CN102538945B - Cross-polarization control-based distributed vibration sensing system and method - Google Patents
Cross-polarization control-based distributed vibration sensing system and method Download PDFInfo
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- CN102538945B CN102538945B CN201210060029.XA CN201210060029A CN102538945B CN 102538945 B CN102538945 B CN 102538945B CN 201210060029 A CN201210060029 A CN 201210060029A CN 102538945 B CN102538945 B CN 102538945B
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Abstract
The invention discloses a cross-polarization control-based distributed vibration sensing system, belonging to the technical field of distributed optical fiber vibration sense. The system comprises a light source, a polarization controller, an optical modulator, a coupler, a photoelectric receiving part, a data processing and control part. The system is mainly characterized in that the light source sends out a narrow-line width continuous linear polarization light, the light is divided into two beams by the coupler, and a polarization controller (PC) respectively controls the polarization state of the two linear polarization light, so that the linear polarization light is changed according to a certain period, and the polarization state of the two linear polarization light is orthogonal with each other. The cross-polarization light is injected into the sensing optical fiber through the coupler, the backscatter light of the cross-polarization light is received by the photoelectric receiving part, and the backscatter light is transmitted into the data processing and control part. The technical difficulties of a distributed vibration sensor such as unstable signal, higher sensitivity undulation and the like caused by polarization fading can be preferably solved.
Description
Technical field
The present invention relates to optical fiber vibration sensing field, particularly relate to the distributed vibration sensing system and method that control based on cross polarization.
Background technology
Radiationless interference, anti-interference are good, good chemical stability except having for distributed fiberoptic sensor (DOFS), can also go up on the way obtain the information of measured amount at Time and place simultaneously at optical fiber.Distributed fiber optic sensing know-why mainly contains two large classes: interference technique and OTDR technology.Interference technique mainly contains Sagnac formula interference technique, M-Z interference technique, Michelson interference technique.What can realize distributed measurement mainly contains first two.OTDR kind is abundanter, and principle is mainly based on Rayleigh scattering, Brillouin scattering, Raman scattering, polarization state change etc.Except common OTDR, also has ROTDR, BOTDR/BOTDA, POTDR, Φ-OTDR etc.In above measuring method, Φ-OTDR is by measuring the phase place change of backward Rayleigh scattering, and the positioning precision advantages of higher be simultaneously provided with in the highly sensitive of interference technique and OTDR technology, in safety protection technique, therefore become a kind of competitive selection.Φ-OTDR technology based on ultra-narrow bandwidth light source has that detection sensitivity is high, system signal process is simple, measuring speed is fast, accurate positioning, measuring distance is longer, signal to noise ratio (S/N ratio) is high, low cost and other advantages, but polarization correlated due to relevant Rayleigh scattered signal, polarization decay phenomenon is there will be in long distance Φ-OTDR system, the impact of distance this polarization decay longer is more serious, can have a strong impact on the detection performance of Φ-OTDR system.But the polarization control technology being applied to Φ-OTDR system is at present considerably less, also there is not yet the method for the better head it off of energy, hinder development and the application of Φ-OTDR system.
Summary of the invention
In order to solve deficiency of the prior art, the invention provides a kind of distributed vibration sensing system controlled based on cross polarization that effectively can solve the intrinsic polarization decay of distributed interference system, and applying the method for sensing of above-mentioned sensor-based system.
The object of the invention is to be achieved by following technical solution:
Based on the distributed vibration sensing system that cross polarization controls, comprise light source, sensor fibre and detector; Described sensor-based system comprises further:
First coupling mechanism, described first coupling mechanism is used for the optically-coupled that described light source sends to enter the first light path and the second light path;
First Polarization Controller, described first polarizer is arranged in described first light path;
Second Polarization Controller, described second polarizer is arranged in described second light path;
Control module, described control module is orthogonal with by the polarisation of light direction of described second Polarization Controller for making by the light of described first Polarization Controller;
Second coupling mechanism, the scattered light in described sensor fibre for described sensor fibre is entered in the optically-coupled in the first light path, the second light path, and is coupled into described detector by described second coupling mechanism;
Signal processing module, the electric signal that described in described signal processing module process, detector sends, thus the extraneous vibration information knowing described sensor fibre perception.
According to above-mentioned sensor-based system, preferably, described light source is light-pulse generator.
