CN107607219A - A kind of distributed temperature measuring system based on optical fiber radiation induced attenuation temperature sensitivity - Google Patents
A kind of distributed temperature measuring system based on optical fiber radiation induced attenuation temperature sensitivity Download PDFInfo
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Abstract
The invention discloses a kind of distributed temperature measuring system based on optical fiber radiation induced attenuation temperature sensitivity, belong to technical field of temperature measurement.The present invention includes laser, impulse generator, coupler, sensor fibre, photodetector, amplifying circuit, microprocessor and computer.Impulse generator sends burst pulse driving laser and produces pulse, tested sensor fibre is incided after directional coupler, rear orientation light and Fresnel reflection optical signal in optical fiber are converted into electric signal, exported by coupler to photodetector, the scattering light and reflected light signal that receive are converted into electric signal by photodetector, microprocessor is sent into after being amplified by amplifier and carries out signal transacting, as a result transmit to computer and carry out realtime curve, while microprocessor is also by Time -based Control pulse pulse generator.The present invention is more simple, and easy to detect, cost is low, and practicality is stronger, ensures gain balance, precision is higher, has broad application prospects.
Description
Technical field
The present invention relates to a kind of distributed temperature measuring system based on optical fiber radiation induced attenuation temperature sensitivity, belong to temperature
Field of measuring technique.
Background technology
Temperature detection occupies highly important status in modern industry system and engineer applied, with thermocouple, platinum alloy
With semiconductor for representative conventional temperature sensor with principle is simple, cost is low, precision is high the advantages of just obtained many years ago
It is widely applied, irreplaceable effect is played in many occasions.But there is electromagnetic interference or inflammable easily fried some severe
Under environment, the conventional temperature sensor based on electric signal measurement is very restricted, or even can not be worked.
In recent years, fibre optical sensor with its it is unique the advantages of --- anticorrosion, immune electromagnetic interference, high sensitivity, volume
Small, flexible structure, it is easily achieved remote remote sensing and distributed sensing etc. and has obtained the extensive concern of people.Particularly optical fiber passes
Sensor may make up sensing network, realize distributed measurement, be more applicable for large-range measuring field, in building, power system, oil
Many application scenarios such as exploratory shaft sinking survey play very important effect.At present, the optical time domain and frequency domain based on optical fiber back scattering are anti-
Penetrate the distributed measurement technology of technology and the fiber grating distributed measurement technology based on Optical multiplexing technology is all applied to thermometric
Field, wherein the wavelength-division multiplex technique (WDM) based on Fiber Bragg Grating FBG (FBG), based on optical fiber Brillouin optical time domain/frequency domain
Analytical technology (BOTDA/BOFDA), based on fiber Raman (Raman) optical time domain reflection technology (ROTDR) distributed optical fiber temperature
Sensor-based system is spent in the health monitorings such as bridge dam, power system temperature survey, tunnel fire hazard early warning and oil exploitation well
Remarkable effect is played in the fields such as lower temperature monitoring.
Distributed temperature sensing system based on FBG is to make multiple gratings on an optical fiber, passes through fibre characteristic ripple
The quasi-distributed measurement of temperature is realized in the drift of personal attendant's temperature, realizes that distributed sensing positions using Optical multiplexing technology.The party
Method measurement sensitivity is high, but sensing element -- the complex manufacturing technology of fiber grating；Demodulating system is caused to be answered using wavelength modulation
It is miscellaneous, and cost is higher.In addition, FBG is often simultaneously sensitive to stress and temperature, the reliability of system is greatly reduced, it is necessary to spy
Different separation compensation technique.
When light (electromagnetism) ripple injects medium, if some inhomogeneities in medium be present, (such as electric field, phase, population are close
Degree n, velocity of sound v etc.) propagation of light (electromagnetism) ripple is changed, some energy deviate the predetermined direction of propagation and to space
In other any direction disperses come, here it is light scattering.Wherein back scattering includes Rayleigh (Rayleigh) scattering, Raman
(Raman) scattering and Brillouin (Brillouin) scatter three types.Rayleigh scattering is identical with incident light frequency, but its energy
It is maximum；Certain frequency displacement, Brillouin shift and stress suffered by optical fiber occur compared with incident light for Brillouin scattering and Raman diffused light
Relevant with change, Raman diffused light is relevant with temperature change suffered by optical fiber.
