Abstract: A system for analyzing smoke has a plurality of units, wherein each unit includes an optical emitter for alternately directing horizontally and vertically polarized light along a beam path, and into a smoke cloud, to generate scattered light. A horizontally polarized detector and a vertically polarized detector are positioned at different locations, but at a same distance and scattering angle relative to the beam path. Each unit has a different wavelength. A computer receives signals from the detectors of all units, in response to each emitter, for analysis of the smoke.