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UBC Theses and Dissertations

On the design of a combined Raman and interferometric scattering high resolution microscope Christy, Ashton


Contemporary imaging science needs label-free methods of microscopy that resolve morphological and chemical information in complex materials on a sub-micron length scale. Many of the most commonly-used techniques require substantial adulteration of samples, and thus are hindered in their utility for in vivo or time-resolved studies. This thesis introduces a new approach that integrates a confocal Raman microscope with interferometric scattering, or iSCAT. The former technique is well-reported in the literature; iSCAT, however, is relatively novel. The principles of iSCAT, developed in the last few years, have established a platform that provides superior resolving power and signal contrast compared with other optical techniques. Our novel approach integrates wide-field iSCAT microscopy acquired at video rate with point-by-point confocal Raman spectroscopy. After first providing a brief overview of contemporary methods in microscopy and the challenges they present, this thesis discusses the basics of iSCAT, and the design and development of the instrument that unites this new technique with confocal Raman microscopy. A discussion of design challenges follows. Next is a description of the instrument’s user-end capabilities, followed by a brief exploration of future prospects. Provided throughout the text are results illustrating the capability of the instrument. These demonstrate how much potential the combination of iSCAT and Raman holds for characterizing complex materials, as well as the precision with which the instrument can do so. Wide-field images, 100 µm square with 200 nm resolution, are sampled at 45 frames per second. The integrated Raman probe provides label-free highly reproducible chemical information without sample degradation. Together, these two data sets provide insights into covariance between morphology and chemistry, all with minimal sample preparation.

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