CN105352626B - A kind of demodulation method and device of Concatenate optical fiber Raman temperature system - Google Patents
A kind of demodulation method and device of Concatenate optical fiber Raman temperature system Download PDFInfo
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- CN105352626B CN105352626B CN201510884347.1A CN201510884347A CN105352626B CN 105352626 B CN105352626 B CN 105352626B CN 201510884347 A CN201510884347 A CN 201510884347A CN 105352626 B CN105352626 B CN 105352626B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/324—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres using Raman scattering
Abstract
The backscattering anti-Stokes optical information and the sensor fibre incidence end temperature information of adjacent sites obtained the invention provides a kind of Concatenate optical fiber Raman temperature system demodulation method using the adjacent sites on sensor fibre, handled by temperature demodulation etc., obtain the temperature of each measurement point on sensor fibre.Invention further provides a kind of Concatenate optical fiber Raman temperature system demodulating equipment.Pass through above-mentioned demodulation method and device, single channel bidirectional demodulation method is developed into two-way demodulation, the measurement accuracy of sensor fibre temperature can not only be improved, and it can effectively reduce equality of temperature flatness, the influence of the random noise of the unstable of light source and coupling is effectively eliminated, sensing length can reach more than 30km between adjacent sites.
Description
Technical field
The invention belongs to electronic information technical field, is related to a kind of photoelectric sense technology, in particular to a kind of tandem light
The demodulation method and device of fine Raman temperature system.
Background technology
Fiber Raman temperature-sensing system collection senses and is transmitted in one, and telemeasurement and monitoring can be achieved, once survey
Determine the one-dimensional distribution map that can obtains whole fiber area；Optical fibre frame is set as raster-like, so that it may determine the two of tested region
Peacekeeping distributed in three dimensions situation, tens, hundreds of even thousands of letters can be obtained on a sensor fibre loop up to thousands of meters
Breath, present sensor fibre becomes very cheap with significantly reducing for manufacturing cost, therefore unit information cost significantly reduces.
Under the adverse circumstances that can not be approached with strong electromagnetic or inflammable and explosive and other sensors, fiber Raman
Temperature-sensing system has the advantages of incomparable.Therefore since the 1980s, people are to realizing that distribution type fiber-optic passes
The various technologies of sense expand widely studied.For fiber optic temperature Raman sensor-based system, first have to solve is to carrying temperature
The identification of the optical signal of information and the determination of measurement position, optical time domain reflection (OTDR) technology and probe beam deflation (OFDR) technology
Good solution method is provided to this；And the distribution temperature measuring application for relatively long distance, the distributed sensor based on scattering mechanism
System then has incomparable superiority, because the power now lost in optical fiber is directly used in sensed signal energy
Amount.
Most strong scattering process is exactly Rayleigh scattering in optical fiber, and backscatter intensity is about the -30dBm of incident light, Rayleigh
Scattering be by the uneven and composition of local density non-propagating in optical fiber it is uneven caused by.Experiment and theory have been found that glass
The temperature control of the rayleigh scattering coefficient of (main component of composition optical fiber) is extremely faint, therefore realizes based on Rayleigh scattering
The temperature distribution system of full optical fiber admittedly is highly difficult.But in some liquid, this temperature control is but very strong, such as in benzene,
Its temperature control is up to 0.033dB/K.Due to the short life of liquid-core optical fibre, and liquid has the presence of freezing point, boiling point, limits
The scope of thermometric, the program can not be on the actual application.What is mainly applied at present is Raman scattering type and Brillouin scattering type.
