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Proceedings Paper

In-plane error analysis in ESPSI: the effect of beam divergence
Author(s): W. S. Wan Abdullah; Jon N. Petzing; John Raymond Tyrer
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Paper Abstract

The application of optical metrology using Electronics Speckle Pattern Shearing Interferometry (ESPSI) in industry, is becoming more prevalent as a method of quality assurance and non-destructive testing (NDT). ESPSI provides non-contact full-field inspection of the test object generating displacement derivative data. The trend of using ESPSI in quality assurance in NDT involves the desire for quantitative measurement. ESPSI may be used for out-of-plane displacement derivative (slope) measurements ((delta) w/(delta) x) or potentially in-plane slope measurements (such as (delta) u/(delta) x), depending on optical configurations and object boundary conditions. Current concern is focussed on accuracy of commercial ESPSI systems and questioning the extent of error compensation in the associated fringe software systems. This paper presents studies which have been analyzing in-plane derivative measurement accuracy, as a function of object illumination wave-front divergence. Theoretical error analysis supported by experimental analysis has been performed using restrained aluminum alloy cantilever beam. The relative error is measured by comparing displacement derivative data of measurements using divergent illumination with respect to collimated illumination. The measurement error has been found to be dependent on the direction of illumination and the shearing amount at a fixed distance, with certain combinations producing values exceeding 30%.

Paper Details

Date Published: 31 August 2000
PDF: 12 pages
Proc. SPIE 4076, Optical Diagnostics for Industrial Applications, (31 August 2000); doi: 10.1117/12.397942
Show Author Affiliations
W. S. Wan Abdullah, Loughborough Univ. (United Kingdom)
Jon N. Petzing, Loughborough Univ. (United Kingdom)
John Raymond Tyrer, Loughborough Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 4076:
Optical Diagnostics for Industrial Applications
Neil A. Halliwell, Editor(s)

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