Holographic PIV with Low Coherent Light – Recent Progress in 3D Flow Measurements

Abstract

Holographic PIV (HPIV) is a fully three-dimensional technique for measuring flows. A field of small tracer-particles is recorded in double-exposure holograms obtained with two reference waves. Particle displacements are extracted from CCD-based 3D-scans of real images with three-dimensional correlation methods. To cope with the problem of noise from out-of-focus particles the technique of light-in-flight holography has been introduced that utilizes properties of low coherent laser light. This drastically increases the signal-to-noise ratio in deep-field particle holography. Some experimental checks of these concepts are presented and first results from measurements in the wake of an airfoil are shown.