CN111780859A - Distributed optical fiber sensing detection system - Google Patents
Distributed optical fiber sensing detection system Download PDFInfo
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- CN111780859A CN111780859A CN202010801050.5A CN202010801050A CN111780859A CN 111780859 A CN111780859 A CN 111780859A CN 202010801050 A CN202010801050 A CN 202010801050A CN 111780859 A CN111780859 A CN 111780859A
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- photodetector
- optical fiber
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/18—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge using photoelastic elements
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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
- G01K11/3206—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 at discrete locations in the fibre, e.g. using Bragg scattering
- G01K11/3213—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 at discrete locations in the fibre, e.g. using Bragg scattering using changes in luminescence, e.g. at the distal end of the fibres
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Abstract
The invention discloses a distributed optical fiber sensing detection system, which comprises a light source output unit, a circulator and an optical fiber which are sequentially connected, wherein the circulator is also sequentially connected with a photoelectric detection unit, an A/D conversion unit, a data acquisition unit and an upper computer; when the device is used, detection light output by the light source output unit passes through the circulator and the optical fiber, Rayleigh scattering light, Raman scattering light and Brillouin scattering light are excited in the optical fiber, and return to the circulator and enter the photoelectric detection unit, and then are transmitted to the upper computer through the A/D conversion unit and the data acquisition unit and return to the light source output unit, so that three parameters of vibration, temperature and strain are measured simultaneously.
Description
Technical Field
The invention belongs to the technical field of optical fiber sensing, and particularly relates to a distributed optical fiber sensing detection system.
Background
The distributed optical fiber sensor has many advantages of long-distance distributed measurement, electromagnetic interference resistance, corrosion resistance, electrical insulation and the like, and is widely applied to the fields of railway/subway communication cables, subway rails, tunnels and the like which need long-distance vibration temperature and strain detection.
The following are widely used at present: the distributed optical fiber sensor based on Rayleigh scattering detects vibration, the distributed optical fiber sensor based on Raman scattering detects temperature, and the distributed optical fiber sensor based on Brillouin scattering detects temperature/strain; in the traditional technology, Rayleigh scattering, Raman scattering and Brillouin scattering can be realized on only one sensor, and are relatively single.
Disclosure of Invention
In order to solve the above problems, the present invention provides a distributed optical fiber sensing detection system, which can realize synchronous detection of vibration, temperature and strain by the same distributed optical fiber sensor by synchronously integrating rayleigh scattering, raman scattering and brillouin scattering.
The technical scheme adopted by the invention is as follows:
a distributed optical fiber sensing detection system comprises a light source output unit, a circulator and optical fibers which are sequentially connected, wherein the circulator is further sequentially connected with a photoelectric detection unit, an A/D conversion unit, a data acquisition unit and an upper computer;
after the detection light output by the light source output unit passes through the circulator and the optical fiber, Rayleigh scattering light, Raman scattering light and Brillouin scattering light are excited in the optical fiber, return to the circulator and enter the photoelectric detection unit, then are transmitted to the upper computer through the A/D conversion unit and the data acquisition unit, and return to the light source output unit to trigger signals to continue to send laser.
Preferably, the photodetection unit includes an optical filter, a wavelength division multiplexer, a first photodetector, a second photodetector, a third photodetector, a fourth photodetector, and a decoupling module, an input end of the optical filter is connected to the circulator, an output end of the optical filter is connected to the wavelength division multiplexer and the first photodetector, the wavelength division multiplexer is connected to the second photodetector, the third photodetector, and the fourth photodetector, and the first photodetector, the second photodetector, the third photodetector, and the fourth photodetector are all connected to the decoupling module;
the Rayleigh scattered light enters the first photoelectric detector, simultaneously, Stokes light and anti-Stokes light in the Raman scattered light respectively enter the third photoelectric detector and the fourth photoelectric detector, and Brillouin scattered light enters the second photoelectric detector.
Preferably, the light source output unit includes a laser, an optical coupler, a pulse optical modulator, and an optical amplifier, the laser, the optical coupler, the pulse optical modulator, and the optical amplifier are connected in sequence, and the optical amplifier is connected to the circulator.
Preferably, the optical fiber sensing detection system further comprises an optical frequency shifter and an optical polarizer, wherein the input end of the optical frequency shifter is connected with the optical coupler, the output end of the optical frequency shifter is connected with the optical polarizer, and the optical polarizer is connected with the second photoelectric detector.
Preferably, the first photodetector, the second photodetector, the third photodetector and the fourth photodetector are all APD photodetectors.