When light passes through optical fiber, in photon and optical fiber because of spontaneous warm-up movement and caused by phonon can produce inelastic collision, from
And spontaneous Brillouin scattering occurs, the frequency range of the frequency of light with respect to incident light is scattered in 10GHz~11GHz.Base
In the typical structure of the sensor of the technology be Brillouin amplifier structure (as shown in Figure 3), including pulse laser 31, isolation
Device (32,38), acousto-optic modulator 33, oscillograph 34, coupler (35,37), sensitive optical fibre 36, continuous-wave laser 39 and spectrum
Analyzer 310.Tunable laser (pulse laser 31 and continuous-wave laser 39) in optical fiber both ends respectively will through every
Sensitive light is injected from the pulsed light that device 32 and acousto-optic modulator 33 are modulated and the continuous light through isolator 38 and coupler 37
Fibre 36, when the difference on the frequency of two-beam is in the brillouin gain bandwidth in fiber area of meeting, two-beam will act on
Point produces Brillouin amplifier effect, and energy transfer occurs each other, and continuously adjustable is carried out in the frequency to two lasers
Meanwhile power of the spectroanalysis instrument 310 by detection from the continuous light of optical fiber one end injection, so that it may determine each segment area of optical fiber
The brillouin gain in domain reaches difference on the frequency corresponding during maximum, identified difference on the frequency and the Brillouin in each section of region on optical fiber
Frequency displacement is equal.Therefore just determined therewith in the optical fiber temperature directly proportional to Brillouin shift and strain.The sensing technology can reach
To measurement accuracy depend on the tuning precisions of two lasers.So the system is more complicated, cost is high, pumping laser and
Exploring laser light must necessarily be placed in the both ends of tested optical cable, and can not survey breakpoint, and the frequency stabilization and light source to laser and control are
The requirement of system is very high.Therefore its application is by a definite limitation.
Raman scattering is the thermal vibration and photon interaction when laser pulse is propagated in a fiber due to optical fiber molecule
Generation energy exchange and it is caused.Specifically, if a part of luminous energy is converted into thermal vibration, then one will be sent and compare light source
The light of wavelength length is referred to as Raman stokes light；If a part of thermal vibration is converted to luminous energy, then will send one and compares light source
The short light of wavelength is referred to as Raman anti-Stokes light.Distributed temperature sensing system based on spontaneous Raman scattering as shown in Fig. 2
Including laser driver 21, laser 22, sensor fibre 23, wavelength division multiplexer 24, photodetector assembly 25, computer 26,
Isolator 27 and coupler 28.Laser driver 21 drives the laser that laser 22 is launched through isolator 27 with being noted after coupler 28
Enter sensor fibre 23, natural backscattering filters out stokes light after coupler 28 and wavelength division multiplexer 24 on sensor fibre 23
And anti-Stokes light, then received by photodetector assembly 25 and be changed into electric signal and amplify, then the letter through computer 26
The processing of number processing system is changed into temperature signal, as a kind of two pass bands method can effectively eliminate the unstable of light source and
Fiber transmission attenuation and the influence of the random noise coupled.The relation of backscattering Raman light and incident light is：
P=η PiR(T)exp(-(α0+αr)L) (1)
Wherein, P is backscattering Raman luminous power, and L is sensor fibre length, α0For fiber Rayleigh scattering average loss system
Number, αrFor fiber raman scattering average loss coefficient, R (T) is the Raman backscatter factor (information of T containing temperature), and η is wavelength etc.
Correlation factor, PiFor incident optical power.
Unique weak point of Raman distributed optical fiber sensing system is that return signal is quite weak, Stokes backscattering
Intensity is about the -60dBm of incident light, and anti-Stokes backscatter intensity is about the -75dBm of incident light, it may be said that temperature is believed
Breath is submerged in noise, in order to avoid signal averaging overlong time in signal processing, the peak power phase of pulsed laser source
Work as height, but (threshold power of anti-Stokes is more than the threshold value of Stokes to the threshold power being excited no more than Raman scattering
Power), and measurement distance is longer, and threshold power is smaller, PiMaximum be the threshold power P that is excited of Raman scatteringi cr:
Pi cr(1-exp(-(α0+αr)L))/(α0+αr)=C (2)
Wherein, C is constant.
