CN201594019U

CN201594019U - Modified fiber grating sensing device

Info

Publication number: CN201594019U
Application number: CN2009202606044U
Authority: CN
Inventors: 赵德春
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-11-20
Filing date: 2009-11-20
Publication date: 2010-09-29
Anticipated expiration: 2019-11-20

Abstract

The utility model discloses an insulating fiber grating sensing device with excellent high and low temperature resistance, which is capable of simultaneously measuring axial strain and working environment temperature of a high-voltage cable. The sensing device is formed by a double-grating optical fiber containing two gratings with different wavelengths, and a sensing assembly, wherein the sensing assembly includes an outer circular encapsulation pipe and a fixing anchor, the outer circular encapsulation pipe is a long circular pipe of polyimide material, and a threaded hole for fixing a capillary tube is respectively arranged at two ends of the outer circular encapsulation pipe. The sensing device of the technical scheme is capable of simultaneously measuring the working environment temperature and the axial strain of the high-voltage cable, and working normally under environment of -40 DEG C to 250 DEG C due to the fact that the device is made by encapsulating special insulation material.

Description

A kind of improved fiber bragg grating sensing device

Technical field

The utility model belongs to a kind of testing tool, especially a kind of fiber bragg grating sensing device.

Background technology

Fiber grating is the light sensitive characteristic that utilizes the fiber core layer material, adopt the method for mask exposure to make the refractive index of the fiber core of a segment length that permanent change take place by UV excimer laser, the change of refractive index is periodic distribution, form Bragg-grating structure, when the broadband incident light passes through fiber grating, satisfy the wavelength of Bragg condition and returned by optical grating reflection, the light of its commplementary wave length is by transmission, the change of reflecting light personal attendant grating pitch and changing.Because grating pitch is very responsive to environment temperature and strain, therefore, can calculate the change amount of environment temperature and strain by the detection of reflected wavelength change.

Because naked fiber grating diameter has only 125 microns, damage easily has only the encapsulation (as imbedding in the backing material) that it is carried out protectiveness in abominable engineering-environment, just can make fiber grating have more stable and more reliable sensing function.By the structure of design encapsulation, select different encapsulating materials for use, can make fiber grating realize more function.At present, the fiber-optic grating sensor physical quantity that can detect comprises temperature, strain, stress, displacement, pressure, torsional angle, torsion (twisting stress), acceleration, electric current, voltage, magnetic field, frequency and concentration etc.

Fiber grating is when being subjected to stress and Temperature Influence, and the centre wavelength of grating can change.For bare optical fibers and bare optical gratings, the about 0.0017nm of center wavelength variation that the microstrain meeting causes grating; The temperature variation of every degree can cause the center wavelength variation 0.0098nm of grating.Be not difficult to find out that in the center wavelength variation process of strain and temperature cross influence grating, Temperature Influence will be much larger than the influence of strain.In actual applications, one of serial or parallel connection is used to eliminate influence of temperature variation with reference to grating near the stress sensing grating of being everlasting.But owing to can not be in the different of same position and sensor construction fully with the stress sensing grating, can not accurately and timely reflect the temperature effect that the stress sensing grating is suffered, cause influencing the accuracy of strain measurement with reference to grating with reference to grating.

Fiber-optic grating sensor all need be demarcated according to design objective after encapsulation is finished, thereby determines the corresponding relation between sensor input quantity and the output quantity.

The topmost defective of prior art is: 1) serviceability temperature can't be measured 250 ℃ high temperature in-40 ℃ to 150 ℃ the scope.2) adopt the metal material encapsulation, bring great risk for the measurement of high-tension cable.3) can only independent measurement temperature or strain, can not be with a sensor measurement temperature and strain.

The utility model content

At the problems referred to above, the utility model aims to provide a kind of insulation and utmost point high-low temperature resistant, can measure the axial strain of high-tension cable and the fiber bragg grating sensing device of operating ambient temperature simultaneously.

For realizing this technical purpose, scheme of the present utility model is: a kind of improved fiber bragg grating sensing device, form by grating fibers and sensory package, described grating fibers comprises the double grating of two different wave length gratings, be respectively small wavelength grating and big wave length grating, the size of the centre wavelength of described two gratings differs and is at least 6nm; Described small wavelength grating section enclosed package temperature influence in first kapillary, the outside of described big wave length grating section is fixed in second kapillary; Described sensory package comprises outer package pipe and mooring anchor, and wherein, the outer package pipe is the oval pipe of polyimide material, and two ends respectively are provided with and are used for fixing threaded hole capillaceous; Mooring anchor is half " worker " font, the polyimide material, and the two ends that are fixed on the outer package pipe are as the tie point between Fibre Optical Sensor and the testee.