According to above-mentioned sensor-based system, alternatively, described sensor-based system comprises further:
Photomodulator, described photomodulator is used for making continuous light be modulated to pulsed light;
Described second coupling mechanism comprises further:
3rd coupling mechanism, described 3rd coupling mechanism is for entering described photomodulator by the optically-coupled in described first light path, the second light path;
4th coupling mechanism, described 4th coupling mechanism is used for the pulsed light by described photomodulator to be coupled into described sensor fibre, and the scattered light in described sensor fibre is coupled into described detector;
Described light source is continuous light source.
According to above-mentioned sensor-based system, preferably, described photomodulator is electrical-optical or acousto-optic modulator.
According to above-mentioned sensor-based system, preferably, described light source is laser instrument.
Object of the present invention is also achieved by following technical solution:
Based on the distributed vibration sensing method that cross polarization controls, described method for sensing comprises the following steps:
(A1) light that light source sends is coupled into the first light path and the second light path;
(A2) adjust the polarisation of light direction in the first light path and the second light path, make polarization direction orthogonal;
(A3) two-way optically-coupled orthogonal for polarization direction is entered the sensor fibre of perception extraneous vibration, the scattered light on sensor fibre is coupled into detector;
(A4) described scattered light is converted to electric signal by detector, and is sent to signal processing module;
(A5) electric signal described in signal processing module process, thus know the extraneous vibration of described sensor fibre perception.
According to above-mentioned method for sensing, preferably, the light that described light source sends is pulsed light.
According to above-mentioned method for sensing, alternatively, described step (A3) comprises the steps: further
(B1) photomodulator is entered in two-way optically-coupled orthogonal for polarization direction, light is modulated to pulsed light;
(B2) be coupled into described sensor fibre from described photomodulator light out, and the scattered light on described sensor fibre is coupled into described detector;
The light that described light source sends is continuous light.
According to above-mentioned method for sensing, preferably, described modulator is electrical-optical or acousto-optic modulator.
According to above-mentioned method for sensing, preferably, described light source is laser instrument.
Compared with prior art, the present invention has following beneficial effect:
The present invention adopts cross polarization control technology, by two Polarization Controllers, light is exported to light source and carry out Polarization Control, solve polarization decay phenomenon intrinsic in Φ-OTDR system, for the development and production realizing reliable and stable Φ-OTDR system provide foundation and reference.
Accompanying drawing explanation
With reference to accompanying drawing, disclosure of the present invention will be easier to understand.Those skilled in the art it is easily understood that: these accompanying drawings only for illustrating technical scheme of the present invention, and and are not intended to be construed as limiting protection scope of the present invention.In figure:
Fig. 1 is the basic block diagram of the distributed vibration sensing system of the embodiment of the present invention 1;
Fig. 2 is the process flow diagram of the distributed vibration sensing method of the embodiment of the present invention 1;
Fig. 3 is the basic block diagram of the distributed vibration sensing system of the embodiment of the present invention 2;
Fig. 4 is the process flow diagram of the distributed vibration sensing method of the embodiment of the present invention 2.
Concrete embodiment
Fig. 1-4 and following description describe Alternate embodiments of the present invention and how to implement to instruct those skilled in the art and to reproduce the present invention.In order to instruct technical solution of the present invention, simplifying or having eliminated some conventional aspects.Those skilled in the art should understand that the modification that is derived from these embodiments or replace will within the scope of the invention.Those skilled in the art should understand that following characteristics can combine to form multiple modification of the present invention in every way.Thus, the present invention is not limited to following Alternate embodiments, and only by claim and their equivalents.
Embodiment 1:
Fig. 1 schematically illustrates the basic block diagram of the distributed vibration sensing system based on cross polarization control of the embodiment of the present invention, and as shown in Figure 1, described sensor-based system comprises light source (being preferably light-pulse generator), sensor fibre and detector; Described sensor-based system comprises further:
First coupling mechanism 1, described first coupling mechanism 1 enters the first light path and the second light path for the optically-coupled sent by described light source;
First Polarization Controller, described first polarizer is arranged in described first light path;
Second Polarization Controller, described second polarizer is arranged in described second light path;
Control module, described control module is orthogonal with by the polarisation of light direction of described second Polarization Controller for making by the light of described first Polarization Controller;
Second coupling mechanism 4, the scattered light in described sensor fibre for described sensor fibre is entered in the optically-coupled in the first light path, the second light path, and is coupled into described detector by described second coupling mechanism 4;
Signal processing module, the electric signal that described in described signal processing module process, detector sends, thus the extraneous vibration information knowing described sensor fibre perception.
