As an important member of optical fiber sensor, Extrinsic Fabry-Perot Interferometer (EFPI) based optical fiber sensor has won widely attention for its simply structure, small configuration, good reliability and flexibility, and is considered as having broad application foreground in industry.First, in this dissertation, we studied the theory of multi-light beam interferometry. After analyzing the demodulation principle of wavelength for EFPI senor, we have carried on the simple analysis contrast to this domain present common several demodulation method——P-P(peak-peak), DFTand DGT(Discrete Gaplength Transform), based on this, draws out the content which this article needs to elaborate.The theoretical analysis of EFPI sensor demodulation technique based on correlation calculation in spectrum domain is given. The discrete correlation calculation is presented. In order to increasing the speed of real-time calculation, a fast algorithm of discrete is presented. The interference spectrum from sensor head is normalized by saving the spectrum of the light source. Based on this demodulation technique, the white light EFPI sensor system with HR2000 spectrometer is realized. By using the EFPI sensor demodulation technique based on correlation calculation, the calibration curve and the measurement curve of EFPI strain/pressure sensor system are measured in strain/pressure measuring experiment. According to the experiment, the measurement resolution can reach 0.06℃in 25~220℃, 0.03μεin 0~800μεand 0.005Mpa in 0~25Mpa. By using the EFPI sensor demodulation technique based on correlation calculation, the resolution of static sensor system has the characteristics of highly precision,highly sensibility,strong capability of anti-disturbance and etc. It would be prospective in the application to petro-chemistry, electric power and military industry.Finally, some problems of prospect in the demodulation system are discussed. |