EFPI光纤传感器腔长解调方法研究

摘要

研究了非本征型法布里-珀罗干涉（ EFPI）光纤传感器系统的传感原理和腔长解调方法，考虑到EFPI传感器的腔长解调精度会直接影响到传感系统的稳定性和测量精确性，提出了一种新的基于傅里叶变换的腔长解调方法。该方法利用傅里叶变换的频移性，有效地消除了快速傅里叶变换的栅栏效应，提高了傅里叶变换的精度。理论和实践证明，相比传统的快速傅里叶变换方法，这种利用傅里叶变换频移特性的方法的解调精度至少提高10倍。%The sensing principle and the cavity length demodulation of fiber optic extrinsic Fabry-Perot interferometric ( EFPI) sensors were studied.Considering that the accuracy of demodulating the cavity length of an EFPI optical fi-ber directly impacts on the stability and measuring accuracy of the sensor system, a new method for cavity-length demodulation based on fast Fourier transform ( FFT) was proposed.The method uses the frequency shift property of Fourier transform to effectively eliminate the grating effect of the transform to improve the Fourier transform accura-cy.It is proved theorelically and practically that the cavity-length demodulating accuracy of the proposed method using the frequency shift property is at least 10 times higher than that of the traditional method using FFT.