Background technology
Present distributed fiberoptic sensor mainly contains two classes: a class is the Raman fiber sensor, and another kind of is the Brillouin light fiber sensor.The Raman fiber sensor is used and is subjected to certain restriction owing to only possess the temperature survey function; And the Brillouin light fiber sensor has been obtained development fast because can temperature and strain parameter be measured simultaneously and obtain extensive studies.The Brillouin light fiber sensor is realized the measurement of distributed sensor to temperature and strain by each position of detection fiber frequency shift amount spontaneous dorsad or the relative incident light of stimulated Brillouin scattering light, and its advantage is that distance sensing is long, the spatial resolution height.But because the Brillouin shift amount is responsive simultaneously to temperature and strain two physical quantitys, and with the two linear dependence, therefore there is temperature strain cross sensitivity problem in actual applications, promptly be difficult to from the Brillouin shift amount that finally obtains, to isolate the variable quantity that temperature and strain cause separately, seriously hindered the engineering of this type of sensor and promoted.Solving the common technology that adopts of temperature strain cross sensitivity problem at present has following several:
1, two parametric methods of scattered light intensity and frequency displacement (J.Smith et al., " Simultaneous distributed strain andtemperature measurement; " Appl.Opt, 38:5372-5377,1999), these class methods are by measuring backscattering light intensity and frequency shift amount simultaneously, simultaneous equations solve temperature and strain variation amount, but the measurement of Brillouin light intensity has limited the detection range of sensor, and light intensity is vulnerable to external disturbance, the influence of problems such as light source output power shake and polarization state drift.
2, Landau-Placzek ratio method (P.C.Wait and T.P.Newson, " Landau-Placzek ratioapplied todistributed fibre sensing; " Optics Communications, 122 (4-6): 141-146,1996), these class methods are measured the Brillouin scattering light intensity and simultaneously to the insensitive Rayleigh scattering light intensity of strain, extract temperature variation by calculating the two ratio (Landau-Placzek ratio), but the measurement of Rayleigh scattering light has limited the detection length and the spatial resolution of sensor, and the simultaneity factor complexity significantly improves.
3, special fiber method (X.Bao, Q.Yu and L.Chen, " Simultaneous strain and temperaturemeasurements with polarization-maintaining fibers and their error analysis by use ofadistributed Brillouin loss system " Optics letters 29 (12): 1342-1344,2004), these class methods adopt polarization maintaining optical fibre, photonic crystal fiber, special fibers such as large effective area fiber are distinguished temperature strain two physical quantitys, but because special fiber mostly costs an arm and a leg, it is too high therefore to be used for long distance applications cost.
For from solving temperature and strain cross sensitivity problem in essence, other physical influence method of associating has been proposed, both at home and abroad as the effect of associating Raman scattering and Brillouin scattering.External paper Proc.SPIE, 2004 " Simultaneousdistributed measurements of temperature and strain using spontaneous raman andBrillouin
In May, 2009, the Chinese utility model patent instructions of CN200710156868.0 of Granted publication on the 27th disclosed a kind of " very-long-range distributed fiber Raman and Brillouin's photon sensor ", proposed the distributed type optical fiber Raman photon temperature sensor, the mode that distribution type fiber-optic Brillouin photon strain transducer and distributed fiber Raman fiber amplifier merge, realization temperature and strain are measured simultaneously, but the light source of the light source of its Brillouin sensing device and Raman sensor has adopted the mode of common optical fiber coupling mechanism, increased the loss of luminous power, and the light source of its Brillouin sensing device has adopted exocoel narrow-band impulse fiber laser, and pulsed light has difficulties when Coherent Detection.
In May, 2009, the Chinese utility model patent instructions of CN200710175868.5 of Granted publication on the 20th disclosed a kind of " optical fiber distributed temperature and stress sensing device ", proposed fiber raman scattering as temperature information, Brillouin scattering as strain information distributed sensing temperature and strain simultaneously, provided the calibration formula of temperature and strain, but its measuring optical fiber is a polarization maintaining optical fibre, has limited the range of application of sensor.
