Messica A, Greenstein A, Katzir A. Theory of fiber-optic, evanescent-wave spectroscopy and sensors.
APPLIED OPTICS 1996;
35:2274-2284. [PMID:
21085364 DOI:
10.1364/ao.35.002274]
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Abstract
A general theory for fiber-optic, evanescent-wave spectroscopy and sensors is presented for straight, uncladded, step-index, multimode fibers. A three-dimensional model is formulated within the framework of geometric optics. The model includes various launching conditions, input and output end-face Fresnel transmission losses, multiple Fresnel reflections, bulk absorption, and evanescent-wave absorption. An evanescent-wave sensor response is analyzed as a function of externally controlled parameters such as coupling angle, f number, fiber length, and diameter. Conclusions are drawn for several experimental apparatuses.
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