CN107782696A - The sensor-based system and method for distributed liquid refractivity are measured using tapered fiber - Google Patents
The sensor-based system and method for distributed liquid refractivity are measured using tapered fiber Download PDFInfo
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- CN107782696A CN107782696A CN201710860221.XA CN201710860221A CN107782696A CN 107782696 A CN107782696 A CN 107782696A CN 201710860221 A CN201710860221 A CN 201710860221A CN 107782696 A CN107782696 A CN 107782696A
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/4133—Refractometers, e.g. differential
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
A kind of sensor-based system and method that distributed liquid refractivity is measured using tapered fiber, it is related to technical field of optical fiber sensing, the back rayleigh scattering intermode interference that conical region part based on tapered fiber occurs, carry out refractive index sensing, the change of extraneous refractive index is perceived by stronger evanescent wave caused by conical region, changes the effective mode refractive index that back rayleigh scattering is propagated in tapered fiber；Tapered fiber is placed in liquid, by distribution type optical fiber sensing equipment, the wavelength movement of the Rayleigh Scattering Spectra of the tapered fiber is detected, analyzes the wavelength movement, obtain the index distribution situation of the continuously distributed formula of liquid.Realize high spatial resolution and reach millimetre-sized distributed measuring refractive indexes of liquid.
Description
Technical field
The present invention relates to technical field of optical fiber sensing, more particularly to one kind to measure distributed liquid refracting using tapered fiber
The sensor-based system and method for rate, applied to probe beam deflation.
Background technology
Material refractive index is an important physical amount for reflecting material internal information.The measurement of material refractive index is ground on basis
Study carefully, chemical analysis, environmental pollution assessment, the field such as medical diagnosis and food industry have a wide range of applications.
Optic fibre refractive index sensor has the essential insulation of sensor, electromagnetism interference, high sensitivity, high accuracy, integrated level
The features such as height, high bandwidth, reusable turn into index sensor study hotspot.Traditional fiber index sensor has Prague light
Fine grating, long-period gratings, microbend fiber, photonic crystal fiber, optical fiber surface plasmon resonance, F-P sensors, online MZ are passed
The structures such as sensor, microballoon, micro-loop oscillator and monomode and multimode fiber concatenation.
Above-mentioned traditional fiber index sensor is typically using wideband light source and spectrometer demodulation or tunable laser
Scanning probe, using transmitted light mode, one point sensing can only be carried out, for discrete sense, can not accurate measurement in certain length
On index distribution.
It can realize that different refractive index senses along optical fiber there is an urgent need to a kind of optic fibre refractive index sensor at present, in optical fiber
Any point is all sensitive spot on certain length, realizes that multiple spot continuously senses.
The content of the invention
The invention provides a kind of sensor-based system and method that distributed liquid refractivity is measured using tapered fiber, this hair
The bright distributed measuring refractive indexes of liquid for realizing high spatial resolution and reaching mm (millimeter) level, can be successfully applied to intensive liquid
The measurement of body distributed index, monitoring liquid diffusion, and liquid layer such as are accurately positioned at the occasion, described below：
A kind of sensor-based system that distributed liquid refractivity is measured using tapered fiber, the sensor-based system are included：Optical frequency
The distribution type optical fiber sensing equipment of domain reflection, the sensor-based system are used to realize that high spatial resolution reaches millimetre-sized distribution
Measuring refractive indexes of liquid；
The sensor-based system includes：Tapered fiber,
The back rayleigh scattering intermode interference that conical region part based on the tapered fiber occurs, carry out refractive index biography
Sense, the change of extraneous refractive index is perceived by stronger evanescent wave caused by conical region, changed in the tapered fiber backwards to auspicious
The effective mode refractive index of sharp beyond-the-horizon communication；
The tapered fiber is placed in liquid, by the distribution type optical fiber sensing equipment, detects the tapered fiber
Rayleigh Scattering Spectra wavelength movement, analyze wavelength movement, obtain the index distribution situation of the continuously distributed formula of liquid.
