Valley Design Corp. offers a silicon carbide mirror finish. The company laps and polishes substrates and mirrors up to 12 in. in diameter to surface finishes better than 10 Å with l/4 flatness. According to the company, its light weight, high flexure strength, rigid structure and thermal properties make the material suitable for scan mirrors and movable optics for space telescopes. Silicon coatings that can be polished for an improved finish are also available.