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Optical Engineering

Results from real-time laser speckle-shift strain measurement system
Author(s): Meg L. Tuma; Lawrence C. Greer; Michael J. Krasowski; Lawrence G. Oberle; Kristie A. Elam; Daniel C. Spina
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Paper Abstract

A real-time two-color laser speckle-shift strain measurement system based on the technique of Yamaguchi was designed, built, and tested at room temperature. This noncontact 1-D system detects surface strain in a structural fiber as it is pulled in a tensile test machine. Interference or speckle patterns from the laser-illuminated fiber test specimen are recorded. As the fiber is pulled, its speckle pattern shifts in proportion to the strain, translational, and rotational components of the sample deformation. Shifting speckle patterns are detected using two linear CCD arrays with image processing performed in realtime by a hardware correlator. Surface strain is detected in fibers with diameters on the order of 100?m and can be resolved to 20 ?m/m. This system was designed to be robust and compact and generally does not require surface preparation of the structural fibers.

Paper Details

Date Published: 1 February 2000
PDF: 7 pages
Opt. Eng. 39(2) doi: 10.1117/1.602399
Published in: Optical Engineering Volume 39, Issue 2
Show Author Affiliations
Meg L. Tuma, NASA Glenn Research Ctr. (United States)
Lawrence C. Greer, NASA Lewis Research Ctr. (United States)
Michael J. Krasowski, NASA Lewis Research Ctr. (United States)
Lawrence G. Oberle, NASA Lewis Research Ctr. (United States)
Kristie A. Elam, Gilcrest Electric (United States)
Daniel C. Spina, NASA Lewis Research Ctr. (United States)

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