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Proceedings Paper

Application Of Laser Speckles To Nondestructive Evaluation
Author(s): F. P. Chiang
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Paper Abstract

When an optically rough surface is illuminated by a coherent laser beam, speckles are created due to multiple interference of the reflected (or transmitted) wavelets. They fill a volume in front of the illuminated surface. By suitably choosing a "plane" of speckles to photograph before and after they are displaced by the surface deformation via double exposure or time-average, the resulting speckle interferogram can yield a variety of information for engineering measurement. Speckles can also be created in the interior of a body by scattered light if it is made of transparent material and a laser beam is sent through it. In this way one can also probe the stress distribution inside a general three dimensional object. In this presentation two types of applications of the basic principle of one-beam laser speckle interferometry will be discussed: one is in the realm of nondestructive quantitative evaluation such as stress analysis of plane problems of elasticity, flexure of plates, vibration, and general three-dimensional problems; and the other is qualitative evaluation such as detection of crack in structure and debonding of laminated composites.

Paper Details

Date Published: 20 October 1977
PDF: 10 pages
Proc. SPIE 0122, Advances in Laser Engineering I, (20 October 1977); doi: 10.1117/12.955774
Show Author Affiliations
F. P. Chiang, State University of New York (United States)

Published in SPIE Proceedings Vol. 0122:
Advances in Laser Engineering I
Malcolm L. Stitch; Eric J. Woodbury, Editor(s)

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