CN106768281A - The distribution type fiber-optic audiphone of phase-sensitive φ OTDR - Google Patents
The distribution type fiber-optic audiphone of phase-sensitive φ OTDR Download PDFInfo
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- CN106768281A CN106768281A CN201710233490.3A CN201710233490A CN106768281A CN 106768281 A CN106768281 A CN 106768281A CN 201710233490 A CN201710233490 A CN 201710233490A CN 106768281 A CN106768281 A CN 106768281A
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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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Abstract
The invention discloses a kind of phase-sensitiveThe distribution type fiber-optic audiphone of OTDR is sensed realizing distributing audio, and realizes building for sensor-based system, is disclosed optical fiber acoustic sensor and is had a wide range of applications in every field.Phase-sensitive optical time domain reflectometer (OTDR optical fiber sensing technology).From Rayleigh scattering and the angle of OTDR technique in optical fiber, centeringThe principle of OTDR technique is described, and is carried out with high sensitivity characteristic.Influence of the extraneous vibration to backward Rayleigh scattering light phase, is subsequently to useOTDR sensor-based systems carry out sound sensor there is provided theories integration.It is rightPrimary Component selection is described in light path design in the build process of OTDR sensor-based systems, in traditionImprovement is made that in the structure of OTDR, introducing relevant heterodyne reception carries out signal reception, has obtained amplitude information and phase information that the backward Rayleigh solution related to acoustic perturbation penetrates light, realizes sound-reducing.
Description
Technical field
The present invention relates to fiber optic communication field, more particularly to a kind of distributed light of phase-sensitive optical time domain reflectometer
Fine audiphone.
Background technology
Distribution type fiber-optic audiphone compared with conventional electrical sound transducer, with bandwidth, anti-Radio frequency interference (RFI),
Detection away from it is farsighted, optical transport network can be directly accessed the advantages of.Over nearly 30 years, people are goed deep into optical fiber acoustic sensor
Research, developed substantial amounts of sound transducer and its correlation technique, including the optical fiber sound sensor skill based on Bragg grating
Art, the optical fiber sensing technology based on fibre optic interferometer etc..Its sensing capabilities has reached level higher, but these are sensed
Device belongs to greatly point sensor, and the difficulty that there is a problem of arranging net is big.From economic and practical angle, a distribution is developed
The optical fiber acoustic sensor of formula has great importance.
The content of the invention
The present invention propose it is a kind of based on phase-sensitive optical time domain reflectometer (- OTDR) optical fiber sensing technology come real
Existing distributing audio sensing, and building for sensor-based system has been carried out, realize the sound-reducing of audiphone.
In order to solve the above technical problems, one aspect of the present invention is：Structure is based on- OTDR technique is carried out
The theoretical frame of distribution type fiber-optic audiphone, and build one, model machine of sensing.Wherein, it is based onThe principle of-OTDR, we are to shadow
The various parameters for ringing sensor-based system performance include laser linewidth, laser frequency stability, injected pulse peak power, acousto-optic
Modulator performance and Signal Regulation method are analyzed.
Optical fiber sensing system is general to be made up of the part such as probe source, Transmission Fibers, sensing unit and signal detection, is relied on
In the conversion of input optical signal to output modulated optical signal, wherein output modulated optical signal carries some information.Such as Fig. 1 institutes
Show, various types of Fibre Optical Sensors by constantly researched and developed and be applied to measurement temperature, pressure, displacement, vibration, rotation, bending, sound
The physical quantitys such as field.
Sound is a kind of extremely important information carrier, and its essence is a kind of pressure wave, and frequency and amplitude are description sound
Two call parameters.Voice signal as a kind of faint vibration signal mankind's daily life with exchange in risen extremely weigh
The effect wanted, it is in military, medical treatment, the monitoring equally tool in field is of great significance under water etc..Detected in acoustical signal and led
The sound transducer of domain electricity is occupied an leading position always.Conventional electrical voice sensor has moving coil microphone, piezoelectric type to pass
Sound device, condenser microphone and electret-type microphone.Because these electrical voice sensors are all active structures so that its
Application in the special dimension such as strong electromagnetic, inflammable and explosive is greatly limited, and the light current mould that sensor ends are exported
Intend signal and be not suitable for long-distance transmissions, therefore, it is difficult to carry out remote sensing remote measurement.Compared to conventional electrical sound transducer, optical fiber sound is passed
Sensor has following advantage：
（1）Optical signal has a performance of electromagnetism interference, thus optical fiber acoustic sensor can in the environment of strong electromagnetic work
Make；
（2）Fibre loss is low so that optical fiber acoustic sensor can carry out remote remote sensing；
（3）Optical fiber sensor head is not charged, and essential safety is suitable under water and inflammable and explosive environmental applications；
（4）Small volume, weight receive be easily installed with it is hidden；
（5）Optical fiber is corrosion-resistant, can be laid in special adverse circumstances.