In sum, can effectively solve temperature and strain cross sensitivity problem in conjunction with Raman scattering and Brillouin scattering effect, but existing combination mainly is a common light source, adopt special fiber or use fiber coupler, like this or the temperature that records and strain parameter precision not enough, perhaps cost height, range of application is narrow, and existing associated methods all is the Brillouin light time domain reflection sense device (BOTDR) at single-ended measurement, the Brillouin optical time domain analysis sensor (BOTDA) that can not be used for the double-end measurement mode, because what Brillouin light time domain reflection sense device (BOTDR) was measured is very faint spontaneous brillouin scattering light, and Brillouin optical time domain analysis sensor (BOTDA) measurement is stronger stimulated Brillouin scattering light, so far above BOTDR, and measurement range is bigger to the measuring accuracy of temperature and strain for BOTDA.
Summary of the invention
Technical problem to be solved in the utility model provides the distributed fiberoptic sensor of a kind of suitable Brillouin optical time domain analysis sensor (BOTDA), utilize this sensor can solve temperature and strain cross sensitivity problem, realization temperature and strain parameter are measured simultaneously.
The utility model solves the problems of the technologies described above the technical scheme that is adopted: a kind of distribution type fiber-optic temperature and strain transducer, comprise the Brillouin light time domain analyzer module, the detection optical fiber module, the Raman fiber temperature sensor module, first optical switch module, second optical switch module and the 3rd optical switch module, described first optical switch module and described the 3rd optical switch module are respectively arranged with two light signal input ports and a light signal output end mouth, described second optical switch module is provided with a light signal input port and two light signal output end mouths, described Brillouin light time domain analyzer module is provided with two output ports, an output port of described Brillouin light time domain analyzer module is connected with a light signal input port of described first optical switch module, another output port of described Brillouin light time domain analyzer module is connected with a light signal input port of described the 3rd optical switch module, described Raman fiber temperature sensor module is connected with the light signal input port of described second optical switch module, two light signal output end mouths of described second optical switch module are connected with vacant light signal input port on described the 3rd optical switch module with described first optical switch module respectively, the light signal output end mouth of described first optical switch module is connected with the input end of described detection optical fiber module, and the light signal output end mouth of described the 3rd optical switch module is connected with the output terminal of described detection optical fiber module.
The Brillouin light fiber sensor that described Brillouin light time domain analyzer module is made for utilizing the stimulated Brillouin scattering effect.
Described Raman fiber temperature sensor module is for measuring the raman type optical fiber temperature-measurement sensor of single-mode fiber.
Described first optical switch module, second optical switch module and the 3rd optical switch module are 1 * 2 photoswitch.
Described detection optical fiber module is a single-mode fiber.
Described detection optical fiber module is made up of multifiber cable and fused fiber splice module.
Compared with prior art, the utility model advantage is the switching controls by three optical switch modules, make the Raman fiber temperature sensor module and the Brillouin light time domain analyzer module of setting relatively independent to the measurement maintenance of temperature and strain, the temperature measurement result of utilizing the Raman fiber temperature sensor module is as benchmark, from having solved Brillouin optical time domain analysis module temperature and strain cross sensitivity problem in essence; Raman fiber temperature sensor module output signal can enter the two ends of detection optical fiber respectively by the switching of three optical switch modules in addition, both can realize the single-ended measurement of fiber optic temperature, also can realize the fiber optic temperature double-end measurement.The double-end measurement mode has the insensitive advantage of fibre loss, particularly when remote optical fiber temperature-measurement, double-end measurement has overcome the weakness of tail end low precision when traditional Raman fiber temperature sensor is single-ended to be measured, effectively guaranteed temperature accuracy when remote fiber-optic probe, increase the length of optical fiber measurement, expanded measurement range; Owing to the application of optical switch module, reduce the switch number of times of laser instrument in Raman fiber temperature sensor module and the Brillouin light time domain analyzer module in addition, prolonged the serviceable life of Fibre Optical Sensor.
Embodiment
Embodiment describes in further detail the utility model below in conjunction with accompanying drawing.
