Methods for measuring refractive index and absorption coefficient of a moving particle using polarized-type phase-Doppler technique

Two methods are proposed for measuring the refractive index or the absorption coefficient simultaneously with the diameter and velocity of a moving spherical particle by using a polarized-type phase Doppler method. A particle refractive index is determined from phases of reflected and refracted rays detected individually by using different polarization angles of scattered light, whereas an absorption coefficient is obtained by applying the Lambert–Beer law to intensity of a dual-burst Doppler signal generated by the reflected and refracted rays. The optimum conditions of an optical system were estimated theoretically. Experiments were performed with polystyrene particles in water, water droplets, and water-black ink droplets to confirm usefulness of the proposed methods.