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Description:
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I experimentally studied ultrasound -modulated optical tomography , which holds the promise for biomedical diagnosis . I measured the degree of polarization of laser speckles generated by scattered light transmitted through turbid media , investigated three signal -detection schemes for extracting the intensity of the ultrasound -modulated light , carried out experiments to image thick biological -tissue samples , and studied two techniques providing resolution in the cross -sections containing the ultrasonic axis .
The study of degree of polarization presented results important for the understanding of polarization phenomena in turbid media . I explored an optical -filtering based signal detection scheme , improved the parallel -lock -in speckle detection scheme and proposed a speckle -contrast detection scheme . With the speckle -contrast detection scheme , I successfully obtained images of biological -tissue samples up to 50 mm thick . Further I studied frequency -swept ultrasound -modulated optical tomography for sub -millimeter resolution imaging , and developed ultrasound -modulated optical computed tomography that was based on a back -projection image reconstruction method and obtained clear images of biological -tissue samples . |