CN208420210U - A kind of temperature-measuring system of distributed fibers - Google Patents
A kind of temperature-measuring system of distributed fibers Download PDFInfo
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- CN208420210U CN208420210U CN201821204973.7U CN201821204973U CN208420210U CN 208420210 U CN208420210 U CN 208420210U CN 201821204973 U CN201821204973 U CN 201821204973U CN 208420210 U CN208420210 U CN 208420210U
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Abstract
The utility model discloses a kind of temperature-measuring system of distributed fibers, belongs to optical-fiber temperature measuring technical field;A kind of temperature-measuring system of distributed fibers of the utility model includes: laser, optical circulator, the first optical filter, the second optical filter, photoelectric conversion circuit and capture card;The laser of the laser transmitting enters sensor fibre to be measured by the optical circulator, the back-scattering light that laser generates in communication process in the sensor fibre to be measured respectively enters first optical filter after returning to the optical circulator and the second optical filter wave is filtered, filtered back-scattering light enters the photoelectric conversion circuit, and the electric signal of the photoelectric conversion circuit output is transferred to processing on computer after capture card acquisition and obtains temperature signal.The temperature-measuring system of distributed fibers of the utility model can effectively improve the temperature accuracy of temperature-measuring system of distributed fibers, enhance stability and compared with low spatial resolution.
Description
Technical field
The utility model relates to a kind of temperature-measuring system of distributed fibers, belong to optical-fiber temperature measuring technical field.
Background technique
Distributed fiber temperature measuring device passes through the development of more than ten years, with its measure distance, precision it is high,
The advantages that no measurement dead area, strong anti-electromagnetic interference capability, be widely used in power cable tunnel, pipe gallery,
Coal industry and data center etc. need thermometric, fire alarm and the field of energy-saving and emission-reduction.
Distributed fiber temperature measuring device is to utilize made of spontaneous Raman scattering effect, anti-Stokes Anti-
Stokes signal is temperature sensitive, and Stokes signal Stokes can calculate temperature-insensitive using the ratio between its light intensity
Out along the temperature value of optical fiber each point, is realized and be accurately positioned using its Rayleigh scattering technology.Therefore, spatial resolution and thermometric essence
Degree is its important characterization parameter.When measuring the temperature field along optical fiber, always wish that spatial resolution is the smaller the better, temperature is smart
The higher the better for degree.And the raising of spatial resolution is limited to the pulse width of laser, the sampling rate of capture card, to guarantee
1 meter of spatial resolution it is necessary to guarantee laser pulse width be less than 10ns, capture card sampling rate be greater than 100Mb/s,
And the common method of temperature accuracy is improved as digital cumulative mean method, this method can improve signal-to-noise ratio to a certain extent, but increase
Add the thermometric time, often deteriorates its real-time to reach enough precision.
Utility model content
The purpose of this utility model is to provide a kind of temperature-measuring system of distributed fibers, can effectively improve distribution type fiber-optic
The temperature accuracy of temp measuring system enhances stability and compared with low spatial resolution.
It is as follows that the utility model provides technical solution:
On the one hand, the utility model provides a kind of temperature-measuring system of distributed fibers, comprising: laser, light
Circulator, the first optical filter, the second optical filter, photoelectric conversion circuit and capture card;
The laser of the laser transmitting enters sensor fibre to be measured, laser by the optical circulator
The back-scattering light generated in communication process in the sensor fibre to be measured divides after returning to the optical circulator
Not Jin Ru first optical filter and the second optical filter wave be filtered, described in filtered back-scattering light enters
Photoelectric conversion circuit, the electric signal of the photoelectric conversion circuit output is transferred on computer after capture card acquisition to be handled
Obtain temperature signal.
An embodiment according to the present utility model, first optical filter and second optical filter are
Tunable optic filter, first optical filter is for being filtered Rayleigh scattering light, the second light filtering
Device is for being filtered the anti-Stokes light of backward Raman scattering.
Another embodiment according to the present utility model, further includes optical splitter, the input of the optical splitter
End connects the optical circulator, two output ends of the optical splitter respectively with first optical filter and institute
The second optical filter is stated to be connected.
Another embodiment according to the present utility model, further includes photoswitch, is used for first optical filter
With the switching of the filtered back-scattering light of the second optical filter.
Another embodiment according to the present utility model, the capture card include a sampling controller, the controlling of sampling
The electric signal deposit caching for the photoelectric conversion circuit output that device is used to acquire.
Another embodiment according to the present utility model, further includes isochronous controller, the isochronous controller respectively with institute
It states laser to be connected with the capture card, the sampling controller is under the clock signal of the first clock domain by the telecommunications of acquisition
The isochronous controller number alternately is sent in two cachings of deposit and by two handshake, and the isochronous controller will receive
Two handshake arrived as second clock domain clock effectively along synchronous handshake, with control to being deposited in caching
The movement that the data of storage are read out, store, being added.
