CN102997848A

CN102997848A - Two-dimensional displacement sensor based on three-core single-mode fiber Bragg grating

Info

Publication number: CN102997848A
Application number: CN2012104046753A
Authority: CN
Inventors: 董新永; 綦菲
Original assignee: China Jiliang University
Current assignee: China Jiliang University
Priority date: 2012-10-18
Filing date: 2012-10-18
Publication date: 2013-03-27

Abstract

The invention relates to a two-dimensional displacement sensor based on a three-core single-mode fiber Bragg grating. Three cores of three-core single-mode fiber are distributed in the form of an equilateral triangle by centering on the center of the fiber. A fiber Bragg grating is written on each core at the sensing part of the fiber. The three fiber Bragg gratings are different in reflection wavelength. One end of the three-core single-mode fiber Bragg grating is fixed, and two-dimensional displacement, the same as that of the measured object, or in proportional increase or decrease, occurs to the other end of the three-core single-mode fiber Bragg grating. Bending of the three-core single-mode fiber is caused by the displacement change, the reflection wavelength of the three fiber Bragg gratings changes differently due to the bending in different directions. Two-dimensional displacement measurement can be achieved through wavelength measurement and a data processing module. The two-dimensional displacement sensor in full-fiber design has the advantages of small size, light weight, electromagnetic radiation resistance, and capability of operating in severe environments, such as high temperature and high pressure, and the like.

Description

Two-dimension displacement sensor based on three core single-mode fiber gratings

Technical field

The invention belongs to technical field of optical fiber sensing, be specifically related to a kind of two-dimension displacement sensor based on three core single-mode fiber gratings.

Background technology

Existing fiber grating displacement sensor needs complicated displacement-strain conversion equipment, such as the elastic bending beam, realizes being displaced to the conversion of fiber grating strain.For example grating is sticked on the surface of overhanging beam, it is crooked that displacement produces semi-girder by web member, thereby fiber grating is stretched or push, reflection wavelength produces corresponding variable quantity, obtain the corresponding relation of displacement and wavelength variations, so just can obtain change in displacement information by the variable quantity of optic fiber grating wavelength.But its shortcoming is obvious: at first, the wavelength variations that the measured position transfer becomes fiber grating need to apply larger power (as making the elastic beam bending), may the change in displacement of testee be exerted an influence; Secondly, realize the sensor that two-dimension displacement is measured needs two quadratures to place, be unfavorable for the miniaturization of sensor; In addition, because the variation of temperature also can make the wavelength of fiber grating change, so generally need subsidiary fiber-optical grating temperature sensor to do temperature compensation.

Summary of the invention

The present invention is directed to the deficiencies in the prior art, proposed a kind of two-dimension displacement sensor based on three core single-mode fiber gratings.Inscribe fiber grating at the optical fiber that comprises three fibre cores, obtain having three core fibre gratings of three different reflection wavelengths, three wavelength correspond respectively to three different cores (specifically can by on three different fibre cores of refractive index write cycle identical grating, perhaps on the fibre core of identical refractive index, write respectively the method for different cycles grating).Then an end of this three core fibres grating is fixed, two-dimension displacement identical or that amplify in proportion or reduce occurs with testee in the other end.Change in displacement is brought the bending of three core fibres, and the bending of different directions causes the strain difference that three fiber gratings bear, i.e. the variation of three reflection wavelengths is different.Therefore, the variation of three reflection wavelengths by monitoring this three core fibres grating can realize the measurement of two-dimension displacement.

The present invention includes light source, general single mode fiber, three core single-mode fiber gratings, wavelength measurement and data processing module.The wavelength of three gratings converts two-dimension displacement information to through wavelength measurement with through data processing module, thus the two-dimension displacement variable quantity of sensing measured object when realizing high-precision real.

The present invention adopts three core fibre gratings with different reflection wavelengths to carry out two-dimension displacement and measures, both solved in the past the drawbacks such as the fiber grating displacement measuring accuracy is not high, poor stability, two-dimensional measurement difficulty, simultaneously sensing head have volume little, lightweight, carry the advantage such as temperature compensation.

The present invention also has following subordinate technical characterictic:

1. described three core single-mode fibers and general single mode fiber are that 200610151033.1 method welding draws cone to merge by the patent No..

2. described shunt can be fiber coupler or circulator.

3. three of described three core single-mode fibers cores become equilateral triangle to distribute centered by the center of optical fiber.

