Method for preparing the base body of a reflecting mirror

摘要

The invention provides a method of preparing a light-weight base body of a reflecting mirror such as a mirror in a reflecting astronomical telescope, which is very stable not only thermally but also mechanically and is highly resistant against adverse environmental influences. The mirror base is composed of a porous foamed disc body of fused quartz glass or high-silica glass sandwiched by two plates of fused quartz glass or high-silica glass, of which one is made from transparent glass and serves to provide an optical surface having flatness or a specified curvature, and the side surface of the porous foamed disc body is protected against environmental influences by providing an air-tight sealing layer formed from a silicone rubber-based sealing agent or a thin sheet of fused quartz glass or high-silica glass.