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Proceedings Paper

Non-Contact Laser Extensometer
Author(s): Michael Hercher; Geert Wyntjes; Herman DeWeerd
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Paper Abstract

A technique has been developed for the non-contact measurement of the lateral motion of a diffusely reflecting surface. This technique, which is based on the use of a commercially available stabilized 2-frequency laser, is capable of sub-micron resolution, and operates with a stand-off distance of up to 50 cm. The principle of the measurement is coherent heterodyne detection of Doppler-shifted light scattered by the diffuse surface. By making two such measurements at spatially separated points on the surface, extension of the surface can be monitored. The resultant extensometer provides a non-contact replacement for conventional strain-gage extensometers, and is particularly applicable to measurements in harsh environments (high temperature, corrosive atmospheres, etc.). Frequency response in excess of 25 KHz has been confirmed, making the sensor particularly useful for closed-loop operation in fatigue testing.

Paper Details

Date Published: 10 September 1987
PDF: 9 pages
Proc. SPIE 0746, Industrial Laser Interferometry, (10 September 1987); doi: 10.1117/12.939780
Show Author Affiliations
Michael Hercher, Optra, Inc. (United States)
Geert Wyntjes, Optra, Inc. (United States)
Herman DeWeerd, Optra, Inc. (United States)


Published in SPIE Proceedings Vol. 0746:
Industrial Laser Interferometry
Ryszard J. Pryputniewicz, Editor(s)

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