It can detect more than 80km optical cable physical arrangement now with backscattering Rayleigh technology, and the Raman temperature reported
The most long only 30km of degree system single-path optical fiber length, reason is to use anti-Stokes/Rayleigh or anti-Stokes/Stokes
Two-way demodulation method, the fibre loss factor matching that anti-Stokes/Rayleigh demodulation is limited by them is bad, is measured according to China
Institute reports that the rayleigh backscattering for obtaining anti-Stokes light co-wavelength using extra increase cost just accomplishes 30km Raman
Temperature system, anti-Stokes/Stokes demodulation are limited by the threshold power of Stokes, and the clock demodulation method of the above two can not
Reduce equality of temperature flatness (it is identical referring to ambient temperature, measurement temperature maximum/minimum on sensor fibre).
In heavy construction in health monitoring, usual one-dimensional more than length 30km, or even more than 100km is, it is necessary to divide
Each section is realized sectional monitoring, according to Shanghai Hua Wei optical fiber sensing technologies company, the anti-stoke of the two-way acquisitions of adjacent sites A and B
This backscattering optical signal PAas、PBas, Stokes backscattering optical signal PAs、PBs, two-way demodulation ((PAas+PBas)/2)/
((PAs+PBs)/2), demodulate PA than each website independence two-wayas/PAsImprove measurement accuracy.
The content of the invention
It is contemplated that it is directed to above-mentioned problems of the prior art, there is provided a kind of Concatenate optical fiber Raman temperature system
Demodulation method and device, it can realize that two-way demodulates fiber Raman temperature system, improve temperature measurement accuracy and equality of temperature flatness,
Sensing length can reach more than 30km between adjacent sites.
In order to achieve the above object, the present invention takes following technical scheme to realize：
The invention provides a kind of Concatenate optical fiber Raman temperature system demodulation method, some detections are set on sensor fibre
Stand, the sensor fibre between adjacent sites comprises the following steps as object：
Step 1, laser is injected by sensor fibre using periodically pulsing laser, obtains what adjacent sites detected
The sensor fibre incidence end temperature information of backscattering anti-Stokes optical information and adjacent sites；
Step 2, the backscattering anti-Stokes optical information of adjacent sites same measurement point on sensor fibre is carried out
Evolution is handled again after phase product, the backscattering anti-Stokes optical information after being handled；
Step 3, using the temperature information of adjacent sites sensor fibre incidence end, demodulate the back of the body after same measurement point processing
To scattering anti-Stokes optical information, obtain sensor fibre on same measurement point relative to adjacent sites measurement temperature；
Step 4, same measurement point is averaged as the measurement temperature of measurement point relative to the measurement temperature of adjacent sites
Degree.
In backscattering anti-stoke of the purpose in the same sensor fibre between adjacent sites are obtained of step 1
Sensor fibre incidence end temperature information at where this optical information and adjacent sites, the Concatenate optical fiber talked about below can be used
Raman temperature system demodulating equipment obtains, and can use can reach the acquisition of above-mentioned purpose similar device.In preferable embodiment party
In formula, the backscattering anti-Stokes optical information of acquisition is the digital average value after multiple recurrent pulses laser；Pass
Sense optical fiber incidence end (starting point) temperature information can be obtained by the electronic thermometer for being arranged on sensor fibre starting point.
In step 2, due to the backscattering anti-Stokes light letter obtained between adjacent sites on same sensor fibre
Breath is symmetrical with horizontal axis, by the way that by two measurement amounts of adjacent sites same measurement point on sensor fibre, (preceding point is with after
Point) be multiplied after again evolution handle, can effectively eliminate the influence of transmission loss.Traditional two-way solution is carried out due to no
Adjust, can effectively reduce equality of temperature flatness.
By step 3, adjacent sites can be obtained to the high-acruracy survey of the same measurement point temperature of sensor fibre and effective
Eliminate the influence of the random noise of the unstable of light source and coupling.
