Project Title:

Silicon Carbide Lightweight, One Meter Class Mirror Development

08.07-0204
900766
Silicon Carbide Lightweight, One Meter Class Mirror Development

Abstract:

Silicon carbide (SiC) is emerging as a serious alternative for lightweight spaceborne
telescope applications due to commercially available reaction bonded fabrication
techniques and replication processing advances. SiC has the significant advantages
of the lightweight features of beryllium, the cryogenic and optical performance and
stability of glass, and the low cost of aluminum. This Phase I SBIR proposes fabricating
mirrors by overcoating SiC subtrates with silicon (Si) to facilitate polishing. The
similarity in thermal expansion between SiC and Si insures an inherently athermal
design. The specific tasks include the conceptual design of a 1 meter class SiC/Si
overcoat mirror and SiC mount assembly for visible to UV spaceborne applications,
and the demonstration of this technology feasibility via fabrication and test of
an 8-inch aperture concave spherical mirror and mount assembly to near diffraction
limited, visible to ultraviolet performance. The goals of Phase II would be to fabricate
and test a prototype 1 meter class SiC/Si mirror and mount assembly.
A SiC/Si telescope has the potential to satisfy stringent spaceborne optical requirements
such as those necessary in one meter class, near diffraction limited, visible to
ultraviolet telescopes for astronomical, earth and atmospheric science applications.
The answers obtained during this endeavor will have broad implications on the sizing
of spacecrafts and launch boosters for both government and commercial applications.
silicon carbide; telescope; visible; ultraviolet; mirrors; structure; cryogenic