Measurement of Three-Dimensional Density and Velocity Distributions Using HPIV : Evaluation of Simultaneous Recording and Filtering Extraction

In this study, a technique for simultaneous measurement of three-dimensional density and velocity distributions was evaluated. Holographic particle image velocimetry (HPIV) was used to reconstruct three-dimensional velocity distributions from three-dimentional particle images recorded on a hgologram. Optical tomography (OT) was used to reconstruct three-dimensional density distributions from multidirectional two-dimensional interferogram images. When a flow field with density variation was illuminated by coherent plane waves, spherical waves were scattered by the particles (particle images), and the illuminating beam was modulated by the density variation (interferogram images). Using a reference beam, both particle and interferogram images could be recorded on a single hologram. Using the spatial filtering extraction (FX) technique, information on both images could be extracted separately from the hologram. In the experiment, a jet of helium gas introduced into air containing small particles was measured. Both particle position and fringe shift caused by the density variation could be observed, demonstrating the effectiveness of the proposed technique.