SUPERPOLISHED SI COATED SIC OPTICS FOR RAPID MANUFACTURE OF LARGE APERTURE UV AND EUV TELESCOPES

SSG/Tinsley proposes an innovative optical manufacturing process that will allow the advancement of state-of-the-art Silicon Carbide (SiC) mirrors for large aperture UV and EUV applications. The manufacturing process combines three critical technologies: a slip cast, Reaction Bonded (RB) SiC, an amorphous silicon (Si) coating, and Computer Controlled Optical Surfacing (CCOS) technology. This combination of technologies addresses two critical areas required for enabling cost effective precision optics for large aperture UV and EUV applications: lightweighting of the optical substrate and polishing effort required for reaching final figure and finish. The proposed optical manufacturing flow provides solutions in both of these areas. The ability to near net shape lightweight RB SiC significantly reduces the machining required to prepare the substrate for optical surfacing. The use of a Si-coating on the RB SiC makes it possible substantially improve the removal rate-reducing the time and cost required to precision figure and finish the optic. CCOS superpolishing techniques will be developed that deterministically achieve excellent figure accuracies (<0.01 waves RMS) and low microroughness (< 10 Angstroms RMS) for very low areal densities (10 kg/m2 at an aperture of 1 meter). Phase 1 process development and demonstration will lead to flight-ready optics in Phase 2.