Distributed temperature measuring system based on Rayleigh scattering, typically realized using optical time domain reflection (OTDR) structure to space
The measurement of the temperature of distribution, this method need not carry out the frequency displacement processing of complexity, and system architecture is relatively easy, and low with realizing
The potentiality of cost, but the temperature sensitive property extreme difference of Rayleigh scattering in solid fiber, therefore to realize this TEMP side
Case, the special fiber with temperature sensitizing ability can only be used, existing program can not be applied to reality, and market is in blank.
Distributed Optical Fiber Sensing Techniques (ROTDR) based on optical time domain Raman scattering has just been suggested the eighties in last century,
And commercialization, it is a kind of main flow distributed temperature measuring technology.General very weak yet with spontaneous Raman scattering light, anti-Stokes dissipates
It is weaker 20-30dB than Rayleigh scattering light intensity to penetrate light, so high input power must be used, and need to be to detecting back scattering
Optical signal takes the average value in the long period, therefore system architecture is complicated, application cost is higher.
Distributed Optical Fiber Sensing Techniques based on Brillouin scattering achieve some Outcome accumulations by the research in more than ten years,
The advantages that because of its high accuracy, overlength sensing scope, good test effect is obtained in some large-scale, ultra-large type structures, but
Certain distance also be present apart from practical application, be primarily present following some problems, Brillouin's strain transducer application first is most
Be tight tube fiber, the sensor engineering site survival rate of this structure is low；Meanwhile Brillouin signal light intensity and frequency displacement in optical fiber
The simultaneously strained and influence of temperature, only can not differentiate the intensity or frequency displacement by single brillouin scattering signal light intensity or frequency displacement
Change is as strain or as caused by temperature, so to obtain accurate temperature respectively and strain information is relatively difficult；Secondly
Requirement to light source and control system is very high, and signal transacting, detecting system are complicated, and cost of manufacture is also higher.
The content of the invention
The invention aims to solve the above problems, the distribution measuring in temperature field is realized, it is proposed that one kind is based on light
Fibre is radiated induced attenuation temperature sensitivity, the distributed temperature measuring system of distributed sensor is realized using optical time domain reflection technology.
A kind of distributed temperature measuring system based on optical fiber radiation induced attenuation temperature sensitivity, it is characterised in that including：Laser
Device, impulse generator, coupler, the sensor fibre by temperature sensor, photodetector, amplifying circuit, microprocessor and based on
Calculation machine.Described sensor fibre is the irradiation optical fiber segmentation structure alternate with non-irradiated optical fiber.
Impulse generator sends broad-adjustable burst pulse driving laser, pulsed light caused by laser, through coupler
Incide sensor fibre, the rayleigh backscattering light rear orientation light and Fresnel reflection optical signal in optical fiber export through coupler
To photodetector, photodetector converts optical signals into electric signal output, and microprocessor is sent into after amplified circuit amplification,
Microprocessor carries out processing output to electric signal to computer；Microprocessor also passes through Time -based Control impulse generator；Microprocessor
Processing of the device to electric signal includes sampling, analog-to-digital conversion and is averaged；Computer according to the test curve on obtained sensor fibre,
Electric signal caused by the backscattering optical signal of irradiation section to same root optical fiber and non-irradiated section of electric signal are carried out at difference
Reason, obtain optical fiber attenuation, and then the corresponding relation temperature varied with temperature according to optical fiber attenuation.
The described sensor fibre for temperature sensor, it is that an optical fiber mark is divided into N sections, setting section is irradiated
And make annealing treatment, form the irradiation optical fiber segmentation structure alternate with non-irradiated optical fiber；N is positive integer.Sensor fibre can be with
It is an optical cable made of the optical fiber described in M roots.
