CN107515033B - Point type liquid level sensor device and its measurement method based on optical frequency domain reflection technology - Google Patents
Point type liquid level sensor device and its measurement method based on optical frequency domain reflection technology Download PDFInfo
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- CN107515033B CN107515033B CN201710673698.7A CN201710673698A CN107515033B CN 107515033 B CN107515033 B CN 107515033B CN 201710673698 A CN201710673698 A CN 201710673698A CN 107515033 B CN107515033 B CN 107515033B
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- 239000000835 fiber Substances 0.000 claims abstract description 167
- 239000013307 optical fiber Substances 0.000 claims abstract description 67
- 230000035559 beat frequency Effects 0.000 claims abstract description 40
- 238000010408 sweeping Methods 0.000 claims abstract description 5
- 238000012360 testing method Methods 0.000 claims description 24
- 238000001228 spectrum Methods 0.000 claims description 17
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- 238000002168 optical frequency-domain reflectometry Methods 0.000 description 7
- 238000001514 detection method Methods 0.000 description 6
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- YNPNZTXNASCQKK-UHFFFAOYSA-N phenanthrene Chemical compound C1=CC=C2C3=CC=CC=C3C=CC2=C1 YNPNZTXNASCQKK-UHFFFAOYSA-N 0.000 description 2
- 235000009566 rice Nutrition 0.000 description 2
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- KPZTWMNLAFDTGF-UHFFFAOYSA-D trialuminum;potassium;hexahydroxide;disulfate Chemical compound [OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Al+3].[Al+3].[Al+3].[K+].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O KPZTWMNLAFDTGF-UHFFFAOYSA-D 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
- G01F23/284—Electromagnetic waves
- G01F23/292—Light, e.g. infrared or ultraviolet
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Abstract
The invention discloses a kind of point type liquid level sensor device and its measurement method based on optical frequency domain reflection technology, wherein sensor device includes linear frequency sweep laser, fiber optic splitter, optical fiber circulator, sensing module, fiber coupler, photodetector, data collecting card, computer and warning circuit；Wherein: sweeping laser is divided into signal light and reference light by fiber optic splitter；Signal light returns along road in the Fresnel reflection signal that the tail end endface of each sensor fibre generates and through being coupled into single mode optical fiber at fiber optic splitter, and backreflected signals light and reference light in single mode optical fiber generate beat frequency interference signal at fiber coupler；Data collecting card acquires the beat frequency interference signal in electric signal；Computer controls the linear frequency sweep laser and the data collecting card.The present invention measures liquid level using the Fresnel reflection characteristic of sensor fibre tail end, and single-point or multiple spot liquid level are monitored and are alerted.
Description
Technical field
The present invention relates to technical field of optical fiber sensing, more specifically, are related to a kind of point type level sensing based on OFDR
Device and measurement method.
Background technique
It is extensive that level monitoring is related to field, and fibre optic liquid level sensor has burn-proof and explosion prevention, precision height, high sensitivity, anti-does
The features such as ability is strong is disturbed, especially suitable for the level monitoring in the industrial productions such as petrochemical industry.Fibre optic liquid level sensor has at present
Many deficiencies, such as based on full optical fiber interferometer liquid level sensor, need to carry out using special optical fiber structure or to optical fiber
Special processing, repeatability is not high, and measurement range is limited；Liquid level sensor based on FBG needs to add respective external component, drop
Low Measurement reliability；Liquid level sensor based on OTDR, spatial resolution is other in centimetre rank even meter level, surveys its liquid level
Amount blind area is big, and sensing head is also needed using special optical fiber fabrication, and fixed form is also more complicated.
Existing fiber liquid level sensor measurement range cannot be compatible with measurement accuracy at present, and there is an urgent need to a kind of big measurement models
It encloses, high-precision fibre optic liquid level sensor, while must assure that the accuracy and stability of measurement.
