Optical Fiber Fence Alarm System Based On Sagnac Loop

Following the fast development of fiber-optic communication technologies, the fiber sensing technology has made great progress. As an important category of fiber optic sensor, based on the measurement of interference technology has been great concern, it's more accurate than other methods, because it uses the wavelength to work. Fiber optic ring interferometric sensor has been a success application of fiber optic gyro because of its high sensitivity.In this thesis, by comparing the popular fence alarm system product in the market, analyzing and using the Sagnac closed-loop fiber internal interference principle and characteristics, a new type of alarm project based on Sagnac fiber ring fence alarm system is designed. When the sensing fiber is touched, the inside ring-interference light stability is changed and trigger alarm. The thesis mainly start from the principle of the measurement method, designing the methods of deal with the data, the result, as well as error analysis, describe the new method-Based on Sagnac fiber ring fence alarm system and the actual feasibility. By comparing the results under different environmental conditions, analyzing the error sources and the impact of the alarm in the actual installation, design the methods to reduce error, they have played a positive role for practical applications. The main works of this thesis include:1. Resumptively introduced the fiber optic sensing technology's principle, features and applications. By comparing several current alarm systems in the market, educed the fiber optic fence based on the Sagnac ring characteristics and advantages.2. Introduced the fiber fence system architecture, and analysised focus on thechoice of light and drive circuit, the module of optic- electricity.3. Through designing the receiving and processing external sensor signalssoftware, completed the the alarm system project based on the PC and data acquisition card.4. Through designing the receiving and processing external sensor signalscircuit hardware, completed the alarm system device project based on PCB board.5. In different external environment, used the different software and hardwareprojects to carry out fiber fence simulation experiments, and for different conditions, setted alarm parameters to reduce the error rate.6. Based on the single fiber fence, for a wide range of monitoring, analysedand designed the multi-channel fiber-optic alarm system which wasconstituted by four single fences, and tested.