By step 4, adjacent sites can be averaged as the final of measurement point to the measurement temperature of same measurement point
Measurement temperature, it can further improve the measurement accuracy of temperature on sensor fibre.
Invention further provides a kind of Concatenate optical fiber Raman temperature system demodulating equipment, on sensor fibre
The acquisition station of setting, including laser driver, laser, optical fiber circulator, wavelength division multiplexer, photodetector assembly, Wei Chu
Reason device, electronic thermometer and the modem with network interface, the webserver send enabled instruction, modem to each website
Enabled instruction is received, starts laser driver so that laser driver periodically drives laser to send laser, laser warp
Optical fiber circulator injects sensor fibre, and wavelength division multiplexer is oriented to through optical fiber circulator through back-scattering light caused by sensor fibre,
Wavelength division multiplexer filters out anti-Stokes light, is received through photodetector assembly, handles and obtain data signal and by data signal
Microprocessor is sent to, then the webserver is transferred to by modem；Sensor fibre is provided at both ends with electronic thermometer；Electricity
Sub- thermometer is connected by cable with microprocessor.
The effect of above-mentioned wavelength division multiplexer is to filter out backscattering anti-Stokes light, can select Raman wavelength-division multiplex
Device.
As a kind of implementation, above-mentioned photodetector assembly is included at APD detectors, A/D modular converters and data
Manage module；The anti-Stokes light of reception is converted to electric signal by APD detectors；A/D modular converters change analog electrical signal
Into data signal；The data signal received is sent to microprocessor by data processing module after cumulative mean several times.
As a kind of implementation, when data processing module newly carries out cumulative mean to the numeral received, digital averaging
Accumulative frequency is more than 30,000 times.
As a kind of implementation, laser can elect recurrent pulses laser as.
Concatenate optical fiber Raman temperature system demodulation method provided by the invention, there is at least one of following beneficial effect：
(1) because the backscattering anti-Stokes optical information obtained between adjacent sites on same sensor fibre has water
It is flat axially symmetric, by the way that two measurement amounts (preceding point and rear point) of adjacent sites same measurement point on sensor fibre are carried out into phase
Evolution is handled again after multiplying, and can effectively eliminate the influence of transmission loss；Traditional two-way demodulation is carried out due to no, can effectively be dropped
Low equality of temperature flatness；
(2) utilize sensor fibre incidence end temperature information and backscattering anti-Stokes optical information, demodulation process its
The backscattering anti-Stokes information of his position, the high-precision measurement temperature of each measurement point of sensor fibre can be obtained, and
Effectively eliminate the influence of the random noise of the unstable of light source and coupling；
(3) essence is the single channel bidirectional demodulation method of innovation, develops into two-way demodulation；
(4) sensing length can reach more than 30km between adjacent sites；
(5) application field of the present invention：Defence engineering, petrochemical industry, power engineering, colliery engineering, communications and transportation, tunnel,
The numerous areas such as dykes and dams, heavy construction, novel serial optical fiber sensor network is formed, turn into online health monitoring and fire-fighting early stage is pre-
Alert innovation means.
By Concatenate optical fiber Raman temperature system demodulating equipment provided by the invention, adjacent sites can be obtained and sensed
The backscattering anti-Stokes optical information of same measurement point and the sensor fibre incidence end temperature information of adjacent sites in optical fiber,
And the temperature of each measurement point in sensor fibre can be obtained based on above- mentioned information, realize and the high accuracy of sensor fibre temperature is surveyed
Amount, and effectively eliminate the influence of the noise immediately of the unstable of light source and coupling.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
There is the required accompanying drawing used in technology description to be briefly described, it should be apparent that, the accompanying drawing in describing below is only this
Some embodiments of invention, for those of ordinary skills, on the premise of not paying creative work, can be with
Other embodiments and its accompanying drawing are obtained according to these accompanying drawing illustrated embodiments.
