Automated classification of single airborne particles from two-dimensional angle-resolved optical scattering (TAOS) patterns by non-linear filtering

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Two-dimensional angular optical scattering patterns as droplets evolve into clusters

Two-dimensional angular optical scattering (TAOS) patterns of droplets composed of a mixture of H2O and D 2 O are detected in the mid infrared. First, a lens is used in the Abbé sine condition to collect a small solid angle of light, where the scattering pattern matches well numerical simulations based on Mie theory. Next, TAOS patterns from droplets spanning a large (ഠ2p sr) solid angle are captured simultaneously at two wavelengths. These light-scattering patterns, and even those over smaller solid angles, provide substantial information about the scattering particle because the detected patterns depend on the particle's morphology (size, shape, and internal structure) and composition. For instance, with certain restrictions on the particle, the solution of the inverse-scattering problem of extracting a particle's shape and size from an angular intensity distribution has been successfully demonstrated. -6 Efforts have been made to extract information about particle internal structure such as whether a cluster is composed of polystyrene latex spheres or of Bacillus subtilis spores

Angularly resolved elastic scattering from airborne particles - Potential for characterizing, classifying, and identifying individual aerosol particles

“The original publication is available at www.springerlink.com” Copyright Springer [Full text of this chapter is not available in the UHRA]Analysing the light scattering properties of individual airborne particles has become a powerful tool by which they may be characterized, classified, and in some cases, identified. The approach offers a non-invasive, nondestructive, and potentially real-time monitoring capability that has widespread application in environmental pollution and occupational fields as well as in the detection of possible deliberate releases of pathogens. In this chapter, we provide an overview of the historical development of the theoretical models and experimental techniques underphining angularly resolved light scattering, address key methods of data analysis used to derive particle characteristics, and describe some of the very latest research results in the field