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Proceedings Paper

Optical Strain Measurement System Development
Author(s): Christian T. Lant; Walid Qaqish
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Paper Abstract

A laser speckle, differential strain measurement system has been built and tested for future applications in hostile environments. One-dimensional electronic correlation of speckle pattern movement allows a quasi-real time measure of strain. The system has been used successfully to measure uniaxial strain reaching into plastic deformation of a test specimen, at temperatures ranging to 450°C. A resolution of 16 microstrain is given by the photodiode array sensor pitch and the specimen to sensor separation. The strain meas-urement error is estimated to be ±18 microstrain ±0.3 percent of the strain reading. The upper temperature limit of the gauge is determined by air density perturbations causing decorrelation of the reference and shifted speckle patterns, and may be improved by limiting convective flow in the immediate vicinity of the test specimen.

Paper Details

Date Published: 17 February 1987
PDF: 9 pages
Proc. SPIE 0814, Photomechanics and Speckle Metrology, (17 February 1987); doi: 10.1117/12.941693
Show Author Affiliations
Christian T. Lant, NASA Lewis Research Center (United States)
Walid Qaqish, NASA Lewis Research Center (United States)

Published in SPIE Proceedings Vol. 0814:
Photomechanics and Speckle Metrology
Fu-Pen Chiang, Editor(s)

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