The tapered fiber draws on cone machine is drawn for thin fiber and formed.
It is 200 μm/s to draw the draw speed during cone, and oxyhydrogen flame reciprocal distance is 2000 μm, reciprocating speed for 360 μm/
S, elongate optical fiber amount are 100000 μm, bore a diameter of 4 μm of area.
A kind of method for sensing that distributed liquid refractivity is measured using tapered fiber, the method for sensing include following step
Suddenly：
Beat frequency interference signal is formed by tapered fiber back rayleigh scattering in main interferometer, and to beat frequency interference signal point
Do not carry out Fast Fourier Transform (FFT), by optical frequency domain information be transformed into each position in corresponding tapered fiber apart from domain information, it is right
The each position for choosing tapered fiber successively by the Moving Window of one fixed width apart from domain information is formed locally apart from domain information；
Reference signal and measurement signal all choose the local apart from domain information of tapered fiber using Moving Window, by local distance
Domain information zero padding, zero padding quantity can be local distance domain data length several times before zero padding, then by local distance domain after zero padding
Information Pull complex Fourier inverse transformation, reconvert to optical frequency domain obtain the local optical frequency domain letter of reference signal and measurement signal
Breath；
Spectral wavelength movement is carried out to the local optical frequency domain information of reference signal and measurement signal using computing cross-correlation to estimate
Meter, the reflection Rayleigh scattering light spectrum wavelength movement of cross-correlation peak amount of movement, the movement of Rayleigh scattering light spectrum wavelength become with liquid refractivity
Change amount is directly proportional, reflects liquid refractivity variable quantity by cross-correlation peak amount of movement.
The beneficial effect of technical scheme provided by the invention is：
1st, the present invention can be successfully applied to intensive liquid refractivity distributed measurement, monitoring liquid diffusion, and liquid layer
The occasion such as it is accurately positioned；
2nd, the distributed measuring refractive indexes of liquid that high spatial resolution reaches 5mm is realized, sensitivity reaches 68.52nm/
RIU；
3rd, experiment proves that, the measurement error of temperature change is up to 0.0002RI, demonstrates effectiveness of the invention.
Brief description of the drawings
Fig. 1 is a kind of structural representation for the sensor-based system that distributed liquid refractivity is measured using tapered fiber；
Fig. 2 is a kind of another structural representation for the sensor-based system that distributed liquid refractivity is measured using tapered fiber；
Fig. 3 is a kind of flow chart for the method for sensing that distributed liquid refractivity is measured using tapered fiber；
Fig. 4 is the schematic diagram of calibration curve；
Fig. 5 is the schematic diagram of testing result citing.
In accompanying drawing, the list of parts representated by each label is as follows：
A：The distribution type optical fiber sensing equipment of probe beam deflation；
1：Tunable laser； 2：Detector；
3：50:50 beam splitters； 4：1:99 beam splitters；
5：50:50 couplers； 6：Clock shaping circuit module；
7：Postpone optical fiber； 8：First faraday's tilting mirror；
9：Second faraday's tilting mirror； 10：Isolator；
11：Computer； 12：Polarization Controller；
13：Circulator； 14 50:50 couplers；
15：Tapered fiber； 16：Polarization beam apparatus；
17：Polarization beam apparatus； 18：Balanced detector；
19：Balanced detector； 20：Harvester；
21：GPIB control modules； 22：Reference arm；
23：Test arm； 24：Clock trigger device based on auxiliary interferometer；
25：Main interferometer； 26：The covering of tapered fiber 15；
27：The fibre core of tapered fiber 15.
Embodiment
To make the object, technical solutions and advantages of the present invention clearer, embodiment of the present invention is made below further
It is described in detail on ground.