As depicted in figs. 1 and 2, a kind of distribution type fiber-optic temperature and strain transducer, comprise Brillouin light time domain analyzer module 1, Raman fiber temperature sensor module 2, first optical switch module 3, second optical switch module 4, the 3rd optical switch module 5 and detection optical fiber module 6, Brillouin light time domain analyzer module 1 is provided with output port 11 and output port 12, first optical switch module 3 is provided with light signal input port 31, light signal input port 32 and light signal output end mouth 33, second optical switch module 4 is provided with light signal input port 41, light signal output end mouth 42 and light signal output end mouth 43, the 3rd optical switch module 5 is provided with light signal input port 51, light signal input port 52 and light signal output end mouth 53, an output port 11 of Brillouin light time domain analyzer module 1 is connected with the light signal input port 31 of first optical switch module 3, another output port 12 of Brillouin light time domain analyzer module 1 is connected with the light signal input port 52 of the 3rd optical switch module 5, Raman fiber temperature sensor module 2 is connected with the light signal input port 41 of second optical switch module 4, the light signal output end mouth 42 of second optical switch module 4 is connected with vacant light signal input port 32 on first optical switch module 3, the light signal output end mouth 43 of second optical switch module 4 is connected with vacant light signal input port 51 on the 3rd optical switch module 5, the light signal output end mouth 33 of first optical switch module 3 is connected with the input end of detection optical fiber module 6, and the light signal output end mouth 53 of the 3rd optical switch module 5 is connected with the output terminal of detection optical fiber module 6.
Embodiment one: as shown in Figure 1, the Brillouin light fiber sensor that Brillouin light time domain analyzer module 1 is made for utilizing the stimulated Brillouin scattering effect, Raman fiber temperature sensor module 2 is for measuring the raman type optical fiber temperature-measurement sensor of single-mode fiber, first optical switch module 3, second optical switch module 4 and the 3rd optical switch module 5 are 1 * 2 photoswitch, detection optical fiber module 6 is a single-mode fiber, and the two ends of single-mode fiber are directly as the input/output terminal of detection optical fiber module.
At first adopt Raman fiber temperature sensor measurement fiber optic temperature, this moment, first optical switch module 3 was set to light signal input port 32 to light signal output end mouth 33 paths, and light signal input port 31 is forbidden to light signal output end mouth 33; The 3rd optical switch module 5 is set to light signal input port 51 to light signal output end mouth 53 paths, and light signal input port 52 is forbidden to light signal output end mouth 53.At this moment, first optical switch module 3 and the 3rd optical switch module 5 disconnect Brillouin light time domain analyzer module 1 and detection optical fiber module 6, and Raman fiber temperature sensor module 2 then links to each other with detection optical fiber module 6 by three optical switch modules.Second optical switch module 4 is set to light signal input port 41 to light signal output end mouth 42 paths, and light signal input port 41 is forbidden to light signal output end mouth 43; At this moment, the detection light signal of Raman fiber sensor for measuring temperature module 2 outputs is from 4 inputs of second optical switch module, import the temperature that detection optical fiber module 6 detects forward optical fiber through first optical switch module, 3 forwards, utilize this moment Raman fiber temperature sensor 2 to measure measured optical fiber forward temperature and be T
R(L).
After obtaining the fiber optic temperature testing result, first optical switch module 3 is set to light signal input port 31 to light signal output end mouth 33 paths, and light signal input port 32 is forbidden to light signal output end mouth 33; The 3rd optical switch module 5 is set to light signal input port 52 to light signal output end mouth 53 paths, and light signal input port 51 is forbidden to light signal output end mouth 53.At this moment, first optical switch module 3 and the 3rd optical switch module 5 disconnect Raman fiber temperature sensor module 2 and detection optical fiber module 6, Brillouin light time domain analyzer module 1 then links to each other with detection optical fiber module 6 by three optical switch modules, optical fiber Brillouin frequency displacement measurement function is enabled by system, the temperature of optical fiber and strain affect Brillouin shift simultaneously, and the frequency shift amount of detection optical fiber module 6 each sections that Brillouin light time domain analyzer module 1 records is designated as Δ v
B(L), the distribution that the relation by Brillouin shift and temperature strain can draw optical fiber strain along the line is designated as ε (L), as shown in the formula (1) formula.
