Fiber Bragg grating accelerometer based on U-type cantilever structure

Abstract

A fiber Bragg grating accelerometer based on a U-type cantilever structure is characterized in that: in a shell, a left bearing is arranged on a base plate left side and a right bearing is arranged on a base plate right side; a left through hole (a) is processed on left end wall of the shell and a right through hole (b) is processed on right end wall; an upper end surface and a lever are arranged on upper portions of the left bearing and the right bearing, wherein the lever is in a same plane with centers of the left through hole (a) and the right through hole (b); an upper end of the lever is provided with fiber Bragg gratings; a left pillar and a right pillar are arranged on the base plate which is under the lever and in the shell; a flat diaphragm is arranged between the left pillar and the right pillar and a mass block is arranged on the flat diaphragm, wherein the upper end of the mass block is connected with the lever. Using the invention can realized visualization observation of inside vibration. Volume is small, frequency response scope is wide and sensitivity is high. If the invention is installed on pipelines, multi-point real-time permanent measurements of a plurality of sensors can be realized with the combination of optical fiber sensing network. The invention can be widely used in oil gas pipelines.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensors, in particular to a fiber grating acceleration sensor used for real-time detection of the amplitude and vibration frequency of seismic wave acceleration in petroleum exploration. Background technique [0002] The basic sensing principle of the fiber grating accelerometer is to use the force of the elastic element to convert the acceleration into the strain of the fiber Bragg grating, thereby converting it into the change of the Bragg wavelength, and to measure the acceleration amplitude by detecting the change of the wavelength. As a new type of optical passive device, the fiber grating accelerometer has many incomparable advantages over electromagnetic accelerometers, such as: encoding the signal with wavelength, which is convenient to form a distributed sensor network; it can realize real-time online absolute measurement of the scene; Can work normally in strong electromagnetic fie...

AI Technical Summary

Problems solved by technology

In 1996, Berkoff et al. proposed the fiber Bragg grating embedded acceleration sensor with a natural frequency of 2000 Hz and a sensitivity coefficient of 112 με / g, but the lateral anti-interference ability was poor; in 2010, Li Chuan et al. proposed a fiber Bragg grating based on an equal-strength cantilever beam. The natural frequency of the low-frequency acceleration sensor is 16.96Hz, and the sensitivity coefficient is 347.5pm / g. Obviously, the frequency response range is too narrow and its use is limited.

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