A kind of high strength temperature sensing optic cable
Technical field
The present invention relates to a kind of high strength temperature sensing optic cable, belong to technical field of optical fiber sensing.
Background technology
At present, temperature sensor is widely used in equipment and the facility such as Aero-Space, energy source base station, oil and gas pipes, dykes and dams, road and bridge, cable, for construction quality monitoring, Long Period Health Monitoring and fire alarm etc.
Electronic temperature transmitter shows in actual applications and is subject to the shortcomings such as the little and signal transmission distance of electromagnetic interference (EMI), poor stability, measurement range is short, and especially when Multi-point detection, a large amount of signal transmission lines causes very big inconvenience to site operation.And the advantage such as temperature sensing optic cable has that monitoring sensitivity is high, volume is little, lightweight, safety anti-explosive.
Temperature sensing optic cable, although as some limitation breaching traditional electrical type temperature sensor based on the temperature sensing optic cable of intensity modulated, but itself still has following defect, such as comparatively large, location difficulty affected by environment and measurement result poor repeatability etc.From structure opinion, existing fiber grating class temperature sensing optic cable needs welding optic fibre grating, namely individually prepares grating in optical fiber stationary state, then adopts optical fiber splicer by the welding one by one of multiple grating, also needs corresponding making more piece sheath when making optical cable.It is low just to there is grating preparation efficiency in this, and the fusion point on optical fiber is many, loss large, and grating series quantity is restricted and the shortcomings such as final grating array bad mechanical property, can not meet the requirement of practical application to optical fiber grating sensing optical cable completely.
In addition, grating for stress and temperature all very sensitive, the impact that must weaken or eliminate stress in actual applications.And in stranding and optical cable the procedures of establishment, optical fiber cable often can be subject to stretching, bends, trample, if process bad, temperature survey can be caused inaccurate, even make sensing optic cable lose efficacy.
In sum, what need to solve for the fiber grating optical cable of sensing is the problems such as grating preparation efficiency in grating array is low, grating quantity is few, fiber strength is low, loss is large, the easy affected by force of optical cable poor reliability, grating, cable configuration complexity.
Summary of the invention
Technical matters to be solved by this invention is that the deficiency existed for above-mentioned prior art provides a kind of vibrational power flow reasonable, and intensity is high, loss is little, measures with transmission range long, and sensing capabilities is reliable, is easy to the high strength temperature sensing optic cable made.
The technical scheme that the problem that the present invention is the above-mentioned proposition of solution adopts is: include oversheath and sensor fibre, sensor fibre is laid in oversheath, when it is characterized in that described sensor fibre is wire drawing, direct-on-line is carved into the complete same grating array optical fiber of grating, metal armor layers is provided with in oversheath, described sensor fibre is lax to be laid in metal armor layers, and described oversheath is the monolithic devices oversheath of an extrusion moulding.
By such scheme, described sensor fibre is the complete same grating array optical fiber of a continuous print weldless point.
By such scheme, the static tensile strength of described sensor fibre is more than or equal to 55N, and the entirety of optical fiber is through the dynamic screening of 100kpsi tension force.
By such scheme, the quantity described sensor fibre being inscribed continuously grating is 5 ~ 10000, and the spacing between two adjacent gratings is 0.5m ~ 20m.
By such scheme, the grating on described sensor fibre is weak reflection Bragg grating, and reflectivity is 1% ~ 0.0001%.
By such scheme, described sensor fibre is made up of the bare fibre surface coated with resins coat or carbon coat or washing layer being carved into grating.
By such scheme, described sensor fibre outer cladding tight sleeve layer or loose jacket layer, form tight cover sensor fibre and pine cover sensor fibre respectively.
By such scheme, between oversheath and metal armor layers, be provided with non-metal reinforced layer.
By such scheme, described oversheath radial section is circular or butterfly.
By such scheme, circumferentially interval or both sides are provided with reinforcement in described oversheath.
