Flow velocities visualization using Doppler picture interference velocimetry

An improved technique for visualizing a velocity field in an entire plane has been developed by taking “Doppler Velocimetry Pictures” using Michelson interferometry (DPV). The Doppler pictures give information about the instantaneous the local velocities of tracers passing through a light sheet. The Doppler shift of the frequency of the light scattered by tracer particles is modified by a Michelson interferometer into varying light intensities. The initial interference fringe system is transformed by flow velocities. Two different techniques for the treatment of the images are presented. The first one is based on the shift of the fringe system, the second one uses the different light intensity distribution of the fringe system. For both cases the Doppler pictures are taken by CCD cameras and the images are computer-processed for velocity presentation