Inclined optical fiber grating ultrasonic sensor
A technology of tilting fiber grating and tilting grating is applied in the field of sensors, which can solve the problems of weak sensitivity, large influence of capacitance, and low detection accuracy, and achieve the effects of no electromagnetic interference, good wide frequency response, and high detection accuracy.
Inactive Publication Date: 2017-01-11
NORTHWEST UNIV(CN)
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Problems solved by technology
The main disadvantages of this device are: it is only sensitive to ultrasonic signals of a specific narrow frequency band, and the sensitivity will become weaker as the volume of the transducer decreases and is greatly affected by capacitance; it is extremely susceptible to interference from environmental electromagnetic fields; The signal will widen as the distance between the transmitting source and the receiver increases (causing signal distortion); the reusability is poor, and the multi-channel real-time monitoring system is complicated; there is no direction recognition, and the ultrasonic direction information cannot be obtained
[0005] The patent number is 201510728121.2, and the name of the invention is "Indirectly Coupled Tapered Fiber Bragg Grating Ultrasonic Sensor". There is a cover on the upper end of the housing, and a center hole is processed in the center of the cover. The lower end of the housing is provided with an acoustic coupling cone. The central position is processed with a central hole, and the optical fiber with gratings is processed from the central position of the acoustic coupling cone to penetrate through the central hole, and passes through the central hole of the cover. This ultrasonic sensor has good response characteristics and stability, etc. Advantages, the main disadvantages are: the sensitivity of the sensor is low, there are many clutter in the detected ultrasonic signal, the detected ultrasonic signal has low energy, and the detection accuracy is low
Method used
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Embodiment 1
[0019] exist figure 1 Among them, the tilted fiber grating ultrasonic sensor of this embodiment is composed of a fiber mounting ring 1, a fiber fixing tube 2, an optical fiber 3, a tilted grating 4, a protective cover 5, an ultrasonic focusing cone 6, and a filter layer 7.
[0020] The shape of the optical fiber installation ring 1 is an annular body. Two optical fiber fixing tubes 2 are radially welded and connected in the central plane of the side wall height of the optical fiber installation ring 1. The center lines of the two optical fiber fixing tubes 2 are on a straight line, and the optical fiber is fixed. Tube 2 is used to pass through the optical fiber. Slanted grating 4 is written on the optical fiber 3, the wavelength of the inclined grating 4 is 1546nm, and the length of the grid area is 6mm. One end of the optical fiber 3 passes through the optical fiber installation ring 1 from an optical fiber fixing tube 2, and the other end is fixed from another optical fiber....
Embodiment 2
[0023] In this embodiment, an oblique grating 4 is written on the optical fiber 3. The wavelength of the oblique grating 4 is 1520 nm, and the length of the grid area is 2 mm.
Embodiment 3
[0025] In this embodiment, an oblique grating 4 is written on the optical fiber 3, the wavelength of the oblique grating 4 is 1580 nm, and the length of the grid area is 10 mm. The other parts and their connections are the same as those in Embodiment 1.
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The invention discloses an inclined optical fiber grating ultrasonic sensor. Two optical fiber fixing tubes are radially disposed on a side wall of an optical fiber installation ring, and an included angle between the central lines of the optical fixing tubes is 180degrees. One end of an optical fiber provided with an inclined grating is extended out of the optical fiber installation ring through one optical fiber fixing tube, and the other end of the optical fiber provided with the inclined grating is extended out of the optical fiber installation ring through the other optical fiber fixing tube. The upper end of the optical fiber installation ring is provided with a protection cover, and the lower end of the optical fiber installation ring is provided with an ultrasonic focusing cone, the cone tip of which is connected with the inclined grating in an overlapped manner. The geometric shape of the protection cover is in the shape of a hemispheroid, and the upper end surface and the upper end of the optical installation ring 1 are in the same plane, and the lower end is disposed in the optical fiber installation ring 1. The lower end surface of the ultrasonic focusing cone is a spherical segment recessed surface. The inclined optical fiber grating ultrasonic sensor can be used as a sensor for monitoring earthquakes, and has advantages of high sensitivity, high detection precision, good wide frequency response, wide dynamic range, and ability of preventing electromagnetic interferences.
Description
technical field [0001] The invention belongs to the technical field of sensors, and in particular relates to a fiber grating ultrasonic sensor. Background technique [0002] The seismic physical model is a simulated structure reduced in proportion to the geological structure of the reservoir. It can be used as a tool for seismic wave transmission and theoretical prediction. Its biggest advantage is the authenticity of the simulated results, which are not limited by calculation methods and assumptions. Measure the response of sound waves under nearly ideal rock model conditions. Compared with the earthquake site, the earthquake model built in the laboratory has the advantages of low cost, good repeatability, intuitive demonstration and controllability. [0003] The ultrasonic sensor is the core device for obtaining the internal information of the earthquake physical model. The optical fiber perceives the intensity, frequency, direction and other information of the ultrasoni...
Claims
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IPC IPC(8): G01H9/00
CPCG01H9/004
Inventor 冯忠耀周瑞祥郝永鑫荣强周
Owner NORTHWEST UNIV(CN)