Research On Theory And Technology Of Temperature And Strain Sensor System Based On Optical Fiber Brillouin Scattering

Compared with traditional sensors, distributed fiber sensor with higher sensitivity,stronger anti-electromagnetic interference, longer distance detection, small size, light weight,can be composed of two-dimensional or three-dimensional sensor networks.It is widely usedin structural health monitoring based on temperature and strain. Distributed optical fibersensing technology based on Brillouin optical time domain analysis not only has theadvantages of fiber optic sensors, and can achieve high-precision, high spatial resolution,real-time online monitoring.It summarizes the research status and development trend on Brillouin optical time domainanalysis (BOTDA) at home and abroad, and introduces Brillouin scattering mechanism, anddeduces the functional relationships between Brillouin frequency shift, temperature and strain,and has temperature and strain experimental study,the1.0012MHz/℃temperature sensitivityand0.031MHz/N strain sensitivity are obtained. Experiment with bare fiber、temperature fiberoptic temperature measurement and find that improve the protective layer of the fiber topromote the temperature measurement accuracy.It was found that the protective layer oftemperature fiber affects the accuracy of the temperature measurement. Bare fiber has higherprecision, but also is affected easily, easily broken, so improve the protective layer of the fiberto promote the measurement accuracy. To improve the accuracy of the temperaturemeasurement, this paper proposes a kind of temperature measurement which uses thermalgrease apply bare fiber.In order to satisfy requirements of small-scale, high-precision leakmonitoring, and further improve monitoring technology of pipeline, in this paper,Brillouinoptical time domain analysis (BOTDA) principle as the theoretical basis, make a kind ofstrain sensing cable based on sensitive material of crude oil,and also the response model ofthe brillouin frequency shift of local strain on the fiber optical cable and hasexperiment.Experimental results show that: the system can quickly and accurately identifyand locate a small leak and we located the small-scale oil leak accurately within9minutes bythe sensor cable One,besides,the spatial resolution of1m and the positioning error of0.1m inthe length of1.70km were realized.