CN202494459U - White-light interference sensing system - Google Patents
White-light interference sensing system Download PDFInfo
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- CN202494459U CN202494459U CN2012201262188U CN201220126218U CN202494459U CN 202494459 U CN202494459 U CN 202494459U CN 2012201262188 U CN2012201262188 U CN 2012201262188U CN 201220126218 U CN201220126218 U CN 201220126218U CN 202494459 U CN202494459 U CN 202494459U
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- fiber coupler
- white light
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Abstract
The utility model relates to a white-light interference sensing system. The white-light interference sensing system of the utility model comprises a white-light light source, two photoelectric detectors, an optical fiber coupler and a sensing optical fiber, wherein the optical fiber coupler is a multi-port optical coupler with the number of the ports of each side being not less than two and the number of the ports of at least one side being greater than two; and the white-light light source and the two photoelectric detectors are respectively connected to the same side of the optical fiber coupler, and two ends of the sensing optical fiber are respectively connected with two ports at the other side of the optical fiber coupler to form an optical closed loop. The white-light interference sensing system of the utility model can assist in solving the problem of insufficient strength and instability of interference signals caused by birefringence which randomly occurs in optical fiber in a traditional optical fiber interference system. By means of the above manner, the white-light interference sensing system of the utility model is advantaged in that the interference 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)
Δ φ (t)=φ (t-t in the following formula
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 Δ φ 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 white light interference sensor-based system 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 white light interference sensor-based system; Comprise white light source, two photodetectors, fiber coupler, sensor fibre, wherein 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; White light source, two photodetectors are connected respectively to same one side of fiber coupler, the two ends of sensor fibre respectively with the fiber coupler another side in two ports be connected to form the optics closed-loop path; The white light that white light source sends divides clockwise and counterclockwise both direction to get into the optics closed-loop path through fiber coupler, and the process sensor fibre is got back to fiber coupler formation interference signal after experiencing disturbing signal, is received by two photodetectors respectively.
Preferably, said fiber coupler is the 3x3 fiber coupler, and splitting ratio is 1: 1: 1.
Preferably, said fiber coupler is the 3x2 fiber coupler, and splitting ratio is 1: 1: 1 and 1: 1.
Preferably, said fiber coupler is the 4x4 fiber coupler, and splitting ratio is 1: 1: 1: 1.
Preferably, said 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, promptly uses white light source 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.
Use white light source, come 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 the input white light was promptly imported different wavelength of laser simultaneously in this optics closed-loop path, 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 average effect.This average 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 white light 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, white light source; 2, fiber coupler; 3, photodetector; 4, sensor fibre.
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, a kind of white light interference sensor-based system, it comprises white light source 1, two photodetectors 3, fiber coupler 2 and sensor fibres 4.Fiber coupler 2 in the present embodiment is the 3X3 fiber coupler.White light source 1, two photodetectors 3 are connected respectively to same one side of fiber coupler 2, the two ends of sensor fibre 4 respectively with fiber coupler 2 another sides in two ports be connected; White light comes out the back to fiber coupler 2 from white light source 1, and the light that is come out by fiber coupler 2 returns fiber coupler 2 through sensor fibre 4, constitutes an optics closed-loop path.During work; The white light that white light source 1 sends is through fiber coupler 2; Divide clockwise and counterclockwise both direction to get into the optics closed-loop path, process sensor fibre 4 is got back to fiber coupler 2 formation interference signals after experiencing disturbing signal, is received by two photodetectors 3 respectively.
The splitting ratio of preferred fiber coupler 2 is 1: 1: 1 in the present embodiment, and sensor fibre 4 is a single-mode fiber.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 problem of the swinging of signal that the white light interference sensor-based system of the utility model brings for the birefringent phenomenon that solves in the optical fiber, the method that the utility model provides are to use white light source and use 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 white light source 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 (6)
1. white light interference sensor-based system; It is characterized in that: comprise white light source, two photodetectors, fiber coupler, sensor fibre, wherein 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; White light source, two photodetectors are connected respectively to same one side of fiber coupler, the two ends of sensor fibre respectively with the fiber coupler another side in two ports be connected to form the optics closed-loop path; The white light that white light source sends divides clockwise and counterclockwise both direction to get into the optics closed-loop path through fiber coupler, and the process sensor fibre is got back to fiber coupler formation interference signal after experiencing disturbing signal, is received by two photodetectors respectively.
2. white light interference sensor-based system according to claim 1 is characterized in that: said fiber coupler is the 3x3 fiber coupler, and its splitting ratio is 1:1:1.
3. white light interference sensor-based system according to claim 1 is characterized in that: said fiber coupler is the 3x2 fiber coupler, and its splitting ratio is 1:1:1 and 1:1.
4. white light interference sensor-based system according to claim 1 is characterized in that: said fiber coupler is the 4x4 fiber coupler, and its splitting ratio is 1:1:1:1.
5. white light interference sensor-based system according to claim 1 is characterized in that: said fiber coupler is the 4x2 fiber coupler, and its splitting ratio is 1:1:1:1 and 1:1.
6. according to the arbitrary described white light interference sensor-based system of claim 1 ~ 5, it is characterized in that: said sensor fibre is a single-mode fiber.
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| CN2012201262188U CN202494459U (en) | 2012-03-30 | 2012-03-30 | White-light interference sensing system |
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| CN2012201262188U CN202494459U (en) | 2012-03-30 | 2012-03-30 | White-light interference sensing system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102620758A (en) * | 2012-03-30 | 2012-08-01 | 苏州攀星光电科技有限公司 | White light interference sensing system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102620758A (en) * | 2012-03-30 | 2012-08-01 | 苏州攀星光电科技有限公司 | White light interference sensing system |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20121017 Termination date: 20180330 |