According to above-mentioned sensor-based system, preferably, described light source is laser instrument.
Each devices such as above-mentioned Polarization Controller, coupling mechanism, detector, photomodulator are all the state of the art, do not repeat them here.
Fig. 2 schematically illustrates the process flow diagram of the distributed vibration sensing method based on cross polarization control of the embodiment of the present invention, and as shown in Figure 2, described method for sensing comprises the following steps:
(A1) light that light source (being preferably light-pulse generator) sends is coupled into the first light path and the second light path;
(A2) adjust the polarisation of light direction in the first light path and the second light path, make polarization direction orthogonal;
(A3) two-way optically-coupled orthogonal for polarization direction is entered the sensor fibre of perception extraneous vibration, the scattered light on sensor fibre is coupled into detector;
(A4) described scattered light is converted to electric signal by detector, and is sent to signal processing module;
(A5) electric signal described in signal processing module process, thus know the extraneous vibration of described sensor fibre perception.
According to above-mentioned method for sensing, preferably, described modulator is electrical-optical or acousto-optic modulator.
According to above-mentioned method for sensing, preferably, described light source is laser instrument.
Be according to the benefit that the embodiment of the present invention 1 reaches: by the control of the first and second Polarization Controllers, the pulsed light injecting sensor fibre is modulated into the mutually orthogonal two parts light of polarization state, make backscatter signal be unlikely to just to disappear due to polarization decay, but total energy keep certain intensity.
Embodiment 2:
Fig. 3 schematically illustrates the basic block diagram of the distributed vibration sensing system based on cross polarization control of the embodiment of the present invention, as shown in Figure 3, as different from Example 1:
1, light source is continuous light source;
2, sensor-based system comprises further:
Photomodulator, described photomodulator is used for making continuous light be modulated to pulsed light; Preferably, described photomodulator is electrical-optical or acousto-optic modulator;
Described second coupling mechanism comprises further:
3rd coupling mechanism 2, described 3rd coupling mechanism 2 is for entering described photomodulator by the optically-coupled in described first light path, the second light path;
4th coupling mechanism 3, the scattered light in described sensor fibre for the pulsed light by described photomodulator is coupled into described sensor fibre, and is coupled into described detector by described 4th coupling mechanism 3.
Fig. 4 schematically illustrates the process flow diagram of the distributed vibration sensing method based on cross polarization control of the embodiment of the present invention, as shown in Figure 4 as different from Example 1:
1, light source is continuous light source;
2, step (A3) comprises the steps: further
(B1) photomodulator is entered in two-way optically-coupled orthogonal for polarization direction, light is modulated to pulsed light; Preferably, described photomodulator is electrical-optical or acousto-optic modulator;
(B2) be coupled into described sensor fibre from described photomodulator light out, and the scattered light on described sensor fibre is coupled into described detector.
Embodiment 3:
The application examples in vibration survey according to the sensor-based system in embodiment 2 and method.Light source adopts narrow linewidth continuous high power laser instrument, has extremely low phase noise and relative intensity noise.The modulation rate of the first and second Polarization Controllers is greater than 1kHz.Adopt acousto-optic modulator (AOM), continuous light is modulated to pulsed light.
Claims (10)
1., based on the distributed vibration sensing system that cross polarization controls, comprise light source, sensor fibre and 1 detector; It is characterized in that: described sensor-based system comprises further:
First coupling mechanism, described first coupling mechanism is used for the optically-coupled that described light source sends to enter the first light path and the second light path;
First Polarization Controller, described first polarizer is arranged in described first light path;
Second Polarization Controller, described second polarizer is arranged in described second light path;
Control module, described control module is orthogonal with by the polarisation of light direction of described second Polarization Controller for making by the light of described first Polarization Controller;
Second coupling mechanism, the scattered light in described sensor fibre for described sensor fibre is entered in the optically-coupled in the first light path, the second light path, and is coupled into described detector by described second coupling mechanism;
Signal processing module, the electric signal that described in described signal processing module process, detector sends, thus the extraneous vibration information knowing described sensor fibre perception.
2. sensor-based system according to claim 1, is characterized in that: described light source is light-pulse generator.
