One-wavelength two-component laser Doppler velocimeter system for surface displacement monitoring

• Published in: Optical Engineering 2008-12, Vol.47 (12), p.123606-1236011
• Main Authors: Garcia-Vizcaino, David, Dios, Federico, Recolons, Jaume, Rodri´guez, Alejandro, Comeron, Adolfo
• Format: Article
• Language: English
• Subjects: Beams (radiation); Computer programs; Detectors; differential Doppler; Doppler shift; Fluid dynamics; Fluid flow; Hydrodynamics; laser Doppler velocimeter (LDV); Laser doppler velocimeters; laser radar; Prototypes; surface displacement measurement; two-component LDV (2D-LDV); velocity measurement
• ISSN: 0091-3286; 1560-2303
• DOI: 10.1117/1.3050421

A two-component laser Doppler velocimeter (2D-LDV) prototype for surface-displacement measurement is presented. The system proposed is based on the Doppler differential technique with a backwardscattering configuration. A reference and two frequency-shifted probe beams are generated departing from a single laser beam by means of two beamsplitters and acousto-optic modulators. This configuration has the advantage of using a single-wavelength laser source and a single detector system, while permitting sign detection of the two vector components of the velocity in surface-displacement measurements. It also enables the implementation of a low-cost multitrigger data acquisition system, which is useful in low signal-to-noise ratio (SNR) situations, such as the velocity measurement of low-dispersion surfaces or in hydrodynamic applications. The prototype has been designed to measure velocities up to , both in industrial (solid target) and hydrodynamic applications, with an error well below 1 in the tests performed. The system works in real time with the use of an acquisition card and C++ based software on a PC.