Optical fiber interferometer arm length difference measurement device and method based on swept frequency laser

Abstract

The invention discloses an optical fiber interferometer arm length difference measuring device and method based on frequency-sweeping laser. The device comprises: a linear frequency-sweeping laser emits frequency-sweeping laser; The optical path of the gas cavity and the optical path of the optical fiber interferometer to be tested; the optical path of the gas cavity selectively absorbs the frequency-sweeping laser light entering the optical path of the gas cavity, and generates gas absorption lines. The optical path of the optical fiber interferometer to be tested generates beat frequency signals with equal frequency intervals, and uses this as a frequency reference to resample the electrical signals of the absorption line of the gas cavity optical path at equal frequency intervals. The data acquisition card collects the voltage signals of the two optical paths; the analysis and processing module processes and analyzes the voltage signals of the collected gas cavity optical path and the optical fiber interferometer optical path to be tested, and calculates the corresponding optical frequency domain between every two points in the gas cavity absorption spectrum The time delay is calculated according to the frequency interval above, and finally the arm length difference of the optical path of the optical fiber interferometer to be tested is calculated according to the time delay.

Description

technical field [0001] The invention relates to the measurement of optical fiber sensor devices, and more specifically, to an accurate measurement device and method for measuring the arm length difference of an optical fiber interferometer. Background technique [0002] Optical fiber interferometers can be divided into balanced and unbalanced interferometers according to whether the arm lengths of the two arms are equal. The main sensing principle of the fiber optic interferometer is that the measured signal acts on one arm of the fiber optic interferometer to cause a change in the length of the arm, resulting in a change in the phase of the light wave in the fiber, and the change in phase will lead to a change in the output light intensity after interference , the information of the signal to be measured can be obtained by detecting the change of the output light intensity. Therefore, the arm length difference of the interferometer determines the performance and sensitivit...

AI Technical Summary

Problems solved by technology

The interferometric measurement method has a large phase change caused by small arm differences, high precision and small measurement range; the time domain pulse method can measure long distances, but the accuracy is reduced or limited by ultra-narrow pulse lasers and high-speed acquisition cards; microwave modulation method, measurement accuracy High measurement range is also large at the same time, microwave sweep source, high-speed detector, etc. make its structure complex

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