CN208902226U - A kind of fiber optic interferometric water level sensor based on frequency shift technique - Google Patents
A kind of fiber optic interferometric water level sensor based on frequency shift technique Download PDFInfo
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- CN208902226U CN208902226U CN201821853042.XU CN201821853042U CN208902226U CN 208902226 U CN208902226 U CN 208902226U CN 201821853042 U CN201821853042 U CN 201821853042U CN 208902226 U CN208902226 U CN 208902226U
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Abstract
The utility model discloses a kind of fiber optic interferometric water level sensor based on frequency shift technique, the water level sensor uses two Mach Zehnder interference structures, the two-way fiber lengths difference of one interference structure is constant, and the signal that photodetector detects has fixed phase value；Another interference structure connects sensing element, and when water level changes, fiber lengths change, the light path of light changes, the phase for transmitting the light in sensor fibre also changes, and can demodulate phase difference value by host computer demodulating system, can go out water level value according to phase difference value with inverse.The utility model has many advantages, such as high sensitivity, corrosion-resistant, electromagnetism interference.
Description
Technical field
The utility model belongs to technical field of optical fiber sensing more particularly to a kind of fiber optic interferometric water level based on frequency shift technique
Sensor.
Background technique
High-precision water level sensor can be used for monitoring the variation of various water levels, such as monitoring city river water level situation,
Monitor reservoir level situation, monitoring ocean water level variation etc..If not carrying out water level monitoring in advance, when water level reaches warning line
Afterwards, it will cause urban flooding, breach a dyke, the disasters such as tsunami, seriously affect the life security and economic asset safety of the people,
Therefore the water level conditions for accurately monitoring various complexity are very necessary, and the development of high-accuracy water level sensor is of great significance.
Water level sensor generally has float type water level sensor, pressure type water level sensor, optical fiber water level sensor etc. no
Same classification proposes a kind of using the floating of datum level in the Chinese patent of disclosed Patent No. CN202974389U
Minor water-level gauge, the water-level gauge use mechanical structure sensor, need logging equipment, it is difficult to operate, it is steady to be only applicable to bank slope
Fixed, change in bed level very little low sand-carrying capacity section, limitation are very big.It is special in the China of disclosed Patent No. CN204286550U
In benefit, a kind of pressure type water gauge for being able to carry out atmospheric pressure compensating is proposed, which uses circuit structure, including signal to adopt
Collection, signal processing, power supply unit etc., structure is complicated for integrated circuit, and transmission range is limited, it is impossible to be used in electromagnetic interference is serious, rotten
Under the adverse circumstances such as corrosion is strong；In the Chinese patent of disclosed Patent No. CN204461547U, it is dry to propose a kind of optical fiber
It paddles level sensor, using optical fiber sensing technology, constructs Michelson interference structure, level measuring is realized by phase demodulating,
But its measurement that can only carry out dynamic water table variation cannot achieve the measurement of static water level, and demodulating algorithm is complicated, in reality
There is certain limitation in.
Utility model content
To overcome above-mentioned the deficiencies in the prior art, the utility model provides a kind of fiber optic interferometric water based on frequency shift technique
Level sensor, the water level sensor use two Mach Zehnder interference structures, the two-way optical fiber length difference of an interference structure
It is worth constant, the signal that photodetector detects has fixed phase value；Another interference structure connects sensing element, works as water level
When changing, fiber lengths change, and the light path of light changes, and the phase for transmitting the light in sensor fibre also changes, and lead to
Phase difference value can be demodulated by crossing host computer demodulating system, can go out water level value according to phase difference value with inverse.The utility model tool
There are high sensitivity, corrosion-resistant, electromagnetism interference, high-precision level measuring may be implemented.
To achieve the above object, one or more embodiments of the utility model provide following technical solution:
A kind of fiber optic interferometric water level sensor based on frequency shift technique, the sensor are dry including the first Mach-Zehnder
Relate to structure and the second Mach Zehnder interference structure；Wherein,
The first Mach Zehnder interference structure includes laser, the first coupler, acousto-optic modulator, the second coupling
Device, third coupler, sensing element, the 4th coupler, the first photodetector,
The output end of laser is connected with the input terminal of the first coupler；The output end of first coupler is divided into two
Road is connected after being connected all the way with acousto-optic modulator with the second coupler input, the output end and sensing element of the second coupler
It is connected again with the 4th coupler after being connected；Another way input terminal with the 4th coupler again after another way is connected with third coupler
It is connected, the output end of the 4th coupler is connected with the first photodetector；
The second Mach Zehnder interference structure includes laser, the first coupler, acousto-optic modulator, the second coupling
Device, third coupler, the 5th coupler, the second photodetector,
The output end of laser is connected with the input terminal of the first coupler；The output end of first coupler is divided into two
Road is connected after being connected all the way with acousto-optic modulator with the second coupler input, and the output end of the second coupler is coupled with the 5th
Device is connected；Another way is connected with the another way input terminal of the 5th coupler again after being connected with third coupler, the 5th coupler
Output end is connected with the second photodetector；
The first Mach Zehnder interference structure and the second Mach Zehnder interference structure pass through the first photoelectricity respectively
Detector and the second photodetector access host computer demodulating system.