Summary of the invention
Aiming at the above defects or improvement requirements of the prior art, the present invention provides a kind of, and the point type liquid level based on OFDR passes
Sensor and measurement method.The present invention uses OFDR and optical heterodyne detection technique to its tail using single mode optical fiber as sensing head
The Fresnel reflection characteristic at end is analyzed, to realize that single-point or multiple spot carry out level monitoring and alert.The sensor can be surveyed
Counting, more, measurement range is big, reproducible, high reliablity, precision are high, and sensor fibre manufacture craft is simple, inexpensively.Suitable for pair
Setting liquid level is alarmed, instruction etc..
In order to solve the above-mentioned technical problem, the technical scheme adopted by the invention is as follows:
A kind of point type liquid level sensor device based on optical frequency domain reflection technology, including linear frequency sweep laser, light are provided
Fine beam splitter, optical fiber circulator, sensing module, fiber coupler, photodetector, data collecting card, computer and alarm electricity
Road；Wherein:
The sweeping laser that the linear frequency sweep laser exports is divided into two-way by the fiber optic splitter, is all the way signal
Light, another way are reference light；Signal light enters the optical fiber circulator, and reference light enters the fiber coupler；
The sensing module is connect by single mode optical fiber with the optical fiber circulator, and signal light is entered by single mode optical fiber should
Sensing module；The sensing module includes fiber optic splitter, single or more sensor fibre, the tail end end of every sensor fibre
Face is smooth through transverse cuts, and the tail end of each sensor fibre is placed in the container of different set liquid level；Signal light passes through the light
Fine beam splitter enters sensor fibre, returns in the Fresnel reflection signal that the tail end endface of each sensor fibre generates along road
And through being coupled into single mode optical fiber at fiber optic splitter, the backreflected signals light in single mode optical fiber passes through the optical fiber circulator
The fiber coupler is imported, beat frequency interference occurs at the fiber coupler with reference light, generates beat frequency interference signal；
The beat frequency interference signal is converted electric signal by the photodetector；
The data collecting card acquires the beat frequency interference signal in electric signal by multichannel simultaneously；
The computer and the linear frequency sweep laser, the data collecting card carry out data communication, and described in control
Linear frequency sweep laser and the data collecting card, which also carries out processing analysis to beat frequency interference signal, and sends number
According to arrive the warning circuit；
The warning circuit data that computer issues based on the received, control instructions lamp and alarm.
Above-mentioned technical proposal is connect, the sweeping laser that the linear frequency sweep laser exports is divided by the fiber optic splitter
50:50 two-way.
The present invention also provides a kind of point type liquid level sensor measurement methods, comprising the following steps:
Linear scan laser issues the laser of optical maser wavelength periodicity linear change, and laser enters fiber optic splitter and is divided into
Two-way light, it is all the way reference light that light, which is signal light, all the way；
Reference light is directly coupled into an input terminal in fiber coupler；
Signal light enters optical fiber circulator and is transferred to single mode optical fiber, enters sensing module, Mei Yigen by single mode optical fiber
The Fresnel reflection signal that the tail end endface of sensor fibre generates is returned along road, and coupling is combined into single mode at fiber optic splitter
Optical fiber, the backreflected signals light in single mode optical fiber imports the fiber coupler by the optical fiber circulator, with reference light
Beat frequency interference occurs at the fiber coupler, generates beat frequency interference signal；
Beat frequency interference signal is converted to electric signal through photodetector, is acquired by data collecting card, is done fastly by computer
Fast Fourier transformation obtains the spectrum information of beat signal.
The present invention also provides a kind of beat frequency interference signal demodulating methods of point type liquid level sensor, comprising the following steps:
Non-uniform Fast Fourier is carried out to the beat frequency interference signal of acquisition and converts to obtain corresponding bat along sensor fibre
Again and again spectrum；
Drop point processing is carried out to beat frequency frequency spectrum；
Beat frequency spectrum signal is smoothed, the difference of Fresnel reflection peak value and ambient noise is improved；
Peak-seeking calculating is carried out to beat frequency frequency spectrum, it includes the transverse and longitudinal seat for finding all reflection peaks of entire spectrogram that peak-seeking, which calculates,
Mark, i.e. distance and peak value size, the transverse and longitudinal coordinates of calculated all Fresnel reflections and preservation, as Local Reference Number；
Data of every acquisition carry out difference calculating with the Local Reference Number of preservation, when the peak value of this acquisition data is big
When small and Local Reference Number peak value magnitude difference is greater than given threshold, otherwise it is 0 that return, which judges numerical value 1, all binary number structures
At truth table；
Truth table data corresponding to each reflection peak are sent to warning circuit, warning circuit control corresponding indicator light with
And alarm is alarmed.
