Heterodyne polarimetry technique for complete amplitude scattering matrix for radiation

The phases and amplitudes of all the elements of the scattering matrix for radiation scattered by microparticles are shown to be measurable by a technique which was inspired by the phase differential scattering method developed by Johnston et al. of the Experimental Pathology Group at the Los Alamos National Laboratory. The present method synthesizes a laser beam from a superposition of two coherent beams in which a small frequency offset between perpendicular polarization components has been acoustooptically introduced. The heterodyne signal in the scattered radiation is used to detect the polarimetric null obtained by a variable phase compensator and linear polarizer placed in front of the scattered intensity detector. The reciprocity theorem is used to obtain a complementary set of data to completely determine all the elements of the matrix.