Preferably, the circulator is a three-terminal circulator.
Preferably, the optical frequency shifter is an electro-optical modulator.
Preferably, the optical frequency shifter is an acousto-optic modulator.
Compared with the prior art, when the device is used, the detection light output by the light source output unit passes through the circulator and the optical fiber, the Rayleigh scattering light, the Raman scattering light and the Brillouin scattering light are excited in the optical fiber, and return to the circulator and enter the photoelectric detection unit, and then are transmitted to the upper computer through the A/D conversion unit and the data acquisition unit and return to the light source output unit, so that three parameters of vibration, temperature and strain are measured simultaneously.
Drawings
Fig. 1 is a system block diagram of a distributed optical fiber sensing detection system according to an embodiment of the present invention.
Wherein:
1. the optical fiber coupling device comprises a light source output unit, 2. a circulator, 3. an optical fiber, 4. a photoelectric detection unit, 5. an A/D conversion unit, 6. a data acquisition unit, 7. an upper computer, 8. an optical frequency shifter, 9. an optical polarizer, 11. a laser, 12. an optical coupler, 13. a pulse optical modulator, 14. an optical amplifier, 41. an optical filter, 42. a wavelength division multiplexer, 43. a first photoelectric detector, 44. a second photoelectric detector, 45. a third photoelectric detector, 46. a fourth photoelectric detector and 47. a decoupling module.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the description of the present invention, it is to be understood that the terms "vertical", "lateral", "longitudinal", "front", "rear", "left", "right", "upper", "lower", "horizontal", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description of the present invention, and do not mean that the device or member to which the present invention is directed must have a specific orientation or position, and thus, cannot be construed as limiting the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The embodiment of the invention provides a distributed optical fiber sensing detection system, which comprises a light source output unit 1, a circulator 2 and an optical fiber 3 which are sequentially connected as shown in figure 1, wherein the circulator 2 is further sequentially connected with a photoelectric detection unit 4, an A/D conversion unit 5, a data acquisition unit 6 and an upper computer 7;
thus, with the above configuration, the detection light output by the light source output unit 1 passes through the circulator 2 and the optical fiber 3, and then the rayleigh scattered light, the raman scattered light, and the brillouin scattered light are excited in the optical fiber 3, and then return to the circulator 2 and enter the photodetection unit 4, and then pass through the a/D conversion unit 5 and the data acquisition unit 6 to the upper computer 7, and return to the light source output unit 1 to trigger the signal to continue to transmit the laser light.
Specifically, the photodetection unit 4 includes an optical filter 41, a wavelength division multiplexer 42, a first photodetector 43, a second photodetector 44, a third photodetector 45, a fourth photodetector 46, and a decoupling module 47, an input end of the optical filter 41 is connected to the circulator 2, an output end is connected to the wavelength division multiplexer 42 and the first photodetector 43, the wavelength division multiplexer 42 is connected to the second photodetector 44, the third photodetector 45, and the fourth photodetector 46, and the first photodetector 43, the second photodetector 44, the third photodetector 45, and the fourth photodetector 46 are all connected to the decoupling module 47;
the rayleigh scattered light enters the first photodetector 43, while stokes light and anti-stokes light in the raman scattered light enter the third photodetector 45 and the fourth photodetector 46, respectively, and brillouin scattered light enters the second photodetector 44.
Specifically, one end of the circulator 2 is input to the optical filter 41 and then divided into two paths, one path is rayleigh scattered light and directly enters the first photodetector 43, the other path enters the wavelength division multiplexer 42 and then is divided into three paths and respectively enters the three photodetectors, brillouin scattered light directly enters the second photodetector 44, and stokes light and anti-stokes light in the raman scattered light respectively enter the third photodetector 45 and the fourth photodetector 46.
The light source output unit 1 comprises a laser 11, an optical coupler 12, a pulse light modulator 13 and an optical amplifier 14, wherein the laser 11, the optical coupler 12, the pulse light modulator 13 and the optical amplifier 14 are sequentially connected, and the optical amplifier 14 is connected with the circulator 2;
the line width of the light source emitted by the laser 11 should be smaller than the Brillouin scattering line width;
in the distributed optical fiber based on the brillouin scattering, generally, lasers are narrow linewidth light sources, and if the linewidth of the light source is larger than the brillouin linewidth, the brillouin scattering phenomenon is not easy to occur.
