Research Of Fiber Grating Sensor Demodulation System Based On Tunable F-P Filter

Fiber bragg grating sensors is widely used in civil engineering, petrochemicalpower electronics and medical fields, for its compact structure, anti-electromagneticinterference capability, corrosion resistance, high temperature, measurable parametertypes, high detection sensitivity, as well as the unique advantages of easy compositionof distributed sensor network. FBG sensor demodulation technology has matured, butdue to the limitation of the demodulation system integration and the high cost ofhigh-precision demodulation system has become a major obstacle in engineeringapplications, therefore, in order to promote market scale application of fiber Bragggrating sensors. It is necessary to develop a high stability, high accuracy and moderatecost universal demodulation system of fiber grating sensor.The FBG sensing mechanism is analysed, as well as the FBG temperature and strainsensitive features. The compensation measures is prososed to overcome the temperatureand strain cross-sensitivity effects while measure a single parameter. Finally, severalcommon demodulation technologies is compared.A universal sensing demodulation system is designed based on fiber F-P tunablefilter. The performance parameters of the desired optical device in the demodulationsystem is analysed, and focus on the impact of optical fiber F-P tunable filter’sparameters to the demodulation system’s performance.Then the reference grating isbrought in to improve the impact of wavelength scan dynamic drift caused by the PZTnonlinearity and repeatability deviation, as well as other hardware and softwarecompensation measures, and the feasibility of the solutions proved to be correct throughexperimental validation.The signal processing control unit hardware circuit has designed, including theC8051F340control unit and its peripheral interface circuit module, FFP-TF2drivingcircuit, photoelectric detection circuit module, A/D sensor data acquisition module,LCD display module, and other functional modules. The above modules are integratedon a single PCB board, and its very convenient to make up an instrument.The PC monitoring software is developed by VC++software based on the hardware platform, and the serial data’s transceiver is based on MSCOMM control,while the TeeChart chart controls make sure the graphical display of the monitoringdata, to realize the online real-time monitoring.Finally, the performance and stability of the hardware and software system isverified by experiment, and the system’s temperature sensor characteristic is tested,then the linearity of the relationship of the FBG center wavelength and temperature isanalysed combined with the experimental data, the compensation program is given toimprove FFP-TF2’s dynamic drift characteristics in practical application, and theexperimental results satisfy the desired requirements.