CN202494461U - Multiple-light source interferometric sensing system - Google Patents
Multiple-light source interferometric sensing system Download PDFInfo
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- CN202494461U CN202494461U CN2012201262205U CN201220126220U CN202494461U CN 202494461 U CN202494461 U CN 202494461U CN 2012201262205 U CN2012201262205 U CN 2012201262205U CN 201220126220 U CN201220126220 U CN 201220126220U CN 202494461 U CN202494461 U CN 202494461U
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Abstract
The utility model relates to a multiple-light source interferometric sensing system. The sensing system of the utility model comprises at least two laser light sources with different wavelengths, two photoelectric detectors, a front-stage optical fiber coupler, a back-stage optical fiber coupler and a sensing optical fiber. The laser light sources are respectively connected to a same side of the front-stage optical fiber coupler; a port of the other side of the front-stage optical fiber coupler and two photoelectric detectors are respectively connected to a same side of the back-stage optical fiber coupler; and both ends of the sensing optical fiber are respectively connected with two ports in the other side of the back-stage optical fiber coupler to form an optical closed loop. The multiple-light source interferometric sensing system of the utility model can assist in solving the problem of insufficient strength and instability of interferometric signals caused by birefringence phenomenon randomly produced in optical fiber in a traditional optical fiber interferometric system. By means of the above manner, the multiple-light source interferometric sensing system of the utility model is advantaged in that: the interferometric signals are stable and are not affected by environment factors.
Description
Technical field
The utility model relates to optical fiber sensing technology, is specifically related to the measuring system of optical fiber interference signal.
Background technology
The utility model is mainly based on principle of optical interference.This fiber optic interferometric system is at same optical fiber, and the light from same lasing light emitter that promptly two bundles are propagated along both forward and reverse directions in the optics closed-loop path forms interferes.When the optics closed-loop path receives external disturbance, the light path of propagating along both forward and reverse directions will be affected.Although the influence that two-way light receives is the same, the time of this influence arrival detector is different.The interference light intensity that measures on the detector will be affected, thereby cause corresponding variation response.
With traditional optical closed-loop path interference ring is example; As shown in Figure 1; The light that laser instrument sends divides clockwise and counterclockwise both direction to get into the optics closed-loop path through the 2x2 coupling mechanism, converges to detector formation interference signal again through disturbing signal induction optical fiber and 2x2 coupling mechanism.Any disturbance is applied on the optics closed-loop path, all can cause the variation Φ (t) of the phase place of propagates light, and the mistiming that this change to arrive detector is determined by position and the length of optics closed-loop path that disturbance occurs on the optics closed-loop path.Mistiming is big more, and the interference electric current that detector detects changes more greatly
I(t)＝I
0(2-2cos(ΔΦ(t)+Φ
0))， (1)
ΔΦ in the following formula (t)=Φ (t-t
1)-Φ (t-t
2),
L
1For disturbance point CW in the optics closed-loop path to the distance of 2x2 coupling mechanism, L
2For disturbance point in the optics closed-loop path counterclockwise arrives the distance of 2x2 coupling mechanism, c is the speed that light is propagated in optical fiber, I
0Detector is from a light intensity that output terminal receives of coupling mechanism, Φ when interfering for not having
0Be initial phase difference, the 2x2 coupling mechanism will bring differing of π, but the birefringence effect in the optical fiber also can have influence on Φ
0
When ΔΦ hour, being changed to of interference light intensity
ΔI(t)≈2I
0sin(Φ
0)ΔΦ(t)+I
0cos(Φ
0)(ΔΦ(t))
2 (2)
Since the characteristic of 2x2 coupling mechanism, Φ when the birefringence effect of not considering in the optical fiber
0=π, first disappearance on following formula the right, so in the optics closed-loop path fiber optic interferometric system to the response of small sample perturbations be disturbance square, rather than linear response, the difficult variation that observes interference signal.
Sensor fibre is made with single-mode fiber usually in this optics closed-loop path, optical fiber meeting bend by pressure in the Construction Arrangement, and birefringence effect wherein is that inevitably this birefringence effect will influence Φ
0Value.The birefringence effect that this specific character of optics closed-loop path interference ring makes the power of its interference signal also formed in the optical fiber of optics closed-loop path influences; Can make the rightabout light experience of the two-way different optical path in the optics closed-loop path, although after they converge again identical polarization state is arranged still.
Optical fiber distortion curvature, the temperature variation when birefringence effect in the optical fiber is installed, put on the influence of the factors such as pressure on the optical fiber.So both made identical disturbance put on two same systems, observed signal power can be not identical yet.Same system is in different time, and as by day and at night, the temperature difference makes identical disturbance also can record different strong and weak signals.Sometimes even do not observe disturbing signal.This system that will make can not reliablely and stablely work.
The problems referred to above are all unavoidable problem of all fibre systems of using principle of interferences; These factors can cause rate of failing to report and the rate of false alarm of optical fiber interference signal instability, signal to noise ratio (S/N ratio) variation, system a series of problems such as to increase.