Optical fiber optical grating array sensing optic cable provided by the invention is a kind of Fiber Bragg Grating quasi-distributed sensor, and Bragg grating wherein can be equidistant arrangement, also can be non-equally arrange.Use the exposure of monopulse UV laser beam, adopt phase mask plate method to inscribe grating, prepare weak reflection Bragg grating, to bare fibre continuous exposure, prepare complete in low light level grid array.Inscribing mounting for grating is that excimer laser is in conjunction with phase mask plate, be arranged on below fiber drawing tower filament mouth, the monopulse UV laser beam that excimer laser exports is through diaphragm shaping, through lens focus, be irradiated on mask plate, thus write grating on the intimate bare fibre being close to mask plate.Inscribe in grating process and be subject to conputer controlled, the spacing between adjacent gratings and laser intensity all can be arranged on request, and package unit automatically inscribes grating continuously at the uniform velocity drop-down bare fibre.After inscribing grating, optical fiber is applied.
Grating array wavelength-division multiplex technique is due to the characteristic of wavelength-modulated, and each Fiber Bragg Grating can take certain bandwidth, does not allow overlap each other simultaneously.Therefore, the wavelength-division multiplex technique of fiber grating is subject to the restriction of light source bandwidth and grating wavelength fabric width, and on an optical fiber, multiplexing 30 gratings substantially reach capacity.Optical fiber optical grating array sensing optic cable provided by the invention raster count wherein has 5 at least, can as many as 10000 or more, determines as required.But the quantity that on an optical fiber, grating is multiplexing more than 30 time, be difficult to carry out signal receiving with wavelength-division multiplex technique separately.
Fiber-optic grating sensor using method of the present invention is: the method adopting wavelength-division multiplex technique and time-division multiplex technology compound use, this be a kind of based on sensing impulse signal in time with the distributed fiber grating sensing signal demodulation technology of wavelength binary variation relation, the narrow-band ping that light source exports is coupled into grating array, this narrow-band ping repeats with fixed frequency, and the change of the wavelength period continuous tuning of signal, incide with the grating of pulse consistent wavelength on time, pulse signal part is got back to (FBG) demodulator by optical grating reflection, remainder continues onwards transmission, if incident pulse wavelength and raster center wavelength inconsistent, the direct transmissive of pulse signal is until run into the consistent grating of centre wavelength, according to pulse signal time of return, optical grating reflection signal wavelength and reflective light intensity, analytical calculation goes out the locus of grating and the size of parameter sensing value.
The invention has the beneficial effects as follows: weldless point on the complete same grating array optical fiber of 1, living broadcast, intensity is high, and loss is little, and the consistance of grating is good, and prepared optical fiber optical grating array can a direct stranding; 2, sensing optic cable vibrational power flow advantages of simple of the present invention, the mechanical property of resistance to compression tension is strong, and when optical cable is subject to tension force, optical fiber can be in relaxed state always, ensures that wherein grating does not stress, can stablize and accurately measure; And environment resistant interference performance is strong, easy construction, and use cost is low; 3, adopt based on time-division/wavelength-division hybrid multiplex signal receiving technology carries out sensing, breaches the limitation of existing sensing optic cable, fast accurately, measurement result is reproducible in location, is easy to carry out growing distance multiple spot distribution measuring, can be multiplexed and form sensing network.
Accompanying drawing explanation
Fig. 1 is the radial section structural drawing of first embodiment of the invention.
Fig. 2 is the radial section structural drawing of second embodiment of the invention.
Fig. 3 is the radial section structural drawing of third embodiment of the invention.
Fig. 4 is the radial section structural drawing of four embodiment of the invention.
Fig. 5 is the radial section structural drawing of fifth embodiment of the invention.
Fig. 6 be in one embodiment of the invention one group entirely with low light level grid array demodulation collection of illustrative plates.
Fig. 7 is the spectrum shape figure of the grating of continuous 6 positions in one embodiment of the invention.
