The Design Of Fiber Optic Distributed Temperature Sensor System

Distributed optic fiber temperature sensor is a new kind of techniquestudied in these years. Utilizing optic fiber back spontaneity dispersionPhenomenon and optic time domain (OTDR) theory, the fiber optic distributedtemperature sensor system can sense the change of temperature along the opticalfiber by the form of continuous function of distance.The optic fiber used in distributed optic fiber sensor is not only transportmedia but also sensing media. It has the characteristics of resistance toelectromagnetic interfere, against fire, small size and little effect to temperaturefield .At the present time, this kind of technology has come into wide use.Based on former theoretical basis, this dissertation takes deep research andanalysis on the fiber optic distributed temperature sensor. The maincontributions are as follows:(1) The domestic and foreign research for distributed optic fibertemperature sensor is discussed. Based on the comparing of several programsand existing element and fabrication process, the program grounded onAnti-stokes light intensity dividing Stokes light intensity is selected.(2) OTDR, the spontaneous Raman scattering and the stimulated Ramanscattering are discussed. The correlation between Anti-stokes light andtemperature is also discussed. It takes a theoretical basis for the design of thesystem of the distributed optic fiber temperature sensing.(3) Designing general diagram and discussing action process. Based onSNR, temperature sensitivity, working stability, the center wavelength of thesystem is determined. Grounded on the Raman scattered signal light power,thermal noise, dark-current and the surrounding temperature, the expression ofoptimal ADP gain is calculated. It provide basis for ADP active state.(4) Several key techniques are discussed. It takes a theoretical basis for thedesign of experiment.