Microdroplet identification and size measurement in sprays with lasing images

Two-dimensional fluorescence and lasing images of a Rhodamine-6G doped water spray are observed with color photography. The orange-red lasing microdroplets are identified by their two reciprocal lasing spots. The microdroplet sizes are measured using the digitized images. The obtained microdroplet size distribution compares favorably with the normal Gaussian size distribution.