Novel, in-situ Raman and fluorescence measurement techniques: Imaging using optical waveguides

The following dissertation describes the development of methods for performing standoff and in-situ Raman and fluorescence spectroscopy for chemical imaging and non-imaging analytical applications.; The use of Raman spectroscopy for the in-situ identification of crack cocaine and cocaine·HCl using a fiberoptic Raman probe and a portable Raman spectrograph has been demonstrated. We show that the Raman spectra of both forms of cocaine are easily distinguishable from common cutting agents and impurities such as benzocaine and lidocaine. We have also demonstrated the use of Raman spectroscopy for in-situ identification of drugs separated by thin layer chromatography.; We have investigated the use of small, transportable, Raman systems for standoff Raman spectroscopy (e.g. <20 m). For this work, acousto-optical (AOTF) and liquid crystal tunable filters (LCTF) are being used both with, and in place of dispersive spectrographs and fixed filtering devices. In addition, we improved the flexibility of the system by the use of a modified holographic fiber-optic probe for light and image collection. A comparison of tunable filter technologies for standoff Raman imaging is discussed along with the merits of image transfer devices using small diameter image guides.; A standoff Raman imaging system has been developed that utilizes a unique polymer collection mirror. The techniques used to produce these mirrors make it easy to design low f/# polymer mirrors. The performance of a low f/# polymer mirror system for standoff Raman chemical imaging has been demonstrated and evaluated.; We have also demonstrated remote Raman hyperspectral imaging using a dimension-reduction, 2-dimensional (2-D) to 1-dimensional (1-D), fiber optic array. In these studies, a modified holographic fiber-optic probe was combined with the dimension-reduction fiber array for remote Raman imaging. The utility of this setup for standoff Raman imaging is demonstrated by monitoring the polymerization of dibromostyrene.; To further demonstrate the utility of in-situ spectral imaging, we have shown that small diameter (350 μm) image guides can be used for in-situ measurements of analyte transport in thin membranes. This has been applied to the measurement of H₂O diffusion in Nafion™ membranes using the luminescent compound, [Ru(phen)₂dppz] 2+, which is a H₂O indicator.