Design and Implementation of Fiber Bragg Grating Sensor Interrogator for Remote Fiber Real-time Monitoring

• Main Authors: Chao-Yang Cheng, 鄭朝陽
• Other Authors: Shien-Kuei Liaw
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/76147892630347470124

碩士 === 國立臺灣科技大學 === 電子工程系 === 105 === This thesis shows that we develop a remote fiber monitoring system by using a remote monitoring software in a FBG interrogation system. The system is potential to replace the optical measuring instrument because it is cheaper in the market. On the other hand, the system synchronize large-scale and multi-viaduct bridge security with real-time monitoring to protect people's safety. After the experiment, we choose the “broadband light source pass through tunable filter type probe light source” in the FBG interrogation system. Because it has the best stability after putting it in the room temperature environment for 8 hours. In this structure, the absorption at 1530 nm of Erbium-doped fiber is 17.5 dB/m and the length is 5 m. The channel of Optoplex's C-band tunable filter is fixed at the middle (M4400) of C-band when the output peak wavelength is stable at 1547.201 nm without any fluttering phenomenon; while the maximum peak power is -24.06 dBm and the minimum is -24.10 dBm. The variation is very stable and the range is only ± 0.02 dB. The wavelength range for scan monitoring is from 1527.996 nm to 1563.029 nm developed in the FBG interrogation system and it contains the whole C-band wavelength. In the remote monitoring software, the initial value of interrogator setting function, single fiber grating scanning function, all bridges automatic monitoring function and resolution/span setting function can all work after the hardware and software integration test. Users are able to control the FBG interrogation system, read the monitoring results and analyze the data with remote monitoring software at a long distance. At last, the vertical stress monitoring experiment is carried out by the remote optical fiber monitoring system. It’s the actual simulation of real-time monitoring. We selected three fiber gratings laid out at different analog bridges and at different distances to do the experiment. The results show that the sensitivity of FBG1-2, FBG2-4 and FBG3-1 for the vertical force is 61.22 pm/N, 61.22 pm/N and 110.2 pm/N and for the linearity R2 is 0.999, 0.999 and 0.9922. In order to ensure the reliability and accuracy of this monitoring system, this chapter performs reproducibility testing. The results are just the same as the ones in the first testing. Besides, we applied 0.98 N vertical force on the selected fiber grating and put it at room temperature for 8 hours to test the stability of the FBG reflection wavelength and the peak power of this surveillance system. The results show that the reflection wavelength is very stable without any fluttering phenomenon. There are only few datum showing the drifting between ±0.1 dB. This monitoring system monitors the signal that shows a fairly stable state at the sensing ends as well as at different distances of the three analog bridges.