Traditional refractive index sensing based on tapered fiber is all one point sensing, and the cone area of tapered fiber can keep certain
Length is several centimetres to several meters, such as longer can reach tens meters even several kilometers using professional wire-drawing equipment, this is distributed light
Fine refractive index sensing provides may.In addition, optical frequency domain reflection technology is combined with tapered fiber, optical frequency domain reflection technology demodulation is drawn
The back rayleigh scattering in optical taper area is bored, is expected to realize that different refractive index senses.
Embodiment 1
Intensive liquid refractivity distributed measurement, monitoring liquid diffusion, liquid layer can not be realized in order to solve prior art
The technical problem such as it is accurately positioned, the embodiments of the invention provide a kind of biography that distributed liquid refractivity is measured using tapered fiber
Sensing system, it is described below referring to Fig. 1：
The design principle of the embodiment of the present invention is as follows：Based in the conical region part of tapered fiber 15, generation is backwards
Rayleigh scattering intermode interference carries out refractive index sensing, is by (the specific strong and weak determination of stronger evanescent wave caused by conical region
Determine that the embodiment of the present invention is without limitation according to practical experience value) change of extraneous refractive index is perceived, draw cone so as to change
The effective mode refractive index that back rayleigh scattering is propagated in optical fiber 15.
The change of back rayleigh scattering effective mode refractive index causes the change of interference phase difference, shows Rayleigh scattering light
Wavelength movement in spectrum.Rayleigh on the region of tapered fiber 15 is detected by the distribution type optical fiber sensing equipment A of probe beam deflation to dissipate
Penetrate wavelength movement spectrally.When tapered fiber 15 is placed in liquid, due to the effect in said process, pass through analysis point
Cloth Rayleigh scattering light spectrum wavelength moves, and obtains the index distribution situation of the continuously distributed formula of liquid.
In summary, the embodiment of the present invention realizes the distributed liquid refracting that high spatial resolution reaches mm (millimeter) level
Rate measures, and can be successfully applied to intensive liquid refractivity distributed measurement, monitoring liquid diffusion, and liquid layer and be accurately positioned
Occasion.
Embodiment 2
The sensor-based system in embodiment 1 is further introduced with reference to Fig. 1, it is described below：The sensing
System includes：The distribution type optical fiber sensing equipment of tapered fiber 15 and probe beam deflation, wherein, tapered fiber 15 is by thin footpath
Draw and form on cone machine is drawn., including：Covering 26 and fibre core 27 (being pulled to taper).
The embodiment of the present invention is 200 μm/s drawing the draw speed during boring, and oxyhydrogen flame reciprocal distance is 2000 μm, past
Complex velocity is 360 μm/s, and elongate optical fiber amount is 100000 μm, bores a diameter of 4 μm of area.
The distribution type optical fiber sensing equipment of probe beam deflation includes：Tunable laser 1,1:99 beam splitters 4, computer
11st, GPIB (general purpose interface bus) control module 21, the clock trigger device 24 based on auxiliary interferometer, main interferometer 25.
Wherein, the clock trigger device 24 based on auxiliary interferometer includes：Detector the 2, the 1st:50 couplers 5, clock
Frequency multiplier circuit module 6, delay optical fiber 7, first faraday's tilting mirror 8, second faraday's tilting mirror 9 and isolator 10.It is dry based on auxiliary
The clock trigger device 24 of interferometer is used for the sampling of the optical frequency spacing such as realization, and the purpose is to suppress the nonlinear scanning of light source.
Wherein, main interferometer 25 includes：50:50 beam splitters 3, Polarization Controller 12, circulator the 13, the 2nd 50:50 couplings
Device 14, the first polarization beam apparatus 16, the second polarization beam apparatus 17, the first balanced detector 18, the second balanced detector 19, collection
Device 20, reference arm 22 and test arm 23.Main interferometer 25 is the distribution type optical fiber sensing equipment A of probe beam deflation core,
It is modified Mach Zehnder interferometer.