Thus, the pulse light sequence generated by the pulse light modulator 13 enters the optical fiber 3 through the optical amplifier 14, the scattered light returned from the optical fiber 3 is transmitted to the optical filter 41 through the circulator and then is divided into two paths, one path of rayleigh scattered light passes through the first photodetector 43, and the other path of rayleigh scattered light passes through the wavelength division multiplexer 42 and is divided into three paths, namely brillouin scattered light, raman anti-stokes scattered light and raman stokes scattered light;
the scattered light is converted into an electric signal by an optical signal after being subjected to photoelectric detection, the electric signal is subjected to A/D conversion after passing through the decoupling module 47, data is acquired and transmitted to the upper computer, and the upper computer triggers the pulse light modulator again after receiving data information to carry out vibration, temperature and strain information detection again.
The optical fiber sensing detection system further comprises an optical frequency shifter 8 and an optical polarizer 9, wherein the input end of the optical frequency shifter 8 is connected with the optical coupler 12, the output end of the optical frequency shifter 8 is connected with the optical polarizer 9, and the optical polarizer 9 is connected with the second photoelectric detector 44;
thus, the light polarizer 9 controls the polarization of the frequency-shifted light to obtain a desired polarized light, controls the polarization direction of the light, and can also attenuate the light intensity of the light.
The first photodetector 43, the second photodetector 44, the third photodetector 45 and the fourth photodetector 46 are all APD photodetectors;
thus, the APD photoelectric detector can realize photoelectric detection of three types of scattering, namely Rayleigh scattering light, Raman scattering light and Brillouin scattering light.
The circulator 2 is a three-terminal circulator.
In one embodiment, the optical frequency shifter 8 is an electro-optical modulator;
in another embodiment, the optical frequency shifter 8 is an acousto-optic modulator;
in this way, the input optical signal is subjected to a certain optical frequency shift by modulation, and the optical signal is output to the photodetector to be subjected to coherent demodulation with the brillouin scattered light signal, or direct photoelectric detection may be employed.
In addition, the optical fiber 3 is a long-distance sensing optical fiber.
The working principle is as follows:
the detection light output by the light source output unit 1 is connected with the wavelength division multiplexer 42, the first photodetector 43 and the long-distance sensing optical fiber 3 through the three-port circulator 2, and rayleigh scattering light, raman scattering light and brillouin scattering light are respectively excited in the long-distance sensing optical fiber 3, wherein the rayleigh scattering light returns to the three-port circulator 2 and enters the first photodetector 43 from the transceiving multiplexing end of the three-port circulator 2, meanwhile, stokes light and anti-stokes light in the raman scattering light enter the third photodetector 45 and the fourth photodetector 46 respectively, and the brillouin scattering light enters the second photodetector 44;
for temperature monitoring: when the external temperature changes and acts on the long-distance sensing optical fiber 3, the Raman scattering light intensity in the optical pulse width range is caused to change, so that the light intensity of the anti-Stokes light in Raman scattering is caused to change, the temperature information carried in the anti-Stokes light can be demodulated by taking the Stokes light as reference light, and the position information of the temperature change can be obtained by performing accumulation average processing on the signals acquired in a plurality of sampling periods;
for vibration monitoring: when external vibration is applied to the long-distance sensing optical fiber 3, the phase of backward Rayleigh scattering light in the optical pulse width range is changed, the light intensity of the backward Rayleigh scattering light is further changed, moving average processing is carried out on a large number of signals acquired in a plurality of sampling periods, vibration position information can be obtained, time domain signals of vibration positions are taken out, non-uniform Fourier transform is carried out on the time domain signals, and vibration frequency information can be obtained;
for strain monitoring, the spectrum of spontaneous Brillouin scattering light of a backward optical fiber is used for measuring the strain of the optical fiber.
In the embodiment, the distributed optical fiber sensing of Brillouin scattering, Raman scattering and Rayleigh scattering is realized in the same optical fiber sensor; simultaneously, the temperature compensation is carried out on the Brillouin scattering by utilizing the Raman scattering, and the simultaneous measurement of the vibration, the temperature and the strain is realized by combining the Rayleigh scattering; and by utilizing pulse modulation and optical coherent detection technologies, the detection signal-to-noise ratio is improved, the sensing distance is prolonged, and the detection precision is improved.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (8)
1. A distributed optical fiber sensing detection system is characterized by comprising a light source output unit (1), a circulator (2) and an optical fiber (3) which are sequentially connected, wherein the circulator (2) is further sequentially connected with a photoelectric detection unit (4), an A/D conversion unit (5), a data acquisition unit (6) and an upper computer (7);
after detected light output by the light source output unit (1) passes through the circulator (2) and the optical fiber (3), Rayleigh scattered light, Raman scattered light and Brillouin scattered light are excited in the optical fiber (3), the Rayleigh scattered light, the Raman scattered light and the Brillouin scattered light return to the circulator (2) and enter the photoelectric detection unit (4), and then are transmitted to the upper computer (7) through the A/D conversion unit (5) and the data acquisition unit (6), and return to the light source output unit (1) to trigger signals to continue to send laser.
