Triangular prism type fiber grating acceleration detector

Abstract

The invention discloses a triangular prism type fiber grating acceleration detector based on a hollow-core column type elastic-mass sensitive structure. The triangular prism type fiber grating acceleration detector comprises a hollow-core triangular prism having a base with a through hole and an open upper end; and an inertial mass block and a Bragg fiber grating are arranged at the top of the hollow-core triangular prism. According to the invention, on the basis of the wavelength sensing principle of the fiber grating, the triangular prism hollow-core tube of the detector is stretched or compressed in a vertical direction under the inertia effect of the mass block under the action of the external excitation vibration signal; and thus the packaged grating makes the axial strain and thus the wavelength makes drift. Detection of an acceleration signal in a vertical direction is realized by detecting the change of the grating wavelength.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensors, in particular to a triangular prism type optical fiber grating acceleration detector. Background technique [0002] Fiber Bragg Grating is a wavelength-type passive device formed by periodically modulating the refractive index of the core of a single-mode fiber by writing a grating. It has a wide range of applications in the fields of optical communication and sensing, especially in optical The field of sensing has aroused eager research by scholars at home and abroad. Fiber Bragg Grating has made great progress in the field of quasi-static sensing, but it is still a research hotspot in the field of dynamic sensing, especially a difficult problem in engineering fields such as low-frequency seismic wave detection. When light encounters a grating in the optical fiber, it reflects and transmits the incident light that satisfies the Bragg condition. According to the Bragg condition, th...

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Problems solved by technology

[0003] Wavelength fiber Bragg grating geophones improve some shortcomings of traditional electrical geophones, intensity modulation and phase modulation fiber optic geophones: (1) Traditional electrical geophones will be affected by electromagnetic interference and are not suitable for harsh Working environment; (2) The measurement accuracy of the signal picked up by the phase modulation optical fiber detector during the detection process is affected by the light intensity, the light source, the connection loss, the fiber bending loss, etc.; (3) There is an "interference type" detector (Reading information is to observe the change of interference fringes) in the unclear phase measurement and the need for a fixed reference point; (3) The phase modulation optical fiber detector realizes the measurement of the vibration signal to be measured by calibrating the phase change before and after the measurement Relative measurement requires an initial reference like an interferometric sensor based on fringe counting; (4) It is not possible to use wavelength division multiplexing technology to connect multiple detectors in series in an optical fiber for distributed measurement to form an optical fiber sensing network

(5) Traditional electric detectors are large in size and mass, and have complex structures and many accessories

The environment in oil wells is relatively harsh, and it is difficult for traditional electrical detectors to detect low-frequency signals, while optical fiber grating detectors have the characteristics of high temperature resistance, corrosion resistance and anti-electromagnetic interference

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