Optical EngineeringFiber optic extrinsic Fabry–Perot accelerometer using laser emission frequency modulated phase generated carrier demodulation scheme
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The principle of a fiber optic Fabry–Perot (F–P) accelerometer (FOFPA) system using the laser emission frequency modulated phase generated carrier (FMPGC) demodulation scheme is first described and experimentally demonstrated. The F–P cavity, which is constituted by placing the end face of a gradient-index lens in parallel with the reflector on the inertial mass, directly translates the inertial mass’s displacement generated by the measured acceleration into phase shifts of the interference output from the F–P cavity. An FMPGC demodulation scheme based on the arctangent (Arctan) algorithm is adapted to demodulate the phase shifts. The sensing model for the FOFPA system using the FMPGC–Arctan demodulation scheme is established and the sensing characteristics are theoretically analyzed. On these bases, the FOFPA is designed and fabricated and a prototyping system is built and tested. The results indicate that: (1) the nonlinearity of the FOFPA system using the FMPGC–Arctan demodulation scheme is less than 0.58%, (2) the resonant frequency, on-axial sensitivity, and resolution are 393 Hz, 13.11 rad/g , and 450 μg/Hz 1/2 , respectively, and (3) the maximum deviation of the phase sensitivity of the FOFPA within the temperature range of 30 to 80°C is 0.49 dB re 1 rad/g .