2. The distributed optical fiber sensing detection system of claim 1, the photoelectric detection unit (4) comprises an optical filter (41), a wavelength division multiplexer (42), a first photoelectric detector (43), a second photoelectric detector (44), a third photoelectric detector (45), a fourth photoelectric detector (46) and a decoupling module (47), the input end of the optical filter (41) is connected with the circulator (2), the output end is connected with the wavelength division multiplexer (42) and the first photoelectric detector (43), the wavelength division multiplexer (42) is connected with a second photo detector (44), a third photo detector (45) and a fourth photo detector (46), the first photoelectric detector (43), the second photoelectric detector (44), the third photoelectric detector (45) and the fourth photoelectric detector (46) are all connected with a decoupling module (47);
the Rayleigh scattered light enters a first photodetector (43), simultaneously, Stokes light and anti-Stokes light in the Raman scattered light enter a third photodetector (45) and a fourth photodetector (46), respectively, and Brillouin scattered light enters a second photodetector (44).
3. A distributed optical fiber sensing detection system according to claim 2, wherein the light source output unit (1) includes a laser (11), an optical coupler (12), a pulsed light modulator (13) and an optical amplifier (14), the laser (11), the optical coupler (12), the pulsed light modulator (13) and the optical amplifier (14) are connected in sequence, and the optical amplifier (14) is connected with the circulator (2).
4. A distributed fibre optic sensing detection system according to claim 3 further comprising an optical frequency shifter (8) and an optical polarizer (9), the input of said optical frequency shifter (8) being connected to the optical coupler (12), the output of said optical frequency shifter (8) being connected to the optical polarizer (9), said optical polarizer (9) being connected to the second photodetector (44).
5.A distributed optical fiber sensing detection system according to any of claims 2-4, wherein the first photodetector (43), the second photodetector (44), the third photodetector (45) and the fourth photodetector (46) are all APD photodetectors.
6. A distributed fibre optic sensing detection system according to claim 1 wherein the circulator (2) is a three-terminal circulator.
7. A distributed optical fiber sensing detection system according to claim 4, wherein said optical frequency shifter (8) is an electro-optical modulator.
8. A distributed optical fiber sensing detection system according to claim 4, wherein said optical frequency shifter (8) is an acousto-optic modulator.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113092082A (en) * | 2021-03-31 | 2021-07-09 | 广东电网有限责任公司清远供电局 | OPGW optical cable life prediction system |
| CN113810106A (en) * | 2021-08-26 | 2021-12-17 | 广东工业大学 | Safety monitoring method and device of optical fiber energy information common transmission system |
| CN115388957A (en) * | 2022-10-26 | 2022-11-25 | 高勘(广州)技术有限公司 | Method, device and system for detecting OPGW optical cable icing and storage medium |
| CN115950482A (en) * | 2022-12-23 | 2023-04-11 | 合肥工业大学 | Time division multiplexing temperature and vibration measurement optical fiber sensing system |
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2020
- 2020-08-11 CN CN202010801050.5A patent/CN111780859A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113092082A (en) * | 2021-03-31 | 2021-07-09 | 广东电网有限责任公司清远供电局 | OPGW optical cable life prediction system |
| CN113092082B (en) * | 2021-03-31 | 2024-06-11 | 广东电网有限责任公司清远供电局 | OPGW optical cable life prediction system |
| CN113810106A (en) * | 2021-08-26 | 2021-12-17 | 广东工业大学 | Safety monitoring method and device of optical fiber energy information common transmission system |
| CN113810106B (en) * | 2021-08-26 | 2022-06-21 | 广东工业大学 | Safety monitoring method and device of optical fiber energy information common transmission system |
| CN115388957A (en) * | 2022-10-26 | 2022-11-25 | 高勘(广州)技术有限公司 | Method, device and system for detecting OPGW optical cable icing and storage medium |
| CN115388957B (en) * | 2022-10-26 | 2023-01-31 | 高勘(广州)技术有限公司 | Method, device and system for detecting OPGW optical cable icing and storage medium |
| CN115950482A (en) * | 2022-12-23 | 2023-04-11 | 合肥工业大学 | Time division multiplexing temperature and vibration measurement optical fiber sensing system |
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