Above-mentioned technical proposal is connect, before and after liquid level is contacted with sensor fibre end face, bat corresponding with the sensor fibre end face
Step evolution jump occurs for the intensity of frequency interference signal, is judged by analyzing the variation of the sensor fibre end face beat frequency interference signal
Whether testing liquid has reached setting liquid level.
Compared with prior art the advantageous effect of present invention is that: the invention proposes the point type liquid levels of OFDR technology
Sensing technology.The present invention is combined using OFDR technology with optical heterodyne detection technique, and the phenanthrene of detection analysis single mode optical fiber tail end is carried out
Nie Er reflection characteristic realizes point type level gauging.Sensor fibre uses general single mode fiber, and no add-on assemble, measurement range is big
In 100 meters, measurement accuracy is better than 20um.Due to the general single mode fiber that sensing head uses, manufacture craft is simple, therefore measure
Reproducible, high reliablity.Sensing head fixed form of the present invention is simple, it is only necessary to be pasted and fixed on sensor fibre with seccotine
On the support rod placed vertically or on testing liquid chamber wall.The present invention can also realize multiple spot level gauging, measurement points
It is unrestricted, only the different sensor fibre of more root long degree need to be connected in fiber optic splitter output end, can realize that multiple spot liquid level is surveyed
Amount.It is particularly suitable in industrial production accurately measuring the inflammable and explosive setting liquid level for waiting dangerous liquids.
Detailed description of the invention
Below by attached drawing, specific embodiments of the present invention will be described in further detail.
Fig. 1 is point type level gauging structural schematic diagram of the invention；
Fig. 2 is Fresnel reflection peak figure when liquid level is separated with sensor fibre end face in single-point level sensing of the present invention；
Fig. 3 is Fresnel reflection peak figure when liquid level and sensor fibre end face contact in single-point level sensing of the present invention；
Fig. 4 is multiple spot liquid level Fresnel reflection peak figure of the present invention；
In Fig. 1: 1 being linear frequency sweep laser, 2 be fiber optic splitter (50:50), 3 be optical fiber circulator, 4 be single-mode optics
It is fine, 5 be sensing module, 6 be fiber coupler (1x2), 7 be photodetector, 8 be data collecting card, 9 be computer, 10 be
Warning circuit, 11 be fiber optic splitter (1xN), 12 be sensor fibre, 13 be sensor fibre end face, 14 be liquid level.
Specific embodiment
The invention will be further described for following example combination attached drawing.
Point type liquid level sensor of the embodiment of the present invention based on OFDR, as shown in Figure 1, including linear frequency sweep laser 1, light
Fine beam splitter (50:50) 2, optical fiber circulator 3, single mode optical fiber 4, sensing module 5, fiber coupler (1x2) 6, photodetector
7, data collecting card 8, computer 9.
Linear scan laser 1 is connect with 2 input terminal of fiber optic splitter (50:50), fiber optic splitter (50:50) output end
It is connect respectively with the port a of the port a of optical fiber circulator and fiber coupler (1x2).The b mouth and single mode optical fiber of optical fiber circulator
Connection, c mouthfuls connect with the b mouth of fiber coupler (1x2).Single mode optical fiber 4 is connect with sensing module 5.
