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Proceedings Paper

New phase method of measuring particle size with laser Doppler radar
Author(s): Vladimir M. Zemlianskii
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Paper Abstract

A vast field of non-contact metrology, vibrometry, dynamics and microdynamics problems solved on the basis of laser Doppler method resulted in the development of great variety of laser Doppler radar (LDR). In coherent LDR few beams with various polarization are generally adopted, that are directed at the zone of measurement, through which the probing air stream moves. Studies of various coherent LDR demonstrated that polarization-phase effects of scattering can in some cases considerably effect on the signal-to-noise ratio of the Doppler signal. On the other side using phase effects can simultaneous measurement of size and velocity of spherical particles. New possibilities for improving the accuracy of measuring spherical particles' sizes come to light when application is made in coherent LDR of two waves- probing and one out of the types of symmetrical reception of scattered radiation, during which phase-conjugate signals are formed. The theoretical analysis on the basis of the scattering theory showed, that in symmetrical reception of scattered radiation with respect to the planes OXZ and OYZ output signal of the photoreceiver contains two high- frequency signal components, which in relation to parameters of the probing and size, can either be in phase or antiphase. Results of numerical modeling are presented: amplitude of high frequency signal, coefficient of phase and polarization matching of mixed waves, the depths of photocurrent modulation and also signal's phase in relation to the angle between the probing beams. Phase method of determining particle's sizes based on the use of two wavelengths probing and symmetrical reception of scattered radiation in which conditions for the formation of phase conjugated high-frequency signals are satisfied is presented.

Paper Details

Date Published: 26 June 1996
PDF: 12 pages
Proc. SPIE 2748, Laser Radar Technology and Applications, (26 June 1996); doi: 10.1117/12.243546
Show Author Affiliations
Vladimir M. Zemlianskii, Kiev International Univ. of Civil Aviation (Ukraine)

Published in SPIE Proceedings Vol. 2748:
Laser Radar Technology and Applications
Gary W. Kamerman, Editor(s)

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