A temperature insensitive fiber grating acceleration sensor

Abstract

The invention provides a temperature insensitive fiber bragg grating acceleration sensor. The temperature insensitive fiber bragg grating acceleration sensor is in a double-rectangular cantilever beam structure; the double-rectangular cantilever beam structure comprises a first cantilever beam, a second cantilever beam, a third cantilever beam, a fourth cantilever beam, an inertia mass block, a first cantilever beam fixed end and a second cantilever beam fixed end, wherein the inertia mass block is located at the geometric center of the four cantilever beams and is fixedly arranged on the four cantilever beams or is connected with the four cantilever beams to form a whole body; the first cantilever beam fixed end and the second cantilever beam fixed end are fixedly arranged at the two ends of the four cantilever beams; the temperature insensitive fiber bragg grating acceleration sensor further comprises a sensor top cover and a base; a certain distance is formed between the sensor top cover and the inertia mass block and the senor top cover and the inertia mass block are fixedly connected with the upper ends of the first cantilever beam fixed end and the second cantilever beam fixed end; a certain distance is formed between the base and the inertia mass block and the base and the inertia mass block are fixedly connected with the lower ends of the first cantilever beam fixed end and the second cantilever beam fixed end; a sensing optical grating is sealed on a non-linear homogeneous strain region of each cantilever beam and is connected with an external demodulating unit through an optical fiber outlet hole.

Description

【Technical field】 [0001] The invention belongs to the technical field of optical fiber sensors, in particular to a temperature-insensitive optical fiber grating acceleration sensor for measuring the vibration amplitude and frequency of objects. 【Background technique】 [0002] As a passive device, a fiber grating is a diffraction grating formed by axially modulating the refractive index of the fiber core through certain technical methods. The wavelength of the reflected or transmitted wave of the fiber grating is related to the refractive index modulation period of the grating and the refractive index of the fiber core, and the change of the external temperature or strain will affect the refractive index modulation period of the fiber grating and the refractive index of the fiber core, thus causing the fiber grating The change of reflection or transmission wavelength, the change of external physical quantity can be obtained by detecting the change of grating reflection center...

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Problems solved by technology

[0004] The application number is 201310092296.X, and the Chinese invention patent application titled "A Double Cantilever Beam Fiber Bragg Grating Acceleration Sensor" discloses that two bare gratings are connected in series and packaged on the outer surfaces of two equal-strength cantilever beams. When the measured object vibrates, it causes the vibration of the mass block in the sensor. Under the action of the inertial force of the mass block, the surfaces of the two cantilever beams connected to the mass block are stretched and compressed, so that the two cantilever beams pasted on it The sensing grating produces strain. Since the parameters of the two gratings are the same and the materials of the two cantilever beams are the same, the temperature coefficient is the same. At the same time, the center wavelength of the two gratings drifts in the opposite direction. It realizes acceleration sensitivity while compensating the temperature. However, this kind of fiber grating acceleration sensor has strict requirements on the central wavelength of the two gratings, and the packaging process will easily cause the central wavelength mismatch of the two gratings, resulting in sensor failure; and its structure is an equal-strength beam, and the stress concentration area is in the inertial mass Near the block, this part is easy to be damaged, these factors can easily cause the grating to chirp and cause the sensor to fail to work normally

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