Abstract: A photoelectric converter of sizes of particles contained in a flow of gas to electric pulses comprises a chamber with a means for directing an aerosol flow into and from said chamber optically connected to an illumination means which forms a convergent light flux to illuminate the aerosol flow, and to a photoreceiver arranged so that its optical axis, as well as that of the illumination means and the axis of the aerosol flow all intersect at a right angle inside the chamber. The converter further includes a channel for transmitting part of the light flux of the illumination means to the photoreceiver, and a calibration light pulse former accommodated in said channel. The latter contains two mirrors installed in the chamber across the optical axes of the illumination means and the photoreceiver, respectively, beyond the point of intersection of said optical axes. The calibration light pulse former comprises a diaphragm and a mechanical shutter which comprises, in turn, a rod and a reciprocating drive.