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Proceedings Paper

Detection of movement with laser speckle patterns
Author(s): Rene Daendliker; Urban Schnell
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Paper Abstract

The dynamic behavior of laser speckle patterns, caused by in-plane motion of a diffusing object under illumination with coherent light, has been sued in the past in many applications to measure the displacement and the velocity of moving objects. In this paper, we present a speckle pattern based detector which measures the movement rather than the velocity of the object.Two pairs of interlaced differential comb-detectors produce two periodic signals in quadratree, which permit to measure the movement and its direction without ambiguity and at arbitrarily low speed. With two orthogonally oriented detector arrays of this type, 2D movements in the plane can be determined. The output signals of these detectors are of statistical nature. The comb- detectors act as periodic filters to the spatial frequency spectrum of the intensity of the speckle pattern. By appropriate choice of the speckle size and the comb-detector period, the output signals versus displacement are quasi- sinusoidal with statistical amplitude and phase. First and second order statistics of these signals have been investigated to determine the reliability and the accuracy of the measurement. All theoretical results have been verified by numerical simulations and by experimental measurements.

Paper Details

Date Published: 1 December 1997
PDF: 9 pages
Proc. SPIE 3317, International Conference on Correlation Optics, (1 December 1997); doi: 10.1117/12.295669
Show Author Affiliations
Rene Daendliker, Univ. of Neuchatel (Switzerland)
Urban Schnell, Univ. of Neuchatel (Switzerland)


Published in SPIE Proceedings Vol. 3317:
International Conference on Correlation Optics
Oleg V. Angelsky, Editor(s)

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