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23 October 1995 Optical surfacing of one-meter-class reaction bonded silicon carbide
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Optical fabrication methods for a one meter reaction bonded optical grade silicon carbide (RBO SiC) substrate have been successfully developed and demonstrated by Itek Optical Systems in Lexington, Massachusetts. A 1.125 m multiplied by .825 m RBO SiC panel, the largest SiC ever fabricated, has been ground and polished to a surface figure of lambda/20 rms at lambda equals .6328 nm. The single most critical technology area for RBO SiC optics has been attaining a high quality optical surface finish; this bimodal material requires particular processing techniques due to the hardness differences between the silicon and silicon carbide components. The measured surface finish quality for this one meter mirror is 15.5 angstrom rms, nearly twice as good as the specified 25 angstrom rms. Furthermore, the variation of surface finish over the mirror area is very low, sigma equals 2 angstrom. The mirror represents the state-of-the-art for lightweight, high quality SiC optical mirrors.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Robert S. Breidenthal, Regina Galat-Skey, and John J. Geany "Optical surfacing of one-meter-class reaction bonded silicon carbide", Proc. SPIE 2543, Silicon Carbide Materials for Optics and Precision Structures, (23 October 1995);

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