Digitally Enhanced Micro-Interferometry

S N Jabr

doi:10.1117/12.939530

13 February 1987 Digitally Enhanced Micro-Interferometry

S N Jabr

Proceedings Volume 0676, Ultraprecision Machining and Automated Fabrication of Optics; (1987) https://doi.org/10.1117/12.939530
Event: 30th Annual Technical Symposium, 1986, San Diego, United States

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.

Citation Download Citation

S N Jabr "Digitally Enhanced Micro-Interferometry", Proc. SPIE 0676, Ultraprecision Machining and Automated Fabrication of Optics, (13 February 1987); https://doi.org/10.1117/12.939530

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