Further, the laser includes first laser device and second laser, and the two output frequency differs 100GHz
Light source.
Further, the optical source wavelength of the first laser device output is 1550nm, narrow linewidth 10M.
Further, the sensor uses single mode optical fiber, and core diameter is 9 μm, and cladding diameter is 125 μm.
Further, the interfere arm of the second Mach Zehnder interference structure and the first Mach Zehnder interference structure
Isometric, the optical path difference 2mm of approximation.
Further, the sensing element includes coupling, water band, compact heap, Optical Fiber Winding portion and clamp clip, wherein
One end of the water band is connect with coupling, and the other end is sealed by two clamp clips；On the water band also
Two compact heaps are oppositely arranged, for compressing the water band, are respectively provided with Optical Fiber Winding portion on each compact heap.
Further, the Optical Fiber Winding between the output end of the second coupler and the 4th coupler input is in Optical Fiber Winding
In portion.
Further, the radius in the Optical Fiber Winding portion is 26mm.
Further, the sensing element further includes frame frame, and the frame frame is sheathed on outside water band, described two compact heaps
Piece is connected and fixed each by one to connect with frame frame far from one end of coupling.
Further, the described two clamp clips being oppositely arranged are connect with frame frame far from one end of coupling.
The above one or more technical solution there are following the utility model has the advantages that
(1) interference structure based on frequency shift technique is used, pair to interference signal after shift frequency and fixed interference signal is passed through
Than the accurate interference arm length difference of two interference structures can be obtained, can then realize the high-acruracy survey to water level.
(3) water level system is built using optical fiber sensing technology, the sensing element for winding sensitive optical fibre can put into seabed, have
The advantages that corrosion-resistant, electromagnetism interference, small transmission loss, is applicable to sea bottom complex environment.
Detailed description of the invention
The Figure of description for constituting a part of the utility model is used to provide further understanding of the present application, the application
Illustrative embodiments and their description for explaining the application, do not constitute an undue limitation on the present application.
Fig. 1 is the system block diagram of fiber optic interferometric water level sensor of the utility model embodiment one based on frequency shift technique；
Fig. 2 is the structure chart of fiber optic interferometric water level sensor of the utility model embodiment one based on frequency shift technique；
Fig. 3 is the sensing element structure chart of fiber optic interferometric water level sensor in the utility model embodiment one；
Fig. 4 is the sensing element sectional view of fiber optic interferometric water level sensor in the utility model embodiment one.
Wherein, 1 --- first laser device, 2 --- second laser, 3 --- the first coupler, 4 --- acousto-optic modulator,
5 --- the second coupler, 6 --- third coupler, 7 --- sensing element, 8 --- the 4th coupler, 9 --- the 5th coupling
Device, 10 --- the first photodetector, 11 --- the second photodetector, 12 --- host computer demodulating system, 13 --- it is external
Head, 14 --- frame frame, 15 --- compact heap, 16 --- Optical Fiber Winding portion, 17 --- it is connected and fixed piece, 18 --- lock-screw,
19 --- water band, 20 --- clamp clip.
Specific embodiment
It is noted that described further below be all exemplary, it is intended to provide further instruction to the application.Unless another
It indicates, all technical and scientific terms used herein has usual with the application person of an ordinary skill in the technical field
The identical meanings of understanding.
It should be noted that term used herein above is merely to describe specific embodiment, and be not intended to restricted root
According to the illustrative embodiments of the application.As used herein, unless the context clearly indicates otherwise, otherwise singular
Also it is intended to include plural form, additionally, it should be understood that, when in the present specification using term "comprising" and/or " packet
Include " when, indicate existing characteristics, step, operation, device, component and/or their combination.
In the absence of conflict, the features in the embodiments and the embodiments of the present application can be combined with each other.
Embodiment one
Present embodiment discloses a kind of fiber optic interferometric water level sensor structure chart based on frequency shift technique.As shown in Figs. 1-2,
The sensor structure include first laser device 1, second laser 2, the first coupler 3, acousto-optic modulator 4, the second coupler 5,
Third coupler 6, sensing element 7, the 4th coupler 8, the 5th coupler 9, the first photodetector 10, the second photodetector
11, host computer demodulating system 12.
The water level sensor includes two Mach Zehnder interference structures.
