FIELD: oceanological investigations. SUBSTANCE: method consists in optical formation of reference volume thanks to transmission of parallel flux of pulse optical radiation of constant intensity in direction specified in advance. Formed reference volume is moved along trajectory perpendicular to direction of radiation flux and bigger side of its rectangular section, particles suspended in water are registered with their appearance in reference volume by reception of optical radiation from reference volume at any angle to it. Optical radiation is converted to electric signals which are analyzed and size and number of particles are estimated by amplitude and duration. It is suggested that relation of dimensions of sides of rectangular section to be equated to relation of maximum and minimum boundaries of size range of registered particles and speed of movement of reference volume to be maintained at level not exceeding relation of length of its smallest side of section to period of repetition of pulses of optical radiation. Gear for implementation of method is fitted with aid forming reference volume of preset configuration, aid determining difference between signal in absence of pulses and signal received during action of pulses and aid forming time interval for time of registration of particle. Optical formation of reference volume and of preset configuration ensure conducting of operations determining size and number characteristics of particles suspended in water without disturbance of their natural distribution and generation of information on distribution of plankton directly in environment. EFFECT: improved authenticity of method. 10 cl, 4 dwg
