Optical System for Atmospheric Particle Measurement

To measure the broad size range of 0.1 micron to 200 micron, we propose an optical instrument that combines two techniques: Forward scattering light intensity (FSLI) and digital holography (DH). FSLI will provide the size and concentration of particles in the 0.1 to 5 micron range while DH will provide the size, concentration and shape of particles larger than 5 micron. Accurate measurements with FSLI rely on precisely knowing the intensity of the illumination beam at the position of the particle. An innovative fiber optic bundle will select for measurement the particles that cross the very center of the illumination beam where the intensity is uniform and known. The proposed DH strategy will employ small CCD with fast data transfer to enable continued scanning of the atmosphere over many meters or even hundreds of meters. Both technologies will employ small, low power components making them suitable for UAV operation. The Phase I work will include modeling and experimental demonstrations culminating with the conceptual design of a field prototype system.