The input of GPIB control modules 21 is connected with computer 11；The output end of GPIB control modules 21 and tunable laser
1 is connected；Tunable laser 1 and 1:The a ports of 99 beam splitters 4 are connected；1:The b ports of 99 beam splitters 4 and isolator 10
One end be connected；1:The c ports and 50 of 99 beam splitters 4:The a ports of 50 beam splitters 3 are connected；The other end of isolator 10 and phase
Connect the 1st:The b ports of 50 couplers 5 are connected；One 50:The a ports of 50 couplers 5 are connected with one end of detector 2；First
50:The c ports of 50 couplers 5 are connected with first faraday's tilting mirror 8；One 50:The d ports of 50 couplers 5 are by postponing optical fiber 7
It is connected with second faraday's tilting mirror 9；The other end of detector 2 is connected with the input of clock multiplier circuit module 6；Clock shaping
The output end of circuit module 6 is connected with the input of harvester 20；50:The b ports of 50 beam splitters 3 are by reference to arm 22 and partially
The input of controller 12 of shaking is connected；50:The c ports of 50 beam splitters 3 are connected by test arm 23 with a ports of circulator 13；
The output end of Polarization Controller 12 and the 2nd 50:The a ports of 50 couplers 14 are connected；The b ports and the 2nd 50 of circulator 13:50
The b ports of coupler 14 are connected；The c ports of circulator 13 are connected with tapered fiber 15；2nd 50:The c ports of 50 couplers 14
It is connected with the input of the first polarization beam apparatus 16；2nd 50:The d ports of 50 couplers 14 are defeated with the second polarization beam apparatus 17
Enter end to be connected；The output end of first polarization beam apparatus 16 input with the first balanced detector 18, the second balance detection respectively
The input of device 19 is connected；The output end of second polarization beam apparatus 17 input with the first balanced detector 18, second respectively
The input of balanced detector 19 is connected；The output end of first balanced detector 18 is connected with the input of harvester 20；The
The output end of two balanced detectors 19 is connected with the input of harvester 20；The output end of harvester 20 and the phase of computer 11
Even.
Device work when, computer 11 by GPIB control modules 21 control tunable laser 1 control tuned speed, in
Cardiac wave is long, tuning starts etc.；The emergent light of tunable laser 1 is by 1:The a ports of 99 beam splitters 4 enter, and with 1:99
Ratio is from 1:The b ports of 99 beam splitters 4 enter the 1st by isolator 10:The b ports of 50 couplers 5, light is from the 1st:
The b ports of 50 couplers 5 enter, from the 1st:C the and d ports outgoing of 50 couplers 5, respectively by the first faraday of two-arm
The faraday's tilting mirror 9 of tilting mirror 8 and second reflects, and returns to the 1st:C, d port of 50 couplers 5, two-beam is the 1st:50
Interfered in coupler 5, from the 1st:The a ports output of 50 couplers 5；One 50：50 coupling outgoing of 5 devices from a ports
Light enters detector 2, and the optical signal detected is converted to interference beat signal and transmitted to clock Shaping Module 6 by detector 2, when
Clock Shaping Module 6 interferes beat signal to be shaped as square wave, and the signal after shaping is transmitted to harvester 20, as harvester 20
External timing signal.