The advantages and positive effects of the present invention are：
(1) present invention use intensity modulated, and principle is simple, without complicated demodulating system and structure and special device,
Thus cost of manufacture is relatively low, and can obtain higher resolution ratio；
(2) the enhanced sensitivity optical fiber that the present invention uses can choose general single mode or multimode doped fiber, only need to be by simple
Radiation treatment and suitably annealing are made, better reliability, and can be adjusted according to being actually needed by change irradiation accumulated dose etc. quick
Photosensitive fine sensitivity, and then realize high-precision temperature survey；
(3) present invention uses the sensor fibre of special construction, and sensing is made in same root optical fiber after special radiation treatment
Optical fiber, sensor fibre be segmentation structure (one section irradiation optical fiber connect one section of non-irradiated optical fiber ...), increases distance sensing with this,
And the scheme of multi-fiber cable can be used, on the premise of spatial resolution and temperature resolution is not lost, expands distance sensing；
(4) Temperature Mechanism of the invention is the temperature dependency of color center model in optical fiber, and only temperature sensitive, stress is curved
The factors such as song can not substantially influence stable colour center, therefore have stronger antijamming capability；
(5) present invention uses Rayleigh scattering as induced signal, and Rayleigh intensity is higher than Brillouin and Raman scattering
Go out at least two magnitude, the intensity of signal of the present invention depends primarily on the radiation induced attenuation of sensing optical fiber；
(6) present invention finally carries out difference processing, same root optical fiber, by exposed portion backscattering to test data curve
It is poor that electric signal caused by signal and the electric signal of the acquisition of non-irradiated part are made, and both differential signals is obtained, so as to improve temperature
Measurement accuracy is spent, reduces the influence of light source fluctuation, improves stability.With dual-wavelength difference method and introducing reference optical fiber calculus of finite differences phase
Than this method is more simple, easy to detect, and cost is low, and practicality is stronger, and the different piece of same root optical fiber does difference, and light exists
One path, guarantee gain balance, precision are higher.
Brief description of the drawings
Fig. 1 is a kind of sensor fibre structural representation provided by the invention；
Fig. 2 is the Making programme figure of sensitive optical fibre provided by the invention；
Fig. 3 is second of sensor fibre structural representation provided by the invention；
Fig. 4 is the structural representation of the first scheme of temp measuring system provided by the invention；
Fig. 5 is the structural representation of the second scheme of temp measuring system provided by the invention；
Fig. 6 is will to irradiate the signal that difference processing is carried out with the electric signal of non-irradiated optical fiber in the temp measuring system of the present invention
Figure；
Fig. 7 is backscattering schematic diagram in sensor fibre of the invention.
In figure：
A1 --- laser；A2 --- coupler；A3 --- sensor fibre；A4-photodetector；
A5 --- impulse controller；A6 --- amplifying circuit；A7 --- microprocessor；A8 --- computer.
Embodiment
Below in conjunction with drawings and examples, the present invention is described in further detail.
The temp measuring system of the present invention, the sensor fibre for temperature sensor of use, for by equitable subsection, quantitative irradiation
And the optical fiber made annealing treatment.Sensor fibre uses special segmentation structure, if including N sections, every section is irradiation optical fiber or non-spoke
Irradiation is fine, as shown in figure 1, irradiation optical fiber and non-irradiated optical fiber are made by same root optical fiber through special radiation treatment, with
This increases distance sensing.The output end of coupler of the sensor fibre welding in temp measuring system.The present invention temperature survey according to
According to the radiation induced attenuation temperature dependency for the optical fiber for irradiating and making annealing treatment in sensor fibre, mainly make use of by radiation treatment
Optical fiber attenuation and temperature corresponding relation.
