Abstract: A remote sensing optical system and method is disclosed that permits detection and discrimination of aerosols. The system outputs a plurality of wavelengths and is equipped with a polarization sensitive receiver capable of measuring the scattered energy in two orthogonal polarization states. By normalizing the depolarization to the total energy received and calculating the ratio of normalized depolarization at different wavelengths it is possible to use this ratio to discriminate materials having wavelength dependent depolarization properties. One use is the discrimination of bioaerosols such as anthrax from other airborne particular matter.