The emergent light of tunable laser 1 is by 1:The a ports of 99 beam splitters 4 enter, from 1:The c ends of 99 beam splitters 4
Mouth enters 50:The a ports of 50 beam splitters 3；By 50：The Polarization Controller that 50 beam splitters 3 enter in reference arm 22 from b ports
12, a ports of the circulator 13 entered from c ports in test arm 23；Light enters from a ports of circulator 13, from circulator 13
C ports enter tapered fiber 15, and the back-scattering light of tapered fiber 15 enters from the port c ports of circulator 13, from going in ring
The port b ports of device 13 export；The reference light that Polarization Controller 12 in reference arm 22 exports passes through the 2nd 50:50 couplers 14
A ports pass through the 2nd 50 with the back-scattering light on circulator 13:The b ports of 50 couplers 14 enter shape and close beam, form beat frequency and do
Relate to and from the 2nd 50:The c ports and d ports of 50 couplers 14 are exported to the first polarization beam apparatus 16 and the first polarization beam apparatus
17, the first polarization beam apparatus 16 and the first polarization beam apparatus 17 are right by the first balanced detector 18 and the second balanced detector 19
The flashlight of the orthogonal direction of two polarization beam apparatus output, the first balanced detector 18 and the second balanced detector 19 should be gathered
The analog electrical signal of output is transmitted to the external clock letter formed to harvester 20, harvester 20 in clock Shaping Module 6
Number effect under the analog electrical signal collected is transmitted to computer 11.
GPIB control modules 21 are used for computer 11 and control tunable laser 1 by it.
Tunable laser 1 is used to provide light source for probe beam deflation system, and its optical frequency can carry out linear scan.
Isolator 10 is prevented the 1st in auxiliary interferometer:The reflected light of the b ports of 50 couplers 5 enters laser.
One 50:50 couplers 5 are used for the interference of light.
Delay optical fiber 7 is used for the beat frequency interference for realizing non-equiarm, can obtain optical frequency according to beat frequency and delay fiber lengths.
First faraday's tilting mirror 8 and second faraday's tilting mirror 9 are used to provide reflection for interferometer, and can eliminate interferometer
Polarization decay phenomenon.
The effect of Polarization Controller 12 is that regulation refers to polarization state, makes its light intensity on two orthogonal directions in polarization beam splitting
It is basically identical.
2nd 50:50 coupler, 14 complete pair signals carry out polarization beam splitting, eliminate the influence of polarization decay noise.
Computer 11：Data processing is carried out to the interference signal that harvester 20 gathers, realizes and is based in probe beam deflation
The Fibre Optical Sensor of distributed liquid refractivity is measured using tapered fiber.
In summary, the embodiment of the present invention realizes the distributed liquid refracting that high spatial resolution reaches mm (millimeter) level
Rate measures, and can be successfully applied to intensive liquid refractivity distributed measurement, monitoring liquid diffusion, and liquid layer and be accurately positioned
Occasion.
Embodiment 3
The embodiments of the invention provide a kind of method for sensing that distributed liquid refractivity is measured using tapered fiber, the biography
Sensing method is corresponding with the sensor-based system in Examples 1 and 2, as shown in Fig. 2 the step of method for sensing is：
101：Beat frequency interference signal is formed by the back rayleigh scattering of tapered fiber 15 in main interferometer 25, and to this beat frequency
Interference signal carries out Fast Fourier Transform (FFT) respectively, by optical frequency domain information be transformed into each position in corresponding tapered fiber 15 away from
Delocalization information, each position that domain information of adjusting the distance chooses tapered fiber 15 by the Moving Window of one fixed width successively form local
Apart from domain information；
102：Reference signal and measurement signal all choose the local apart from domain information of tapered fiber using Moving Window, will be local
Apart from domain information zero padding, zero padding quantity can be local distance domain data length several times before zero padding, then by this distance after zero padding
Delocalization Information Pull complex Fourier inverse transformation, reconvert to optical frequency domain obtain the local optical frequency domain of reference signal and measurement signal
Information；
103：Spectral wavelength shifting is carried out to the local optical frequency domain information of reference signal and measurement signal using computing cross-correlation
Dynamic estimation, the reflection Rayleigh scattering light spectrum wavelength movement of cross-correlation peak amount of movement, the movement of Rayleigh scattering light spectrum wavelength and liquid refracting
Rate variable quantity is directly proportional, reflects liquid refractivity variable quantity by cross-correlation peak amount of movement.
