Self-aligned heterodyne laser radar system for surface displacement monitoring

Alejandro Rodriguez; David Garcia; Adolfo Comeron; Federico Dios; Francesc Rocadenbosch

doi:10.1117/12.413830

31 January 2001 Self-aligned heterodyne laser radar system for surface displacement monitoring

Alejandro Rodriguez, David Garcia, Adolfo Comeron, Federico Dios, Francesc Rocadenbosch

Proceedings Volume 4167, Atmospheric Propagation, Adaptive Systems, and Laser Radar Technology for Remote Sensing; (2001) https://doi.org/10.1117/12.413830
Event: Europto Remote Sensing, 2000, Barcelona, Spain

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.

Citation Download Citation

Alejandro Rodriguez, David Garcia, Adolfo Comeron, Federico Dios, and Francesc Rocadenbosch "Self-aligned heterodyne laser radar system for surface displacement monitoring", Proc. SPIE 4167, Atmospheric Propagation, Adaptive Systems, and Laser Radar Technology for Remote Sensing, (31 January 2001); https://doi.org/10.1117/12.413830

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