Abstract

Chemically vapor-deposited silicon carbide (CVD SiC) is a leading candidate material for large, space-based high energy mirror applications. Because of its large specific stiffness, 99.9999 percent purity, and structural stability, CVD SiC is also being used in less exotic applications, such as in the production of lens molds and replicated optics. Polished CVD SiC is an excellent reflector, particularly for 11-12.5 μm wavelengths [1]. It is, however, an extremely difficult material to polish, because of its low polishing rates (compared to glass). This paper describes a high-precision, fixed abrasive diamond grinding process aimed at eliminating the need for post-polishing for this material. Aside from poor polishing performance, CVD SiC could replace glass in high-technology optical applications because of its toughness, stiffness, and large critical-depth-of-cut with regard to damage-free machining. Table 1 compares some of the relevant material properties of CVD SiC with those of a high-performance optical glass (ULE) made by Coming.

© 1992 Optical Society of America