Summary of the invention
The purpose of the utility model is to overcome the deficiency that above-mentioned prior art exists, and a kind of Photodetection system of measuring optical fiber interference signal is provided, and it has the stable and very little advantage affected by environment of optical fiber interference signal.
For achieving the above object; The technical scheme that the utility model adopts is: a kind of multiple light courcess is interfered sensor-based system; It comprises at least two different wavelength of laser light sources, two photodetectors, prime fiber coupler, back level fiber coupler and sensor fibres; Wherein the prime fiber coupler has at least on one side port number to be no less than the quantity of LASER Light Source, and back level fiber coupler is that the port number on multiple port fiber optical coupling mechanism and every limit is no less than 2 and have port number on one side at least greater than 2; Each LASER Light Source is connected respectively to same one side of prime fiber coupler; A port of the another side of prime fiber coupler, two photodetectors are connected respectively to same one side of back level fiber coupler, the two ends of sensor fibre respectively with back level fiber coupler another side in two ports be connected to form the optics closed-loop path; The light that each LASER Light Source sends is the level fiber coupler after the prime fiber coupler converges to; Divide clockwise and counterclockwise both direction to get into the optics closed-loop path again; The process sensor fibre is got back to back level fiber coupler formation interference signal after experiencing disturbing signal, is received by two photodetectors respectively.
Preferably, said prime fiber coupler is the 1X2 fiber coupler, and the quantity of said different wavelength of laser light source is 2.
Preferably, said back level fiber coupler is the 3x3 fiber coupler, and splitting ratio is 1: 1: 1.
Preferably, said back level fiber coupler is the 3x2 fiber coupler, and splitting ratio is 1: 1: 1 and 1: 1.
Preferably, said back level fiber coupler is the 4x4 fiber coupler, and splitting ratio is 1: 1: 1: 1.
Preferably, a said back level fiber coupler is the 4x2 fiber coupler, and splitting ratio is 1: 1: 1: 1 and 1: 1.
Preferably, said sensor fibre is a single-mode fiber.
The beneficial effect of the utility model is:
The problem of the swinging of signal of bringing for the birefringent phenomenon that solves in the optical fiber; The utility model has adopted two kinds of methods to strengthen the stability of interference signal simultaneously, has promptly used multiple different wavelength of laser to match with two photodetectors with use multiple port fiber optical coupling mechanism with the laser that replaces the single wavelength in the conventional solution.
Used multiple different wavelength of laser to replace the laser of the single wavelength in the conventional solution, it comes down on the optics closed-loop path, to import simultaneously the light of different wave length.And the birefringence effect in this optics closed-loop path all bring different differing can for the light of each different wave length, promptly for the light of each wavelength, and the Φ in the formula (2)
0Distortion curvature, the temperature variation of optical fiber in the time of installed by optical fiber, put on the influence of the factors such as pressure on the optical fiber.Therefore, when in this optics closed-loop path, importing different wavelength of laser simultaneously, because the interference in this optics closed-loop path is very low to the requirement of coherent length, we still can observe interference, and to the light of different wavelengths, the Φ in the formula (1) (2)
0All inequality, thus observe a kind of effect of complementation.This complementary effect makes that observed interference strength is more stable, receives the influence of environmental change littler.
Use the multiple port fiber optical coupling mechanism to replace the 2x2 coupling mechanism in the conventional solution, its objective is in order to insert two photodetectors.Because the two paths of signals of the output of multiple port fiber optical coupling mechanism has certain correlativity, therefore through detecting the correlativity of signal between two photodetectors, the stability of compensated optical fiber interference signal effectively, thus make signal to noise ratio (S/N ratio) be improved significantly.
Description of drawings
Fig. 1 is that illustration is implemented in the optical interference of traditional optical closed-loop path;
Fig. 2 is that the utility model is used for multiple light courcess interference sensor-based system embodiment synoptic diagram;
Fig. 3 is traditional optical closed-loop path optical interference change in signal strength figure;
Fig. 4 is the electro-optical system optical interference change in signal strength figure of the utility model.
The mark of each parts is following among accompanying drawing 1 and Fig. 2:
1, first LASER Light Source; 2, back level fiber coupler; 3, photodetector; 4, sensor fibre; 5, prime fiber coupler; 6, second LASER Light Source.
Embodiment
Below in conjunction with accompanying drawing the preferred embodiment of the utility model is set forth in detail, thereby the protection domain of the utility model is made more explicit defining so that advantage of the utility model and characteristic can be easier to it will be appreciated by those skilled in the art that.
