Prediction of the photodetector signal generated by Doppler-induced speckle fluctuations: theory and some validations

A theoretical framework is proposed for describing the laser Doppler photod etector signal. The theory allows for predicting the power of the photocurr ent fluctuations. It is valid for a detector of arbitrary size. The input d ata required for application of the theory are the angular distribution of the detected light, the fraction of Doppler-shifted photons, and the active detector size. The theory is based on the time-domain approach to the stat istics of dynamic speckle patterns on the photodetector. An experiment was carried out to validate some aspects of our theory. The consequences of the speckle dynamics for the various modes of laser Doppler flowmetry are disc ussed. (C) 2001 Optical Society of America.