An optical/digital approach to the classification of small quasicircular grains is described. The setup consists of a coherent optical system to generate the Fourier irradiance of a random scene and a digital computer to process data. The sampling of Fourier spectra is achieved with a wedge ring detector. The inversion formula technique is used to estimate the particle distribution. A scene of three classes of varying sizes of Fe203, FeO rock grains is analyzed, and experimental results are given.