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19 October 1983 Ultrasensitive Optical Rotation And Refractive Index Measurements
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Among the many techniques that benefited from the developement of laser technology, two examples are the improved detectability in optical rotation and in refractive index meas-urements. The former is an interesting physical property because it is usually associated with biological activity. The latter is useful because it is a universal physical property. In conjunction with liquid chromatography, one can take advantage of the improved detectability to study molecules that are present in small quantities in fairly complex samples, such as biological fluids and fossil fuels. The high degree of collimation of the laser allows better levels of extinction to be achieved between crossed polarizers. The amount of scattered light, and thus the amount of depolarization, can be greatly reduced. This then allows small rotations of the polarization axis of light to be detected. A detectability of 1.5 x 10-5 degrees can be achieved. The high monochromaticity of the laser brings about new applications of Fabry-Perot interferometry. The interference fringes can be used to monitor refractive index changes inside the interferometer. In conjunction with a flow cell interfaced to a liquid chromatograph, a detectability of 4 x 10-9 RI units is possible.
© (1983) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Edward S. Yeung "Ultrasensitive Optical Rotation And Refractive Index Measurements", Proc. SPIE 0426, Laser-Based Ultrasensitive Spectroscopy and Detection V, (19 October 1983);

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