Under radiation parameter, radiating particle interacts with optical fiber, can cause to produce in optical fiber so-called " colour center ".Colour center
It is a kind of special point defect with effective charge, its energy bound electron and hole, causes the electronics in crystal or hole to excite,
So as to produce light absorbs, its absorption spectrum extends to region of ultra-red from ultra-violet (UV) band.There is stablize colour center in optical fiber after irradiation
With unstable colour center, wherein, a part of unstable colour center can gradually degenerate after irradiation, and other unstable colour centers can move back in high temperature
Occur to degenerate or change into other colour centers during fire processing.Irradiate the stabilization and the direct phase of annealing temperature of colour center in optical fiber
Close, after abundant high annealing is lived through, when fiber optic temperature is less than annealing temperature, the colour center in optical fiber no longer occurs substantially
Degenerate or convert, thus color center model has stable dynamic temperature dependence.Research finds that stable colour center is in specified temp ring
There is stable temperature dependency, i.e., when the temperature is changed, colour center can be sent out in the intensity of single light absorbs under border and test condition
Changing, causes the decay (i.e. radiation-induced decay) of optical fiber also to vary with temperature；It the experiment proved that, it is after irradiation and appropriate
The decay of the optical fiber of annealing and temperature have the dependence of temperature and dullness, are supervised in real time by optical fiber attenuation measuring system
The decay of the temperature sensitive optical fibre is surveyed, so as to realize the measurement of temperature.
According to researching and analysing, in temperature applicable range Tmin~TmaxIt is interior, the temperature control δ of optical fiber radiation induced attenuationFCan
It is expressed as：
Wherein, E represents photon energy, TminRepresent minimum temperature, TmaxRepresent maximum temperature.
The optical fiber radiation induced attenuation (Radiation Induced Attenuation, RIA) that difference is irradiated and fully annealed
The Universal Model of temperature sensitivity can be expressed as：
Wherein, i represents the i-th class colour center in optical fiber, and n is the species number of related colour center in optical fiber.ai(T), EiAnd ω (T)i
(T) it is the parameter of the i-th class color center model spectral line, represents absorption intensity respectively, absorbs peak position, Gaussian lineshape halfwidth.
The manufacturing process of sensor fibre provided by the invention is as shown in Figure 2.The first step, choose the optical fiber matched with light source and make
For raw material, the higher optical fiber of the temperature control of optical fiber radiation induced attenuation is selected, such as selection operation wavelength is 1310nm's
Single mode or multimode mix P, mix Ge or mix Ge-P optical fiber.Second step, the optical fiber raw material of selection are carried out at sectional quantitative irradiation
Reason, one section of radiation treatment of same root optical fiber, one section without any processing, so as to form sectional segmentation structure.It can incite somebody to action
The part for needing to irradiate is exposed to radiation environment, the part for being not required to irradiation is made into shielding processing with aluminium sheet, or will need what is irradiated
Part winds up receiving irradiation, it is not necessary to which the part of irradiation does not process, and radiation source can use common60Co-γ.3rd
Step, a series of temperature of the annealings such as high temperature to the decay of optical fiber in whole operating temperature range is carried out to the optical fiber after irradiation
To spend dependence and keep stable, be i.e. the condition of temperature change, the corresponding relation that optical fiber attenuation varies with temperature is constant, such as selection
Temperature measurement range is -40-60 DEG C, then the annealing temperature of selection should be higher than that 60 DEG C, such as 70 DEG C or 80 DEG C.Finally, according to reality
Border is required, the optical fiber that above-mentioned steps treat is turned into given shape, so as to the stable sensitive light of stability characteristic (quality) that obtains decaying
Fibre, for example, can fill optical fiber coiling cyclization in emphasis monitored area, to increase the length of the area sensitive optical fiber, so as to increase
Add the temperature sensitivity of the area sensitive optical fiber.
The invention provides two kinds of sensor fibre structures to be used for temp measuring system, and two kinds of realization sides of solid line temp measuring system
Case.
The first sensor fibre structure is as shown in figure 1, can be according to required for the ratio of irradiation optical fiber and non-irradiated optical fiber
Total distance sensing presses 1:1 or 2:1 or self-defined suitable ratio is allocated, and equitable subsection is carried out according to the demand of reality,
As shown in figure 1, wherein 2, the irradiated processing of 4,6,8 sections of optical fiber is made temperature sensitive segment, 1,3,5,7 section then for non-irradiated optical fiber not
Do it is any handle for optical transport, distance sensing is increased with this.
