DocumentCode :
2197420
Title :
Adaptive Volterra processor for fringe order identification in white-light interferometric systems
Author :
Rizk, M. Sabry ; Romare, D. ; Grattan, K.T.V. ; Palmer, A.W.
Author_Institution :
Dept. of Electr. Electron. & Inf. Eng., City Univ., London, UK
Volume :
1
fYear :
1995
fDate :
24-27 Jul 1995
Firstpage :
413
Abstract :
Comparatively high success rates with the application of linear adaptive least mean square (LMS) algorithms to identify the zero order fringe in the presence of additive Gaussian noise only have been reported in spatially-scanned white-light interferometric (WLI) systems. However, when the corrupting noise causing the problems with fringe identification is signal-dependent and/or exhibits transient behaviour mainly attributable to mechanical vibrations (shocks) in such systems, nonlinear filtering accompanied by a suitable adaptation algorithm should lead to better overall performance. The paper presents a study conducted to appraise the use of Volterra processors in conjunction with adaptive LMS, against the linear filtering counterpart previously published, when the analogue-to-digital (A/D) converters employed in the interferometric system introduce quadratic and/or cubic nonlinearity distortion. The paper also attempts to resolve the linear/nonlinear modelling dilemma of a suspected kind of nonlinearity due to chromatic aberration effects which manifests two important characteristics in the fringe pattern, namely, skewness and nonGaussianity. It is shown that the Volterra processor produces less satisfactory results than a linear filter with optimal choice of the step size parameter. Thus contradicting the hypothesis which regards the effects of chromatic aberrations as nonlinear
Keywords :
aberrations; adaptive filters; image recognition; least mean squares methods; light interferometry; nonlinear filters; optical information processing; optical noise; adaptation algorithm; adaptive Volterra processor; adaptive least mean square algorithms; analogue-to-digital converters; chromatic aberration effects; corrupting noise; cubic nonlinearity distortion; fringe order identification; mechanical vibrations; nonGaussianity; nonlinear filtering; nonlinearity; quadratic nonlinearity distortion; signal-dependency; skewness; transient behaviour; white-light interferometric systems; zero order fringe; Additive noise; Appraisal; Electric shock; Filtering algorithms; Gaussian noise; Least squares approximation; Maximum likelihood detection; Nonlinear filters; Signal processing; Vibrations;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Microwave and Optoelectronics Conference, 1995. Proceedings., 1995 SBMO/IEEE MTT-S International
Conference_Location :
Rio de Janeiro
Print_ISBN :
0-7803-2674-1
Type :
conf
DOI :
10.1109/SBMOMO.1995.509654
Filename :
509654
Link To Document :
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