Time-resolved studies of light scattering in random media.
Item
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Title
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Time-resolved studies of light scattering in random media.
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Identifier
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AAI9020822
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identifier
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9020822
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Creator
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Yoo, Kwong Mow.
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Contributor
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Adviser: R. R. Alfano
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Date
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1990
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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 | Physics, General
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Abstract
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The goal of this thesis is to study photon migration and light scattering in random media. The backscattering and transmission of an ultrafast laser pulse in random media were measured by a time and angle resolved technique using ultrafast laser and streak camera technology.;The angular and temporal information of the light backscattered from random media was measured simultaneously. Weak photon localization which is due to coherent interference of the multiply scattered light and its time reverse counterpart was observed in the scattered femtosecond laser pulse. The angular width of the coherent peak was shown to become narrower as the light undergoes a longer scattering path in the random medium. The intensity of the backscattered pulse in the exact backward direction is higher than those scattered in other directions. The temporal profile of the backscattered pulse can be characterized by the transport mean free path and the absorption length. The temporal and angular profiles of the backscattered light can be used to determine the optical properties of biological and medical tissues. This backscattering technique is a potentially noninvasive medical diagnostic tool. The dynamics of depolarization of light scattering in random media were measured and can be important for determining the size of the particle in the random media.;In the experiment on ultrafast laser propagation through a slab of random media, the coherent and incoherent components of forward light scattering were time resolved. The pulse width and the direction of the coherent component remain unchanged. The incoherent component has a wide angular and temporal spread. The diffusion approximation fails to describe the temporal spread of the incoherent component when the thickness of the random medium is less than ten transport mean free paths.
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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.
