethacrylate or a polycarbonate, or inorganic material such as glasses of compositions A to L in the Table (not shown). Applications include sunglass lenses (ophthalmic or piano), image displays, storage systems and windows.
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