Fig. 1 is the structural representation of Concatenate optical fiber Raman temperature system demodulating equipment provided by the invention；
Fig. 2 is the structural representation of Raman scattering type distributed optical fiber temperature sensor；
Fig. 3 is the structural representation of Brillouin scattering type distributed optical fiber temperature sensor.
Wherein, 11,21- laser drivers, 12,22- lasers, 13- optical fiber circulators, 14,23- sensor fibres, 15,
24- wavelength division multiplexers, 16,25- photodetector assemblies, 17- microprocessors, 18- electronic thermometers, 19- modems,
26- computers, 27,32,38- isolators, 28,35,37- couplers, 31- pulse lasers, 33- acousto-optic modulators, 34- oscillographys
Device, 36- sensitive optical fibres, 39- continuous-wave lasers, 310- spectroanalysis instruments.
Embodiment
Clear, complete description is carried out to the technical scheme of various embodiments of the present invention below with reference to accompanying drawing, it is clear that retouched
The embodiment stated is only the part of the embodiment of the present invention, rather than whole embodiments.Based on the embodiment in the present invention,
Those of ordinary skill in the art's all other embodiment resulting on the premise of creative work is not made, belongs to this
The protected scope of invention.
The present invention has anti-Stokes optical power threshold using the luminous power of the laser of injection, and adds sensor fibre
Armouring stainless steel sleeve pipe device, Concatenate optical fiber Raman temperature is demodulated by single channel bidirectional mode.For the understanding become apparent from
The present invention, it is described in detail with reference to embodiment and accompanying drawing.
Embodiment 1
A kind of Concatenate optical fiber Raman temperature system demodulation method is present embodiments provided, is comprised the following steps：
Step 1, laser is injected by sensor fibre using periodically pulsing laser, obtains what adjacent sites detected
The sensor fibre incidence end temperature information of backscattering anti-Stokes optical information and adjacent sites；
Step 2, the backscattering anti-Stokes optical information of adjacent sites same measurement point on sensor fibre is carried out
Evolution is handled again after phase product, the backscattering anti-Stokes optical information after being handled；
Step 3, using the temperature information of adjacent sites sensor fibre incidence end, demodulate the back of the body after same measurement point processing
To scattering anti-Stokes optical information, obtain sensor fibre on same measurement point relative to adjacent sites measurement temperature；
Step 4, same measurement point is averaged as the measurement temperature of measurement point relative to the measurement temperature of adjacent sites
Degree.
In step 1, the Concatenate optical fiber Raman temperature system demodulating equipment for implementing to provide in 2 can be used to obtain two
Backscattering anti-Stokes optical information and adjacent sites institute in same sensor fibre of the adjacent sites between adjacent sites
Sensor fibre incidence end temperature information at place.Using periodically pulsing laser, following Concatenate optical fiber Raman temperature are utilized
Spend Demodulation Systems device and obtain the backscattering anti-Stokes after multiple digital averaging.As to how pass through Concatenate optical fiber
Raman temperature system demodulating equipment obtains backscattering anti-Stokes optical information and will be described in detail in example 2.Sensing
Optical fiber incidence end (starting point) temperature information can be obtained by the electronic thermometer 18 for being arranged on sensor fibre starting point.Numeral
The generally choosing of average accumulative frequency is more than 30,000 times.
In step 1, the Distributed optical fiber Raman temperature sensor demodulating equipment provided in embodiment 2 can be used to obtain
The temperature information of backscattering anti-Stokes information, backscattering Rayleigh optical information and sensor fibre incidence end.Using week
The pulse laser of phase property, obtained using above-mentioned Distributed optical fiber Raman temperature sensor demodulating equipment after multiple digital averaging
Backscattering anti-Stokes optical information, backscattering Rayleigh optical information.Sensor fibre incidence end (starting point) temperature information by
The electronic thermometer 18 of sensor fibre starting point is arranged on to obtain.
