ADAPTIVE THRESHOLDING OF DIFFERENTIAL INTERFEROGRAMS
E. V. Sysoev, A. K. Potashnikov
Technological Design Institute of Scientific Instrument Engineering, Siberian Branch, Russian Academy of Sciences, ul. Russkaya 41, Novosibirsk, 630058 Russia
Keywords: interference of partially coherent light, scanning interferometer, adaptive threshold, interference control of surface topography, differential interferogram
Abstract
A method is proposed for selecting an adaptive threshold for the detection of an interference signal in an optical profilometer based on estimation of optical quantum noise in interferograms of each measurement point. It is shown that when using differential interferograms, this approach allows extending the dynamic range of detection of interference and automate the process of measuring surface topography with a large variation in the light reflection coefficient in the measurement zone. Theoretical calculations, and results of calculations and experiments are presented.
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