The Affordable Pre-Finishing of Silicon Carbide for Optical Applications

Large aperture, lightweight optical mirror technologies are critical for the future of lightweight telescopes and their attendant missions to explore the planets in our solar system and beyond. Chemical vapor deposition (CVD) coated silicon carbide (SiC) has been shown to be a viable alternative for lightweight mirrors due to its thermal stability; however, cost-effective manufacturing techniques to pre-finish this material have not been sufficiently developed. During the Phase I project, we established the feasibility of the low-rate step of our hybrid machining approach by successfully completing ductile-regime machining (DRM) of CVD SiC. We were able to produce a surface that had a roughness of a near-optical quality. We established key partnerships that will enable the development of the high rate machining step and demonstrated that our hybrid machining approach will reduce the cost of fabricating a finished mirror by up to 46% when compared with the current state-of-the-art. During the Phase II project, we will work further to develop our hybrid machining process, demonstrate it on a large scale optic, and deliver it to NASA.