STP1141: Ion Beam Milling of Fused Silica for Window Fabrication

    Wilson, SR
    University of New Mexico Center for High Technology Materials, Albuquerque, NM

    Reicher, DW
    University of New Mexico Center for High Technology Materials, Albuquerque, NM

    Kranenberg, CF
    University of New Mexico Center for High Technology Materials, Albuquerque, NM

    McNeil, JR
    University of New Mexico Center for High Technology Materials, Albuquerque, NM

    White, PL
    Rockwell International, Canoga Park, CA

    Martin, PM
    University of New Mexico Center for High Technology Materials, Albuquerque, NM

    McCready, DE
    University of New Mexico Center for High Technology Materials, Albuquerque, NM

    Pages: 5    Published: Jan 1991


    Abstract

    Ion beam figuring has been demonstrated to be a deterministic, efficient, flexible technique for removing material from optical surfaces. Recent interest in using this process to produce high quality optical components has driven the need to fully characterize the resulting surfaces. We have performed a polishing parameter matrix investigation to optimize fused silica (Corning 7957) surfaces for subsequent ion milling. Samples were characterized for surface scatter, surface absorption, surface roughness, subsurface damage, and laser damage as a function of mill depth. Small defects (pits) were evident on surfaces after milling a few microns, with pit density dependent to some degree upon the surface preparation technique. The defects were often in lines, apparently following a surface or subsurface scratch in the material. Surface scatter decreased significantly (up to 10X), and laser damage threshold increased in some cases by 400%. Laser damage was not correlated with defects in the material.

    Keywords:

    ion beam milling, laser damage, scatter, fused silica, absorption


    Paper ID: STP23616S

    Committee/Subcommittee: F01.19

    DOI: 10.1520/STP23616S


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