Development of a Laser Micromachining Process for the Fabrication of SiC Mirrors

The key goal of this program is to reduce the non-recurring and recurring costs and shorten cycle times for fabrication of the next generation cryogenic telescope structural and optical components. Currently beryllium is used for both the mirrors and the optical bench assemblies in these high performance optical telescopes due to its 1) high stiffness at very light weights and 2) very good thermal properties. However, the use of Be in these telescopes is costly because of the substantial fabrication lead-times associated with the machining and mechanical polishing of mirror surfaces. In addition, the health/environmental hazard related to handling Be is a very significant issue. Over the last few years, silicon carbide (SiC) materials and technologies have matured to the point that they are being baselined for DoD and NASA's operational space flight systems. Recently, Raytheon and MDA have initiated a laser microfabrication process for SiC in the critical optical components of cryogenic telescopes. Developing a laser micromachining capability to fabricate the mirror shape and ultimately polish the surface of a silicon carbide mirror blank will drastically reduce the required lead-time and eliminate the hazards associated with the Be fabrication process. The program outlined in this proposal will determine the appropriate laser for the microfabrication tasks and determine the conceptual design for a SiC mirror fabrication workstation.