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26 August 1996 Optimizing the optics for evanescent wave analysis with laser diodes (EWALD) for monitoring chlorinated hydrocarbons in water
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Proceedings Volume 2783, Micro-Optical Technologies for Measurement, Sensors, and Microsystems; (1996) https://doi.org/10.1117/12.248499
Event: Lasers, Optics, and Vision for Productivity in Manufacturing I, 1996, Besancon, France
Abstract
Fiber evanescent field analysis (FEFA) is a novel promising sensing technique for on-line and in situ analysis of hydrocarbons in water. With a conventional IR light source and FTIR spectroscopy it allows multicomponent analysis, while using MIR-tunable diode lasers results in more sensitive and faster single component analysis. Compared to common attenuated total reflection elements, silver halide (AgCl/Br) fibers offer more convenient application for remote sensing and field measurements because the fibers can be used for both, guidance of MIR radiation to and from the sensing part, and the sensing part itself. At present these fibers are multimode. The sensor response can be expected to depend strongly on the mode distribution in the fiber. We hence performed a model calculation that allows us to compare the FEFA absorption and the intrinsic fiber losses for given mode distributions and dependent on the optical parameters such as the coupling conditions and the fiber design. In order to link theoretical results to experimental data, the theory is based on an internal mode distribution derived from far field fiber emission data. We present far field data and the resulting internal distributions.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Joachim F. Kastner, Maurus Tacke, S. Silverstein, and Abraham Katzir "Optimizing the optics for evanescent wave analysis with laser diodes (EWALD) for monitoring chlorinated hydrocarbons in water", Proc. SPIE 2783, Micro-Optical Technologies for Measurement, Sensors, and Microsystems, (26 August 1996); https://doi.org/10.1117/12.248499
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