Directional laser velocimetry without frequency biasing: part 2

Abstract

In an earlier paper, Agrawal and McCullough demonstrated that a single laser beam focused at the point of measurement can be used to obtain both the magnitude and direction of local fluid velocity without the use of beam-splitting optics or frequency biasing devices. Additionally, the photoelectric signal was shown to be a zero-mean sine wave suitable for existing counter-type laser Doppler velocimeter signal processors. The method described in the above paper indicated the use of two offset photodetector arrays; the resulting photocurrents from the two arrays were correlated to give direction. In this paper we describe the implementation of the method using a self-scanning diode array. Detector sensitivity in the array is discussed and microchannel plate detectors are suggested for increased sensitivity.