FIELD: instrumentation, granulometric analysis of aerosols. SUBSTANCE: in agreement with invention reference coherent beam is employed to divide flows of scattered radiation and radiation passed through scattering medium of optical radiation in plane of photodetector. Beams of reference radiation and radiation passed through scattering medium are focused. Focal spots of above-mentioned beams are matched in one of minima of interference picture. In this case period of interference picture of reference and sounding beams of optical radiation is chosen to be larger than diameters of focal spots of specified beams. EFFECT: simplified procedure of determination of indicatrix of diffusion in entire region of small angles, direction of angle of zero degree included. 1 dwg, 1 tbl