In summary, the embodiment of the present invention realizes the distributed liquid refracting that high spatial resolution reaches mm (millimeter) level
Rate measures, and can be successfully applied to intensive liquid refractivity distributed measurement, monitoring liquid diffusion, and liquid layer and be accurately positioned
Occasion.
Embodiment 4
Feasibility checking, ginseng are carried out to the sensor-based system in embodiment 1-3 and method for sensing with reference to specific experiment
See Fig. 3 and Fig. 4, it is described below：
Confirmatory experiment of the embodiment of the present invention is to draw to bore using thin fiber, and refractive index is measured using the centrum of the thin fiber
Distribution change, the refractive index sensing coefficient of the tapered fiber 15 measured according to early stage, as shown in figure 3, being K=68.52nm/
RIU。
Tapered fiber 15 is inserted into measuring tank, glycerine water solution refractive index is measured, glycerine water solution is altered in steps
Concentration, and then change its refractive index and measure.
True variations in refractive index can be drawn by calculating and tabling look-up.Utilize the sensor-based system in 1-3 of the embodiment of the present invention
Variations in refractive index is demodulated with method for sensing to be compared with true variations in refractive index value, to verify that the validity of the application is shown in Table
1。
Table 1 measures variations in refractive index and contrasted with true variations in refractive index
| True variations in refractive index/RI | Measure variations in refractive index/RI | Error (measured value-actual value)/RI |
| 1.3574 | 1.3576 | 0.0002 |
| 1.3585 | 1.3585 | 0 |
| 1.3595 | 1.3595 | 0 |
| 1.3604 | 1.3604 | 0 |
| 1.3614 | 1.3613 | -0.0001 |
| 1.3624 | 1.3623 | -0.0001 |
| 1.3633 | 1.3632 | -0.0001 |
| 1.3642 | 1.3641 | -0.0001 |
| 1.3651 | 1.3651 | 0 |
| 1.3660 | 1.3660 | 0 |
| 1.3669 | 1.3669 | 0 |
| 1.3678 | 1.3679 | 0.0001 |
| 1.3686 | 1.3688 | 0.0002 |
As can be seen from Table 1, the measurement error of temperature change is up to 0.0002RI, demonstrates design of the embodiment of the present invention
Sensor-based system and method validity.
As shown in figure 4, being testing result for example, being located at the 3.51m to 3.54m of whole piece optical fiber in tapered fiber 15
In the range of, detect that liquid has variations in refractive index, reach 5mm per space of points resolution ratio.Abscissa is distance, and ordinate is the back of the body
To Rayleigh scattering wavelength amount of movement, different refractivity change correspond to different curves, it is seen that wavelength corresponding to different refractivity moves
Momentum is different.
In summary, the embodiment of the present invention realizes the distributed liquid refracting that high spatial resolution reaches mm (millimeter) level
Rate measures, and can be successfully applied to intensive liquid refractivity distributed measurement, monitoring liquid diffusion, and liquid layer and be accurately positioned
Occasion.
To the model of each device in addition to specified otherwise is done, the model of other devices is not limited the embodiment of the present invention,
As long as the device of above-mentioned function can be completed.
It will be appreciated by those skilled in the art that accompanying drawing is the schematic diagram of a preferred embodiment, the embodiments of the present invention
Sequence number is for illustration only, does not represent the quality of embodiment.
The foregoing is only presently preferred embodiments of the present invention, be not intended to limit the invention, it is all the present invention spirit and
Within principle, any modification, equivalent substitution and improvements made etc., it should be included in the scope of the protection.
