LOCALIZATION EFFECTS IN FORWARD SCATTERING DURING LASER DIAGNOSTICS OF TWO–PHASE FLOWS
N. V. Semidetnov
St. Petersburg State Marine Technical University, ul. Lotsmanskaya 3, St. Petersburg, 190008 Russia
Keywords: particle sizing, light scattering, Mie theory, Debye-series expansion, geometrical optics, diffraction, edge wave
Abstract
The effects of local interaction of light with a particle used for diagnostics of the dispersed phase of flows are usually well described by the laws of geometrical optics. For forward scattering, geometrical optics is complemented by Fraunhofer diffraction by an opaque disk. Accurate calculations using Mie theory reveal an additional intensity of the radiation scattered in a direction close to the the direction of illumination. This additional contribution is attributed to the edge wave. The components of forward scattered light, namely, diffraction, reflection, and edge wave are studies in order to refine the contribution to the scattered intensity and locality of the interaction with the particle. It is shown that localization of the interaction with the particle occurs for all of these components. The distributions of the intensity of the individual components in forward scattering are obtained.
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