Mirror and method of making same

Abstract

A mirror, and method of making same, is disclosed. The mirror includes a metallic base material having a low coefficient of thermal expansion, an intermediate layer bonded to the base by a plasma spray process and a reflecting surface overlying the intermediate layer, the coefficients of thermal expansion of the materials of the intermediate layer and the reflecting surface differing from each other and from the coefficient of thermal expansion of the base material. The disclosed method contemplates: The casting of a mirror blank from a material having a low coefficient of thermal expansion and machining the surface to a desired contour, with stress-relieving heat treatments before and after such machining; plasma spraying an intermediate coating of a material having a Rockwell hardness equal to, or greater than, 60; grinding the intermediate coating to a desired contour and lapping and cleaning such ground coating to produce an optically smooth contoured surface; and finally plating such surface to provide the desired mirror surface.

Dependencies are inferred from the claim text.