Distributed stress/temperature sensing optical fiber coordinate locating method

Abstract

The invention belongs to the technical field of distributed optical fiber sensing in photoelectric technology and in particularly relates to a locating method capable of measuring corresponding coordinate position of a distributed sensing optical fiber in a measured structure. A distributed stress / temperature sensing optical fiber coordinate locating method is characterized in that the method comprises the following steps: (1) arranging a distributed stress / temperature sensing optical fiber on a to-be-measured circuit of the measured structure, and arranging a heating and locating device at a to-be-measured specific position of the measured structure, and enabling the distributed stress / temperature sensing optical fiber to pass through the heating and locating device; and (2) in a measuring process, electrifying the heating and locating device to emit heat to the distributed stress / temperature sensing optical fiber, and acquiring an optical fiber measuring point coordinate at the to-be-measured specific position of the measured structure. According to the method, the measurement circuit composed of the distributed sensing optical fiber can be subjected to accurate coordinate location, and the optical fiber measurement data can be accurately projected on the specific position of the measured structure, so that the measurement error is reduced.

Description

technical field [0001] The invention belongs to the technical field of distributed optical fiber sensing in photoelectric technology, and specifically relates to a positioning method capable of measuring the corresponding coordinate position of a distributed sensing optical fiber in a measured structure. Background technique [0002] Brillouin Optical Time Domain Analyzer (BOTDA) is a technology that uses the frequency change of light scattered in the optical fiber to measure the change of optical fiber strain (temperature). It can measure temperature and strain simultaneously. Its working principle is: The laser transmitters at both ends of the fiber inject a beam of pulsed light and a beam of continuous light into the fiber respectively. When the frequency difference between the pulsed light and the continuous light is equal to the Brillouin frequency shift of a certain interval in the fiber, the area will be affected. Exciting the Brillouin amplification effect, energy tr...

AI Technical Summary

Problems solved by technology

However, the optical fiber sensing points in one-dimensional coordinates also bring difficulties to the three-dimensional spatial positioning of the measured structure

The data obtained by the distributed sensing optical fiber measurement is meaningful only when it is accurately projected on the measured structure. However, the actual situation is that although most distributed sensing optical fibers are marked with one-dimensional coordinates, the surface has no Label the length coordinates (or the labeling accuracy is more than 1 meter, which cannot meet the requirements for accurate positioning of the coordinates), so it is difficult to correspond to the specific position of the measured structure. Even if there are a small number of centimeter-level length labels for distributed sensing fibers, It will be difficult to meet the measurement accuracy requirements due to the following factors:

[0004] 1. The distributed sensing optical fiber is laid in the structure, usually the surface of the optical fiber will be completely wrapped by glue and other protective materials, so that the coordinate positioning cannot be performed by reading the marked length

[0005] 2. The optical fiber is elongated due to pretension during laying, or the length changes due to other factors, which will cause the difference between the actual length and the marked length, and eventually cause the deviation of the measurement position;

[0006] 3. The difference between the actual length and the marked length of the measuring line composed of distributed sensing optical fibers can no longer be calculated after multiple connections, so it is difficult to carry out precise coordinate positioning in space;

[0007] 4. The positioning error of the signal demodulator will expand as the length of the optical fiber increases, resulting in the inconsistency between the theoretical coordinates of the measurement point and the marked coordinates during long-distance measurement, making the marked coordinates unavailable

[0008] In view of the above reasons, the difficulty of coordinate positioning has reduced the measurement accuracy of distributed sensing optical fiber, so a new technology is urgently needed to accurately determine the coordinates of the optical fiber measurement point corresponding to the specific position of each measured structure

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