Photon migration and imaging of objects hidden in layered and bulk random scattering media.
Item
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Title
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Photon migration and imaging of objects hidden in layered and bulk random scattering media.
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Identifier
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AAI9618059
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identifier
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9618059
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Creator
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Dolne, Jean J.
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Contributor
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Adviser: R. R. Alfano
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Date
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1996
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Optics | Engineering, Nuclear
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Abstract
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Three wavelengths of laser light operating in the CW mode and a spatial filter system were used to image an object hidden behind a random scattering medium. The best image contrast was obtained when the spatial filter aperture was closed to allow only the lowest spatial frequencies representing mostly the ballistic/snake light to pass through and for the longest wavelength of radiation.;A two-layered medium was reconstructed using the Fourier transform of the diffusion equation. The inverse parameters of the two layers were found to be unique when the top layer thickness was less than half the source detector separation.;Light scattered all around a random scattering medium has been measured by a multiple-fiber collection system. It was found that the scattered signal decreased all around the medium. A novel method to measure the optical parameters such as the transport mean free path and the absorption length of a scattering medium has been found. This method uses only the peak intensity and the risetime of the pulse intensity profile.;It has been shown that light scattering data around the reference medium can be "measured" by using only one detector at an appropriate position and an appropriate theory.;The angular dependence of scattered light was measured. It was found that in the non-diffuse region, the detected light intensity depended strongly on the orientation of the detector. In the diffuse region, however, there was only a negligible angular dependence in the scattered intensity profile.;The photon trajectories that photons follow inside a scattering medium have been measured. It has been found that these paths arrive at specific times and angles at the detector. These specific times of arrival make it possible to locate a hidden object inside a scattering medium.;The transmitted light scattered from random media of different sizes has been found to be independent of the sizes of the particles in the diffusion region.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
