Research On FBG Dynamic Demodulation Technology Based On Non-equilibrium Interferometer

FBG sensors become a hot part in sensing research field, and FBG sensor demodulation technology is FBG sensor is very important part. In this thesis, we investigate a FBG dynamic demodulation technique based on equilibrium Michelson interferometer, the phase signal demodulation could be realized by used PGC (Phase Generated Carrier) technology based on ARCTAN calculation. The PGC demodulation technology based on ARCTAN calculation makes the measured signal become the sidebands of large carrier which is outside the frequency range of measured signal. It ensures the constant stationary change of Michelson interferometer in a larger range and eliminates signal amplitude fluctuations and reduces SNR that caused by the initial random phase shifts of the Michelson interferometer. This thesis covers the following major works:we elaborates the PGC dynamic demodulation principle based on the non-equilibrium Michelson interferometer and a derive demodulation formula; the influence of the differences of the non-equilibrium interferometric arms to system sensitivity and contrast are analyzed, which provide a certain high contrast by experimentally improving the system sensitivity and optimizing the difference of the non-equilibrium Michelson interferometer arms; we also develop a PGC demodulation programs based on ARCTAN calculation by using Lab View, and optimize it to eliminate the effects of phase delay and carrier amplitude of the PGC dynamic demodulation technology and to improve the system SNR; finally, a FBG dynamic demodulation based on the non-equilibrium Interferometer Experimental system is set up and tested in the laboratory, in a sampling frequency of100KHz, a frequency response range of0～1KHz and measured resolution of2.71nε/??Hz in strain can be realized and the response characteristics for the abrupt signals will be inspected, which demonstrates the designed system has good stability.