Research On Fiber Fabry-Perot Pressure Sensing System

With the development of fiber-optic sensing technology,fiber-optic Fabry-Perot pressure sensors are widely used because of their small size,light weight,and immunity to electromagnetic interference.Therefore,it is of great significance to study optical fiber Fabry-Perot pressure sensor with strong practicability,high measurement accuracy and good consistency.This thesis first introduces the research status and applications of fiber Fabry-Perot pressure sensors and demodulation systems,then introduces the principle of fiber Fabry-Perot multi-beam interference,and based on this,the output spectral characteristics of fiber Fabry-Perot cavities were studied,and the theoretical researches on several demodulation algorithms for fiber optic Fabry-Perot sensing are done.The mesa membrane sensor structure was designed,and the influence of the length of the Fabry cavity on the reflection signal and the influence of the mesa membrane radius,diaphragm thickness,and mesa height on the deflection were analyzed.The structure of the mesa membrane was modeled using ANSYS structural mechanics simulation.In the case of uniformly distributed load,the change of the center point displacement of the table is analyzed.It provides theoretical and simulation basis for the optimal design of the mesa structure,has a certain reference value.The fiber Fabry-Perot pressure sensor system is studied,including the design of the hardware and software parts of the demodulation system.Among them,the hardware part mainly performs testing and analysis on the broad-spectrum light source and the etalon;the software part uses the virtual instrument development platform Lab VIEW software to write the acquisition program,design the interpolation algorithm,and program the etalon wavelength algorithm,analysis of several peak-seeking algorithms.The algorithm of spectral data collection,peak finding and wavelength calculation is realized.Finally,the existing F-P pressure sensor and demodulator in the laboratory were evaluated,and the performance of the demodulator was experimentally verified.The wavelength of the fiber Fabry-Perot pressure sensor was calibrated using a high-precision demodulator.The repeatability and stability of the demodulator to be evaluated were experimentally verified.