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Proceedings Paper

A Novel Approach To Whole Field Vibration Analysis Using A Pulsed Laser System
Author(s): F. Mendoza Santoyo; D. Kerr; J. R. Tyrer; T. West
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Paper Abstract

Holographic and Speckle Pattern Interferometry utilising continuous wave lasers has so far been useful only as a laboratory tool. A major drawback limiting its introduction to industrial applications is the degree of environmental stability needed to obtain high quality fringes. Application of a pulsed laser to Holographic Interferometry has been demonstrated by several workers to show significant improvement in stability and scope of application. In a similar way, a pulsed laser can produce speckle correlation fringes on a single frame from a CCD TV camera, thus eliminating environmental sensitivity problems and rigid body motion. Results obtained with Electronic Speckle Pattern Interferometry (ESPI) incorporating a pulsed YAG laser are reported. Vibration and static deformation fringes have been produced for a clamped metal plate. With a double pulse laser, the first pulse can he positioned at any time during the vibration cycle. The firing of the second pulse depends on the scanning time of a single field of the CCD camera. Due to the pulsing action of the laser the vibration amplitude fringe pattern can he animated on the TV screen to gain a visual impression of the surface motion. A new technique has been developed for extracting deformation and shape information from interferometric fringes. It involves a significant improvement in environmental stability and reduced computational effort. Problems due to noise and data ambiguity are eliminated with the extraction of phase information from only two digitised interferograms. Continuous wave, stroboscopic and pulsed laser illumination are all amenable to this one technique. Results employing the new fringe processing algorithms are presented. Comparisons are made with data obtained with a computer Finite Element prediction for the same target.

Paper Details

Date Published: 26 October 1989
PDF: 11 pages
Proc. SPIE 1136, Holographic Optics II: Principles and Applications, (26 October 1989); doi: 10.1117/12.961705
Show Author Affiliations
F. Mendoza Santoyo, Loughborough University of Technology (England)
D. Kerr, Loughborough University of Technology (England)
J. R. Tyrer, Loughborough University of Technology (England)
T. West, Loughborough University of Technology (England)

Published in SPIE Proceedings Vol. 1136:
Holographic Optics II: Principles and Applications
G. Michael Morris, Editor(s)

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