Based on the first sensor fibre structure, there is provided second of sensor fibre structure, as shown in figure 3, using multi-fiber cable
Structure realizes there is the sensitive optical fibre of the irradiated annealing of M roots and segment processing in an optical cable, and M is the positive integer more than 1.If light
Two optical fiber No. 1 and No. 2 are used in cable, then every fibre optic rediation and non-irradiated ratio are 1:1, No. 1 optical fiber and No. 2 fibre optic rediations
Section staggers, and stepped arrangement, i.e., No. 1 fibre optic rediation section is 1,3,5... sections, and remaining is without radiation treatment, No. 2 fibre optic rediations
Section is 2,4,6... sections, and remaining is without radiation treatment.If three optical fiber No. 1, No. 2 and No. 3, every optical fiber spoke are used in optical cable
According to non-irradiated ratio be 1:2, and every fibre optic rediation section staggers, stepped arrangement, i.e. No. 1 optical fiber Isosorbide-5-Nitrae, the irradiation of 7.. sections,
Remaining is non-irradiated；No. 2 section of optical fiber 2,5,8.. irradiation, remaining is non-irradiated；No. 3 section of optical fiber 3,6,9.. irradiation, remaining is non-irradiated.Then
M root optical fiber is used in optical cable, every fibre optic rediation and non-irradiated ratio are 1:(M-1).If only sensed with an irradiation optical fiber
Distance is L (km)；If an optical cable is made with 2 irradiated and segment processing optical fiber, distance sensing is 2L (km)；With this
Analogize, if an optical cable is made in irradiated with M roots and segment processing optical fiber, distance sensing is M*L (km).This scheme can be with
On the premise of spatial resolution and temperature resolution is not lost, distance sensing is significantly increased.
Distributed temperature measuring system provided by the invention based on optical fiber radiation induced attenuation temperature sensitivity, produce laser coupled
Sensor fibre is incided, Rayleigh scattering in a fiber be present, exists in optical fiber junction and reflects, the backscattering in detection optical fiber
Light and Fresnel reflection optical signal, electric signal is converted optical signals into, and carry out the processing such as signal amplification, sampling, analog-to-digital conversion
Afterwards, the test curve data on sensor fibre are obtained.To the test curve finally obtained, same root optical fiber, exposed portion is carried on the back
It is poor to make to electric signal caused by scattered signal and the electric signal of non-irradiated part, obtains both differential signals.Believed using difference
Number, so as to improve temperature measurement accuracy, reduce the influence of light source fluctuation, improve stability.
The present invention is a kind of distributed temperature measuring system based on optical fiber radiation induced attenuation temperature sensitivity, there is two kinds of embodiment party
Formula, it is respectively as shown in Figure 4 and Figure 5, specifically described below.
The first sensor-based system is as shown in figure 4, including the laser A1 for providing pulsed light, the coupling for optic communication
It is device A2, the sensor fibre A3 for temperature sensor, the photodetector A4 for measuring optical signal, broad-adjustable for sending
The impulse generator A5 of burst pulse, the amplifying circuit A6 for the small-signal detected to be amplified to processing, for signal
Processing and pulse controlled microprocessor A7, the computer A8 shown for data.
Impulse generator A5 sends broad-adjustable burst pulse driving laser A1, the pulse of width, classical prescription needed for generation
Tested sensor fibre A3, the sensor fibre welding that N sections are made up of irradiation optical fiber and non-irradiated optical fiber are incided after to coupler A2
In coupler A2 output end, Rayleigh scattering in a fiber be present, optical fiber junction, which exists, to be reflected, the rear orientation light in optical fiber
Electric signal is converted into Fresnel reflection optical signal, is exported by coupler A2 to photodetector A4, photodetector A4 handles
The scattering light and reflected light signal received is converted into electric signal, and being sent into microprocessor A7 after amplified circuit A6 amplifications carries out letter
Number processing, including sampling, analog-to-digital conversion peace equalization process, as a result transmit to computer A8 carry out realtime curve, simultaneously
Microprocessor A7 is also by Time -based Control impulse generator A5.Finally, to the test curve on obtained sensor fibre, irradiation portion
Divide and carry out difference processing with non-irradiated part, improve temperature measurement accuracy, reduce light source disturbance.
