CN101581586B - Distributed optical fiber sagnac positioning sensor inhibiting dead zone of sensor - Google Patents
Distributed optical fiber sagnac positioning sensor inhibiting dead zone of sensor Download PDFInfo
- Publication number
- CN101581586B CN101581586B CN2009101171251A CN200910117125A CN101581586B CN 101581586 B CN101581586 B CN 101581586B CN 2009101171251 A CN2009101171251 A CN 2009101171251A CN 200910117125 A CN200910117125 A CN 200910117125A CN 101581586 B CN101581586 B CN 101581586B
- Authority
- CN
- China
- Prior art keywords
- port
- optical fiber
- fiber coupler
- sensor
- coupler
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Optical Transform (AREA)
- Gyroscopes (AREA)
Abstract
The invention relates to a distributed optical fiber sagnac positioning sensor inhibiting the dead zone of a sensor, which is characterized by comprising a first optical fiber coupler and a second optical fiber coupler; the light-inlet port of the first optical fiber coupler is a second port, and the light-outlet port of the first optical fiber coupler is a first port, a third port, a fourth port,a fifth port and a sixth port; the third and the fourth ports of the first optical fiber coupler are mutually connected by a delay optical fiber, a photoelectric detection unit is arranged in front o f the first port of the first optical fiber coupler, and the output signal of the photoelectric detection unit is switched in an A/D conversion digital collection card which is electrically connected with a computer; the sensor also comprises a sensing optical fiber and the second optical fiber coupler; and a reference light source is arranged in front of the second port of the first optical fibercoupler, and an optoisolator is arranged between the reference light source and the second port. The invention reduces insertion consumption, and the delay of optical fiber length by reasonable selec tion can not only inhibit sensing dead zone in the sensing optical fiber, but also eliminate pseudo-zero frequency points appearing in signal demodulation, and improve the signal-to-noise ratio.
Description
Technical field
The present invention relates to the optical sensor field, especially a kind of distributed optical fiber sagnac alignment sensor that suppresses the sensor dead band.
Background technology
In optical fiber Sagnac interferometer, the light that comes out from light source is divided into two bundles through coupling mechanism, and along the clockwise of fiber optic loop and propagation counterclockwise, certain point is subjected to the disturbance of extraneous variation in optical fiber, makes by this light beam and produces phase change respectively.Two propagate in opposite directions only pass through this point constantly in difference, make that the additive phase variable quantity that produces is unequal, when two light of propagating are in opposite directions got back to coupling mechanism, interfere the positional information that can obtain being correlated with by this signal of demodulation.Because two-way produces the light of interfering and propagates in same light path, just the direction of propagation is opposite, thereby avoided in other interference structures adjusting the difficulty of light path, reduced requirement to the coherence length of laser, and insensitive to the noise such as the variation of temperature that slowly change in the environment.The sensor of interfering based on Sagnac has sensitivity and resolution height, volume is little, in light weight, corrosion-resistant, simple in structure, anti-electromagnetic interference capability strong and can be under inflammable and explosive environment reliability service, be easy to respond to tested parameter, highly sensitive, response is fast, dynamic range is big, therefore the advantage that loss is low has and realizes long Inherent advantage apart from the many reference amounts monitoring, is widely used at aspects such as optical fibre gyro, optical fiber perimeter safety monitoring, line leakages.
In distributed fiberoptic sensor, because interference such as the various fiber birefringences in the optic fibre light path, bending loss of optical fiber, optical fiber distortion, the light intensity fluctuation of light source, the noise of photodetector, the noise of circuit and data collecting card etc., make the sensing light path when not being subjected to extraneous disturbance, the light signal that obtains has certain amplitude fluctuation.When light path was disturbed, if the interference signal amplitude that produces because of disturbance during less than the noise in the system, then this moment, useful signal can be buried in the middle of the noise, can't demodulate the disturbance location, Here it is sensing dead band.And present great majority are not considered the sensing dead-time problem based on the distributed fiberoptic sensor of Sagnac, more do not propose to eliminate the way in sensing dead band.General single axle optical fiber Sagnac distributed sensor is by realize the circulation of light in the end face coating of fiber axis or the method that adds catoptron, but the optical fiber head of plated film exist plated film inhomogeneous, very easily be worn, problem such as volatilization for a long time, and can influence the transmission quality of light, need the high-quality plated film and add the first-class measure of protection, this has increased cost and complexity virtually; Adding catoptron can increase the insertion loss, also is difficult to realize the total reflection of light, causes interference signal intensity to weaken, and has reduced the signal to noise ratio (S/N ratio) of signal, unfavorable to the signal demodulation.