Referred to based on OFDR technology: linear scan laser 1 issues optical maser wavelength periodicity linear change as light source
Narrow linewidth laser, scanning range 1520nm-1630nm, sweep velocity 2nm/s-2000nm/s can be used in laser.Laser into
Enter 2 points of fiber optic splitter (50:50) for two-way light.Light is signal light all the way, is all the way reference light.Reference light is directly coupled into
A mouth in fiber coupler (1x2) 6.Signal light enters a mouth of optical fiber circulator 3 and is transferred to single mode optical fiber 4.Signal light into
Sensor fibre 12 is entered back into after entering fiber optic splitter (1xN) 11.In entire pickup arm back scattering, back scattering occur for signal light
The road Guang Yan enters the b mouth of fiber coupler (1x2) 6 back to optical fiber circulator 3 and by the outgoing of the c of optical fiber circulator 3 mouth.Two-way
Light interferes at fiber coupler (1x2) 6.Since reference light is different with the light path of rear orientation light, time delay is introduced, then
Contain beat signal in interference signal.After photodetector 7, interference light signal is converted to electric signal, is adopted by data collecting card 8
Collection, and do Fast Fourier Transform (FFT) in the computer 9 and obtain the spectrum information of beat signal.
Sensing module 5 includes fiber optic splitter (1xN) 11, single or more sensor fibre 12, for realizing single-point or
Multiple spot level gauging.Wherein, sensor fibre 12 is general single mode fiber, is connect simultaneously with the output end of fiber optic splitter (1xN) 11
Fixed placement is in testing liquid.
In order to enable sensor fibre endface is reflected into vertical reflection (intensity vertically reflected is most strong, is easy to differentiate),
Sensor fibre tail end optical fiber cutter transverse direction flat cut is handled, and in vertical fixed placement testing liquid.Testing liquid
Rise or decline, liquid level can pass through sensor fibre tail end end face.
The measurement method of point type liquid level sensor of the embodiment of the present invention based on optical frequency domain reflection technology: linear scan laser
Device 1 issues the laser of optical maser wavelength periodicity linear change, and laser enters 2 points of fiber optic splitter (50:50) for two-way light.All the way
Light is signal light, is all the way reference light.Reference light is directly coupled into an input terminal in fiber coupler 6.Signal light into
Enter optical fiber circulator 3 and is transferred to single mode optical fiber 4.Back scattering occurs on single mode optical fiber 4 for signal light, and rear orientation light is along road
Enter another input terminal of fiber coupler 6 back to optical fiber circulator 3 and by the outgoing of the c of optical fiber circulator mouth.Two-way light
It is interfered at fiber coupler 6.Since the light path of two-way light return signal is different, time delay is introduced, then in interference signal
Contain beat signal.After photodetector 7, interference light signal is converted to electric signal, is acquired by data collecting card, and does quickly
Fourier transformation obtains the spectrum information of beat signal.
The light velocity and laser sweep rate determine that the beat signal frequency measured can be mapped as physical distance, and beat frequency is believed
Number intensity proportional is in the intensity of reflection signal.
Rear orientation light is mainly Rayleigh scattering and Fresnel reflection.Due to Fresnel reflection be by light in transmission process
Medium refraction index mutation generates, and it is poor to be proportional to medium refraction index.When sensor fibre tail end is in air, optical fiber
Refractive index and the refringence of air refraction are larger, have stronger Fresnel reflection.When liquid level to be measured rise or fall with
When sensor fibre tail end contacts, optical fiber tail-end exit end medium refraction index mutates, at this time optical fiber and testing liquid refractive index
Difference becomes smaller.And then Fresnel reflection dies down, then step change type jump is presented in the beat signal intensity at optical fiber tail-end, believes the beat frequency
Number Processing Algorithm analysis is carried out, can determine whether liquid level to be measured reaches sensor fibre tail end end face, realize level gauging.In
In sensing module 5,11 output end of fiber optic splitter (1xN) can connect the different sensor fibre of more root long degree, realize multiple spot liquid level
Measurement.
