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Proceedings Paper

Self-aligned heterodyne laser radar system for surface displacement monitoring
Author(s): Alejandro Rodriguez; David Garcia; Adolfo Comeron; Federico Dios; Francesc Rocadenbosch
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Paper Abstract

A novel configuration for a reference-beam, continuous-wave, heterodyne low-power radar prototype is presented. It measures both magnitude and sign of the radial component of the displacement velocity. The basic set-up includes a low power (~10 mW) commercial HeNe laser, a beam-splitter, an acousto-optic modulator, and a two-lens system that both focuses the transmitted beam on the target surface and collects the scattered light. Both the reference beam and the radiation collected are focused onto a Si avalanche photo-detector. The self-aligned configuration of the receiver makes possible, theoretically, to perform optimal mixing between the received scattered radiation and the reference beam. The resulting electrical signal is fed to a transimpedance amplifier and displayed on a spectrum analyzer. Laboratory experiments employing as a target the rim of a 50 cm-diameter rotating wheel placed at several distances have been performed. Results concerning detected signal-to-noise ratio, detected- signal spectral width, accuracy of the radial component of the velocity under measurement, system working range, and system tolerance in focus-adjustment distance will be presented and discussed. Compared to a previous homodyne prototype presented by the authors, the present system shows a shorter working range (~12 m compared to nearly ~16 m in the homodyne prototype). We attribute this smaller range to the additional losses in the acousto-optic modulator.

Paper Details

Date Published: 31 January 2001
PDF: 9 pages
Proc. SPIE 4167, Atmospheric Propagation, Adaptive Systems, and Laser Radar Technology for Remote Sensing, (31 January 2001);
Show Author Affiliations
Alejandro Rodriguez, Univ. Politecnica de Catalunya (Spain)
David Garcia, Univ. Politecnica de Catalunya (Spain)
Adolfo Comeron, Univ. Politecnica de Catalunya (Spain)
Federico Dios, Univ. Politecnica de Catalunya (Spain)
Francesc Rocadenbosch, Univ. Politecnica de Catalunya (Spain)

Published in SPIE Proceedings Vol. 4167:
Atmospheric Propagation, Adaptive Systems, and Laser Radar Technology for Remote Sensing
John D. Gonglewski; Gary W. Kamerman; Anton Kohnle; Ulrich Schreiber; Christian Werner, Editor(s)

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