Summary of the invention
The purpose of this invention is to provide a kind of distributed optical fiber sagnac alignment sensor that suppresses the sensor dead band, have the sensing dead band to solve conventional art, and the light of the conventional art circulation problem that causes interference signal intensity to weaken easily.
In order to achieve the above object, the technical solution adopted in the present invention is:
A kind of distributed optical fiber sagnac alignment sensor that suppresses the sensor dead band, it is characterized in that: comprise first fiber coupler and second fiber coupler that have a plurality of ports respectively, the port of described two fiber couplers is symmetrically distributed in the both sides of fiber coupler respectively, a port of described first fiber coupler is the light inlet mouth, two other port of first fiber coupler interconnects by postponing optical fiber, the 4th its place ahead of port of described first fiber coupler is provided with the photodetection unit, described photodetection unit is electrically connected with A/D changed digital capture card, described A/D changed digital capture card is electrically connected with computing machine, also include sensor fibre, the 5th port of described first fiber coupler is connected with a port of sensor fibre, another port of described sensor fibre is connected with a port of described second fiber coupler, also has two ports to connect by optical fiber on described second fiber coupler.
Described a kind of distributed optical fiber sagnac alignment sensor that suppresses the sensor dead band, it is characterized in that: described first fiber coupler has six ports, is 3 * 3 structures, wherein has a port vacant.
Described a kind of distributed optical fiber sagnac alignment sensor that suppresses the sensor dead band, it is characterized in that: described second fiber coupler has four ports, is 2 * 2 structures, wherein has a port vacant.
Described a kind of distributed optical fiber sagnac alignment sensor that suppresses the sensor dead band, it is characterized in that: described first fiber coupler and second fiber coupler are all single-mode optical-fibre coupler.
Described a kind of distributed optical fiber sagnac alignment sensor that suppresses the sensor dead band, it is characterized in that: described photodetection unit comprises photodetector, prime amplifier and the high-pass filtering circuit that is electrically connected successively, after light signal enters photodetector, be converted to electric signal by photodetector, pass through prime amplifier and high-pass filtering circuit more successively, be sent to A/D changed digital capture card.
Among the present invention, optoisolator guarantees a kind of device of light beam one-way transmission, the harm that the reflected light that prevents to occur in the light path brings light source.First fiber coupler and second fiber coupler all are single-mode optical-fibre couplers, are respectively 3 * 3 and structures 2 * 2, can make splitting ratio even like this.The function of photodetection unit is light signal is converted to electric signal and amplifies and filtering, therefore comprise photodetector, prime amplifier and a high-pass filtering circuit, the response wave length of photodetector should can be a PIN photodiode at the light signal wave band of light emitted.
The present invention has following characteristics and advantage:
1) the present invention adopts full optical fibre device, and photodetector has tail optical fiber, can with the direct welding of optical fiber, reduced the insertion loss.
2) the present invention's length of postponing optical fiber by rational selection both can suppress the sensing dead band in the sensor fibre, the pseudo-zero-frequency point that occurs in again can the erasure signal demodulation.
3) the present invention constitutes fiber loop mirror by one 2 * 2 fiber coupler, realizes the light reflection, has reduced the complicacy of manufacture craft, has improved signal to noise ratio (S/N ratio).
Description of drawings
Fig. 1 is a structural representation of the present invention.
Fig. 2 disturbs for light path has and the signal when noiseless, wherein:
Fig. 2 a is the signal of the midpoint of light path when not having disturbance.Fig. 2 b is the signal of the midpoint of light path when disturbance is arranged.
Fig. 3 is after the disturbance and the FFT undesired signal after the conversion, wherein:
Fig. 3 a is the interference signal after the disturbance.Fig. 3 b is the undesired signal after the FFT conversion.
Fig. 4 is the signal after handling, wherein:
Fig. 4 a is the signal behind small echo denoising and the neighborhood averaging.Fig. 4 b is a signal behind the segmentation least square fitting.