Second of sensor-based system is as shown in figure 5, including the laser A1 for providing pulsed light, the coupling for optic communication
It is device A2, the sensor fibre A3 for temperature sensor, the photodetector A4 for measuring optical signal, broad-adjustable for sending
The impulse generator A5 of burst pulse, the amplifying circuit A6 for the small-signal detected to be amplified to processing, for signal
Processing and pulse controlled microprocessor A7, the computer A8 shown for data.
Impulse generator A5 sends broad-adjustable burst pulse driving laser A1, the pulse of width, classical prescription needed for generation
Tested sensor fibre A3 is incided after to coupler A2, M root identical optical fiber, every irradiates optical fiber and non-irradiated light by N sections
Fibre is formed, and it is output end of the sensor fibre welding in coupler A2 that M root optical fiber is made into an optical cable (multi-fiber cable), in optical fiber
In Rayleigh scattering be present, there is reflection in optical fiber junction, the rear orientation light and Fresnel reflection optical signal in optical fiber are converted into
Electric signal, exported by coupler A2 to photodetector, photodetector A4 is the scattering light and reflected light signal received
Be converted into electric signal, microprocessor A7 be sent into after amplified circuit A6 amplifications and carries out signal transacting, including sampling, analog-to-digital conversion and
Flat equalization process, as a result transmit to computer A8 and carry out realtime curve, while microprocessor A7 is also by Time -based Control arteries and veins
Rush generator A5.Finally, the test curve on obtained sensor fibre, exposed portion are carried out at difference with non-irradiated part
Reason, temperature measurement accuracy is improved, reduce light source disturbance.
Described laser A1 is high power pulse light source, and optical source wavelength can commonly use ripple according to selection communication is actually carried out
Section, enters 850nm, 1310nm or 1550nm, to reduce the cost of optical fiber and related device, can also according to sensitive optical fibre characteristic and
The requirement of sensitivity is measured, selects operation wavelength in 400-2000nm any achievable light source.
Difference processing is made to the test curve of gained in the present invention, same root optical fiber is collected backwards by exposed portion
It is poor that electric signal caused by scattered light signal is made with the electric signal that non-irradiated part obtains, and both differential signals is obtained, such as Fig. 6 institutes
Show, i.e., 2 and 1 work is poor, and 4 and 3 works are poor, and 6 and 5 works are poor, and 8 and 7 works are poor, and by that analogy, difference processing can be eliminated from detector
Receiving terminal, optical fiber caused random noise in itself or in measurement process, reduce disturbance, so as to improve temperature measurement accuracy.Figure
In give 2 and 1 work difference schematic diagram.It is of the invention compared with dual-wavelength difference method and tradition introduce reference optical fiber calculus of finite differences
Method is more simple, easy to detect, and cost is low, and practicality is stronger, and the different piece of same root optical fiber does difference, and light is logical at one
Road, guarantee gain balance, precision are higher.
The just pulse signal that laser A1 is sent in the present invention, on sensor fibre A3 at the z of optical pulse strikes end
The time that back-scattering light reaches optical fiber incidence end is t=2z/vg, wherein vg=c/r, r be optical fiber refractive index, vgRepresent light
Spread speed in a fiber, c are the light velocity, it can thus be concluded that the position z to each fixed point event on optical fiberk=ct/2r, k are to set
The label put.
The scattering of optical fiber is mainly Rayleigh scattering, and light source launches light pulse to optical fiber one end, and light is along optical fiber transmitting procedure
In, the defects of due to optical fiber itself and dopant material so that inside of optical fibre has inhomogeneities, causes optical signal to be produced along optical fiber
Raw irregular scattering, wherein the scattering light for being back to optical fiber incidence end in reverse direction is back-scattering light, as shown in Figure 7.
