Phase Doppler particle sizing--reduction of the phase error using polarization

摘要

Phase Doppler anemometry (PDA) is useful for sizing small spherical particles. This method is, however, sensitive to phase fluctuation errors caused by the Gaussian beam illumination. This phase fluctuation arises from the interference between reflected light and refracted light from the particle. Thus, we should detect either reflected or refracted light in order to eliminate the errors. This paper studies a reduction of phase errors which is based on the separation of reflected and refracted light by using polarization effect. We numerically investigated the characteristics of phase fluctuations in relation to polarization by using geometrical optics approximation and generalized Lorenz-Mie theory, and estimated the optimum measuring condition. We experimentally confirmed the usefulness of the polarization technique for reducing the phase errors.