Embodiment
Referring to Fig. 1, a kind of distributed optical fiber sagnac alignment sensor that suppresses the sensor dead band is provided with light source 1, optoisolator 2, and optoisolator 2 is a kind of devices that guarantee the light beam one-way transmission, the harm that the reflected light that prevents to occur in the light path brings light source.Comprise first fiber coupler 3 and second fiber coupler 6 that have a plurality of ports respectively, first fiber coupler 3 and second fiber coupler 6 are all single-mode optical-fibre coupler, the port of two fiber couplers is symmetrically distributed in the both sides of fiber coupler respectively, first fiber coupler 3 has six ports, be 3 * 3 structures, wherein ports having 306 is vacant, and second fiber coupler 6 has four ports, be 2 * 2 structures, wherein have a port 602 vacant.The port 302 of first fiber coupler 3 is the light inlet mouth, and the light that light source 1 sends is injected the light inlet mouth 302 of first fiber coupler 3 through behind the optoisolator 2.Two other port 303 of first fiber coupler 3,304 interconnect by postponing optical fiber 4, port 301 its place aheads of first fiber coupler 3 are provided with photodetection unit 7, photodetection unit 7 is electrically connected with A/D changed digital capture card, A/D changed digital capture card is electrically connected with computing machine 8, photodetection unit 7 comprises the photodetector that is electrically connected successively, prime amplifier and high-pass filtering circuit, photodetector can be selected PIN photodiode for use, after light signal enters photodetector, be converted to electric signal by photodetector, pass through prime amplifier and high-pass filtering circuit more successively, be sent to A/D changed digital capture card.Also include sensor fibre 5, the port 305 of first fiber coupler 3 is connected with a port of sensor fibre 5, another port of sensor fibre 5 is connected with the port 601 of second fiber coupler 6, also has two ports 603,604 to connect by optical fiber on second fiber coupler.
The light that light source 1 sends enters first fiber coupler 3 through behind the optoisolator 2, because the branch light action of first fiber coupler 3, a part of light enters from port 304 and postpones optical fiber 4, and some light enters sensor fibre 5.After the light that enters sensor fibre enters from the port 601 of second fiber coupler 6 respectively from port 603 and port 604 outgoing, the light at these two ends all enters second fiber coupler 6 from relative port 604 and 603 again because of this two-port has linked to each other then, part light is from port 601 outgoing, the light of outgoing arrives first fiber coupler 3 from sensor fibre 5 again, enter from 303 through the branch light action part of first fiber coupler 3 and to postpone optical fiber 4, enter the light that postpones optical fiber 4 from port 303 and enter first fiber coupler 3 from port 304 again; A part of light enters sensor fibre 5 after the reflection of second fiber coupler 6 from port 305 after entering the light that postpones optical fiber 4 and enter first fiber coupler from port 303 from port 304,305 enter first fiber coupler 3 and interfere with last road light along sensor fibre 5 from port, interference signal is from port 301 outgoing of first fiber coupler, received by photodetection unit 7 and to become electric signal, after send into computing machine 8 and carry out the signal demodulation.Because the branch light action of first fiber coupler 3, the coherent light that in whole optical path, except this two-way coherent light, also has other, but every beam split through one time first fiber coupler 3, the intensity of signal will reduce, make the interference signal of these residue coherent lights compare very little with the dried interference of light signal value of principal phase, can ignore, whole like this interference system can only be considered main coherent light.
When certain a bit was subjected to external disturbance on the sensor fibre 5, the disturbance meeting produced a phase perturbation to the light by this point, is expressed as:
Be the amplitude of disturbance phase place, γ is a constant, and ω is the disturbing signal frequency, and every road light is twice by the number of times of disturbance point respectively in the coherent light, and then interference signal can be expressed as:
B is different constant in the formula, and Δ φ is the intrinsic phase differential of light path, and t1, t2, t3, t4 are the disturbance moment that same point is different on the light path.Because there is not certain fluctuation in the signal of system's output when having disturbance, some amplitudes of variation that relate to signal are less than this noise, and then signal is buried in the middle of the noise, sensing dead band phenomenon that Here it is.And be positioned at the point midway of light path when disturbance point, i.e. the phase differential minimum that obtains during t2=t3.Therefore to eliminate the dead band phenomenon, disturbance moment t4 and t1 are divided open enough greatly, and the minimal disturbances phase difference value is increased.By increasing the length L that postpones optical fiber
2Can make t4 (
Wherein x is the disturbance point position, and v is the velocity of propagation of light in optical fiber) increase with the t1 difference, can estimate L
2〉=44.44m just can eliminate the dead band.
