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Research On Double Light Path Distributed Optical Fiber Temperature Sensing System Based On Brillouin Scattering

Posted on:2012-10-30Degree:MasterType:Thesis
Country:ChinaCandidate:X QinFull Text:PDF
GTID:2218330362956662Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Distributed optical fiber temperature sensor has some advantages, such as a high sensitivity etc. It can realize real time monitoring one-dimensional to several-dimensional temperature profile field along the optic fiber. Distributed optical fiber temperature sensors have applied in temperature profile measurement of oil well and tunnel, protect and warning system in fire of the large-scale warehouse, mine etc. This paper reviewed current developments in both domestic and international about distributed optical fiber temperature sensors. A double light path BOTDR system was proposed, detailed design was made, the parameters were calculated, and method of signal detection was analyzed.In this paper, the characteristics of the three kinds of different temperature sensors based on Rayleigh, Raman and Brillouin scattering were compared. The relationship between optical fiber temperature change and Brillouin scattering, and principles of temperature sensing based on Brillouin scattering system and demodulation methods were analyzed, and coherent detection method for measurement of Brillouin frequency shift was used to achieve the purpose of measuring temperature changes in optical fiber.Temperature resolution, spatial resolution, time resolution, temperature measuring range and sensing distance are important parameters of system. This paper analyzed main factors to impact these parameters, put forward the system desired performance indicators.Signal processing module is a key part. Some general methods of faint signal processing were present, and practicability was analyzed. After quantitative analysis to the signal and the noise characteristic, the signal average processing and least-square fitting method to improve SNR was forwarded, and simulation of the system allowable error range when two fiber in asymmetric condition by matlab was made.
Keywords/Search Tags:distributed optical fiber sensor, Brillouin scattering, resolution, signal processing
PDF Full Text Request
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