Claims (5)
1. a kind of sensor-based system that distributed liquid refractivity is measured using tapered fiber, the sensor-based system are included：Optical frequency domain
The distribution type optical fiber sensing equipment of reflection, it is characterised in that
The sensor-based system is used to realize that high spatial resolution reaches millimetre-sized distributed measuring refractive indexes of liquid；
The sensor-based system includes：Tapered fiber,
The back rayleigh scattering intermode interference that conical region part based on the tapered fiber occurs, refractive index sensing is carried out,
The change of extraneous refractive index is perceived by stronger evanescent wave caused by conical region, changes and is dissipated in the tapered fiber backwards to Rayleigh
Penetrate the effective mode refractive index of propagation；
The tapered fiber is placed in liquid, by the distribution type optical fiber sensing equipment, detects the auspicious of the tapered fiber
The wavelength movement of sharp scattering spectrum, the wavelength movement is analyzed, obtain the index distribution situation of the continuously distributed formula of liquid.
2. a kind of sensor-based system that distributed liquid refractivity is measured using tapered fiber according to claim 1, it is special
Sign is that the tapered fiber is that thin fiber forms by drawing cone machine to draw.
3. a kind of sensor-based system that distributed liquid refractivity is measured using tapered fiber according to claim 2, it is special
Sign is that the drawing cone machine, which is drawn, is specially；Draw speed is 200 μm/s, and oxyhydrogen flame reciprocal distance is 2000 μm, reciprocating speed
For 360 μm/s, elongate optical fiber amount is 100000 μm, bores a diameter of 4 μm of area.
4. one kind according to any claim in claim 1-3 measures distributed liquid refractivity using tapered fiber
Sensor-based system, it is characterised in that the high spatial resolution reaches 5mm distributed measuring refractive indexes of liquid, and sensitivity reaches
To 68.52nm/RIU.
A kind of 5. method for sensing that distributed liquid refractivity is measured using tapered fiber, it is characterised in that the method for sensing
Comprise the following steps：
Beat frequency interference signal is formed by tapered fiber back rayleigh scattering in main interferometer, and beat frequency interference signal is entered respectively
Row Fast Fourier Transform (FFT), by optical frequency domain information be transformed into each position in corresponding tapered fiber apart from domain information, adjust the distance
Each position that domain information chooses tapered fiber by the Moving Window of one fixed width successively is formed locally apart from domain information；
Reference signal and measurement signal all choose the local apart from domain information of tapered fiber using Moving Window, and local distance domain is believed
Zero padding is ceased, zero padding quantity is local distance domain data length several times before zero padding, then by local distance domain Information Pull after zero padding
Complex Fourier inverse transformation, reconvert to optical frequency domain obtain the local optical frequency domain information of reference signal and measurement signal；
Spectral wavelength movement estimation is carried out to the local optical frequency domain information of reference signal and measurement signal using computing cross-correlation, mutually
The reflection Rayleigh scattering light spectrum wavelength movement of relevant peaks amount of movement, the movement of Rayleigh scattering light spectrum wavelength and liquid refractivity variable quantity into
Direct ratio, liquid refractivity variable quantity is reflected by cross-correlation peak amount of movement.
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| CN111220646A (en) * | 2020-01-19 | 2020-06-02 | 国兴汇金(深圳)科技有限公司 | Liquid interface sensing detection method and device |
| CN111982859A (en) * | 2020-08-31 | 2020-11-24 | 山东大学 | Refractive index sensor based on Mach-Zehnder structure and detection method thereof |
| CN111982859B (en) * | 2020-08-31 | 2021-12-24 | 山东大学 | Refractive index sensor based on Mach-Zehnder structure and detection method thereof |
| WO2023004181A1 (en) * | 2021-07-23 | 2023-01-26 | Nec Laboratories America, Inc. | Identification of inner fibers of deployed fiber cables using distributed fiber optic sensing |
| CN113465528A (en) * | 2021-08-09 | 2021-10-01 | 天津大学 | High-speed distributed strain measurement system and method based on optical frequency domain reflection |
| CN113465528B (en) * | 2021-08-09 | 2022-08-23 | 天津大学 | High-speed distributed strain measurement system and method based on optical frequency domain reflection |
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