3. sensor-based system according to claim 1, is characterized in that: described sensor-based system comprises further:
Photomodulator, described photomodulator is used for making continuous light be modulated to pulsed light;
Described second coupling mechanism comprises further:
3rd coupling mechanism, described 3rd coupling mechanism is for entering described photomodulator by the optically-coupled in described first light path, the second light path;
4th coupling mechanism, described 4th coupling mechanism is used for the pulsed light by described photomodulator to be coupled into described sensor fibre, and the scattered light in described sensor fibre is coupled into described detector;
Described light source is continuous light source.
4. sensor-based system according to claim 3, is characterized in that: described photomodulator is electrical-optical or acousto-optic modulator.
5., according to the arbitrary described sensor-based system of claim 1-4, it is characterized in that: described light source is laser instrument.
6., based on the distributed vibration sensing method that cross polarization controls, described method for sensing comprises the following steps:
(A1) light that light source sends is coupled into the first light path and the second light path;
(A2) adjust the polarisation of light direction in the first light path and the second light path, make polarization direction orthogonal;
(A3) two-way optically-coupled orthogonal for polarization direction is entered the sensor fibre of perception extraneous vibration, the scattered light on sensor fibre is coupled into 1 detector;
(A4) described scattered light is converted to electric signal by described detector, and is sent to signal processing module;
(A5) electric signal described in signal processing module process, thus know the extraneous vibration of described sensor fibre perception.
7. method for sensing according to claim 6, is characterized in that: the light that described light source sends is pulsed light.
8. method for sensing according to claim 6, is characterized in that: described step (A3) comprises the steps: further
(B1) photomodulator is entered in two-way optically-coupled orthogonal for polarization direction, light is modulated to pulsed light;
(B2) be coupled into described sensor fibre from described photomodulator light out, and the scattered light on described sensor fibre is coupled into described detector;
The light that described light source sends is continuous light.
9. method for sensing according to claim 8, is characterized in that: described modulator is electrical-optical or acousto-optic modulator.
10., according to the arbitrary described method for sensing of claim 6-9, it is characterized in that: described light source is laser instrument.
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| CN105004355B (en) * | 2015-07-15 | 2017-05-24 | 南京大学 | Phi-OTDR reinforcing method based on polarized orthogonal optical pulse pair and device thereof |
| CN107084713B (en) * | 2017-05-26 | 2019-08-06 | 北京交通大学 | Method for measuring angular velocity and device based on optical-electronic oscillator |
| CN107289978B (en) * | 2017-06-09 | 2019-05-07 | 南京大学 | A kind of system and method for the survey disturbance based on POTDR |
| CN107643120A (en) * | 2017-11-10 | 2018-01-30 | 武汉理工光科股份有限公司 | The distributed fiber Rayleigh of polarization decay is avoided to scatter vibration sensing system and method |
| EP3855138A1 (en) | 2020-01-24 | 2021-07-28 | Nokia Solutions and Networks Oy | Fiber phase sensing using a ladder topology |
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| US4709145A (en) * | 1986-08-20 | 1987-11-24 | Simmonds Precision Products, Inc. | Method and apparatus for compensating fiber optic lead and connector losses in a fiber optic sensor by using a dual wavelength optical source and matched polarizer |
| CN101620764A (en) * | 2009-06-15 | 2010-01-06 | 上海华魏光纤传感技术有限公司 | Distributed optical fiber vibration sensing system based on polarization beam splitting detection and sensing method |
| CN101634571A (en) * | 2009-08-18 | 2010-01-27 | 重庆理工大学 | Optical pulse raster distributed fiber sensing device |
| CN101639379A (en) * | 2009-08-26 | 2010-02-03 | 南京大学 | Vibration monitoring structure and method based on optical fiber polarized light time domain reflection sense |
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| CN101975626B (en) * | 2010-10-13 | 2012-01-25 | 华中科技大学 | Brillouin scattering based distributive fiber sensing system |
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| US4709145A (en) * | 1986-08-20 | 1987-11-24 | Simmonds Precision Products, Inc. | Method and apparatus for compensating fiber optic lead and connector losses in a fiber optic sensor by using a dual wavelength optical source and matched polarizer |
| CN101620764A (en) * | 2009-06-15 | 2010-01-06 | 上海华魏光纤传感技术有限公司 | Distributed optical fiber vibration sensing system based on polarization beam splitting detection and sensing method |
| CN101634571A (en) * | 2009-08-18 | 2010-01-27 | 重庆理工大学 | Optical pulse raster distributed fiber sensing device |
| CN101639379A (en) * | 2009-08-26 | 2010-02-03 | 南京大学 | Vibration monitoring structure and method based on optical fiber polarized light time domain reflection sense |
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