Holograms were made of the light scattered by small clouds of water droplets. The far-field radiation patterns of individual droplets can be determined from the reconstructed image of the droplet cloud, and intensity plots of such patterns were recorded with a TV-camera system and a chart recorder with a photomultiplier attachment. Particular attention was paid to radiation patterns in the angular range from 10°–40° from the direction of propagation of the laser pulse illuminating the droplet cloud. According to the Mie theory of scattering by liquid spheres, a significant relation exists between the form of the scattered radiation pattern and the diameter of a droplet. Therefore, given sufficient agreement between Mie theory and the recorded radiation patterns, it is possible to use the recorded patterns to determine the sizes of droplets in a cloud. The feasibility of the idea is demonstrated in the present experiments. Good agreement was obtained with Mie theory and it was possible thereby to determine droplet sizes with an accuracy that appeared better than ±1%.
© 1969 Optical Society of AmericaFull Article | PDF Article
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