A dual wavelength fiber optic strain sensing system
Abstract
The extrinsic Fabry-Perot interferometer (EFPI) has been extensively used as a strain
sensor in various applications. However, like other interferometric sensors, the EFPI
suffers from ambiguity in detecting directional changes of the applied perturbation, when
the operating point is at a maxima or a minima on the transfer function curve. Different
methods, or sensor configurations have been proposed to solve this problem. This thesis
investigates the use of dual wavelength interferometry to overcome this limitation.
Possible systems configurations based on dual wavelength interferometry were considered,
and the comprehensive design and implementation of a dual laser time division multiplexed
(TOM) system based is presented. The system operates by alternately pulse modulating
two laser diodes, which are closely spaced in center wavelength. Although the strain rate
measurement capability of the system is dependent primarily on the speed of its hardware
and the accuracy of its software, it is shown that it can be considerably enhanced by
employing digital signal processing techniques.
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- Masters Theses [19412]