The working principle of the invention is based on optical frequency domain reflection technology.It will be put after 12 tail end transverse direction flat cut of sensor fibre
It sets and is containing at testing liquid.When 12 tail end of sensor fibre contacts front and back with testing liquid, rolled at the exit end of sensor fibre end face
Rate mutation is penetrated, so that refringence changes at 13 incidence end of sensor fibre end face and exit end, to use probe beam deflation
Step evolution jump occurs for the beat signal amplitude at 12 end-position of sensor fibre of technology detection.By analyzing the beat signal
To judge whether testing liquid reaches 13 height of setting liquid level.
Spatial resolution can be achieved in tens micron dimensions, therefore in optical frequency domain reflection technology in 100 meters of Distance-sensings
The precision of point type level monitoring of the present invention is very high.The distance sensing of optical frequency domain reflection technology is even thousands of up to several hundred rice simultaneously
Rice, thus the range of point type level monitoring of the present invention is very wide.
Generally, the beat signal frequency size that optical frequency domain reflection technology measures can be mapped as physical distance, short distance
Spatial resolution, while can also be with long distance monitoring in tens micron dimensions.The beat signal that optical frequency domain reflection technology measures is strong
Degree is then proportional to the intensity of reflection signal.
In single-point level gauging, any one optical fiber of fiber optic splitter (1xN) 11 output end connection is chosen as biography
Photosensitive fine 12 are placed in testing liquid, and sensor fibre end face 13 is enabled to be located at setting liquid level.The liquid level set at this time is high
Degree is 13 position of sensor fibre end face of sensor fibre 12.When liquid level 14 is located at 13 lower section of sensor fibre end face, pass
Feel is air, refractive index 1 at 13 exit end of fiber end face.When liquid level 14 rises and contacts with sensor fibre end face 13, pass
Feel is testing liquid, refractive index n at 13 exit end of fiber end faceliquid, optical fibre refractivity n is vertical according to Fresnel reflection
End face reflection rate R formula when incident:
Wherein n1And n2It is the refractive index of incident end face front and back medium respectively.
Substitute into medium refraction index n at optical fibre refractivity n and 13 exit end of sensor fibre end faceXAnd the available luxuriant and rich with fragrance alunite of abbreviation
End face reflection rate R when your reflection vertical incidence
Wherein n is optical fibre refractivity, nXMedium refraction index at 12 exit end of sensor fibre end face.
When 13 exit end of sensor fibre end face is air, nXIt is 1, when 13 exit end of sensor fibre end face is testing liquid
When, nXFor nliquid.And nliquidGreater than 1.
Therefore, front and back is contacted with sensor fibre end face 13 when testing liquid liquid level 14 rises, sensor fibre end face 13 is emitted
Step evolution jump occurs for reflectivity at end, so that Fresnel reflection intensity mutates.
Since the beat signal frequency of optical frequency domain reflection technology detection is mapped as physical distance, intensity proportional is in reflection signal
Intensity.Therefore, front and back is contacted with sensor fibre end face 13 when liquid level 14, corresponding beat signal is strong at sensor fibre end face 13
Step evolution jump occurs for degree.Judge whether testing liquid reaches by analyzing the variation of 13 beat signal of sensor fibre end face
Set liquid level.
As shown in Fig. 2, when this monitoring result is that liquid level 14 is located at 13 lower section of sensor fibre end face, sensor fibre end face 13
Set the Fresnel reflecting peak of place (i.e. at distance setting 9.48564 meters of positions of starting point).Testing liquid and sensor fibre end face at this time
13 separate, and are air, refractive index 1 at 13 exit end of sensor fibre end face.It is anti-according to end face when Fresnel reflection vertical incidence
Penetrate rate R formula:
Wherein n is optical fibre refractivity, nXFor medium refraction index at 13 exit end of sensor fibre end face.
According to reflectance formula, 13 reflectivity of sensor fibre end face and testing liquid at this time connects with sensor fibre end face 13
Reflectivity comparison when touching, reflectivity are higher.To reflection signal demodulation, show that the Fresnel reflection intensity at the position is larger,
And then it is higher to obtain Fresnel reflection peak amplitude at the position.
