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Optical Engineering

Stabilized and accelerated speckle strain gauge
Author(s): Ichirou Yamaguchi; Tamiki Takemori; Koichi Kobayashi
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Paper Abstract

We have improved the stability and temporal response of the laser speckle strain gauge that detects strain from speckle displacement caused by surface deformation. In the gauge, a narrow laser beam is incident on a diffuse surface, and speckle patterns appearing in the light scattered through the symmetrical angles are detected by a pair of linear image sensors. Speckle displacement is derived by a real-time correlator as the peak of the cross correlation between the current frame and a reference frame of the sensor driven at 1000 frames per second. The reference frame is fixed until the correlation peak becomes lower than a threshold. Using a pair of image sensors, followed by the correlators, and a laser of output power of a few tens of milliwatts, we could measure dynamic strain of polymer films at the frequency between a fraction of hertz and 100 Hz. The resolution of the gauge, which only depends on geometry of the optical system and the sensor pitch, is a few tens of microstrains. The upper limit of the measurement can be extended arbitrarily because small incremental strain is integrated.

Paper Details

Date Published: 1 March 1993
PDF: 8 pages
Opt. Eng. 32(3) doi: 10.1117/12.61043
Published in: Optical Engineering Volume 32, Issue 3
Show Author Affiliations
Ichirou Yamaguchi, RIKEN--Institute of Physical and Chemical Research (Japan)
Tamiki Takemori, Hamamatsu Photonics K.K. (Japan)
Koichi Kobayashi, Toyo Seiki Co. (Japan)

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