Another embodiment according to the present utility model, the laser are pulse width tunable laser.
Another embodiment according to the present utility model, the laser are semiconductor laser or optical fiber laser.
Another embodiment according to the present utility model, the photoelectric conversion circuit are list APD photoelectric conversion circuit.
Another embodiment according to the present utility model, the capture card are single channel capture card, and sampling rate is
250Mb/s。
The beneficial effects of the utility model are as follows:
The temperature-measuring system of distributed fibers of the utility model include laser, optical circulator, the first optical filter,
Second optical filter, photoelectric conversion circuit and capture card, structure are simple.The laser of laser transmitting is through ring of light row
Device enters in sensor fibre to be measured, after the back-scattering light that laser generates in communication process in optical fiber returns to optical circulator
It respectively enters the first optical filter and the second optical filter wave is filtered, obtain filtered Rayleigh scattering light and backward Raman
Through photoelectric conversion circuit after the anti-Stokes light of scattering, in the electric signal transmission to computer after capture card acquisition conversion
Reason obtains temperature signal.The temperature-measuring system of distributed fibers of the utility model embodiment is filtered by the first optical filter and the second light
Wave device, which is respectively adopted, is filtered the anti-Stokes light of Rayleigh scattering light and backward Raman scattering, is obtained by twofold detection
Anti-Stokes and the ratio of Stokes backward Raman scattering light intensity and the ratio of anti-Stokes and Rayleigh scattering light intensity
Value, integrated temperature measurement result effectively improve temperature measurement accuracy.
The temperature-measuring system of distributed fibers of the utility model is synchronous with capture card by isochronous controller control laser, real
The synchronous acquisition of existing data can effectively increase sampling rate, and then reduce spatial resolution;Using the laser of adjustable pulse width
Pulse width can be effectively controlled, effectively adjusting spatial resolution;Photoelectric conversion signal can be guaranteed using single APD sample circuit
Consistency, reduce signal-to-noise ratio, increase stability and temperature accuracy;It can guarantee that analog signal is put using single channel capture card
Greatly, analog-to-digital conversion reduces signal-to-noise ratio to the consistency of effect of signals, increases stability and temperature accuracy.
Detailed description of the invention
Fig. 1 is the structural block diagram of one embodiment of the temperature-measuring system of distributed fibers of the utility model;
Fig. 2 is the structural block diagram of another embodiment of the temperature-measuring system of distributed fibers of the utility model.
Specific embodiment
In order to make the technical problems, technical solutions and advantages to be solved by the utility model clearer, below in conjunction with attached drawing
And specific embodiment is described in detail.
The sensing principle of temperature-measuring system of distributed fibers is mainly based on optical time domain reflection (O principle and the optical fiber of optical fiber
Backward Raman scattering temperature effect.
Optical time domain reflection principle: when laser pulse transmits in a fiber, due in optical fiber there are refractive index it is microcosmic not
Uniformity can generate scattering.In time domain, it is t, laser arteries and veins that incident light, which returns to optical fiber incidence end required time through back scattering,
Rushing the distance passed by a fiber is 2L, and wherein v is light spread speed in a fiber, C is the light velocity in vacuum, and n is light
Fine refractive index.When measuring moment t, so that it may acquire away from the distance at light source L, i.e.,, realize the positioning of temperature spot in optical fiber
Function.Backward Raman scattering temperature effect: when a laser pulse injects optical fiber from one end of optical fiber, this light pulse can edge
Optical fiber advance direction propagate.Since elastic collision and inelastic collision, Gu Guangmai occur for light pulse and inside of optical fibre molecule
Punching every bit in the air can all generate reflection, there is the reflected light of sub-fraction in reflection, direction just with incident light
It is contrary (also referred to as backward).The intensity of this back reflected laser and the temperature of the reflection point in light have certain related
Relationship.The temperature (environment temperature locating for the optical fiber) of reflection point is higher, and the intensity of reflected light is also bigger.It is existing using this
As if the intensity of back reflected laser can be measured, so that it may which the temperature for calculating reflection point, here it is utilize optical fiber measurement temperature
Basic principle.According to Raman scattering theory, under the conditions of natural Raman scattering, anti-Stokes light intensity IaWith Stokes light intensity
IsRatio R (T) are as follows:
Wherein, h is planck constant;C is the light velocity in vacuum;U is wave-number migration amount;K is Boltzmann constant;T is
Thermodynamic temperature, Vs are Stokes Raman photon frequency;Vas is the frequency of anti-Stokes Raman photon;αs,αas
The respectively optical loss coefficient of stokes light and anti-Stokes light in a fiber;L indicates the position in optical fiber.It can see
OutIt is only related with temperature T, it accordingly can be by detecting the ratio between anti-Stokes and Stokes backward Raman scattering light intensity
Value realizes temperature precise measurement.