Summary advantage, optical fiber acoustic sensor is examined in the health status monitoring of building structure, partial discharge of transformer
The field such as detection of sound wave has a wide range of applications field in disconnected, underwater sound monitoring, aerospace safety, and air.
The present invention is proposedThe signal processing method of the distribution type fiber-optic audiphone of-OTDR technique.
Brief description of the drawings
Fig. 1 is distribution type fiber-optic audiphone Fibre Optical Sensor basic functional principle figure of the present invention；
Fig. 2 is distribution type fiber-optic audiphone system construction drawing of the present invention；
Fig. 3 is distribution type fiber-optic audiphone laser linewidth test chart of the present invention；
Fig. 4 is distribution type fiber-optic audiphone Orthogonal modification process of the present invention.
Specific embodiment
Below describe in, in order to illustrate rather than in order to limit, it is proposed that such as particular system structure, interface, technology it
The detail of class, thoroughly to understand the application.However, it will be clear to one skilled in the art that specific without these
The application can also be realized in the other embodiment of details.In other situations, the detailed of device, circuit and method is omitted
Illustrate, in case unnecessary details hinders the description of the present application.
Fig. 2 is referred to, the light source that the present invention is used is narrow-line width single frequency optical fiber laser, and parameter is 1550nm, 1kHz's
Continuous light, two-way is divided into through beam splitter, wherein 5% light is local oscillator light, 95% light is used as detection light.Detection light is by optical fiber sound
Optical modulator is modulated, and acousto-optic modulator parameter is：Shift frequency 150MHz, pulsewidth 30ns.Backward Rayleigh in sensor fibre dissipates
Light is penetrated by circulator and local oscillator light by 50:50 coupler carries out beat frequency, and beat signal is by double balanced detectors（DB-
PD）Be converted to analog electrical signal.Subsequent data collecting card carries out analog-to-digital conversion to analog electrical signal, and enters industrial computer treatment letter
Breath.
In order to improve the distance sensing of sensor-based system as far as possible in distributed sensing system, light wave should be made as far as possible
Long-distance communications are, it is necessary to reduce the decay of light, therefore use the optical source wavelength of 1550nm.
Because using backward Rayleigh scattering light coherent interference, therefore require the coherence of injected pulse light enough, so just can be with
Improve sensitivity.
Assuming that the scattered optical field of i-th scattering point is expressed as：
Interference light intensity in pulse width is：
Assuming that the light field expression formula of single-frequency laser light source is, centre frequency is, spectrum width is, according to quasi-monochromatic source
Independent propagation principle, it can be decomposed in frequency domain, carried out Fourier transformation：
The power distribution of its frequency, and be Gaussian Profile.
Then i-th scattered optical field of scattering point can be decomposed on field again
Interference light intensity can be expressed as：
It is the function on center spectral line and spectrum width, it is Gaussian function, can be obtained after quadrature conversion：
WhenWhen=0,, interfere density output to reach maximum, but in actual conditions＞ 0,, and output decline amplitude byDetermine,Bigger, the envelope decline of its interference output is rapider.
So should causeAs far as possible small, the optical fiber laser cash test result that we use in the present invention is as shown in figure 3, cash is
3.03kHz。
Another requirement to light source is low frequency drift, because system is used thinks dry heterodyne reception, the elegant meeting of frequency meter
It is converted into the phase for receiving flashlight, increases the ground noise of system.
Assuming that the frequency drift amount of the two neighboring pulse of laser emitting is, in a cycle, the frequency of pulsed light
Rate is, for the scattering light at L meters, light pulse returns to detector from fibre is entered to Rayleigh scattering, its phase delayCan be with table
It is shown as
In second period, the frequency of pulsed light is, for the scattering light at L meters, light pulse is fine to Rayleigh from entering
Detector is scattered back into, its phase delayCan be expressed as：
In the case where system is without any disturbance, the scattering point at L rice brings the additional phase noise to be：
With the rear shifting of sensing location, because the phase noise that frequency jitter brings is bigger, so the frequency stabilization of laser
Property to system noise suppress it is most important.