Fig. 8, Fig. 9 are respectively the centre wavelength curve over time of two gratings at diverse location place on grating array in one embodiment of the invention.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described in further detail.
First embodiment of the invention as shown in Figure 1, is a kind of round fiber grating array temperature sensing optic cable, includes the oversheath 3 of round section, be provided with metal armouring 2 in oversheath, relaxes and lay sensor fibre 1 in metal armor layers; Wherein, described oversheath can be made up of pvc sheathing compound, flame-retardant sheath material or resistance to electric track resistant jacket material; Described metal armor layers can be made up of aluminium-plastic tape, composite steel-plastic belt, spiral steel armour, steel strand wires or stainless-steel tube, and the aperture of metal armor layers is 0.8 ~ 6mm; When described sensor fibre is wire drawing, direct-on-line is carved into the complete same grating array optical fiber of grating, the quantity inscribing grating is 5 ~ 10000, spacing between two adjacent gratings is 0.5m ~ 20m, can be equidistant or Unequal distance, grating on described sensor fibre is weak reflection Bragg grating, and reflectivity is 1% ~ 0.0001%.Described sensor fibre is made up of the bare fibre surface coated with resins coat being carved into grating, and coat is 1 ~ 2 layer.Described oversheath is the monolithic devices oversheath of an extrusion moulding.Optic cable diameter 2mm in the present embodiment, spiral steel armour diameter 1mm, cable length 1964m, the spacing between grating is wherein 2m.
As shown in Figure 2, be that both sides are provided with reinforcement 4 in oversheath with the difference of first embodiment, described reinforcement is steel wire to second embodiment.Other structures are identical with first embodiment.
As shown in Figure 3, and the difference of first embodiment is that circumferentially 90 °, interval arranges 1 reinforcements 4 in oversheath to 3rd embodiment, and described reinforcement is steel wire.Other structures are identical with first embodiment.
As shown in Figure 4, and the difference of first embodiment is between oversheath and metal armor layers, be provided with non-metal reinforced layer 5 4th embodiment, and non-metal reinforced layer is aramid yarn.Other structures are identical with first embodiment.
5th embodiment as shown in Figure 5, for a kind of butterfly optical fiber optical grating array temperature sensing optic cable, include the oversheath 3 in butterfly cross section, in oversheath, be provided with metal armor layers 2, metal armor layers is spiral steel armour, relaxes and lay sensor fibre 1 in metal armor layers; In oversheath, both sides are provided with reinforcement 4, and described reinforcement is steel wire.The present embodiment cable cross-section 4.5mm × 6.6mm, spiral steel armour diameter 3mm, cable length 1099m, the spacing wherein between grating is 20m.
The scribing process of optical fiber optical grating array of the present invention is:
First, photosensitive prefabricated rods is sent into fiber drawing furnace to reel off raw silk from cocoons.Start to inscribe grating online after the string diameter of optical fiber is stable.Inscribe mounting for grating be excimer laser in conjunction with phase mask plate, the monopulse UV laser beam that excimer laser exports, through diaphragm shaping, through lens focus, is irradiated on mask plate, thus writes grating being close on the bare fibre being close to mask plate.Inscribe in grating process and be subject to conputer controlled, the spacing between adjacent gratings and laser intensity all can be arranged on request, and package unit automatically inscribes grating continuously at the uniform velocity drop-down bare fibre.After inscribing grating, surface application is carried out to optical fiber.
Optical fiber optical grating array sensing optic cable cabling process (for embodiment 3) of the present invention is as follows:
In cabling process, optical fiber is all released in small tension receiving coil active unwrapping wire mode, first vertical bag reinforcement around optical fiber, diameter is 2 ~ 5mm preferably, then releases steel wire, places by reinforcement position in embodiment 3, extrude Polyvinylchloride through extrusion head and form sheath, then by selecting suitable traction wheel speed, make sheath stressed stretching in cold rinse bank, now vertical bag reinforcement stretches together, and wherein optical fiber is in loose tube structure and does not affect by traction wheel, gathers more long optical fibers in sheath.Then wait sheath by traction wheel, vertical bag reinforcement and sheath elasticity are recovered, contraction in length, thus make the optical fiber in loose tube structure obtain required plus-efl value, finally upper dish, and stranding terminates.
