A technique for the study of acoustic scattering from microparticles

A technique for observing acoustic scattering from individual particles with volumes on the order of 100 micron3 is described. The apparatus consists of an array of focused acoustic transducers, a fluid jet to position the particles, and electronics incorporating quadrature detection. A maximum likelihood estimator is developed for the scattering amplitude that combines the data received from a series of pulses as a particle is carried through the focal zone of the transducers. A calibration method and performance of the apparatus are discussed.