The Reserch And Imapplication Of Grating Demodulation System Based On Fabry-Perot Filter

Fiber Bragg grating （FBG） sensor has become an important kind of fiber sensor. FBGsensor mainly uses the resonant wavelength drift for accurate measurement. Compared withelectronic sensors, it has not sensitive electromagnetic, distribution remote monitoring andother advantages, so has a broad prospect of application in civilian use and industrial fields.Demodulation technology has relationships with the sensor’s working methods,application range and performance, so the research of demodulation technology and thedesign of demodulation system, is a very important research direction.First, this paper analysis of the temperature of Fiber Bragg grating and the principle ofstrain sensor. And then introduces the four existing fiber Bragg grating demodulation, theprinciple of method, And make analysis and comparison through the matching gratingfiltering method, the unbalance M-Z interferometer method, the edge of filtering method andcan be tuned F-P filter method performance, choose F-P filter method of tunability as thisdemodulation method; Make design of demodulation scheme of the Fiber Bragg gratingsensor system, analysis of each function selection demodulation system components, andcomplete the building and commissioning of the fiber Bragg grating demodulation systemlight path parts; And make calibration by grating and F-P with standard of fiber gratingwavelength. Completes the design of hardware circuit with Virtex^TM -4 series FPGA chipXC4VLX25-10SF363I as controller demodulation. In the software ISE of Xilinx, the A/Dacquisition circuit sequential control is completed by VHDL language , achieved datacollecting; Completed the D/A converter control procedures, achieved the triangle voltageoutput wave to F-P filter scanning; Completion the Ethernet communication of the use ofthe realization of DM9000A system, realized data transmission; And completes the decodingalgorithm. Finally it finishes the verification of the demodulation system designed in thispaper and proves the feasibility of this system through constructing test platform ,of whichdemodulation accuracy can reach±1²pm.