A FBG Temperature Demodulation System Software Design Based On LabVIEW

For the unique advantage of being immune to EMI, fiber Bragg grating (FBG) sensors have been used increasingly in power, chemical, mining and other industries. The core technology for FBG sensing is the demodulation of a grating’s central wavelength. The demodulation module we used is a product named FBGA (Fiber Bragg Grating Analyzer) which is developed by Bay Spec Company. It has attractive merits such as being fast and accurate in demodulation, wavelength being non-drift, having moderate price and stable structure and so on.The project is organized by the wiring product department of Nanjing Putian Telecommunication co., Ltd., to develop software based on FBGA demodulation module that can be used in a substation switch cabinet for temperature monitoring. The main works are illustrated as follows:Firstly, the temperature sensing mechanism of fiber Bragg grating is introduced. Also being introduced is some typical demodulation method, especially the principles of the FBGA module.Secondly, a peaks searching algorithm based on the output characteristics of FBGA module is developed. The algorithm guarantees a certain demodulation accuracy (<5pm) while greatly simplified user’s setting.Thirdly, there has a detailed analysis on the characteristic of os4200series sensor’s wavelength varying with temperature. According to the analysis, a temperature-wavelength fitting method is proposed, which facilitate the using of FBG temperature sensors in engineering.Finally, a FBG temperature monitoring system software based on FBGA demodulation module is developed in LabVIEW platform. The software communicates with the FBGA demodulation module by way of calling dynamic link library. The software can achieve the following functions:data acquiring, optical channel switching, waveform graphical displaying, sensor finding peaks, sensor wavelength-temperature fitting, data saving and temperature alarming.It’s proved that the software can accomplish real-time measurement for multi-channel FBG temperature sensors and meet the basic laboratory and engineering applications.