SiC Optics for Earth Observing Applications

An overview of silicon carbide (SiC) materials is provided, focusing on the optical properties required for space-based earth observing applications. NASA’s SiC Advanced Land Imager (ALI), produced by SSGPO and flown under the New Millennium Program, is described in order to illustrate the suitability of SiC to provide high-quality optics for these critical applications. The manufacturing processes used to produce SiC optics are described and recent improvements in the surface figure, surface finish, and stray light performance associated with SiC optics are reported. The two critical optical properties associated with the ALI instrument are surface figure and Bi-directional Reflectance Distribution Function (BRDF). In the results reported here, we demonstrate the ability to exceed these requirements by an order of magnitude using mature and repeatable processes.