Digital in-line holography for the analysis of Bénard-convection

Digital in-line holography (Skarman et al., Flow Measurement and Instrumentation 7 (1) (1996) 1–6) represents a novel optical method for flow and temperature measurements of transparent liquid media. A CCD-camera is used to record digital holograms of tracer particles in a fluid volume. The procedure is based on the phase-shift method. Algorithms for computational focusing on individual particles in three dimensions have been developed. As an additional benefit the holographic recording contains interferometric information about the optical path length which in turn enables the calculation of the density and temperature profile of the flow.