In step 2, because the both ends of sensor fibre 14 respectively have a website, two websites can be to sensor fibre
On profiling temperatures measure, and because this anti-support of the backscattering obtained between adjacent sites on same sensor fibre
Gram this optical information has that horizontal axis is symmetrical, by by two measurement amounts of adjacent sites same measurement point on sensor fibre
Evolution processing again after (preceding point and rear point) is multiplied, can effectively eliminate the influence of transmission loss.Tradition is carried out due to no
Two-way demodulation, can effectively reduce equality of temperature flatness.
In step 3, the temperature information and backscattering anti-Stokes light of adjacent sites sensor fibre incidence end are utilized
Information, demodulation process step 2 handled after measurement point position backscattering anti-Stokes optical information, can obtain
Adjacent sites in the high-precision measurement temperature of the same measurement point of sensor fibre, and effectively eliminate light source unstable and coupling with
The influence of machine noise.
In step 4, adjacent sites can be averaged as the final of measurement point to the measurement temperature of same measurement point
Measurement temperature, it can further improve the measurement accuracy of temperature on sensor fibre.
The operation principle of the present invention is as follows：
If measuring one-dimensional length L rice between actual adjacent sites A, B, measurement point distance A website length x rice, then measurement point
Distance B websites length is (L-x) rice.
If the backscattering anti-Stokes luminous power that the A websites in step 1 after multiple digital averaging obtain is：
Px=ηasPAiR(T)exp(-(α0+αas)x) (3)；
B websites are in the backscattering anti-Stokes luminous power that same measurement point obtains：
PL-x=ηasPBiR(T)exp(-(α0+αas)(L-x)) (4)；
Wherein, R (T)=[exp (h Δ ν/κ T) -1]-1For the anti-Stokes backscattering factor, h is Plank coefficients, and κ is
Boltmann coefficients, Δ ν=1.32 × 1013Hz, ηasFor the correlation factors such as backscattering anti-Stokes optical wavelength, PAi、PBiPoint
Not Wei A websites and B websites incident optical power.
If the temperature that sensor fibre is determined at A websites by electronic thermometer 18 is TA0, after being handled according to step 2
The backscattering anti-Stokes luminous power of measurement point isAccording to step
Rapid three obtain temperature of the measurement point away from A website x rice：
If the temperature that sensor fibre is determined at B websites by another electronic thermometer 18 is TB0, at step 2 acquisition
The backscattering anti-Stokes luminous power of measurement point is after reasonPress
Temperature of the measurement point away from B websites (L-x) rice is obtained according to step 3：
According to step 4 obtain measurement point temperature be：
Tx=(TAx+TBx)/2 (7)。
TxThe final measurement temperature of the measurement point that as obtains.
It should be noted that：
(1) the step of this demodulation method is a kind of does not have backscattering Reyleith scanttering light, and reason is intermediate range time zone backscattering
Reyleith scanttering light includes laser fl transmission part, more than detector ability to bear.
(2) the step of this demodulation method is a kind of does not have backscattering stokes light, and reason is to use such as luminous power
With anti-Stokes optical power threshold, sensing length has been excited to amplify more than 30km, backscattering stokes light.
(3) the sensor fibre armouring stainless steel sleeve pipe device of this demodulation method, can bear less than 8 grades earthquake shocks.
(4) selected in this demodulation method step 2Compared to (Px+P2L-x)/2, it is higher to calculate signal to noise ratio.
