Multimode fiber-based method and multimode fiber-based system for simultaneously measuring temperature and strain

Abstract

The invention belongs to the technical field of measurement, and particularly relates to a multimode fiber-based method and a multimode fiber-based system for simultaneously measuring temperature and strain. The system comprises a laser device, a first coupling device, a polarization controller, an electro-optical modulator, a pulse generator, a first optical amplifier, a first circulator, a first optical grating, a multimode circulator, a multimode optical fiber, a second optical amplifier, a second circulator, a second optical grating, a second coupler, a polarization scrambler, a photoelectric detector, a data application and processing module and a computer display module; by measuring two modes with different brillouin frequency shift-temperature coefficient and brillouin frequency shift-strain coefficient of the multimode optical fiber, a coefficient matrix is formed to realize the simultaneous measurement of the temperature and strain, the cross sensitivity problem in brillouin distribution type optical fiber sensing can be solved, the measurement precision is high, the positioning is accurate, and the cost is low.

Description

technical field [0001] The invention belongs to the technical field of measurement, and in particular relates to a method and system for simultaneously measuring temperature and strain based on a multimode optical fiber. Background technique [0002] In addition to the advantages of general optical fiber sensors such as anti-electromagnetic interference, corrosion resistance, and good electrical insulation, the distributed optical fiber sensor also has the advantages of obtaining distribution information along the entire optical fiber measured field with only one measurement, high measurement accuracy, accurate positioning, and sensing The distance can reach hundreds of kilometers and other unique advantages, so it has broad application prospects. Among them, the distributed sensing technology based on optical fiber Brillouin scattering has higher measurement accuracy, measurement range and spatial resolution in temperature measurement than other sensing technologies, so thi...

AI Technical Summary

Problems solved by technology

[0003] Since the Brillouin frequency shift in the optical fiber is affected by temperature and strain at the same time, it is impossible to distinguish whether the frequency shift is caused by temperature or strain only by a single Brillouin frequency shift, which results in the Brillouin distributed optical fiber transmission. The problem of cross-sensitivity in sensing also restricts the practical application of Brillouin distributed optical fiber sensors

The initial solution to the problem of cross-sensitivity is to arrange a reference fiber in a relaxed state next to the sensing fiber, so that the reference fiber is insensitive to strain, so as to perform temperature compensation on the sensing fiber to achieve the purpose of measuring dual parameters, but this arrangement of fiber method is difficult to apply in practice

However, due to the small power of Raman scattered light, it is difficult to achieve long-distance sensing

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