Multiple Wavelength Demodulation Temperature Measurement System Of Long Period Fiber Grating And Fiber Bragg Grating

With the development of science and technology, Fiber Bragg Grating(FBG) has attracted more and more attention, FBG becomes one of the most promising passive fiber devices. FBG has a strong anti electromagnetic interference, good corrosion resistance, quick response, small volume, and form the distributed measurement system etc. In order to demodulate the center wavelength of the FBG, this paper proposes a Long Period Fiber Grating(LPFG)- FBG wavelength demodulation method, the method combinates LPFG transmission spectrum and reflection spectrum characteristics of the FBG. This method has the advantages of simple structure, high accuracy, can be achieved on the temperature and stress of multi parameter measurement. This paper mainly carries on the following work:Firstly, this paper researches the FBG research status at home and abroad deeply and makes clear the research significance. Through the coupled mode theory of fiber grating to analyze sensing principle of FBG and LPFG, focusing on the effect of temperature on FBG and LPFG transmission characteristics.Secondly, we analys several common FBG demodulation method, based on the study of traditional demodulation methods, A multi wavelength demodulation method LPFG-FBG is proposed. The system can demodulate the change of center wavelength of FBG reflected light power, which can improve the FBG measuring points by the high bandwidth of the transmission spectrum loss peak of LPFG.Again, the FBG temperature sensitive characteristics are studied. To improve the temperature sensitive characteristics of FBG we use several different methods to package the FBG, and use different methods to test the temperature sensitive of the package protection methods, finally selected the aluminum as the substrate of FBG temperature sensor system.Finally, we can obtain the voltage- temperature relationship through the experiment, The preparation of STM32 signal acquisition and processing machine program and PC program Lab VIEW, PC is used to display the measured temperature, and store the outside temperature value. The host computer can communicate each other. The experimental system was built. Through repeated experiments verify the system’s stability, reliability and high accuracy. The system can demodulate the center wavelength of multiple FBG, and it has a certain application prospect.Again, the FBG temperature sensitive characteristics are studied. we use several different methods to package the FBG, and use different methods to test the temperature sensitive of the package protection methods, finally selected the aluminum as the substrate of FBG temperature sensor system. The preparation of STM32 signal acquisition and processing machine program and PC program Lab VIEW, PC is used to display the measured temperature, and store the outside temperature value. The host computer can communicate each other.Finally, the FBG center wavelength voltage calibration experiment and FBG center wavelength temperature test are carried out. At last the relationship between voltage and temperature is obtained. The experimental system was set up, and the stability, reliability and high accuracy of the system are verified by repeated experiments. The system can be used for the demodulation of the center wavelength s of a plurality of FBG and it has a certain application prospect.