Lightweight Optics for High Energy Applications

The corrected system wavefront error (WFE) for tactical airborne and relay mirror systems can be minimized using low figure error/surface finish, low print-through, SLMST technology with high-reflectivity VLA coatings. The performance requirements of corrective mirrors in the system (DMs, FSMs) might also be relaxed as the result of the improved system WFE offered by SLMST. SLMST and Silicon Carbide SLMST (SiC-SLMST) have demonstrated the highest structural efficiency for high-bandwidth fast steering mirror applications (e.g. ABL). SLMST can exceed the 1st frequency of lightweighted beryllium. Vacuum-cryogenic testing (27 K) of SLMST at NASA MSFC demonstrated lower print-through than lightweighted fused silica, ULE, Zerodur, beryllium and silicon carbide mirrors, making SLMST ideal for the -20oC tactical airborne or -50oC high-altitude Relay Mirror operational environments. In Phase I, Schafer will perform thermal and structural analysis and estimate cost for SLMST in diameters from 5 to 33-inch. We shall fabricate a 5-inch plano SLMST mirror, polished to a figure of <&#61548;HeNe/10 PV and surface roughness of <10 Å RMS, and coat it with a Very Low Absorption (VLA) dual-band (3.8 and 1.315 micron) high reflectivity coating deposited by the Air Force Optical Components Evaluation Laboratory (OCEL). This prototype would be suitable for high-power testing.