Research On Multi-channel Synchronous Demodulation System For Fiber Fabry-perot Sensors Based On A Matrix CCD

Optical fiber Fabry-Perot(F-P)sensing technology is widely used in aerospace,deep-sea exploration and petroleum exploration for its high demodulation precision,large dynamic demodulation range and anti-electromagnetic interference.With the deepening of application,the need for simultaneous demodulation of multiple fiber F-P sensors is becoming increasingly apparent.However,due to the traditional multi-channel multiplexing technologies use a linear array CCD,in order to distinguish the interference signals of the respective channels,they should have high requirements on the central wavelength of the system light source or the cavity length control of F-P sensors when realizing synchronous demodulation of multi-channel fiber F-P sensors,which limits its scope of application.In order to solve the above problems,in this paper,we establish a multi-channel F-P sensors synchronous demodulation system and demodulation method based on a matrix CCD,and prove that the synchronous demodulation system has high demodulation performance and reliability.It also avoids the limitations on system light sources or F-P sensors of traditional multi-channel multiplexing technologies.The specific research contents of this paper include:1?A multi-channel fiber F-P sensor synchronous demodulation system based on matrix CCD is proposed.The influence of the system optical path structure on the number of synchronous demodulation channels is deduced in detail by establishing a simplified system optical path model and the theoretical derivation results are verified by the simulation imaging result of matrix CCD.According to the distribution model of multi-channel interference signals collected by matrix CCD,a multi-channel synchronous demodulation method is proposed,and its feasibility is analyzed by multi-channel interference pattern simulation.2?A four-channel air pressure synchronous demodulation experimental system was built.Four-channel air pressure synchronous demodulation experiment was carried out using F-P pressure sensors and air pressure control system in the laboratory,and compared with single-channel air pressure experiment based on a linear array CCD.The experiment results showed that when the range of air pressure varies from 100kPa to 200kPa,the demodulation errors of the four channels in the four-channel air pressure synchronous demodulation experiment were all controlled in ±0.2kPa,and the demodulation accuracy was better than 0.2%F.S.,basically as same as that of the air pressure demodulation based on linear array CCD.3?An air pressure-temperature dual-parameter synchronous demodulation experimental system was built.The F-P temperature sensor was added to the air pressure demodulation experimental system.The air pressure-temperature dual-parameter synchronous demodulation experiment was carried out,and compared with single-channel temperature experiment based on a linear array CCD.The experiment results showed that when the range of air pressure varied from 100kPa to 200kPa and the range of temperature varied from 0? to 100?,the demodulation error of the air pressure demodulation module was within ±0.2kPa,reached 0.196%F.S.,and the demodulation error of the temperature demodulation module remained within±0.8?.In addition,we have verified the system with good channel demodulation consistency and demodulation stability by using standard thickness birefringent crystal blocks.