Lightweight Athermal Silicon Innovative Telescope for Airborne Laser Relay Mirrors

The Air Force is interested in lightweight, high-stiffness optical telescopes, capable of operating with geometric stability under varying thermal conditions (-55 to 50oC). NASA MSFC recently vacuum-cryogenic qualified Schafer's SLMS Athermal Technologyto a temperature of 27 K and demonstrated figure stability of  /60 rms HeNe for an un-mounted f/3 mirror, and /13.6 rms HeNe for the mirror in a prototype mount. Schafer offers to advance the development of athermal high-energy lasertelescopes for bifocal relays (ARMS), using a 3 Phase approach that provides high cost leverage to the Government. In Phase I we will design a 50 cm aperture Lightweight Athermal Silicon Innovative Telescope (LASIT) using ARMS specifications. The LASITprimary mirror will be fabricated using Silicon Lightweight Mirrors (SLMS) Athermal Technology produced under Phase II of Air Force SBIR Contract No. F29601-02-C001476 (COTR Dr. Robbie Robertson, AFRL/VSSV). In Phase II, the metering structure and mirrormounts will be fabricated using Vanguard lightweight, carbon fiber reinforced cyanate ester technology (M55J/954-3 is used as the ABL primary mirror reaction structure). The telescope would be integrated during Phase II, and would include interfaces withBrashear gimbals. The LASIT would be qualified in the Boeing SVS ARMS testbed during Phase III. Telescopes and other optical instruments operating in the high-altitude aerospace environment (50-65,000 feet), high-earth orbit (HEO) and geosynchronous orbitexperience varying thermal conditions, which can adversely impact the performance of the instrument. Silicon Lightweight Mirrors (SLMS) Athermal Technology provides an athermal, lightweight, low cost solution for instruments used in these environments.Applications include telescopes and scan mirror assemblies for space imaging, weather monitoring, and surveillance satellites, and transmitter, receiver, and beam director telescopes for high-energy laser systems.