First interference structure includes laser, the first coupler 3, acousto-optic modulator 4, the second coupler 5, third coupling
Device 6, sensing element 7, the 4th coupler 8, the first photodetector 10, the input of the output end of laser and the first coupler 3
End is connected, and the output end of the first coupler 3 is divided into two-way, and be connected with acousto-optic modulator 4 rear and 5 input terminal of the second coupler all the way
Be connected, the output end of the second coupler 5 is connected with the 4th coupler 8 again after being connected with sensing element 7, the first coupler 3 it is another
It is connected again with the another way input terminal of the 4th coupler 8 after output end is connected with third coupler 6 all the way, the 4th coupler 8
Output end is connected with the first photodetector 10, this structure constitutes first Mach Zehnder interference.
Second interference structure includes laser, the first coupler 3, acousto-optic modulator 4, the second coupler 5, third coupling
Device 6, the 5th coupler 9, the second photodetector 11, the output end of laser are connected with the input terminal of the first coupler 3, and first
The output end of coupler 3 is divided into two-way, is connected after being connected all the way with acousto-optic modulator 4 with 5 input terminal of the second coupler, the second coupling
The output end of clutch 5 is connected with the 5th coupler 9, the another output end of the first coupler 3 be connected with third coupler 6 after again
It is connected with the another way input terminal of the 5th coupler 9, the output end of the 5th coupler 9 is connected with the second photodetector 11, this
Structure constitutes second Mach Zehnder interference.
First interference structure and second interference structure pass through the first photodetector 10 and the second photodetection respectively
Device 11 accesses host computer demodulating system 12.
First interference structure of the water level sensor, which is connected to sensing element, can experience the variation of water level, when water level changes
When change, optical fiber is stretched, and fiber lengths change, and the phase of interference signal also changes correspondingly；The two-way light of second interference structure
Fine length difference is invariable, and the phase of interference signal is fixed as reference, and two can be demodulated in host computer demodulating system
The phase difference of interference structure then can go out water level value with inverse.
Wherein, the sensing element structure is as shown in Figure 3-4, including coupling 13, frame frame 14, compact heap 15, optical fiber twine
Around portion 16, it is connected and fixed piece 17, lock-screw 18, water band 19 and clamp clip 20.Specifically, the sensing element structure is as follows:
Described 13 one end of coupling connects with tested water level, and the other end is connect by frame frame 14 with water band 19.Frame frame is arranged
Outside water band.
One end of the water band 19 is connect with coupling 13, and the other end is sealed by two clamp clips 20, specifically,
Two clamp clips pass through lock-screw 18 for one side seal of water band.
The water band 19 is compressed by the way that two compact heaps 15 are arranged, is respectively provided with Optical Fiber Winding portion on each compact heap 15
16, and compact heap 15 of the water with two sides, Optical Fiber Winding portion 16 are structure as a whole, the one end for being connected and fixed piece 17 and frame frame are far from outer
One end of connector is fixed by lock-screw 18, and the other end is fixed together with compact heap 15 with Laser Welding.It is described to be connected and fixed
Piece 17 is preferably flexible sheet metal.
Optical Fiber Winding between 8 input terminal of output end and the 4th coupler of second coupler 5 is in Optical Fiber Winding portion 16.
Coupling 13 is directly contacted with water, and when water level changes, water enters water band 19, water band 19 by coupling 13
Middle water becomes more, increases the distance between two compact heaps 15, Optical Fiber Winding causes in the Optical Fiber Winding portion 16 on compact heap 15
Fiber-draw, therefore the length of feeler arm changes in the system, then causes the phase of optical signal to change, by upper
Position machine demodulating system demodulates phase change, and the variation of water level can be gone out with inverse.
In one or more embodiments, first laser device 1 exports the light that stable wavelength is 1550nm narrow linewidth 10M or so
Source, second laser 2 are the laser with 1 frequency phase-difference 100GHz of first laser device.
The optical fiber being previously mentioned is 9 μm of core diameter, 125 μm of cladding diameter of single mode ordinary optic fibre, and first laser device is defeated
Stable wavelength is the light source of 1550nm narrow linewidth 10M or so out, and second laser output is and first laser device frequency phase-difference
The radius of the light source of 100GHz, optical fibre optical fibre wound portion is 26mm, greater than the bending radius of optical fiber.
If in the first Mach Zehnder interference structure, the optical path difference of two paths of signals when light passes through two arms of interference structure
For L1, in second Mach Zehnder interference structure, two-way optical fiber length difference is that fixed value is set as L2, L3=L2-L1, value is
2mm。
The above one or more embodiment has following technical effect that
The utility model uses the interference structure based on frequency shift technique, has high sensitivity, corrosion-resistant, electromagnetism interference
The advantages that.
