Abstract: Lightweight, high performance optical systems have historically relied upon ultralightweight optical components to achieve high stiffness, low weight, high quality optical surfaces exhibiting high thermal stability. Composite Optics, Incorporated (COI) has independently pursued state-of-the-art graphite fiber reinforce composite (GFRC) substrates for microwave and infrared (IR) applications. Eastman Kodak Company (Kodak) and COI have participated in a joint evaluation of hybrid optical mirrors fabricated from low coefficient of thermal expansion (CTE) graphite composite materials and ULE$+TM$/ low CTE glass. While glass can be polished to achieve an optical quality surface, relative to other mirror substrates, GFRC attractively offers high specific stiffness and low steady state and transient distortion characteristics as shown. This joint effort between Kodak and COI has resulted in the demonstration of processed optical surfaces within 0.05 waves rms (at 0.63 $mu@m). Optical surfaces have remained stable to within 2 waves rms over a wide range of temperatures ($MIN@13 to 65$DGR@C). The optical performance demonstrated meets the requirements for long wavelength systems, with promise of satisfying visible wavelength performance with further development.!5
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