Research On Driving And Detecting System Of Fiber Bragg Grating Sensing Demodulation Based On Grating-Matching Method

Fiber Bragg Grating (FBG) sensor is one of the current hotest researches in the optical fiber grating sensor technique field. It is widely applied in many fields such as structure monitoring of large scale compound material and the concrete, performance monitoring of intelligent material, electric power industry, medicine, chemical engineering etc. The demodulation technique of FBG is a critical and difficult problem nowadays in FBG sensing field.The development of FBG sensing demodulation in last ten years is reviewed and the problems existing in this field are analyzed. The demodulation methods of fiber grating sensor are systematically introduced in the paper, and then their advantages and disadvantages are analyzed respectively. Considering the practicability and feasibility, grating-matching demodulation method is employed in the demodulating system introduced in this paper.The single-chip microprocessor is made as the core microprocessor of the circuit module. Under the control of the microprocessor, sawtooth wave voltage signal is generated by D/A converter and sent to the simulative import end of HPV series piezoelectricity chinaware driving power. The PZT cell sticked to the matched FBG is drived by the driving power. When the PZT is exerted to some voltage, the reflect wave peak value of matched FBG will be shifted. Thus the scan of the sensing FBG is formed. When the peak value wavelengths of matched FBG and the sensing FBG are matched, the output signal of photodetector reaches the max value. The optical signal is turned into electrical signal by the photodetector and the A/D converter is used to collect electrical signal. The single-chip microprocessor performs filter processing to the collected data, and then works out the location of the strongest light strength in one scan cycle and the central wavelength of sensing grating.