The optical parametrics such as the reflectivity of the low light level grid of sensor fibre of the present invention, centre wavelength and bandwidth are identical, are called complete in low light level grid.LG1-100B type (FBG) demodulator is used to detect, demodulation can be carried out to prepared complete same low light level grid array, the data of demodulation save as FBG and RAW file, certain grating (locate grating by distance, namely demarcate with the distance of certain grating to (FBG) demodulator) can be observed at centre wavelength sometime and grating spectral type curve thereof by the analysis software of correspondence.Figure 6 shows that one group entirely with the demodulation collection of illustrative plates of low light level grid array, this is 2m with the spacing between the grating among low light level grid array entirely, the total length 1965m of grating array.According to the centre wavelength of the grating on diverse location on the known grating array sometime of Fig. 6, namely sometime the centre wavelength of grating array with the change of distance.Figure 7 shows that the spectrum shape figure of the grating of continuous 6 positions.Fig. 8,9 is depicted as under a certain temperature system, and the centre wavelength of two gratings of 20.89m and the 50.25m position on grating array over time.Wherein the grating of 20.89m position belongs to temperature experiment group, sees Fig. 8; The grating of 50.25m position belongs to temperature experiment contrast groups, sees Fig. 9.From Fig. 8,9, can determine that the position of grating also can measure the change of the center wavelength with temperature of grating on this position by (FBG) demodulator.
By Fig. 6 to Fig. 9 known used in combination time-division/the LG1-100B type (FBG) demodulator of wavelength-division technology can realize to complete same low light level grid array demodulation, can gather, preserve and show entirely with the overall center wavelength profile situation at all gratings sometime of low light level grid array, can find out that in grating array, each grating is successfully written to, there is no water clock, between grating, the interval error of 2m is very little, the reflection strength of grating is basically identical, the reflection strength fluctuation of the grating on grating array is very little, the symmetry of grating is better, extinction ratio is larger, the consistance of grating spectrum shape is better.Can accomplish that the accurate addressing of grating is located by the known (FBG) demodulator of Fig. 6 to Fig. 9, and the centre wavelength of real time record and each grating of preservation situation over time, under normal temperature state, raster center wavelength is substantially constant, and the grating on intensification experimental result display light grid array can accomplish temperature sensing well.
The complete static tensile strength with grating array optical fiber of the present invention is more than or equal to 55N, and the entirety that length reaches the optical fiber of 5000m can remain intact after the dynamic screening of 100kpsi tension force, concrete embodiment is be drawn on unwrapping wire driving wheel and take-up driving wheel by the optical fiber containing grating array through propelling sheave, driving wheel pressure zone prevents optical fiber from skidding on wheel but not having extra-stress not damage fibre coating to optical fiber, the tension force seat being configured with belt sensor between two driving wheels applies the fixed weight corresponding to fiber dimensions, thus tension force is passed to optical fiber realize the tension force of optical fiber is checked.In practical operation, linearly stress being added on optical fiber gradually, after stable, optical fiber integrally being screened, being verified again from dropping to zero stress i.e. pine at full capacity linearly around state.And the grating of existing more than the 2m with fusion point cannot bear the entirety screening of equality strength.Easy understand, because fused fiber splice causes intensity impaired, the probability that fracture occurs is high, especially longer, and such as on the optical fiber of 100m length, even if only have 10 fusion points, as long as there is a fracture, so whole sensing optic cable all can lose efficacy.Can not compare so the high strength of the fiber grating of this entirety of the present invention is all gratings with fusion point.The present invention has increased substantially the reliability of stranding by the overall high strength optical fiber grating loading tension force screening, significant to the life-span extending sensing optic cable.