Nonlinear optical spectroscopy and microscopy of model random and biological media.
Item
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Title
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Nonlinear optical spectroscopy and microscopy of model random and biological media.
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Identifier
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AAI9908320
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identifier
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9908320
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Creator
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Guo, Yici.
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Contributor
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Advisers: Robert R. Alfano | P. P. Ho
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Date
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1998
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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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Engineering, Electronics and Electrical | Engineering, Biomedical | Physics, Optics
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Abstract
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Nonlinear optical (NLO) spectroscopy and microscopy applied to biomedical science are emerging as new and rapidly growing areas which offer important insight into basic phenomena. Ultrafast NLO processes provide temporal, spectral and spatial sensitivities complementary or superior to those achieved through conventional linear optical approaches. The goal of this thesis is to explore the potential of two fundamental NLO processes to produce noninvasive histological maps of biological tissues. Within the goal of the thesis, steady state intensity, polarization and angular measurements of second- and third-harmonic generations (SHG, THG) have been performed on model random scattering and animal tissue samples. The nonlinear optical effects have been evaluated using models. Conversion efficiencies of SHG and THG from animal tissue interfaces have been determined, ranging from {dollar}10\sp{lcub}-7{rcub}{dollar} to {dollar}10\sp{lcub}-10{rcub}.{dollar} The changes in the multiharmonic signals were found to depend on both local and overall histological structures of biological samples. The spectral signatures of two photon excitation induced fluorescence from intrinsic fluorophores have been acquired and used to characterize the physical state and types of tissues. Two dimensional scanning SHG and TPF tomographic images have been obtained from in vitro animal tissues, normal and diseased human breast tissues, and resolved subsurface layers and histo-chemical distributions. By combining consecutive 2D maps, a 3D image can be produced. The structure and morphology dependence of the SH signal has been utilized to image and evaluate subsurface tumor progression depth. Second harmonic microscopy in model random and biological cells has been studied using a CCD camera to obtain direct images from subcellular structures. Finally, near infrared (NIR) NLO spectroscopy and microscopy based on SHG and TPF have demonstrated high spatial resolution, deeper penetration depth, low level photo-damaging and enhanced morphological sensitivity for the noninvasive characterization and visualization of biological systems.
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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.
