The present invention relates to an optical glass for an optical path, having a refractive index of at least 1.55, an Abbe number of at least 48 and a specific gravity of at most 2.90 and being excellent in chemical durability, having a chemical composition of:
A glass composition for a photoetching mask is described, which comprises, all by mol, 55 to 70% SiO.sub.2, 7 to 11% Al.sub.2 O.sub.3, 7 to 20% CaO, 3 to 13% MgO, 3 to 13% ZnO, 0.5 to 3% K.sub.2 O or Na.sub.2 O, 0 to 11% PbO and 0 to 3% ZrO.sub.2. This glass is free from defects such as pinholes, has a relatively low coefficient of thermal expansion and contains no air bubbles, and a photoetching mask composed of the glass composition.
Lead-free ceramic frits for producing glazes with intrinsic opacity, and methods of coationg ceramic substrates with the ceramic frits, wherein the ceramic frits have the following composition:
This invention relates to lead-free silicate glasses that find use in producing fine crystal glassware and in laminated ware applications. The glasses consist essentially, in weight percent, of:
The optical fiber fixing member made of glass, especially optical fiber guide block, is conventionally produced by a mechanical processing. However, the mechanical processing has problems that a production cost becomes high and mass-production is difficult. The problems above can be solved by the present invention providing a method for producing an optical fiber fixing member comprising: disposing a glass shaping preform whose plane view resembles to the plane view of the molded article and whose faces to be positioned in the pressurizing direction during press-molding assumes planes or outwardly convex curved surfaces, in a mold having a cavity of a given shape; and heating the glass shaping preform up to a temperature at which the glass shaping preform can be mold-shaping and thereby press-molding it into a molded article having at least one edge formed of a free surface.