Light is propagated in a fiber, is decayed while rayleigh backscattering is produced, due to the optical wavelength and lambda1-wavelength of Rayleigh scattering
It is identical, thus the incident optical power of rayleigh backscattering luminous power and scattering point reduces in direct ratioly.Return to optical fiber incidence
The rayleigh backscattering light at end, by appropriate coupling, detection and processing, the optical fiber attenuation with regard to light pulse place of arrival can be obtained
Information, so as to be measured to optical fiber attenuation, i.e., so-called optical time domain reflection technology.
The rayleigh backscattering light intensity received at light source top temporally exponentially decays, i.e. along the auspicious of fiber link
Sharp backscattering light intensity exponentially decays by distance.Therefore, data photodetector received make Logarithm conversion, so that it may
To the curve of an approximately linear.The experiment curv that photodetector obtains enters line slope extraction, you can obtains optical fiber along link
Dampening information, the decay of optical fiber has dependence to temperature, outgoing link temperature can be calculated according to optical fiber attenuation.If fiber position
z1The rayleigh backscattering luminous power at place is P (z1), fiber position z2The rayleigh backscattering luminous power at place is P (z2), according to light
The theoretical calculation formula of fibre decay, can obtain fiber position z1And z2Between decay.Optical fiber attenuation α calculation formula are as follows：
Test data is handled using above-mentioned formula, can obtain the dampening information between any two position, and then
The temperature distribution information along fiber link can be obtained.
For the radiation treatment fiber segment in sensor fibre, due to fiber segment that is irradiated and making annealing treatment, its tool of decaying
There is stable and dull temperature dependency, when the temperature at this section of optical fiber changes, this section of optical attenuation can occur accordingly
Change, cause this section of incident power that significant change occurs.Because backscattering (mainly Rayleigh scattering) luminous intensity enters with this section
It is directly proportional to penetrate light intensity, therefore, the backscattering light intensity of this section also can produce change with temperature.Secondly, the section scatters light backwards
During propagation, also due to this section of optical fiber color center model and further decay, double semaphore, ultimately result in detector and receive
Light signal strength occur significant change, according to detection light intensity come to temperature carry out quantitative measurment.With reference to time domain reflection technology, root
The backscattering light intensity received according to detector changes, so that it is determined that the change of measured point temperature.
Because the present invention program is really the multimetering on an optical fiber, really quasi-distributed serial temperature survey,
Suitable for the application background of multiple spot distribution measuring.
The present invention proposes a kind of distribution based on optical fiber radiation induced attenuation temperature dependency and optical time domain reflection technology
Optical fiber temperature measurement system, have the characteristics that：First, temperature survey of the invention is to be based on fiber strength modulation type TEMP,
Principle is simple, compared with main flow distributed temperature sensor, cost-effective simplified system, and high-resolution can be obtained；The
Two, the enhanced sensitivity optical fiber that the present invention uses can choose general single mode or multimode doped fiber, only need to pass through simple radiation treatment
And suitably annealing is made, better reliability, and can be according to being actually needed, by changing the adjustment sensitive optical fibre such as irradiation accumulated dose
Sensitivity, and then realize high-precision temperature survey；3rd, the present invention uses the sensor fibre of special construction, same root optical fiber
Be made sensor fibre after special radiation treatment, sensor fibre be segmentation structure (one section of irradiation optical fiber connect one section it is non-irradiated
Optical fiber ...), distance sensing is increased with this, and can use the scheme of multi-fiber cable, it not lose spatial resolution and temperature point
On the premise of resolution, distance sensing is expanded；4th, Temperature Mechanism of the invention is the temperature dependency of color center model in optical fiber,
Only temperature sensitive, stress, the factor such as bending can not substantially influence stable colour center, therefore have stronger anti-interference energy
Power；5th, the present invention using Rayleigh scattering as induced signal, and Rayleigh intensity than Brillouin and Raman scattering be higher by
Few 2 magnitudes, the intensity of signal of the present invention depend primarily on the radiation induced attenuation of sensing optical fiber；6th, the present invention is finally to surveying
Try data and curves carry out difference processing, same root optical fiber, by electric signal caused by exposed portion backscatter signals with it is non-irradiated
It is poor that the electric signal of partial acquisition is made, and obtains both differential signals, so as to improve temperature measurement accuracy, reduces light source fluctuation
Influence, improve stability.Compared with dual-wavelength difference method and introducing reference optical fiber calculus of finite differences, this method is more simple, detection side
Just, cost is low, and practicality is stronger, and the different piece of same root optical fiber does difference, and light is in a path, guarantee gain balance, essence
Du Genggao；7th, the present invention uses optical time domain reflection technology to carry out optical fiber attenuation distribution measuring to realize Temperature Distribution or accurate point
Cloth measures, available for the power system temperature survey with high voltage, high current, strong electromagnetic and narrow space etc., tunnel
The field such as fire alarm and the monitoring of oil exploitation downhole temperature.
