Demodulation of a fiber Fabry-Perot strain sensor using white light interferometry

A method is demonstrated for demodulating the signal from a fiber-optic Fabry-Perot (FFP) strain gauge using white light interferometry. In particular, a Michelson interferometer with an identical path imbalance to the sensing FFP interferometer is used to recombine the sensing and reference components. Far-field interference from the Michelson interferometer, with one tilted mirror, is then projected onto a CCD camera where the fringes can be captured and analyzed on an accompanying microcomputer. The advantages of the system include the absolute measurement capability and the potential for multiprocessing.