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Low Reflectivity Fbg Sensing System And Fiber Optic Interferometer Reuse

Posted on:2012-04-15Degree:MasterType:Thesis
Country:ChinaCandidate:C LiuFull Text:PDF
GTID:2208330332986677Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
With the rapid development of science and technology in the information age, photoelectric technology and information technology play a more and more important role in various industries and fields. Optical fiber communication and optical fiber sensor in the photoelectric technology have attracted increasing close attention. This paper will mainly discuss optical fiber sensor system. Compared with electronic sensors, Optical fiber sensors have the virtue of strong anti-electromagnetic interference, good insulation, and prone to be received by all kinds of photo-detectors. They are universally applied in our daily life, such as large-scale structure, electricity, aviation, security protection, geology, transportation, petrifaction, and military, etc. According to different needs, they have developed from the single-point detection into the multi-point and distributed detection. This paper introduces the sensing system based on low-reflectivity Fiber Bragg Grating (FBG), and further discusses the multiplexing between this sensing system and fiber optic interferometer.Firstly, this paper analyzes a variety of common technical route in optical fiber sensing systems, including the quasi-distributed optical fiber sensing system, distributed optical fiber sensing system based on optical fiber interferometer or Optical Time Domain Reflectermetry(OTDR). In the quasi-distributed optical fiber sensing system part, we mainly discuss the application and the research status of FBG sensing system. Then we make an analysis of the principle and structure of the three basic fiber optic interferometers, such as fiber-optic Mach-Zehnder interferometer, fiber-optic Michelson interferometer, and fiber-optic Sagnac interferometer. Finally, we give a brief introduction to the classification and theory about the OTDR distributed optical fiber sensing system.Secondly, this paper analyzes the principle of the FBG sensor and sensing system, as well as the strain characteristics and temperature characteristics about FBG, and then discusses the various kinds of demodulation technique and multiplex technique in relation to FBG. Furthermore, we in-depth analyze the factors that affect the system capacity and also simulate the system capacity. According to the simulation results, we build low-reflectivity FBG optical fiber sensing systems based on time division multiplexing and narrow-wavelength scanning laser. The program greatly improves the capacity and distance of the FBG sensor system to achieve multi-sensor point parameter measurement.In the last place, we research the multiplexing between low-reflectivity FBG sensing system and fiber optic interferometer. This paper indicates the principle of the wavelength-scanning white-light interferometry at first. We do sorts of emulation experiments for Fourier demodulation method using LabView. By way of contrast, we also emphatically discuss the demodulation technique with a 3×3 coupler-based interferometer and its principle. Then, we do some simulation experiments for the demodulation method by MatLab and build a 3×3 coupler-based Michelson interferometer to simulate actual conditions. At last, we set up a multiplexed sensor system with wide-wavelength scanning laser FBG sensing system and fiber optic interferometers. In this system, we use white-light interferometry to demodulate interference signal and use peak detection method to demodulate FBG sensing signal. The fusion of FBG sensing system and interference sensing system will greatly make up the shortfall of a single FBG sensor system to achieve multi-point detection in engineering and improve the sensitivity of the whole system.
Keywords/Search Tags:optical fiber sensor, low-reflectivity Fiber Bragg grating, fiber optic interferometer, white-light interference
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