In OTDR sensor-based systems, the distance sensing of system is relevant with the pulse power of injected pulse light, the power of pulse
Higher, system sensing distance is more remote.Pulse power is improved, two methods can be taken to improve pulse width and pulse peak is improved
Value power.But pulse width is improved by the spatial resolution of the system of influence, so general by improving pulse peak in practice
Value power improves pulse power.But too high peak power can excite nonlinear effect so that pulse power declines rapidly, cause
Decline back scattering luminous intensity, system signal noise ratio and distance sensing largely effect on system sensing by strong influence for this
Energy.In fiber nonlinear effect, stimulated Brillouin scattering threshold value is minimum, and the influence to sensing is the most notable.Therefore it is being based on
In the interference type distributed optical fiber sensor-based system of Rayleigh scattering, should try one's best avoid the appearance of stimulated Brillouin scattering first.To arteries and veins
It is a width ofPulsed light, inject continuous light when excited Brillouin threshold value be:
WhereinIt is stimulated Brillouin scattering gain coefficient,It is effective core area.
Bit pulse length.The excited Brillouin threshold value of pulsed light be 3.8w, the pulse peak power that we use in this experiment for
3.4w。
- OTDR distributing audios sensing system is positioned using optical time domain reflection principle, in order to reduce substrate light
Crosstalk to signal, extinction ratio pulsed light higher is necessary in injection sensor fibre, and direct internal modulation can occur chirp effect
Should, optical signal distortion is caused, it is necessary to using acousto-optic modulator（AOM) extinction ratio is 50dB, with more excellent temperature stability
With more preferable optical spot quality.And invention using heterodyne reception, it is necessary to there is difference on the frequency between flashlight and local oscillator light, so adopting
It is that shift frequency is carried out to direct impulse light with another purpose of acousto-optic modulator.Also require that acousto-optic modulator drift frequency is steady in addition
It is fixed, with the phase noise that the frequency disturbance for reducing by above-mentioned point of compromise causes.
Backward Rayleigh projection optical signal is converted into photo-signal after double balanced detectors, and photoelectric current is via industrial computer number
Analog-to-digital conversion is carried out according to collection is busy, of the invention, the photoelectric current from photodetector output is：
As shown in figure 4, be multiplied by frequency being respectivelySine and cosine signal, by after a LPF, obtainingWithTwo
Road signal.
WithThe output result of two paths of signals is respectively：
Have：
WithBackward Rayleigh scattering light light amplitude value and phase value as required by us.If the external world is without disturbance,
WithIt will not at any time ask and change, if there is disturbance in the external world,WithAlso will be with shock wave, this change is by poor
Dividing to obtain.
The present invention is from the Rayleigh scattering and the angle of OTDR technique in optical fiber, centeringThe principle of-OTDR technique is carried out
Introduce, carry out with high sensitivity characteristic.Influence of the extraneous vibration to backward Rayleigh scattering light phase, is subsequently to use-
OTDR sensor-based systems carry out sound sensor there is provided theories integration.It is rightLight path design in the build process of-OTDR sensor-based systems
Middle Primary Component selection is described, in traditionImprovement is made that in the structure of-OTDR, relevant heterodyne reception is introduced and is entered
Row signal is received, and has obtained amplitude information and phase information that the backward Rayleigh solution related to acoustic perturbation penetrates light, realizes sound
Sound is reduced.
Claims (3)
1. one kind utilizes phase-sensitiveThe method of the audiphone of the distribution type fiber-optic of-OTDR, it is characterised in that including：
Light source is narrow-line width single frequency optical fiber laser；
Managed using beam splitter and acousto-optic modulation junction, be converted to analog electrical signal, carry out novel treatment, reduce optical source wavelength,
Improve coherence's injected pulse light high；
The LASER Light Source of use reduces the decay and dispersion of the long-distance communications that light ware energy is realized, light.
2., according to claim 1, a kind of application method of application acousto-optic modulator is proposed, it is characterised in that including：
Using the limitation to pulse light path, brought phase noise is moved after reducing sensing location, the frequency for improving laser is steady
Qualitative, causing can reduce system noise；
Modulation photoelectric effect, output pulse has extinction ratio higher, the luminous point matter of temperature and Geng Gao with more good stable
Amount.
3., according to claim 2, a kind of application method of the Signal Regulation of application OTDR sensor-based systems is proposed, it is characterised in that
Including：
Laser light source generation local oscillator light, backward Rayleigh scattering light carries out beat frequency with local oscillator light, and beat signal turns by detector
Analog electrical signal is changed to, subsequent data collecting card is modulated to analog electrical signal；
The strong pulsed light of backward Rayleigh scattering light requirement injection coherence, can improve sensitivity；
Light source requirements frequency drift is low, and frequency meter drift can be converted into the phase for receiving flashlight, make the ground noise of system
Increase；
It is required that laser frequency stabilization, reduces noise.