In Rayleigh scattering and Raman scattering techniques used in temperature-measuring system of distributed fibers, Rayleigh scattering and Raman dissipate
The stokes light hit is temperature independent, and the anti-Stokes light in Raman scattering is directly proportional to temperature, i.e., temperature is got over
High anti-Stokes light intensity is stronger.That is pass through detection anti-Stokes and Stokes backward Raman scattering light intensity
Ratio realize temperature measurement, can also
To realize temperature measurement by detection the ratio between anti-Stokes and Rayleigh scattering light intensity value, i.e.,
Wherein,It is the Phonon frequency of an optical fiber molecule, is 13.2Thz,For the frequency of Rayleigh scattering photon, i.e.,
The frequency of incident light.
On the one hand, as shown in Figs. 1-2, the utility model embodiment provides a kind of distributed optical fiber temperature measurement system
System, comprising: laser 10, optical circulator 20, the first optical filter 30, the second optical filter 40, photoelectric conversion electricity
Road 50 and capture card 60;
The laser that the laser 10 emits enters sense light to be measured by the optical circulator 20
Fine X, the back-scattering light that laser generates in communication process in the sensor fibre X to be measured return to the ring of light
Respectively enter first optical filter 30 after row device 20 and the second optical filter wave 40 be filtered, it is filtered backwards
It scatters light and enters the photoelectric conversion circuit 50, the electric signal that the photoelectric conversion circuit 50 exports is acquired through the capture card 60
After be transferred on computer processing and obtain temperature signal.
The temperature-measuring system of distributed fibers of the utility model embodiment includes laser, optical circulator, the first light
Filter, the second optical filter, photoelectric conversion circuit and capture card, structure are simple.The laser of laser transmitting
It is entered in sensor fibre to be measured through optical circulator, the back-scattering light that laser generates in communication process in optical fiber returns to light
Respectively enter the first optical filter after circulator and the second optical filter wave be filtered, obtain filtered Rayleigh scattering light and
Through photoelectric conversion circuit after the anti-Stokes light of backward Raman scattering, capture card acquires the electric signal transmission after conversion to meter
Processing obtains temperature signal on calculation machine.The temperature-measuring system of distributed fibers of the utility model embodiment by the first optical filter and
Second optical filter, which is respectively adopted, is filtered the anti-Stokes light of Rayleigh scattering light and backward Raman scattering, by dual
Detect the ratio for obtaining anti-Stokes and Stokes backward Raman scattering light intensity and anti-Stokes and Rayleigh scattering light
Strong ratio, integrated temperature measurement result, effectively improves temperature measurement accuracy.
As one for example, described the first of the temperature-measuring system of distributed fibers of the utility model embodiment
Optical filter and second optical filter are tunable optic filter, and first optical filter is used to dissipate Rayleigh
It penetrates light to be filtered, second optical filter is for being filtered the anti-Stokes light of backward Raman scattering.
As another for example, the temperature-measuring system of distributed fibers of the utility model embodiment further includes light
Splitter 70, the input terminal connection optical circulator 20 of the optical splitter 70, the two of the optical splitter 70
A output end is connected with first optical filter 30 and second optical filter 40 respectively.The utility model embodiment
Optical splitter is the optical splitter that splitting ratio does not wait, such as splitting ratio is 5:95.
As another for example, the temperature-measuring system of distributed fibers of the utility model embodiment further includes light
Switch 80, for cutting for first optical filter and the filtered back-scattering light of the second optical filter
It changes.
As another for example, the capture card 60 of the temperature-measuring system of distributed fibers of the utility model embodiment
It is not shown including a sampling controller 61(), the photoelectric conversion circuit output that the sampling controller 61 is used to acquire
Electric signal deposit caching.
As another for example, the temperature-measuring system of distributed fibers of the utility model embodiment further includes synchronously control
Device 90, the isochronous controller 90 are connected with the laser 10 and the capture card 60 respectively, the sampling controller 61
The electric signal of acquisition is alternately stored in two cachings under the clock signal of the first clock domain and sends two handshake
To the isochronous controller 90, the isochronous controller 90 is using receive two handshake as second clock domain
Clock is effectively along synchronous handshake, to control the movement for being read out, storing, being added to the data stored in caching.
The temperature-measuring system of distributed fibers of the utility model embodiment controls laser and capture card by isochronous controller
It is synchronous, it realizes the synchronous acquisition of data, sampling rate can be effectively increased, and then reduce spatial resolution.