4. described three core single-mode fibers are carved with respectively fiber grating on its each core for the position of sensing, and three fiber gratings have different reflection wavelengths (specifically can by on three different fibre cores of refractive index write cycle identical grating, perhaps on the fibre core of identical refractive index, write respectively the grating of different cycles)

Description of drawings

Fig. 1 is structural drawing of the present invention;

Fig. 2 is the present invention's three core single-mode fiber grating synoptic diagram;

Fig. 3 is the distribution plan of the present invention's three core single-mode fiber fibre cores

Embodiment

Below in conjunction with accompanying drawing the present invention is further described.

As shown in Figure 1, a kind of two-dimension displacement sensor based on three core single-mode fiber gratings comprises light source, general single mode fiber, three core single-mode fiber gratings, wavelength measurement and data processing module.The coupled zone is general single mode fiber and three core single-mode fiber gratings by the patent No. is the cone coupled zone that 200610151033.1 method welding draws cone to merge.On three each fibre core of core single-mode fiber a grating is arranged all, three fiber gratings have different reflection wavelengths.

Its working method: the light of wide spectrum light source is inputted three core single-mode fibers by general single mode fiber, and the light that optical grating reflection is returned also by general single mode fiber output, arrives the wavelength measurement module through shunt.Two-dimension displacement identical or that amplify in proportion or reduce occurs with testee in the three core fibre other ends, when testee is moved, bring the bending of three core fibres, the bending of different directions causes the strain difference that three fiber gratings bear, the i.e. variation of three reflection wavelengths is different, the wavelength of three gratings converts the two-dimension displacement information output to through wavelength measurement with through data processing module, by detecting the wavelength variable quantity of three core fibre gratings, and pass through wavelength---the relation of displacement records two-dimension displacement and the change information thereof of testee.Because three fibre cores of three core single-mode fibers become the center equilateral triangle to distribute, the environment temperature variation can cause that the variation of total wavelength of three fiber gratings increases or reduces, but this symmetrical so that the relative variation of optic fiber grating wavelength is constant, so this invention can realize temperature self-compensation.

Claims

1. fiber grating two-dimensional displacement transducer, its characteristic is: comprise light source, optical fiber, fiber grating, wavelength measurement and data processing module; Described optical fiber comprises three core single-mode fibers and is of coupled connections in the general single mode fiber of three core single-mode fibers that three described fiber gratings are scribed on the three core single-mode fibers; The light of wide spectrum light source is inputted described three core single-mode fibers by described general single mode fiber, and the light that three described fiber gratings reflect is exported by general single mode fiber, arrives described wavelength measurement module through shunt; One end of described three core single-mode fibers is fixed, two-dimension displacement identical or that change in proportion occurs with testee in the other end, change in displacement causes the bending of described three core single-mode fibers, the bending of different directions causes the strain difference that three described fiber gratings bear, thereby the variation of three reflection wavelengths is different, the variation of three reflection wavelengths by monitoring three described fiber gratings, convert two-dimension displacement information to through wavelength measurement and data processing module, two-dimension displacement is measured when realizing high-precision real.

2. fiber grating two-dimensional displacement transducer, it is characterized in that: the variation of described three core single-mode fiber free end travels has caused the bending of three described fiber gratings, thereby causes the variation of reflectance spectrum.

3. a kind of fiber grating displacement sensor according to claim 1, it is characterized in that: described three core fibres and ordinary optic fibre are single-mode fiber.

4. a kind of fiber grating displacement sensor according to claim 1 is characterized in that: three cores of described three core single-mode fibers become equilateral triangle to distribute centered by the center of optical fiber.

5. a kind of fiber grating displacement sensor according to claim 1, it is characterized in that: be carved with respectively a fiber grating on described three each core of core single-mode fiber, fiber grating writes by the phase mask method, obtain having three different reflection wavelengths three core fibre gratings (specifically can by on three different fibre cores of refractive index write cycle identical grating, perhaps on the fibre core of identical refractive index, write respectively the different cycles grating); Temperature is identical on the impact of three described fiber gratings, and therefore described fiber grating displacement sensor is to temperature-insensitive.

6. a kind of fiber grating displacement sensor according to claim 1 is characterized in that: the method for attachment of described three core single-mode fibers and general single mode fiber is to be that 200610151033.1 method welding draws cone to merge by the patent No..