Claims (7)
- A kind of 1. distributed temperature measuring system based on optical fiber radiation induced attenuation temperature sensitivity, it is characterised in that including：Laser Device, impulse generator, coupler, the sensor fibre by temperature sensor, photodetector, amplifying circuit, microprocessor and based on Calculation machine；Described sensor fibre is the irradiation optical fiber segmentation structure alternate with non-irradiated optical fiber；Impulse generator sends broad-adjustable burst pulse driving laser, and pulsed light caused by laser is incident through coupler To sensor fibre, back-scattering light and Fresnel reflection optical signal in optical fiber are exported to photodetector, photoelectricity through coupler Detector converts optical signals into electric signal output, is sent into microprocessor after amplified circuit amplification, microprocessor is to electric signal Processing output is carried out to computer；Microprocessor also passes through Time -based Control impulse generator；Processing of the microprocessor to electric signal Including sampling, analog-to-digital conversion and it is averaged；Computer is according to the test curve on obtained sensor fibre, to the spoke of same root optical fiber Difference processing is carried out according to electric signal caused by the backscattering optical signal of section and non-irradiated section adjacent of electric signal, obtains optical fiber Decay, and then the corresponding relation temperature varied with temperature according to optical fiber attenuation.
- 2. temp measuring system according to claim 1, it is characterised in that described sensor fibre, be to mark an optical fiber It is divided into N sections, setting section is irradiated and made annealing treatment, forms the irradiation optical fiber segmentation structure alternate with non-irradiated optical fiber；N For positive integer.
- 3. temp measuring system according to claim 1, it is characterised in that the described sensor fibre for temperature sensor, be By an optical cable made of M root optical fiber, wherein, every optical fiber mark is divided into N sections, and setting section is irradiated and made annealing treatment, Form the irradiation optical fiber segmentation structure alternate with non-irradiated optical fiber；In M root optical fiber, the irradiation section of every optical fiber staggers, M root light The fine stepped arrangement of irradiation section；N is positive integer, and M is the positive integer more than 1.
- 4. the temp measuring system according to Claims 2 or 3, it is characterised in that described sensor fibre, the making of an optical fiber Method is：First, the optical fiber matched with light source is chosen as raw material；Secondly, the optical fiber raw material of selection be segmented calmly Radiation treatment is measured, one section of radiation treatment of same root optical fiber, one section without any processing；3rd, the optical fiber after irradiation is moved back Fire processing to temperature dependency of the decay in whole operating temperature range of optical fiber keeps stable；Finally, by above-mentioned steps The sensor fibre managed turns to required shape.
- 5. temp measuring system according to claim 1, it is characterised in that described laser, caused pulsed light are height Power pulse light, the wavelength of pulsed light select any in the conventional wave band that communicates, or selection operation wavelength according to the actual requirements Light source can be achieved.
- 6. according to the temp measuring system described in claim 1 or 2 or 3, it is characterised in that described sensor fibre, its material are to mix P Optical fiber, mix Ge optical fiber or Ge-P doped fibers.
- 7. according to the temp measuring system described in claim 1 or 2 or 3, it is characterised in that described temp measuring system, using described Sensor fibre realizes quasi-distributed serial temperature survey, and distance is pressed exponentially according to along the rayleigh backscattering light intensity of fiber link The theoretical foundation of decay, to any two position on sensor fibre, the decay between two positions is obtained, and then obtain along optical fiber The temperature distribution information of link.
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