Holographic particle image velocimetry: Simultaneous recording of several light sheets by coherence encoding in a photorefractive crystal

This paper deals with a new version of multi-beam particle-image velocimetry. Double-exposure holograms of several light sheets are recorded simultaneously within the volume of a photorefractive BSO crystal. A coherence coding approach and an orthogonal geometry are used to separate holograms from each other. In the reconstruction step, different holograms are read out sequentially starting from the exit face of the crystal. The phase shift introduced by the axial displacement is determined from the analysis of interference fringes. In particular, a procedure which consists of two successive fast Fourier transformation algorithms is applied.