Raman-scattering-based method and device for simultaneously measuring temperature and strain of identical weak fiber gratings

Abstract

The invention discloses a Raman-scattering-based method and device for simultaneously measuring the temperature and the strain of identical weak fiber gratings. According to the method and device, by the utilization of the wire-drawer-tower technology, ultralow-reflectivity identical weak fiber gratings are dynamically and continuously inscribed through single pulse energy to serve as a sensing probe; after modulation of pulse signals is performed, Bragg reflection signals and backward Raman scattering signals of the sensing probe are sent to a high-speed CCD wavelength demodulation module and a Raman temperature demodulation module respectively; temperature distribution T[i] at all the fiber gratings and reflection center wavelength lambda[i] of the fiber gratings are obtained respectively; temperature measurement of the Raman temperature demodulation module serves as temperature compensation data of strain measurement, and measurement data of the high-speed CCD wavelength demodulation module serve as correction for temperature measurement. The method and device can overcome the defects that the Raman sensing technology is low in accuracy and speed, and strain can not be measured, meanwhile, large capacity weak optical grating array fiber cabling complexity and operability can also be simplified, and cross sensitivity of the temperature and the strain of the gratings is avoided.

Description

technical field [0001] The invention relates to a quasi-distributed identical weak fiber grating sensing and its demodulation technology, in particular to a method and device for simultaneously measuring the temperature and strain of an identical weak fiber grating based on Raman scattering. Background technique [0002] Temperature and strain are two key test parameters for structural health checks of large systems. The stress state of the local key positions of the structure is directly related to the safe service state of the structure, and the temperature has a greater impact on large-volume structures such as concrete dams and foundation pits. The action of temperature and stress often leads to damage such as microcracks inside the structure. Simultaneously and accurately measuring the temperature and strain of large structures has always been an engineering challenge due to the cross-sensitivity of temperature and strain. [0003] Distributed Raman optical fiber sensi...

AI Technical Summary

Problems solved by technology

However, this method brings inconvenience to the engineering installation, and the measurement accuracy of the reference fiber will have a great impact on the measurement accuracy of the system

Images