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Proceedings Paper

Gradient operators for extracting the derivative of a function described by an interferometric fringe field
Author(s): David Kerr; Jon N. Petzing; Massimo Facchini
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Paper Abstract

Many engineering applications of interferometry, such as fracture mechanics and stress analysis, require the extraction of the first derivative of some measured function g(x,y) which is in turn represented by a 2 dimensional, digitized fringe pattern I(x,y). The conventional approach is to obtain an intermediate function (phi) (x,y) which represents the modulo 2(pi) interferometric phase change related to some change in optical path. It is first necessary to `unwrap' this phase information to obtain a smooth and continuous function, which may then be numerically differentiated to obtain the desired quantity of g(x,y). This analysis process, while reasonably straightforward, may be computationally expensive and in any case sensitive to noise, bad data, and quantization error. In this paper, we investigate the use of gradient operators for the direct extraction of the derivative of the interferometric phase function. Our goals are to be able to apply local gradient operators directly to the wrapped phase data, thus removing the `unwrapping' part of the process, and to reduce the susceptibility to noise of such operators.

Paper Details

Date Published: 12 December 1994
PDF: 10 pages
Proc. SPIE 2340, Interferometry '94: New Techniques and Analysis in Optical Measurements, (12 December 1994); doi: 10.1117/12.195913
Show Author Affiliations
David Kerr, Loughborough Univ. of Technology (United Kingdom)
Jon N. Petzing, Loughborough Univ. of Technology (United Kingdom)
Massimo Facchini, EU Joint Research Ctr. (Italy)

Published in SPIE Proceedings Vol. 2340:
Interferometry '94: New Techniques and Analysis in Optical Measurements
Malgorzata Kujawinska; Krzysztof Patorski, Editor(s)

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