As another for example, the laser of the temperature-measuring system of distributed fibers of the utility model embodiment is
Pulse width tunable laser.The temperature-measuring system of distributed fibers of the utility model embodiment can using the laser of adjustable pulse width
Effectively to control pulse width, spatial resolution is effectively adjusted.
As another for example, the laser of the temperature-measuring system of distributed fibers of the utility model embodiment is
Semiconductor laser or optical fiber laser.
As another for example, the photoelectric conversion of the temperature-measuring system of distributed fibers of the utility model embodiment
Circuit is list APD photoelectric conversion circuit.Photoelectric conversion is carried out to Stokes and anti-Stokes compared to using double APD, by
In using double APD introduced inconsistent accuracys that will affect measurement of noise, the distribution type fiber-optic of the utility model embodiment
Temp measuring system uses list APD photoelectric conversion circuit, can solve this problem.It can guarantee the consistency of photoelectric conversion signal,
Signal-to-noise ratio is reduced, stability and temperature accuracy are increased.
As another for example, the capture card of the temperature-measuring system of distributed fibers of the utility model embodiment
For single channel capture card, sampling rate 250Mb/s.The temperature-measuring system of distributed fibers of the utility model embodiment uses single-pass
Road capture card can guarantee that analog signal amplification, analog-to-digital conversion to the consistency of effect of signals, reduce signal-to-noise ratio, increase stability
And temperature accuracy.
Therefore, the temperature-measuring system of distributed fibers of the utility model embodiment can effectively improve distributed optical fiber temperature measurement system
The temperature accuracy of system enhances stability and compared with low spatial resolution, spatial resolution 0.5m, temperature within the scope of 10km may be implemented
Spend the space temperature measurement of precision ± 0.5 DEG C.
The above is preferred embodiments of the present invention, it is noted that for the ordinary skill of the art
For personnel, under the premise of not departing from principle described in the utility model, it can also make several improvements and retouch, these improvement
It also should be regarded as the protection scope of the utility model with retouching.
Claims (10)
1. a kind of temperature-measuring system of distributed fibers characterized by comprising laser, optical circulator,
First optical filter, the second optical filter, photoelectric conversion circuit and capture card;
The laser of the laser transmitting enters sensor fibre to be measured, laser by the optical circulator
The back-scattering light generated in communication process in the sensor fibre to be measured return to the optical circulator after respectively into
Enter first optical filter and the second optical filter wave is filtered, filtered back-scattering light enters the photoelectricity
Conversion circuit, the electric signal of the photoelectric conversion circuit output are transferred to processing on computer after capture card acquisition and obtain
Temperature signal.
2. a kind of temperature-measuring system of distributed fibers according to claim 1, which is characterized in that institute
It states the first optical filter and second optical filter is tunable optic filter, first optical filter is used for Rayleigh
Scattering light is filtered, and second optical filter is for being filtered the anti-Stokes light of backward Raman scattering.
3. a kind of temperature-measuring system of distributed fibers according to claim 2, which is characterized in that also
Including optical splitter, the input terminal of the optical splitter connects the optical circulator, two outputs of the optical splitter
End is connected with first optical filter and second optical filter respectively.
4. a kind of temperature-measuring system of distributed fibers according to claim 3, which is characterized in that also
Including photoswitch, for cutting for first optical filter and the filtered back-scattering light of the second optical filter
It changes.
5. a kind of temperature-measuring system of distributed fibers according to claim 1 to 3, which is characterized in that the capture card packet
A sampling controller is included, the electric signal deposit for the photoelectric conversion circuit output that the sampling controller is used to acquire is slow
It deposits.
6. a kind of temperature-measuring system of distributed fibers according to claim 5, which is characterized in that it further include isochronous controller,
The isochronous controller is connected with the laser and the capture card respectively, and the sampling controller is in the first clock domain
The electric signal of acquisition is alternately stored in two cachings under clock signal and two handshake are sent to the synchronously control
Device, the isochronous controller are effectively held along synchronous using receive two handshake as the clock in second clock domain
Hand signal, to control the movement for being read out, storing, being added to the data stored in caching.
7. a kind of temperature-measuring system of distributed fibers according to claim 1, which is characterized in that
The laser is pulse width tunable laser.
8. a kind of temperature-measuring system of distributed fibers according to claim 7, which is characterized in that
The laser is semiconductor laser or optical fiber laser.
9. a kind of temperature-measuring system of distributed fibers according to claim 1, which is characterized in that the photoelectric conversion circuit is
Single APD photoelectric conversion circuit.
10. a kind of temperature-measuring system of distributed fibers according to claim 1, which is characterized in that the capture card is single
Channel capture card, sampling rate 250Mb/s.
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