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109210385A (en) * | 2018-06-08 | 2019-01-15 | 张益平 | A kind of distributed optical fiber sensing system and method based on Phase-OTDR |
| CN110132331A (en) * | 2019-05-22 | 2019-08-16 | 电子科技大学 | A kind of COTDR measurement method and its system extracted based on sub- chirped pulse |
| CN110657878A (en) * | 2019-09-20 | 2020-01-07 | 山东大学 | Sound collection distributed optical fiber sensing system based on Mach-Zehnder interferometer and phi-OTDR |
| CN111147133A (en) * | 2019-12-24 | 2020-05-12 | 武汉理工光科股份有限公司 | Real-time monitoring system and method for traffic flow based on phi-OTDR |
| WO2021036580A1 (en) * | 2019-08-28 | 2021-03-04 | 之江实验室 | Distributed hydrophone based on ultra strong bending-resistant flexible optical cable containing multi-core optical fiber |
| CN113447772A (en) * | 2021-06-18 | 2021-09-28 | 安徽龙联智能光电有限公司 | High-voltage cable partial discharge online monitoring system and method |
| CN113483790A (en) * | 2021-06-18 | 2021-10-08 | 安徽龙联智能光电有限公司 | Distributed acoustic sensing phase demodulation method and system |
| CN114459589A (en) * | 2021-12-20 | 2022-05-10 | 军事科学院系统工程研究院网络信息研究所 | Underwater acoustic signal detection method based on rydberg atomic radar |
| WO2022107128A1 (en) * | 2020-11-17 | 2022-05-27 | Teldor Cables & Systems Ltd. | Distributed vibration sensing over optical fibers |
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| CN103411660A (en) * | 2013-08-29 | 2013-11-27 | 山东省科学院激光研究所 | Optical fiber distributed type sound wave monitor system |
| CN106500823A (en) * | 2016-12-05 | 2017-03-15 | 华南理工大学 | Based on the device that thin footpath multimode fibre realizes the distributed sound wave sensing of high sensitivity |
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| CN103411660A (en) * | 2013-08-29 | 2013-11-27 | 山东省科学院激光研究所 | Optical fiber distributed type sound wave monitor system |
| CN106500823A (en) * | 2016-12-05 | 2017-03-15 | 华南理工大学 | Based on the device that thin footpath multimode fibre realizes the distributed sound wave sensing of high sensitivity |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109210385A (en) * | 2018-06-08 | 2019-01-15 | 张益平 | A kind of distributed optical fiber sensing system and method based on Phase-OTDR |
| CN110132331A (en) * | 2019-05-22 | 2019-08-16 | 电子科技大学 | A kind of COTDR measurement method and its system extracted based on sub- chirped pulse |
| CN110132331B (en) * | 2019-05-22 | 2021-05-07 | 电子科技大学 | COTDR measurement method and system based on sub-chirp pulse extraction |
| WO2021036580A1 (en) * | 2019-08-28 | 2021-03-04 | 之江实验室 | Distributed hydrophone based on ultra strong bending-resistant flexible optical cable containing multi-core optical fiber |
| CN110657878A (en) * | 2019-09-20 | 2020-01-07 | 山东大学 | Sound collection distributed optical fiber sensing system based on Mach-Zehnder interferometer and phi-OTDR |
| CN111147133A (en) * | 2019-12-24 | 2020-05-12 | 武汉理工光科股份有限公司 | Real-time monitoring system and method for traffic flow based on phi-OTDR |
| CN111147133B (en) * | 2019-12-24 | 2021-09-14 | 武汉理工光科股份有限公司 | Real-time monitoring system and method for traffic flow based on phi-OTDR |
| WO2022107128A1 (en) * | 2020-11-17 | 2022-05-27 | Teldor Cables & Systems Ltd. | Distributed vibration sensing over optical fibers |
| CN113447772A (en) * | 2021-06-18 | 2021-09-28 | 安徽龙联智能光电有限公司 | High-voltage cable partial discharge online monitoring system and method |
| CN113483790A (en) * | 2021-06-18 | 2021-10-08 | 安徽龙联智能光电有限公司 | Distributed acoustic sensing phase demodulation method and system |
| CN114459589A (en) * | 2021-12-20 | 2022-05-10 | 军事科学院系统工程研究院网络信息研究所 | Underwater acoustic signal detection method based on rydberg atomic radar |
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