Purely optical parallel processing in particle image velocimetry and the study of flow structures

The pointwise interrogation of records obtained by particle image velocimetry is time-consuming and cumbersome. Problems in fluid mechanics that require the evaluation of large sets of flow records require faster methods. A philosophy is developed that utilizes the great information handling capacity of optical processing. The costly scanning procedure is replaced by parallel processing with an array of holographically produced interrogation beams. Specialized processing of the resulting array of Young’s fringe systems renders the position resolved velocity field, accumulated velocity data or information about structural features of the field. Experimental examples are shown.