Principles of instrumentation and signal processing method of PLDA

It is shown in this paper that in geometrical space two polarization planes of the linearly polarized light waves scattered by particles in measuring ellipsoid constitute an angle of π/2, while in sequence of lime the signals sent out by two symmetric photodetectors in PLDA are separated by a phase angle π. This property of PLDA enables the improvement of SNR.The similarity between power spectrum of pholoeleclrical current of PLDA and probability density junction P_d (u_o) of investigated flow velocity has been proved theoretically and checked by agreement of obtained results with classical theory and generally accepted experiments.