STP1117: Low Scatter Surfaces on Silicon Carbide

    Paquin, RA
    Hughes Danbury Optical Systems, Inc., Danbury, CT

    Magida, MB
    Hughes Danbury Optical Systems, Inc., Danbury, CT

    Pages: 7    Published: Jan 1990


    Abstract

    Reaction bonded silicon carbide (RB SiC) can be readily fabricated to near net shape and mirror blanks produced by this method can potentially be less costly than those fabricated by chemical vapor deposition (CVD). However, RB SiC is two phase, SiC and up to 30% silicon (Si), and can not normally be directly polished to low scatter and roughness levels due to the difference in hardness of the two phases. We have investigated the polishability of RB SiC as a function of Si content and microstructure. Our results show that with a favorable microstructure, RB SiC can be polished to less than 10Å rms. For reduced roughness and lower scatter surfaces, we have developed low temperature deposition techniques to apply polishable, single phase coatings to the figured two phase surfaces. Scatter and roughness measurements show levels are comparable to CVD SiC.

    Keywords:

    BRDF, coatings, finishing, grinding, ion assisted deposition, ion beam sputtering, low scatter, microstructure, mirrors, polishing, reaction bonded silicon carbide, silicon, silicon carbide, surface roughness


    Paper ID: STP26494S

    Committee/Subcommittee: E13.15

    DOI: 10.1520/STP26494S


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