Embodiment 2
The Concatenate optical fiber Raman temperature system demodulating equipment that the present embodiment provides (thick line table in connecting line as shown in Figure 1
Show cable, fine rule represents optical cable), the acquisition station set on sensor fibre, including laser driver 11, laser 12,
Optical fiber circulator 13, wavelength division multiplexer 15, photodetector assembly 16, microprocessor 17, electronic thermometer 18 and with network interface
Modem 19, the webserver send enabled instruction to each website, and modem 19 receives enabled instruction, starts and swashs
CD-ROM driver 11 so that laser driver 11 periodically drives laser 12 to send laser, and laser is through the note of optical fiber circulator 13
Enter sensor fibre 14, wavelength division multiplexer 15, wavelength-division are oriented to through optical fiber circulator 13 through back-scattering light caused by sensor fibre 14
Multiplexer 15 filters out anti-Stokes light, is received through photodetector assembly 16, handles and obtain data signal and by data signal
Microprocessor 17 is sent to, then the webserver is transferred to by modem 19；Sensor fibre 14 is provided at both ends with electronics temperature
Degree meter 18；Electronic thermometer 18 is connected by cable with microprocessor 17.
Modem 19 receives the numeral letter containing backscattering anti-Stokes optical information from microprocessor 17
Number and the temperature information containing sensor fibre incidence end be transferred to the webserver.Each website production of webserver received in-order
Raw backscattering anti-Stokes optical information and temperature information, sense light is calculated according to the demodulation method of the present invention by server
The temperature of every on fibre, can also be according to acquisition backscattering anti-Stokes optical information and sensor fibre incidence end temperature information
Demodulate the physical arrangement in sensor fibre using other analysis methods of the prior art and obtain in sensor fibre and measure
The temperature of point.A data processing mould can be constructed according to tandem Raman fiber temperature system demodulation method provided by the invention
Block is embedded into the webserver.
The frequency of above-mentioned laser driver 11 is C/ (4nL), and C is that speed, n are optical fiber effective refractive index to light in a vacuum.
The spatial resolution of system is determined by the laser pulse width and A/D sample frequencys of laser 12, generally chooses recurrent pulses laser
Laser pulse width 10ns, A/D the sample frequency 100MHz, the spatial resolution 1m of such system of device.Above-mentioned data processing module pair
The digital averaging accumulative frequency generally choosing that the data signal received carries out cumulative mean is more than 30,000 times.
The back-scattering light of return includes Reyleith scanttering light, Brillouin light and Raman light；After above-mentioned wavelength division multiplexer 15, filter
Go out Reyleith scanttering light and Raman light, and main effect is to filter out backscattering anti-Stokes light.Above-mentioned wavelength division multiplexer 15 can
To select Raman wavelength division multiplexer.Due to the ability to bear of photodetector 16 and sensor fibre over long distances transmission etc. original
Cause, the only backscattering anti-Stokes optical information detected by photodetector 16, believes without backscattering Reyleith scanttering light
Breath and backscattering Stokes optical information.
Above-mentioned photodetector assembly 16 includes APD detectors, A/D modular converters and data processing module.APD detectors
The anti-Stokes light of reception is converted into electric signal；Analog electrical signal is converted into data signal by A/D modular converters；At data
The data signal received is sent to computer by reason module after cumulative mean several times.
The above-mentioned webserver can utilize figure and the digital mode being combined to present on a display screen on sensor fibre
The temperature of every.The form that each measurement temperature is completed on webserver backstage from the background preserves.
It should be noted that embodiment 2 is only used for the further solution to tandem Raman fiber temperature system demodulating equipment
Release, do not form to any restriction to above-mentioned tandem Raman fiber temperature system demodulating equipment.
Reality has been carried out to being placed on 45km bare fibres in regulatable 25 degree of sweat boxs using above-mentioned demodulation method and device
Border thermometric checking.Using the solid state laser with light amplification, regulation light amplification gain makes the 45km returned through 50,000 digital averagings
End is backwards to Anti-Stokes signal noise and front end backwards to Anti-Stokes signal noise same order.Utilize the demodulation side of the present invention
Method, 25.5 DEG C of maximum temperature values at optical fiber 42km are measured, 24.6 DEG C of minimum temperature value at 1.7km, measurement, temperature wave are repeated several times
It is dynamic to be less than 1 DEG C.It is demonstrated experimentally that demodulation method provided by the invention and device substantially increase temperature measurement accuracy and equality of temperature is flat
Degree.
