An experimental method is presented that detects whether a droplet is spherical. The method is based on a comparison between two droplet diameters deduced from two different optical interference patterns observed in a rainbow that is created by a droplet scattering laser light. Experimental validation has been carried out with a CCD camera. Once a rainbow pattern has been identified as coming from a spherical droplet, we can derive a reliable droplet velocity and diameter from the same interference patterns, using theories for the rainbow that are valid only for spherical droplets. Preliminary experiments have been carried out with a laser beam and a photomultiplier.
© 1996 Optical Society of America
Original Manuscript: October 10, 1995
Revised Manuscript: December 12, 1995
Published: May 1, 1996
J. P. A. J. van Beeck and M. L. Riethmuller, "Rainbow phenomena applied to the measurement of droplet size and velocity and to the detection of nonsphericity," Appl. Opt. 35, 2259-2266 (1996)