Quasi-distributed fiber sensor capable of measuring temperature and vibration simultaneously and manufacturing method

Abstract

Provided is a quasi-distributed fiber sensor capable of measuring the temperature and vibration simultaneously. The fiber sensor comprises common single mode fibers and a protective casing. The inner wall of the protective casing is welded with the outer walls of the common single mode fibers. The common single mode fiber between a first welding position and a second welding position forms a temperature correction section, and a first Bragg grating is arranged on the temperature correction section. The common single mode fiber between the second welding position and a third welding position forms a vibration measurement section, a vibration amplification block is arranged in the middle of the vibration measurement section, and the two sides of the vibration measurement section are provided with two vibrating beams respectively; a second Bragg grating is arranged on the vibrating beam between the vibration amplification block and the temperature correction section; the first Bragg grating differs from the second Bragg grating in central wavelength. The quasi-distributed fiber sensor has the technical advantages that the size of a device is greatly shortened, adaptability of the sensor for installation positions is improved, influences on measuring results caused by the thermal expansion effect of the sensor are avoided, the structure is simple, and the application range is wide.

Description

technical field [0001] The invention relates to an optical fiber sensing technology, in particular to a quasi-distributed optical fiber sensor capable of simultaneously measuring temperature and vibration and a manufacturing method thereof. Background technique [0002] It is an important means to detect the quality of cable-stayed bridges by measuring the vibration and temperature information of cable-stayed bridges to realize the detection of bridge health. Compared with traditional electrical vibration and temperature sensors, fiber optic sensors based on fiber Bragg gratings (FBG) have the advantages of high precision, small size, anti-electromagnetic interference, large capacity, and reusability. Therefore, fiber optic sensors based on fiber Bragg gratings It has broad prospects in practical applications. In the prior art, there are relatively few optical fiber sensors that can measure vibration and temperature at the same time, and when measuring vibration, th...

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Problems solved by technology

In the prior art, there are relatively few optical fiber sensors that can measure vibration and temperature at the same time, and when measuring vibration, the existing optical fiber sensors need to rely on an external deformation transmission device to excite the central wavelength shift of the fiber Bragg grating. The introduction of the device has two disadvantages: one is that it leads to an increase in the size of the sensor. The diameter of the measuring fiber is generally 125 μm, and the thickness of the coating layer is only about 250 μm, and the volume of the additional deformation transmission device is generally The unit of centimeters leads to a sudden increase in the size of the device at the position of the deformation transmission device, which makes it difficult for the sensor to be placed in some structures with narrow gaps, such as between the cables of a cable-stayed bridge, which greatly limits the application of the sensor The second is that the thermal expansion and contraction effect of the deformation transmission device itself will cause errors in the measurement of the fiber Bragg grating. The sensitivity of the fiber Bragg grating to temperature is very high, and the general sensitivity is 10pm / ℃. The transmission device is in contact with each other, so the deformation of the deformation transmission device itself under the effect of thermal expansion and contraction will also cause the period of the fiber Bragg grating to change, which in turn will cause the wavelength of the fiber Bragg grating to change, which will affect the measurement results of the fiber Bragg grating. great influence

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