In the formula, C
T, C
εBe respectively temperature, the coefficient of strain of Brillouin shift, for common single mode optical fibres, temperature coefficient C
TGet 1.07MHz/ ℃, coefficient of strain C
εGet 0.05MHz/ μ ε.
In sum, in conjunction with the optical fiber forward temperature T that from Raman fiber sensor assembly 2, obtains
R(L) with Brillouin light time domain analyzer module 1 in the Brillouin shift Δ v that obtains
B(L) can draw the strain information of optical fiber whole process, realize that temperature and strain measure simultaneously.
Embodiment two: as shown in Figure 2, the Brillouin light fiber sensor that Brillouin light time domain analyzer module 1 is made for utilizing the stimulated Brillouin scattering effect, Raman fiber temperature sensor module 2 is for measuring the raman type optical fiber temperature-measurement sensor of single-mode fiber, and first optical switch module 3, second optical switch module 4 and the 3rd optical switch module 5 are 1 * 2 photoswitch; Detection optical fiber module 6 is made up of fused fiber splice module 7 and twin fiber cable 8, wherein twin fiber cable 8 comprises two single-mode fibers, a wherein end of two single-mode fibers links together by fused fiber splice module 7, the other end 61 of two single-mode fibers and 62 two input ends as detection optical fiber module 6.
At first adopt Raman fiber temperature sensor measurement fiber optic temperature, this moment, first optical switch module 3 was set to light signal input port 32 to light signal output end mouth 33 paths, and light signal input port 31 is forbidden to light signal output end mouth 33; The 3rd optical switch module 5 is set to light signal input port 51 to light signal output end mouth 53 paths, and light signal input port 52 is forbidden to light signal output end mouth 53.At this moment, first optical switch module 3 and the 3rd optical switch module 5 disconnect Brillouin light time domain analyzer module 1 and detection optical fiber module 6, and Raman fiber temperature sensor module 2 then links to each other with detection optical fiber module 6 by three optical switch modules.Second optical switch module 4 is set to light signal input port 41 to light signal output end mouth 42 paths, and light signal input port 41 is forbidden to light signal output end mouth 43; At this moment, the detection light signal of Raman fiber sensor for measuring temperature module 2 outputs is from 4 inputs of second optical switch module, import the temperature that detection optical fiber modules 6 detect detection optical fiber through first optical switch module 3, utilize Raman fiber temperature sensor 2 measured optical fiber forward temperature to be T this moment
R(L).
After obtaining the fiber optic temperature testing result, first optical switch module 3 is set to light signal input port 31 to light signal output end mouth 33 paths, and light signal input port 32 is forbidden to light signal output end mouth 33; The 3rd optical switch module 5 is set to light signal input port 52 to light signal output end mouth 53 paths, and light signal input port 51 is forbidden to light signal output end mouth 53.At this moment, first optical switch module 3 and the 3rd optical switch module 5 disconnect Raman fiber temperature sensor module 2 and detection optical fiber module 6, Brillouin light time domain analyzer module 1 then links to each other with detection optical fiber module 6 by three optical switch modules, optical fiber Brillouin frequency displacement measurement function is enabled by system, the temperature of optical fiber and strain affect Brillouin shift simultaneously, and the frequency shift amount of detection optical fiber module 6 each sections that Brillouin light time domain analyzer module 1 records is designated as Δ v
B(L), the distribution that the relation by Brillouin shift and temperature strain can draw optical fiber strain along the line is designated as ε (L), as shown in the formula (1) formula.
In the formula, C
T, C
εBe respectively temperature, the coefficient of strain of Brillouin shift, for common single mode optical fibres, temperature coefficient C
TGet 1.07MHz/ ℃, coefficient of strain C
εGet 0.05MHz/ μ ε.
In sum, in conjunction with the optical fiber forward temperature T that from Raman fiber sensor assembly 2, obtains
R(L) with Brillouin light time domain analyzer module 1 in the Brillouin shift Δ v that obtains
B(L) can draw the strain information of optical fiber whole process, realize the measurement of temperature and strain.
Embodiment three: the present embodiment structure is with embodiment two, and different with embodiment two is originally to be implemented in and to have adopted double-end measurement mode, double-end measurement mode temperature stack synoptic diagram in the Raman fiber thermometric shown in figure (3).
