The System Of Fiber Grating Demodulation Based On FPGA And Volume Phase Grating

The fiber grating sensor of Bragg has been widely used in the areas of chemical, electric power, coal mine etc., because of the excellent ability of resistance to electromagnetic interference, insulation and the large dynamic range.Based on the dynamic demodulation methods of RVPG(Reflective volume phase grating), the demodulation system of optical fiber grating sensing which center on FPGA was designed combined with grating demodulation module of Linear CCD array from Ibsen company. The program of data collection, processing, serial communication and software design were developed.In this paper, the theory of temperature sensing and the main ways of demodulation were researched. Furthermore, the principle of dynamic demodulation methods was analyzed, which also present the optical device used and analyzed the performance indicators and the output sequence in detail.The hardware parts of the system completed the design of the function module using the Verilog HDL and verification based on Modelsim, which also made the further Debug test using Signaltap. The design of the internal hardware circuit of FPGA consist of clock source, PLL, data collection, FIFO buffer and gear box, data sending modules.Based on the Labview programming environment, the upper computer parts of the system called the API function from VISA, and realized the communication between the device and computer. Finally, the designed software completed the data reading from 80 pins of CCD, and rebuilded the image of the reflectance spectrum.The system has the advantage of simple design, steady and r eliability, practicality, on the basis of which, the friendly human-computer interface which can meet further specific needs maybe customized. At the end of paper, it also put forward many improvements for the system.