Two optical methods for simultaneous measurement of particle size, velocity, and refractive index

Two optical methods that were developed for recognizing the composition of moving spherical particles as well as measuring their sizes and velocities are described here. Both methods are meant for characterizing single particles with a high spatial and temporal resolution. One method is an extension of the phase-Doppler technique, whereas the other is a newly developed method that utilizes cylindrical waves of laser light to illuminate the particles. The principles of both methods are described, and some experimental data are presented to demonstrate the feasibility of the theoretical concepts.