Frequency Extraction Method for Low Frequency Vibration Detection using Compliant Cylinder Michelson Optic-fiber Interferometric Geophone

Demodulation of Michelson optic fiber interferometer is an important part of Michelson interferometer acceleration detector, and demodulating options of which has a great impact on operating range. In order to explore more appropriate options using for low-frequency seismic wave detection, the photoelectric inspected signal of the interferometer was analyzed in detail by Fourier-Bessel expansion. And presenting a new simple solution adopting a rectangular window in frequency domain cannot introduce phase delay, using it to extract low-frequency components in the signal. The simulation verified feasibility of demodulation scheme, and proved it with comparison test methods. Compare the compliant cylinder detector with PZT modulating a single frequency, and compare compliant cylinder detector with magnetic-electric geophone, with result that the demodulation scope is 10~20 Hz, which proved the correction of the theory analysis.