16 March 2016 Fast and accurate read-out of interferometric optical fiber sensors
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Abstract
We present results from an evaluation of phase and frequency estimation algorithms for read-out instrumentation of interferometric sensors. Tests on interrogating a micro Fabry-Perot sensor made of semi-spherical stimuli-responsive hydrogel immobilized on a single mode fiber end face, shows that an iterative quadrature demodulation technique (IQDT) implemented on a 32-bit microcontroller unit can achieve an absolute length accuracy of ±50 nm and length change accuracy of ±3 nm using an 80 nm SLED source and a grating spectrometer for interrogation. The mean absolute error for the frequency estimator is a factor 3 larger than the theoretical lower bound for a maximum likelihood estimator. The corresponding factor for the phase estimator is 1.3. The computation time for the IQDT algorithm is reduced by a factor 1000 compared to the full QDT for the same accuracy requirement.
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Ingebrigt Bartholsen, Ingebrigt Bartholsen, Dag Roar Hjelme, Dag Roar Hjelme, "Fast and accurate read-out of interferometric optical fiber sensors", Proc. SPIE 9754, Photonic Instrumentation Engineering III, 97540E (16 March 2016); doi: 10.1117/12.2212611; https://doi.org/10.1117/12.2212611
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