Abstract
A white light non-scanning correlation interrogation system was proposed and built to interrogate absolute length of the air cavity of fiber-optic compound Fabry–Perot pressure sensors for the extraction of pressure value. By carefully choosing thickness range and tilt angle of the optical wedge used for cavity length matching, correlation interferometric signal of the basal cavity can be naturally filtered out. Based on peak positioning by Fourier transform, bandpass filtering in frequency domain, inverse Fourier transform back to time domain, envelope fitting and zero fringe finding through a gravity center method, cavity length can be determined with an accuracy of 0.04%. The system was used for the interrogation of a fiber-optic compound Fabry–Perot pressure sensor under different pressures. For a pressure range of 0.1~2.9 Mpa, the linear relationship between the air cavity length and the gas pressure imposed was successfully extracted.
Highlights
Fiber-optic Fabry–Perot (FP) sensors, can be widely used for the accurate measurement of various quantities, such as temperature, strain/stress, refractive index, vibration, displacement, velocity, rotation, electric/magnetic field, and pH value
Sensors 2019, 19, 1628 cavity length changes in a limited range can be measured, and the laser wavelength has to be stabilized at the Q-point of the fiber FP cavity
The white light non-scanning correlation method is very suitable for single cavity length interrogation of fiber-optic compound fiber FP pressure sensors
Summary
Zilong Guo 1,2 , Wentao Lv 1 , Wei Wang 1,2, * , Qingqing Chen 1 , Xiongxing Zhang 1,2 , Haibin Chen 1,2 and Zhibo Ma 3,4. Shaanxi Key Lab of MEMS/NEMS, Northwestern Polytechnical University, Xi’an 710072, China
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