Dynamic strain measurement instrument based on multiple overlapped gratings

Abstract

The invention provides a dynamic strain measurement instrument based on multiple overlapped gratings. The dynamic strain measurement instrument comprises the multiple overlapped gratings, a wideband light source, a tunable filter, a positioning coupler, an etalon, a photoelectric detector and a demodulation and control circuit. The multiple overlapped gratings are formed in a way that a plurality of sensing gratings with center wavelengths being distributed at equal intervals are inscribed in an overlapped manner in a same area on a sensing optical fiber by selecting different phase templates, wherein the center wavelengths of a fiber Bragg grating, which are inscribed in the overlapped together, are continuously distributed at equal intervals within a wavelength scanning range of the tunable filter, so that sensing information of the same physical quantity to be measured can be continuously obtained for a plurality of times within each wavelength scanning period, and a peak value position and wavelength variation of each sensing grating in the multiple overlapped gratings, namely reconfigurable original dynamic strain signals, can be recorded. Therefore, the purpose of improving a measurement bandwidth of the dynamic strain signals based on a grating demodulation system of the tunable filter can be realized. According to the dynamic strain measurement instrument provided by the invention, the sensed measurement bandwidth of the fiber Bragg grating based on the tunable filter can be effectively improved, so that the high-speed and high-precision simultaneous measurement requirement of the dynamic strain signals can be met.

Description

technical field [0001] The invention relates to a dynamic strain measuring instrument based on overlapping multiple gratings, which is mainly used for sensing and measuring dynamic strain signals and belongs to the field of sensing technology. Background technique [0002] Fiber Bragg gratings can convert changes in the external environment (such as stress, strain, vibration, temperature changes, etc.) Sensors have been widely used in the fields of long-distance optical sensing and optical communication due to their characteristics of being immune to electromagnetic radiation interference, small size, simple fabrication, and wavelength sensitivity. [0003] At present, the technologies for demodulating the center wavelength of fiber gratings usually include the following types, which are spectral analysis technology, wavelength scanning technology based on tunable filters, edge filter technology, unbalanced M-Z interferometer demodulation technology and matched grating demo...

AI Technical Summary

Problems solved by technology

[0005] (1) The tunable speed of the tunable filter itself is limited. In order to ensure the long-term stability and reliability of the laser, the tuning speed of the existing fiber laser based on the tunable filter is usually on the order of 1 Hz to several kHz

[0006] (2) The limitation of signal acquisition and processing speed. Under the condition of keeping the scanning wavelength resolution unchanged, the conversion rate of A / D and D / A is proportional to the wavelength scanning rate of the tunable filter, and the demodulation system The data processing capability limits the improvement of the A / D sampling frequency, and under the condition that the A / D sampling frequency remains unchanged, the wavelength scanning range and wavelength resolution can only be reduced to increase the wavelength scanning rate, but this will affect the demodulation Multiplexing capability and demodulation accuracy of the system

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