SYMPOSIA PAPER Published: 01 January 1991
STP23616S

Ion Beam Milling of Fused Silica for Window Fabrication

Source

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.

Author Information

Wilson, SR
Reicher, DW
Kranenberg, CF
McNeil, JR
White, PL
Rockwell International, Canoga Park, CA
Martin, PM
McCready, DE
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Details
Developed by Committee: F01
Pages: 82–86
DOI: 10.1520/STP23616S
ISBN-EB: 978-0-8031-5179-6
ISBN-13: 978-0-8194-0532-6