Phase differential in the interference signal can be expressed as:
Δ γ is a phase constant, and the phase modulated signal that general disturbance produces is a broadband signal, when
The time or
The time (N, M are integer),
Be zero, this moment, the intensity of interference signal was zero, and the frequency values that satisfies above-mentioned first condition is called the zero-frequency point.Because disturbing signal is very weak at the above energy of 50KHZ, so as long as make
The pseudo-zero-frequency point of decision is greater than 50KHZ both L
2The pseudo-zero-frequency point of this formula decision of≤4000m or filtering, the L that selects in the system
2Length is 2000m, and this sensor has been eliminated the sensing dead band as can see from Figure 2.Seek zero-frequency point f from signal spectrum figure figure
kJust can determine the position of disturbance point:
Claims (3)
1. distributed optical fiber sagnac alignment sensor that suppresses the sensor dead band, it is characterized in that: comprise first fiber coupler and second fiber coupler, the light inlet mouth of described first fiber coupler is second port, and going out optical port is the first, the 3rd, the 4th, the 5th, the 6th port; The the 3rd, the 4th port of first fiber coupler interconnects by postponing optical fiber, its the place ahead of first port of described first fiber coupler is provided with the photodetection unit, the output signal of described photodetection unit inserts A/D changed digital capture card, and described A/D changed digital capture card is electrically connected with computing machine; Also include sensor fibre, the five-port of described first fiber coupler is connected with a port of sensor fibre, another port of described sensor fibre is connected with a port of described second fiber coupler, also has on described second fiber coupler between two other ports to connect by optical fiber; Second port the place ahead of described first fiber coupler is provided with reference light source, is provided with optoisolator between the reference light source and second port;
Described first fiber coupler has six ports, is 3 * 3 structures, wherein has a port vacant;
Described second fiber coupler has four ports, is 2 * 2 structures, wherein has a port vacant.
2. a kind of distributed optical fiber sagnac alignment sensor that suppresses the sensor dead band according to claim 1, it is characterized in that: described first fiber coupler and second fiber coupler are all single-mode optical-fibre coupler.
3. a kind of distributed optical fiber sagnac alignment sensor that suppresses the sensor dead band according to claim 1, it is characterized in that: described photodetection unit comprises photodetector, prime amplifier and the high-pass filtering circuit that is electrically connected successively, after light signal enters photodetector, be converted to electric signal by photodetector, pass through prime amplifier and high-pass filtering circuit more successively, be sent to A/D changed digital capture card.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009101171251A CN101581586B (en) | 2009-06-23 | 2009-06-23 | Distributed optical fiber sagnac positioning sensor inhibiting dead zone of sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009101171251A CN101581586B (en) | 2009-06-23 | 2009-06-23 | Distributed optical fiber sagnac positioning sensor inhibiting dead zone of sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101581586A CN101581586A (en) | 2009-11-18 |
| CN101581586B true CN101581586B (en) | 2010-11-10 |
Family
ID=41363840
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2009101171251A Expired - Fee Related CN101581586B (en) | 2009-06-23 | 2009-06-23 | Distributed optical fiber sagnac positioning sensor inhibiting dead zone of sensor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101581586B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102128673A (en) * | 2010-09-02 | 2011-07-20 | 上海华魏光纤传感技术有限公司 | Interferometric fiber vibration sensor |
| CN102095435A (en) * | 2010-09-02 | 2011-06-15 | 上海华魏光纤传感技术有限公司 | Two-channel feedback loop fiber interferometer |
| CN103345808B (en) * | 2013-06-26 | 2015-09-09 | 武汉理工光科股份有限公司 | The intrusion model recognition methods of fiber grating circumference and system |
| CN110058198B (en) * | 2019-03-25 | 2021-01-12 | 杭州电子科技大学 | Underwater positioning method based on distributed optical fiber sensor |
| CN111220881A (en) | 2019-11-18 | 2020-06-02 | 南京航空航天大学 | Optical fiber detection device for detecting discharge fault of high-voltage bushing |
| CN112198591B (en) * | 2020-09-29 | 2023-02-28 | 中国石油天然气股份有限公司 | Fresnel noise suppression unit at tail end of optical fiber and manufacturing method thereof |
