High Quality, Low-Scatter SiC Optics Suitable for Space-based UV & EUV Applications

SSG Precision Optronics proposes the development of a novel optical manufacturing process that will allow the production of state-of-the-art Silicon Carbide (SiC) optics. The work proposed combines three different manufacturing technologies, a slip cast SiC mirror forming process and low temperature CVD SiC coating process, which have been developed by SSG, and Computer Controlled Optical Surfacing technology (CCOS) which has been developed by Tinsley, a subsidiary of SSG. The combination of these technologies will provide SiC optics with state-of-the-art surface figures (low frequency and mid-frequency errors will both be addressed) and low-scatter surface finishes. SiC optics offer a number of critical advantages for space-based optical systems. The superior material properties of SiC provide a high degree of lightweighting (70% - 90% of beryllium) and a superior thermal stability (1.5x ? 2.5x better than ULE). The manufacturing process proposed will allow the technical advantages associated with SiC materials to be realized, providing the capability to produce imaging mirrors which are capable of providing excellent accuracies (<0.01 waves RMS), low micro-roughness (< 10 Angstroms RMS), and very low areal densities (10 kg/m2 at an aperture of 1 meter) while maintaining the thermal stability required for space-based imaging applications. The quality and micro-roughness of these optics will be good enough to address the stressing needs associated with visible, UV and EUV wavebands. In our Phase I work the process development proposed will be verified by the production of a lightweighted SiC aspheric mirror to a set of stressing figure and finish requirements.