Abstract: The present invention is directed to the production of spontaneous opal glasses exhibiting softening points in excess of 750.degree. C., a coefficient of thermal expansion between about 60-90.times.10.sup.-7 /.degree.C., a crystal liquidus temperature below 1350.degree. C., a liquidus viscosity of at least 200 poises, and excellent resistance to attack by alkalies. Spherically-shaped glassy droplets constitute the opal phase in the glasses which consist essentially, in weight percent, of______________________________________ SiO.sub.2 50-72 Na.sub.2 O 0-8 CaO 10-40 Al.sub.2 O.sub.

Abstract: There is disclosed a composite photochromic glass article composed of a glass core and a thin surface layer substantially encasing that core, the core preferably containing a copper-cadmium halide photochromic crystal system and the substantially encasing glass layer preferably containing a copper-cadmium-silver halide photochromic crystal system. The article may be made by fusion laminating two separately formed glasses, or by introducing silver into a surface layer on a glass article by ion exchange.

Abstract: A fluorine containing silicate glass substrate is heated to a temperature sufficiently high to permit fluorine to out-diffuse from the surface thereof. A surface region is formed having a gradient fluorine concentration in a direction perpendicular to the substrate surface, the region of lowest fluorine concentration having the highest refractive index. The resultant device is capable of functioning as an optical waveguide.

Abstract: Alkali boroaluminosilicate glass compositions providing refractive index-corrected copper-cadmium halide photochromic glasses of optical quality, particularly useful for making ophthalmic lenses, are described. Ion-exchange-strengthenable glasses exhibiting good chemical durability and a satisfactory liquidus-viscosity relationship in combination with good photochromic properties and the required refractive index are also provided.

Abstract: The absorptive and refractive properties of additively colored glasses containing an absorptive metallic silver phase and a separated silver halide phase are altered by irradiating the colored glasses with visible light. Polarization effects and multicolored images can be produced.

Abstract: Silver halide-containing photochromic glasses are rendered optically anisotropic by darkening with actinic radiation and irradiating with linearly polarized bleaching light. A photochromic glass so treated will be optically isotropic when it returns to the clear state, but may again become optically anisotropic when redarkened. Color adaptation results when darkened silver halide-containing photochromic glasses are irradiated with colored optical bleaching light.

Abstract: A fluorine containing silicate glass substrate is heated to a temperature sufficiently high to permit fluorine to out-diffuse from the surface thereof. A surface region is formed having a gradient fluorine concentration in a direction perpendicular to the substrate surface, the region of lowest fluorine concentration having the highest refractive index. The resultant device is capable of functioning as an optical waveguide.