Introduction into active spectroscopy of elastic light scattering

Summary form only given. The paper introduces elements of active spectroscopy available in elastic light scattering. The new principal approach is based on the application of an innovative vector optical heterodyning technique and active signal processing, which appears to be available by beating several scattered vector waves within a square-low photo-detector by their registration. While the classical spectroscopy of optical beating deals with the problem to study a scalar optical signal that is due to elastic scattering of a single narrow-band laser beam, the active spectroscopy of elastic scattering deals with two vector waves simultaneously undergo scattering by a scatterer. In case one of the vector waves (heterodyne) has strong periodical modulation of direction of polarization, coherent light beating scattering (CLBS) occurs, which unites elastic light scattering and coherent non-linear beating (mixing). As a result, the vector optical signal provides with the information about both size and velocity of a scatterer, which is not available for well-known spectroscopy of scalar optical beating.