Holography of fast-moving cloud droplets

Abstract

In order to test the feasibility of measuring the size distribution of cloud particles from an aircraft with a holographic technique, small water droplets (diameters 15-100 μm) were recorded holographically in the laboratory using Gabor's original lensless `in-line' technique. Using a Q-switched ruby laser (pulse duration similar 10-20 ns) it was found that droplets could be reconstructed satisfactorily even when moving at speeds comparable to those of an aircraft in cloud (similar 100 m s−1).