At first adopt Raman fiber temperature sensor measurement fiber optic temperature, this moment, first
optical switch module 3 was set to light
signal input port 32 to light signal
output end mouth 33 paths, and light
signal input port 31 is forbidden to light signal
output end mouth 33; The 3rd
optical switch module 5 is set to light
signal input port 51 to light signal
output end mouth 53 paths, and light
signal input port 52 is forbidden to light signal output end mouth 53.At this moment, first
optical switch module 3 and the 3rd
optical switch module 5 disconnect Brillouin light time domain analyzer module 1 and detection
optical fiber module 6, Raman fiber temperature sensor module 2 then links to each other with detection
optical fiber module 6 by three optical switch modules, can be respectively with
input end 61 and
input end 62 inputs of Raman fiber temperature measurement signal from detection
optical fiber module 6 by the switching of second optical switch module 4.Second
optical switch module 4 is set to light
signal input port 41 to light signal
output end mouth 42 paths, and light
signal input port 41 is forbidden to light signal
output end mouth 43; At this moment, the detection light signal of Raman fiber sensor for measuring temperature module 2 outputs detects detection optical fiber forward temperature from 4 inputs of second optical switch module through first optical switch module, 3 input detection
optical fiber modules 6, and this moment, the measuring optical fiber temperature was designated as T
1(L
1).Second
optical switch module 4 is set to light
signal input port 41 to light signal
output end mouth 43 paths, and light
signal input port 41 is forbidden to light signal
output end mouth 42; At this moment, the detection light signal of Raman fiber sensor for measuring temperature module 2 outputs detects the reverse temperature of detection optical fiber from 4 inputs of second optical switch module through the 3rd
optical switch module 5 input detection
optical fiber modules 6, and this moment, the measuring optical fiber temperature was designated as T
2(L
2).This moment, fiber distance L2 was the distance at the fiber distance second optical switch module place, and L1 is the distance at the fiber distance first optical switch module place, and therefore, it is L1=L-L2 that two fiber position are closed, and wherein L is a fiber lengths, and forward is measured temperature T
1(L
1) and oppositely measure temperature T
2(L
2) be temperature detection result apart from being averaged after the negate in whole piece detection
optical fiber module 6, utilize this moment the fine distance of Raman fiber temperature sensor 2 double-end measurement mode institutes photometry to be designated as for the temperature variation at L place
Shown in figure (3), little at the measuring junction temperature noise, the tail end temperature noise is bigger when single-ended measurements, behind the employing double-end measurement, measuring junction and tail end noise are all less, and the temperature on the whole piece optical fiber is even.
After obtaining the fiber optic temperature testing result, first optical switch module 3 is set to light signal input port 31 to light signal output end mouth 33 paths, and light signal input port 32 is forbidden to light signal output end mouth 33; The 3rd optical switch module 5 is set to light signal input port 52 to light signal output end mouth 53 paths, and light signal input port 51 is forbidden to light signal output end mouth 53.At this moment, first optical switch module 3 and the 3rd optical switch module 5 disconnect Raman fiber temperature sensor module 2 and detection optical fiber module 6, Brillouin light time domain analyzer module 1 then links to each other with detection optical fiber module 6 by three optical switch modules, optical fiber Brillouin frequency displacement measurement function is enabled by system, the temperature of optical fiber and strain affect Brillouin shift simultaneously, and the frequency shift amount of detection optical fiber module 6 each sections that Brillouin light time domain analyzer module 1 records is designated as Δ v
B(L), the distribution that the relation by Brillouin shift and temperature strain can draw optical fiber strain along the line is designated as ε (L), as shown in the formula (1) formula.
In the formula, C
T, C
εBe respectively temperature, the coefficient of strain of Brillouin shift, for common single mode optical fibres, temperature coefficient C
TGet 1.07MHz/ ℃, coefficient of strain C
εGet 0.05MHz/ μ ε.
In sum, the fiber optic temperature T that obtains in conjunction with double-end measurement from Raman fiber sensor assembly 2
R(L) with Brillouin light time domain analyzer module 1 in the Brillouin shift Δ v that obtains
B(L) can draw the strain information of optical fiber whole process, realize the measurement of temperature and strain.