Optical fiber strain and temperature measuring device and optical fiber strain and temperature measuring method

Abstract

The optical fiber strain and temperature measurement device and the optical fiber strain and temperature measurement method use a self-delay type homodyne interferometer to obtain strain and temperature separately. It has a light source unit, a branch unit, an interference signal acquisition unit, a scattered light intensity acquisition unit, and a signal processing unit. The light source unit generates probe light. The branch part bifurcates the backscattered light generated in the optical fiber to be measured by the probe light. The interference signal acquisition unit receives one scattered light branched out by the branching unit, and generates an interference signal by self-delay type homodyne interference. The scattered light intensity acquiring unit receives the other scattered light bifurcated by the branching unit, and acquires the intensity of the scattered light. The signal processing unit separates and acquires strain (δε) and temperature change (δT) based on the frequency shift amount obtained based on the intensity of the interference signal and the intensity of the scattered light. Here, in the interference signal acquisition unit, the phase of one scattered light branched out from the two branches can be changed.

Description

technical field [0001] The invention relates to an optical fiber strain and temperature measuring device and an optical fiber strain and temperature measuring method using Brillouin scattered light. Background technique [0002] With the development of optical fiber communication, distributed optical fiber sensing using optical fiber itself as the sensing medium is being actively studied. In particular, optical fiber sensing using scattered light can realize long-distance distributed sensing unlike electrical sensors that measure for each point, and therefore can measure the physical quantity of the entire object to be measured. [0003] In distributed optical fiber sensing, the representative one is time domain reflectometer (OTDR: Optical Time Domain Reflectometry: Optical Time Domain Reflectometry). Backscattered light was measured over time. Backscattering in optical fiber includes Rayleigh scattering, Brillouin scattering and Raman scattering. Among them, an instrume...

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Problems solved by technology

Therefore, in the homodyne interferometer, the intensity information of the Brillouin scattered light itself cannot be obtained

Therefore, the optical fiber strain and temperature measuring device and the optical fiber strain and temperature measuring method disclosed in Patent Document 2 are effective techniques for heterodyne interferometers, but cannot be applied for homodyne interferometers

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