It will be understood by those skilled in the art that each module or each step of above-mentioned the application can be filled with general computer
It sets to realize, optionally, they can be realized with the program code that computing device can perform, it is thus possible to which they are stored
Be performed by computing device in the storage device, perhaps they are fabricated to each integrated circuit modules or by they
In multiple modules or step be fabricated to single integrated circuit module to realize.The application be not limited to any specific hardware and
The combination of software.
The foregoing is merely preferred embodiment of the present application, are not intended to limit this application, for the skill of this field
For art personnel, various changes and changes are possible in this application.Within the spirit and principles of this application, made any to repair
Change, equivalent replacement, improvement etc., should be included within the scope of protection of this application.
Although above-mentioned be described in conjunction with specific embodiment of the attached drawing to the application, model not is protected to the application
The limitation enclosed, those skilled in the art should understand that, on the basis of the technical solution of the application, those skilled in the art are not
Need to make the creative labor the various modifications or changes that can be made still within the protection scope of the application.
Claims (10)
1. a kind of fiber optic interferometric water level sensor based on frequency shift technique, which is characterized in that the sensor include first Mach-
Zeng Deer interference structure and the second Mach Zehnder interference structure；Wherein,
The first Mach Zehnder interference structure includes laser, the first coupler, acousto-optic modulator, the second coupler,
Three couplers, sensing element, the 4th coupler, the first photodetector,
The output end of laser is connected with the input terminal of the first coupler；The output end of first coupler is divided into two-way,
It is connected after being connected all the way with acousto-optic modulator with the second coupler input, the output end of the second coupler is connected with sensing element
It is connected again with the 4th coupler afterwards；Another way be connected with third coupler after again with the another way input terminal phase of the 4th coupler
Even, the output end of the 4th coupler is connected with the first photodetector；
The second Mach Zehnder interference structure includes laser, the first coupler, acousto-optic modulator, the second coupler,
Three couplers, the 5th coupler, the second photodetector,
The output end of laser is connected with the input terminal of the first coupler；The output end of first coupler is divided into two-way,
It is connected after being connected all the way with acousto-optic modulator with the second coupler input, the output end of the second coupler and the 5th coupler phase
Even；Another way is connected with the another way input terminal of the 5th coupler again after being connected with third coupler, the output of the 5th coupler
End is connected with the second photodetector；
The first Mach Zehnder interference structure and the second Mach Zehnder interference structure pass through the first photodetection respectively
Device and the second photodetector access host computer demodulating system.
2. a kind of fiber optic interferometric water level sensor based on frequency shift technique as described in claim 1, which is characterized in that described to swash
Light device includes first laser device and second laser, and the two output frequency differs the light source of 100GHz.
3. a kind of fiber optic interferometric water level sensor based on frequency shift technique as claimed in claim 2, which is characterized in that described the
The optical source wavelength of one laser output is 1550nm, narrow linewidth 10M.
4. a kind of fiber optic interferometric water level sensor based on frequency shift technique as described in claim 1, which is characterized in that the biography
Sensor uses single mode optical fiber, and core diameter is 9 μm, and cladding diameter is 125 μm.
5. a kind of fiber optic interferometric water level sensor based on frequency shift technique as described in claim 1, which is characterized in that described the
Two Mach Zehnder interference structures and the interfere arm of the first Mach Zehnder interference structure are approximate isometric, optical path difference 2mm.
6. a kind of fiber optic interferometric water level sensor based on frequency shift technique as described in claim 1, which is characterized in that described quick
Sensing unit includes coupling, water band, compact heap, Optical Fiber Winding portion and clamp clip, wherein
One end of the water band is connect with coupling, and the other end is sealed by two clamp clips；It is also opposite on the water band
Two compact heaps are set, for compressing the water band, are respectively provided with Optical Fiber Winding portion on each compact heap.
7. a kind of fiber optic interferometric water level sensor based on frequency shift technique as claimed in claim 6, which is characterized in that the second coupling
Optical Fiber Winding between the output end of clutch and the 4th coupler input is in Optical Fiber Winding portion.
8. a kind of fiber optic interferometric water level sensor based on frequency shift technique as claimed in claim 6, which is characterized in that the light
The radius of fine wound portion is 26mm.
9. a kind of fiber optic interferometric water level sensor based on frequency shift technique as claimed in claim 6, which is characterized in that described quick
Sensing unit further includes frame frame, and the frame frame is sheathed on outside water band, and described two compact heaps are connected and fixed piece each by one
It is connect with frame frame far from one end of coupling.
10. a kind of fiber optic interferometric water level sensor based on frequency shift technique as claimed in claim 6, which is characterized in that opposite
The described two clamp clips being arranged are connect with frame frame far from one end of coupling.
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