Angularly-resolved elastic scatter from single particles collected over a large solid angle and with high resolution

• Published in: Journal of physics. Conference series 2005-01, Vol.6 (1), p.90-96
• Main Authors: Aptowicz, Kevin B, Chang, Richard K
• Format: Article
• Language: English
• Subjects: Aerosols; Angular resolution; Bioaerosols; Clusters; Clutter; Elastic scattering; Feature extraction; Islands; Latex; Morphology; Neodymium lasers; Physics; Pixels; Polystyrene resins; Pulse duration; Semiconductor lasers; Spores; YAG lasers
• ISSN: 1742-6596; 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/6/1/006

Elastic light scattering from a single non-spherical particle of various morphologies has been measured simultaneously with a large angular range (90° < θ < 165° and 0° < φ < 360°) and with high angular resolution (1024 pixels in θ and 512 pixels in φ). Because the single-shot laser pulse is short (pulse duration of 70 ns), the tumbling and flowing particle can be treated as frozen in space. The large angle two-dimensional angular optical scattering (hereafter referred to as LA TAOS) intensity pattern, I(θ,φ), has been measured for a variety of particle morphology, such as the following: (1) single polystyrene latex (PSL) sphere; (2) cluster of PSL spheres; (3) single Bacillus subtilis (BG) spore; (4) cluster of BG spores; (5) dried aggregates of bio-aerosols as well as background clutter aerosols. All these measurements were made using the second harmonic of a Nd:YAG laser (0.532 μm). Islands structures in the LA TAOS patterns seem to be the prominent feature. Efforts are being made to extract metrics from these islands and compare them to theoretical results based on the T-matrix method.