Optical fiber strain and temperature distribution composite test BOTDR and working method thereof

Abstract

The invention discloses an optical fiber strain and temperature distribution composite test BOTDR and a working method thereof, and belongs to the field of optical fiber sensing. Multiplexing detection and information extraction are carried out on a dual-wavelength Brillouin backscattering signal, the strain coefficient and the temperature coefficient of an optical fiber are combined, and based ona spontaneous Brillouin backscattering signal strain and temperature test principle, the strain distribution data and the temperature distribution data of the single tested optical fiber are extracted, so that the temperature compensation of the strain distribution data of the tested optical fiber is realized by utilizing the tested optical fiber. The temperature compensation can be realized by utilizing the tested optical fiber without increasing the engineering cost, the workload and the test time, the optical fiber strain distribution test precision in actual engineering application is improved, and the application range of a Brillouin optical time domain reflectometer is further expanded.

Description

technical field [0001] The invention belongs to the field of optical fiber sensing, and in particular relates to a composite test BOTDR for optical fiber strain and temperature distribution and a working method thereof. Background technique [0002] The Brillouin Optical Time Domain Reflectometer (BOTDR for short) relies on measuring the Brillouin backscattered light distribution information of the optical fiber to calculate the strain distribution of the optical fiber. Brillouin optical time domain reflectometer can be used in geotechnical engineering health monitoring, geological disaster early warning monitoring, cable and pipeline health monitoring and other fields. It is one of the most powerful products used to replace traditional point sensors in the engineering field. However, during the use of BOTDR, since the Brillouin backscattering signal is sensitive to fiber strain and temperature, the temperature distribution of the fiber will interfere with the fiber strain d...

AI Technical Summary

Problems solved by technology

However, during the use of BOTDR, since the Brillouin backscattering signal is sensitive to fiber strain and temperature, the temperature distribution of the fiber will interfere with the fiber strain distribution data. In practical engineering applications, this interference will As a result, the test error of the optical fiber strain distribution data increases, and it is difficult to ensure the accuracy of the optical fiber strain distribution data after a large change in temperature

[0003] At present, after BOTDR tests the optical fiber strain distribution data, the compensation method for its temperature data is one under the premise that the temperature change is not large, it is considered that the temperature has little influence, and no temperature compensation is performed on it, which is feasible in the laboratory, but in practice Difficult to achieve in engineering applications

In addition, it is a compensation scheme for actual engineering. One is to lay out temperature-sensing optical cables in parallel. It is believed that the temperature-sensing optical cables are only affected by temperature and not affected by strain. The temperature distribution data of BOTDR is used to compensate the strain distribution data. However, this scheme Not only does it need to lay additional temperature-sensing optical cables in parallel, which increases the workload of engineering construction, but also increases the cost. At the same time, when the temperature-sensing optical cables are subjected to large strains, the temperature data obtained by the test will also be affected by their own strain distribution, resulting in The test error increases, and the temperature compensation effect decreases or even disappears; another engineering solution is to lay a redundant unstrained optical cable at intervals during the laying of the strained optical cable for temperature compensation, which will lead to the strained optical cable used in the project The distance is greatly increased, and the construction difficulty and workload are also increasing sharply. The data calculation and analysis are very complicated and difficult to apply in actual engineering.

[0004] At present, after BOTDR tests the optical fiber strain distribution data, the compensation method for its temperature data is one under the premise that the temperature change is not large, it is considered that the temperature has little influence, and no temperature compensation is performed on it, which is feasible in the laboratory, but in practice Difficult to achieve in engineering applications

In addition, it is a compensation scheme for actual engineering. One is to lay out temperature-sensing optical cables in parallel. It is believed that the temperature-sensing optical cables are only affected by temperature and not affected by strain. The temperature distribution data of BOTDR is used to compensate the strain distribution data. However, this scheme Not only does it need to lay additional temperature-sensing optical cables in parallel, which increases the workload of engineering construction, but also increases the cost. At the same time, when the temperature-sensing optical cables are subjected to large strains, the temperature data obtained by the test will also be affected by their own strain distribution, resulting in The test error increases, and the temperature compensation effect decreases or even disappears; another engineering solution is to lay a redundant unstrained optical cable at intervals during the laying of the strained optical cable for temperature compensation, which will lead to the strained optical cable used in the project The distance is greatly increased, and the construction difficulty and workload are also increasing sharply. The data calculation and analysis are very complicated and difficult to apply in actual engineering.

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