One of ordinary skill in the art will be appreciated that embodiment described here is to aid in reader and understands this hair
Bright principle, it should be understood that protection scope of the present invention is not limited to such especially statement and embodiment.This area
Those of ordinary skill can make according to these technical inspirations disclosed by the invention various does not depart from the other each of essence of the invention
The specific deformation of kind and combination, these deform and combined still within the scope of the present invention.
Claims (7)
1. a kind of Concatenate optical fiber Raman temperature system demodulation method, some acquisition stations are set on sensor fibre, with adjacent sites
Between sensor fibre be object, it is characterised in that comprise the following steps：
Step 1, laser is injected by sensor fibre using periodically pulsing laser, adjacent sites is obtained and detects backwards
Scatter anti-Stokes optical information and the sensor fibre incidence end temperature information of adjacent sites；
Step 2, by adjacent sites, the backscattering anti-Stokes optical information of same measurement point is multiplied on sensor fibre
Evolution is handled again after product, the backscattering anti-Stokes optical information after being handled；
Step 3, using the temperature information of adjacent sites sensor fibre incidence end, demodulate dissipating backwards after same measurement point processing
Penetrate anti-Stokes optical information, obtain on sensor fibre same measurement point relative to the measurement temperature of adjacent sites；
Step 4, same measurement point is averaged as the measurement temperature of measurement point relative to the measurement temperature of adjacent sites.
2. Concatenate optical fiber Raman temperature system demodulation method according to claim 1, it is characterised in that acquisition is backwards
Scattering anti-Stokes optical information is the digital average value after multiple recurrent pulses laser；The temperature of sensor fibre incidence end
Degree information can be obtained by the electronic thermometer for being arranged on sensor fibre incidence end.
A kind of 3. Concatenate optical fiber Raman temperature system demodulating equipment, it is characterised in that the spy set on sensor fibre
Survey station, including laser driver (11), laser (12), optical fiber circulator (13), wavelength division multiplexer (15), photodetector group
Part (16), microprocessor (17), electronic thermometer (18) and the modem (19) with network interface, the webserver is to each website
Enabled instruction is sent, modem (19) receives enabled instruction, starts laser driver (11) so that laser driver
(11) laser (12) is periodically driven to send laser, laser injects sensor fibre (14) through optical fiber circulator (13), through passing
Back-scattering light caused by photosensitive fibre (14) is oriented to wavelength division multiplexer (15), wavelength division multiplexer (15) filter through optical fiber circulator (13)
Go out anti-Stokes light, received through photodetector assembly (16), processing obtains data signal and is sent to data signal micro-
Processor (17), then the webserver is transferred to by modem (19)；Sensor fibre (14) is provided at both ends with electron temperature
Count (18)；Electronic thermometer (18) is connected by cable with microprocessor (17).
4. Concatenate optical fiber Raman temperature system demodulating equipment according to claim 3, it is characterised in that the wavelength-division is answered
It is Raman wavelength division multiplexer with device (15).
5. Concatenate optical fiber Raman temperature system demodulating equipment according to claim 3, it is characterised in that photodetector
Component (16) includes APD detectors, A/D modular converters and data processing module；APD detectors are by the anti-Stokes light of reception
Be converted to electric signal；Analog electrical signal is converted into data signal by A/D modular converters；The numeral that data processing module will receive
Signal is sent to microprocessor (17) after cumulative mean several times.
6. Concatenate optical fiber Raman temperature system demodulating equipment according to claim 5, it is characterised in that digital averaging tires out
Number is added to be more than 30,000 times.
7. Concatenate optical fiber Raman temperature system demodulating equipment according to claim 6, it is characterised in that laser (12)
For recurrent pulses laser.
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