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Proceedings Paper

Digitally Enhanced Micro-Interferometry
Author(s): S N Jabr
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Paper Abstract

Surface roughnesses of 1 angstrom rms were measured on low reflectance polished Zerodur and silica substrates by quantitative analysis of Nomarski differential phase contrast images with a fast digital image processor. A measure of roughness was obtained from the standard deviation of intensities in the Nomarski image observed by a vidicon tube with linear response and digitized in real time. The images were averaged over 256 video frames in order to eliminate vidicon noise since the signal-to-noise ratio required to see 1 angstrom roughnesses is 60 dB. Image subtraction was very effectively used to eliminate unwanted intensity variations due to dirt on the surfaces, spurious reflections from optical surfaces and vidicon shading. Work is ongoing to perform the image processing on a generic micro-computer and to reconstruct the surface profiles.

Paper Details

Date Published: 13 February 1987
PDF: 6 pages
Proc. SPIE 0676, Ultraprecision Machining and Automated Fabrication of Optics, (13 February 1987); doi: 10.1117/12.939530
Show Author Affiliations
S N Jabr, Litton Guidance and Control Systems (United States)

Published in SPIE Proceedings Vol. 0676:
Ultraprecision Machining and Automated Fabrication of Optics
Donald L. Decker, Editor(s)

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