Standoff Polarimetric Aerosol Detection (SPADE) for Biodefense
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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The polarization of laser light elastically scattered by small particles is investigated for the purpose of remotely detecting bio-aerosol presence in typical ambient background aerosols. The information source is small-particle scattering code computations, not actual measurements. Two separate types of particles - natural background aerosols vs. bio-aerosols - are combined with a concentration ratio of 100-to-1. The objective is to assess the feasibility of detecting the introduction of the bio-aerosol into the typical background aerosol by analyzing the polarization state of the laser light scattered by the combination of particles. The incident laser light is assigned two elementary linear polarizations, oriented parallel to or at 45 deg relative to the scattering plane. The state of polarization of the light redirected through various scattering angles is specified by polarimetric quantities developed from the scattered light Stokes parameters. Incoherent laser and receiver specifications are employed to evaluate signal-to-noise for three scenarios outdoor stadium, indoor auditorium, and building heating-ventilating-air-conditioning HVAC system. Of these, the HVAC application is very feasible with conventional laser and detector technology. The indoor application is feasible. Coherent laser and advanced photo-diode detector technologies substantially enhance signal-to-noise especially for the outdoor application.
- Chemical, Biological and Radiological Warfare
- Optical Detection and Detectors
- Lasers and Masers