HIGH-RESOLUTION LASER DOPPLER VELOCITY MEASUREMENT OF BIDIRECTIONAL PULSATILE FLUID FLOW

Abstract
A laser Doppler heterodyning system has been developed for localized measurement of the magnitude and direction of time‐varying fluid flow velocity. Directional sensitivity is achieved by shifting the frequency of the reference laser beam by an acoustical diffraction cell. A Doppler frequency shift proportional to fluid flow velocity is obtained by heterodyning the scattered laser light with a frequency‐shifted reference laser beam. Experimental results for time‐varying flow velocity in perturbed flow sections are presented.