Determination of the velocity gradient in laminar liquid flow by the method of optical homodyning in the case of partial spatial coherence of a probe laser beam

A calculation is reported of the autocorrelation function of a signal from a laser homodyne spectrometer generated by laminar flow of a liquid with a velocity gradient in the case of partial spatial coherence of a probe laser beam. It is shown that under certain conditions the time correlation scale of the spectrometer signal represents the velocity gradient and is independent of the coherence radius of the probe radiation. The results are given of a numerical modeling of the energy spectra of the spectrometer signal.