As shown in Figure 2; It comprises two different wavelength of laser light sources i.e. first LASER Light Source 1 and second LASER Light Source 6, two photodetectors 3, prime fiber coupler 5, back grade fiber coupler 2 and sensor fibres 4; Wherein the prime fiber coupler is the 1X2 fiber coupler, and back level fiber coupler is the 3X3 fiber coupler.First LASER Light Source 1 is connected with same one side of prime fiber coupler 5 respectively with second LASER Light Source 6; A port of the another side of prime fiber coupler 5, two photodetectors 3 are connected respectively to same one side of back level fiber coupler 2, the two ends of sensor fibre 4 respectively with back level fiber coupler 2 another sides in two ports be connected.The different wavelength of laser that first LASER Light Source 1 and second LASER Light Source 6 send respectively is level fiber coupler 2 after prime fiber coupler 5 converges to; Light level fiber coupler 2 after sensor fibre 4 returns by back level fiber coupler 2 comes out constitutes an optics closed-loop path.During work; The different wavelength of laser that first LASER Light Source 1 and second LASER Light Source 6 send respectively is level fiber coupler 2 after prime fiber coupler 5 converges to; Divide clockwise and counterclockwise both direction to get into the optics closed-loop path again; Process sensor fibre 4 is got back to back level fiber coupler 2 formation interference signals after experiencing disturbing signal, is received by two photodetectors 3 respectively.
Use two different wavelength of laser light sources in this embodiment, also available more a plurality of different wave length LASER Light Sources, should adopt the prime fiber coupler with the port that is no less than LASER Light Source quantity to be complementary with the quantity with LASER Light Source this moment.The splitting ratio of preferred back level fiber coupler 2 is 1: 1: 1 in the present embodiment; Sensor fibre 4 is a single-mode fiber; Back level fiber coupler 2 also can by 3x2,4x4,4x2 fiber coupler or more the fiber coupler of multiport replace the light that these fiber couplers should be able to the arbitrary passage input of uniform distribution.
The multiple light courcess of the utility model is interfered the problem of the swinging of signal that sensor-based system brings for the birefringent phenomenon that solves in the optical fiber, and the method that the utility model provides has been to use multiple different wavelength of laser and has used the multiple port fiber optical coupling mechanism to match with two photodetectors.
Can find out that by Fig. 3 in the traditional optical closed-loop path, because the interference that birefringent phenomenon brings, the optical interference signal is suddenly big or suddenly small, the point of null value particularly occurred much approaching.
Can find out by Fig. 4; Owing to adopted multiple different wavelength of laser and used the multiple port fiber optical coupling mechanism to match with two photodetectors; In the electro-optical system of the utility model, the intensity of optical interference signal is obviously improved, and a large amount of points near null value that occur disappear basically in Fig. 3.
The above is merely the embodiment of the utility model; Be not thus the restriction the utility model claim; Every equivalent structure or equivalent flow process conversion that utilizes the utility model instructions and accompanying drawing content to be done; Or directly or indirectly be used in other relevant technical fields, all in like manner be included in the scope of patent protection of the utility model.
Claims (7)
1. a multiple light courcess is interfered sensor-based system; It is characterized in that: comprise at least two different wavelength of laser light sources, two photodetectors, prime fiber coupler, back level fiber coupler and sensor fibres; Wherein the prime fiber coupler has at least on one side port number to be no less than the quantity of LASER Light Source, and back level fiber coupler is that the port number on multiple port fiber optical coupling mechanism and every limit is no less than 2 and have port number on one side at least greater than 2; Each LASER Light Source is connected respectively to same one side of prime fiber coupler; A port of the another side of prime fiber coupler, two photodetectors are connected respectively to same one side of back level fiber coupler, the two ends of sensor fibre respectively with back level fiber coupler another side in two ports be connected to form the optics closed-loop path; The light that each LASER Light Source sends is the level fiber coupler after the prime fiber coupler converges to; Divide clockwise and counterclockwise both direction to get into the optics closed-loop path again; The process sensor fibre is got back to back level fiber coupler formation interference signal after experiencing disturbing signal, is received by two photodetectors respectively.
2. multiple light courcess according to claim 1 is interfered sensor-based system, and it is characterized in that: said prime fiber coupler is the 1X2 fiber coupler, and the quantity of said different wavelength of laser light source is 2.
3. multiple light courcess according to claim 1 is interfered sensor-based system, it is characterized in that: said back level fiber coupler is the 3x3 fiber coupler, and its splitting ratio is 1:1:1.
4. multiple light courcess according to claim 1 is interfered sensor-based system, it is characterized in that: said back level fiber coupler is the 3x2 fiber coupler, and its splitting ratio is 1:1:1 and 1:1.
5. multiple light courcess according to claim 1 is interfered sensor-based system, it is characterized in that: said back level fiber coupler is the 4x4 fiber coupler, and its splitting ratio is 1:1:1:1.
6. multiple light courcess according to claim 1 is interfered sensor-based system, it is characterized in that: said back level fiber coupler is the 4x2 fiber coupler, and its splitting ratio is 1:1:1:1 and 1:1.
7. interfere sensor-based system according to the arbitrary described multiple light courcess of claim 1 ~ 6, it is characterized in that: said sensor fibre is a single-mode fiber.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102607622A (en) * | 2012-03-30 | 2012-07-25 | 苏州攀星光电科技有限公司 | Multi-source interference sensing system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102607622A (en) * | 2012-03-30 | 2012-07-25 | 苏州攀星光电科技有限公司 | Multi-source interference sensing system |
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Granted publication date: 20121017 Termination date: 20180330 |