As a kind of improvement, the two ends of described first kapillary and small wavelength grating section are airtight fixing with 353ND glue; Described second kapillary is fixed with 353ND glue with big wave length grating section outer fibers.

As a kind of improvement, described first, second kapillary is the caliber of 3mm.

As further improving,, be separately installed with the water joint of the high low temperature of ability at the end of mooring anchor.

The sensing device of this programme is measured the axial strain of high-tension cable and the temperature of working environment simultaneously.This sensor is High-voltage Cable Design specially, uses the encapsulation of special insulating material to form, can be under-40 ℃ to 250 ℃ environment operate as normal, realize that single-sensor measures the axial strain of high-tension cable and the temperature of working environment simultaneously.

Description of drawings

Fig. 1 is a double grating kapillary encapsulation synoptic diagram of the present utility model.

Fig. 2 is the cross section view of outer package pipe of the present utility model.

Fig. 3 is the main skeleton view of mooring anchor of the present utility model.

Fig. 4 is the skeleton view of facing upward of mooring anchor of the present utility model.

Embodiment

Below in conjunction with accompanying drawing, the utility model is described in further detail according to specific embodiment.

The used fiber grating of the utility model is a double grating, just makes the grating of two different wave lengths on same optical fiber continuously.For the production technique of grating, can on same optical fiber, make more than 20 grating continuously at present.Among Fig. 1, the centre wavelength of the grating of 1 section part is small wavelength, and the centre wavelength of the grating of 2 sections parts is big wavelength, and the size of both centre wavelength differs and be at least 6nm, in order to avoid both center wavelength variation and cause wavelength overlapping.For two gratings among Fig. 1, use two capillary tubings to encapsulate, among the figure, small wavelength grating section is encapsulated in first kapillary 1, and two ends fix optical fiber and kapillary with 353ND glue, make grating only be subjected to Temperature Influence and are not subjected to the influence of external force; The outside in big wave length grating section penetrates optical fiber in second kapillary 2, with 353ND glue optical fiber and kapillary is fixed.Two diameters capillaceous all are 3mm.

As shown in Figure 2, in this specific embodiment, the outer package pipe is the polyimide pipe, and its two ends are respectively with one screw hole.Packaged grating among Fig. 1 is put into the pipe of Fig. 2, make first kapillary and second kapillary expose each several millimeter of pipe two ends respectively.By the screw hole of pipe one end, a kapillary is fixed earlier; Apply certain pulling force then and give the another one kapillary, when keeping pulling force, second kapillary fixed by the screw hole of the other end of pipe.

The mooring anchor of half " worker " font shown in Fig. 3,4 is respectively installed at the two ends of outer package pipe, as the tie point between Fibre Optical Sensor and the testee.The material of mooring anchor is a polyimide.By the mooring anchor at stretching or compression sensor two ends, big wavelengths centered wavelength can change in the double grating; The temperature of working sensor environment changes, and the centre wavelength of medium and small wave length grating of double grating and big wave length grating all can change.

At last, respectively add the anti-head of the high low temperature of ability (40 ℃-300 ℃), make sensor have the excellent waterproof characteristic on the both sides of the mooring anchor of sensor.

The above; it only is preferred embodiment of the present utility model; not in order to restriction the utility model, every foundation technical spirit of the present utility model to any trickle modification that above embodiment did, be equal to and replace and improve, all should be included within the protection domain of technical solutions of the utility model.

Claims

1. improved fiber bragg grating sensing device, form by grating fibers and sensory package, it is characterized in that: described grating fibers comprises the double grating of two different wave length gratings, is respectively small wavelength grating and big wave length grating, and the size of the centre wavelength of described two gratings differs and is at least 6nm; Described small wavelength grating section enclosed package temperature influence in first kapillary (1), the outside of described big wave length grating section is fixed in second kapillary (2); Described sensory package comprises outer package pipe and mooring anchor, and wherein, the outer package pipe is the oval pipe of polyimide material, and two ends respectively are provided with and are used for fixing threaded hole capillaceous; Mooring anchor is half " worker " font, the polyimide material, and the two ends that are fixed on the outer package pipe are as the tie point between Fibre Optical Sensor and the testee.

2. fiber bragg grating sensing device according to claim 1 is characterized in that: the two ends of described first kapillary and small wavelength grating section are airtight fixing with 353ND glue; Described second kapillary is fixed with 353ND glue with big wave length grating section outer fibers.

3. fiber bragg grating sensing device according to claim 2 is characterized in that: described first, second kapillary is the caliber of 3mm.

4. according to each described fiber bragg grating sensing device in the claim 1 to 3, it is characterized in that:, be separately installed with the water joint of the high low temperature of ability at the end of mooring anchor.