| CN113324569B (en) * | 2021-05-21 | 2022-03-18 | 复旦大学 | Dual-wavelength unidirectional ring type distributed optical fiber sensing and positioning system |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030043697A1 (en) * | 1998-04-03 | 2003-03-06 | Vakoc Benjamin J. | Apparatus and method for processing optical signals from two delay coils to increase the dynamic range of a sagnac-based fiber optic sensor array |
| JP2004258506A (en) * | 2003-02-27 | 2004-09-16 | Fujikura Ltd | Depolarizer and optical raman amplifier provided with the same |
| CN101183014A (en) * | 2007-12-13 | 2008-05-21 | 北京理工大学 | Full polarization-preserving fiber interferometer based on 3X3 polarization-preserving fiber coupling mechanism |
| CN101275834A (en) * | 2007-03-30 | 2008-10-01 | 黄宏嘉 | Passive bias optical fiber gyroscope and current sensor |
-
2009
- 2009-06-23 CN CN2009101171251A patent/CN101581586B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030043697A1 (en) * | 1998-04-03 | 2003-03-06 | Vakoc Benjamin J. | Apparatus and method for processing optical signals from two delay coils to increase the dynamic range of a sagnac-based fiber optic sensor array |
| JP2004258506A (en) * | 2003-02-27 | 2004-09-16 | Fujikura Ltd | Depolarizer and optical raman amplifier provided with the same |
| CN101275834A (en) * | 2007-03-30 | 2008-10-01 | 黄宏嘉 | Passive bias optical fiber gyroscope and current sensor |
| CN101183014A (en) * | 2007-12-13 | 2008-05-21 | 北京理工大学 | Full polarization-preserving fiber interferometer based on 3X3 polarization-preserving fiber coupling mechanism |
Non-Patent Citations (1)
| Title |
|---|
| JP特开2004-258506A 2004.09.16 |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101581586A (en) | 2009-11-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101581586B (en) | Distributed optical fiber sagnac positioning sensor inhibiting dead zone of sensor | |
| CN102168808B (en) | Distributed optical fiber vibration sensor | |
| CN100561144C (en) | Distributed optical fiber vibration sensing method and device | |
| CN104236697B (en) | Distribution type optical fiber vibration detection method and system based on wavelength division multiplexing | |
| CN101634571B (en) | Optical pulse raster distributed fiber sensing device | |
| CN102721459B (en) | Optical fiber hydrophone array adopting reflective quasi-reciprocity optical path | |
| CN105973450B (en) | Optical fiber Fizeau interference arrays distributed vibration sensing system and method | |
| CN110440900A (en) | A kind of optical fiber distributed type acoustic wave sensing system | |
| US10145726B2 (en) | Fiber optic acoustic wave detection system | |
| CN106680535A (en) | Differential motion type optical acceleration meter for achieving laser beat frequency based on fiber bragg optical grating reflection spectrum features | |
| US10145727B2 (en) | Method and structure for diminishing signal interference of transmission path of optical fibre interference system | |
| CN108415067A (en) | A kind of earthquake wave measuring system based on microstructured optical fibers distribution sound wave sensing | |
| CN104180831A (en) | Sensitivity-enhanced optical time domain reflection distributed Michelson interferometer based on two-core optical fiber | |
| CN103017887A (en) | Optical fiber vibration sensing system and detection method thereof | |
| CN111308125B (en) | Acceleration detection method based on optical fiber Sagnac interferometer and acceleration meter | |
| CN105091919A (en) | High-sensitivity double optical fiber and cable sensor | |
| CN108592963A (en) | A kind of suppressing method and its system of time division multiplexing optical fiber sensing system multiplicative noise | |
| CN102721458A (en) | Optical fiber hydrophone adopting reflective quasi-reciprocity optical path | |
| CN111307270A (en) | Distributed optical fiber sensing system for improving vibration measurement sensitivity | |
| CN104180832A (en) | Distributed orthogonal vector disturbance sensing system based on four-core optical fiber | |
| CN115200691A (en) | Few-mode optical fiber distributed acoustic sensing system and signal processing method thereof | |
| CN103528666A (en) | Long-distance optical fiber vibration detection device and method on basis of Sagnac interference | |
| CN100538309C (en) | The online modular testing device of fiber optic loop in the optical fibre gyro | |
| CN102692268B (en) | Distributed optical fiber vibration sensor for structural vibration detection | |
| CN201993214U (en) | Distributed optical fiber vibrating sensor for structural vibration detection |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20101110 Termination date: 20130623 |