It can be seen that being 12 Fresnel reflection of sensor fibre end face at distance setting 9.48564 meters of positions of starting point in Fig. 2
The corresponding beat signal of signal, intensity are -84.8dBm.
As shown in figure 3, when this monitoring result is that liquid level 14 is located at 13 top of sensor fibre end face, sensor fibre end face 13
Set the Fresnel reflecting peak of place (i.e. at distance setting 9.48564 meters of positions of starting point).At this time at 13 exit end of sensor fibre end face
Medium refraction index nXFor nliquid, and nliquidGreater than 1.Therefore, the beat signal intensity at the sensor fibre end face 13 is jumped
Become, and then the Fresnel reflection peak intensity at the position jumps, and jumps as -94.6dBm.After the jump Fresnel reflecting peak
Amplitude it is related with testing liquid refractive index, Fig. 3 be testing liquid be pure water.
Comparison diagram 2 and Fig. 3 can be seen that testing liquid liquid level 14 and contact front and back with sensor fibre end face 13, set in distance
Determine the corresponding beat signal intensity of the reflection signal of sensor fibre end face 13 at 9.48564 meters of positions of starting point and step evolution jump has occurred
Become, and then Fresnel reflection peak intensity jumps at the position.13 position of sensor fibre end face is setting liquid level
Position.
The intensity for analyzing the reflection signal at the position by algorithm in a computer changes, it can be determined that liquid level to be measured is
The no height of liquid level 14 for reaching setting, and slave computer is sent by computer by judging result, and control corresponding indicator light and
Warning device.To realize monitoring, the alarm to liquid level.
Another embodiment of the invention is based in the multiple spot level gauging of optical frequency domain reflection technology, fiber optic splitter
(1xN) 11 output end connects the different sensor fibre of more root long degree.Selection and tested point can be determined according to prepare liquid number of sites
The matched fiber optic splitter (1xN) 11 of number.Theoretically, the branch's number that can be added is unrestricted, the sense light in each branch
Fibre 12 chooses length according to setting liquid level.The selection principle of length is: so that the sensor fibre end of every sensor fibre 12
Face is located at each setting liquid level of liquid level to be measured.The testing liquid height one of each sensor fibre 12 and each setting
One is corresponding.Because the beat signal frequency that optical frequency domain reflection technology measures can be mapped as physical distance, the sense light of different length
The sensor fibre end face 1 of fibre 12 corresponds to different distances.In multiple spot level monitoring, 11 output end of fiber optic splitter (1xN)
Connect the different sensor fibre of more root long degree.Fresnel reflection letter at the sensor fibre endface position of each sensor fibre 12
Number along road return, coupling is combined into single mode optical fiber 4, the backreflected signals in single mode optical fiber 4 at fiber optic splitter (1xN) 11
Fresnel reflection information at sensor fibre endface position with each sensor fibre 12.Back reflected laser and reference light exist
It is interfered at fiber coupler (1x2) 6, interference signal enters photodetector 7 and is converted to electric signal, by data collecting card 8
Acquisition.Demodulation analysis is carried out to beat signal corresponding at the sensing endface position of every sensor fibre 12, it is every available
Whether the Fresnel reflection intensity at the sensor fibre endface position of sensor fibre 12 changes, and then judges that testing liquid is
The no sensor fibre end face for reaching any one sensor fibre 12.Since the sensor fibre 12 of each different length corresponds to not
With setting liquid level, therefore, the Fresnel reflection intensity of the sensor fibre endface by analyzing every sensor fibre 12
Change to judge whether liquid level reaches corresponding setting liquid level, realizes multiple spot level gauging.
General single mode fiber can be used in single mode optical fiber 4, and 1550 communication bands are used for optical signal transmission.
If Fig. 4 is multiple spot level gauging schematic diagram.It is anti-to sensor fibre end face 12 in 4 sensor fibres 12 of different length
Signal is penetrated to be demodulated to obtain 4 Fresnel reflecting peaks.Each Fresnel reflecting peak corresponds at 4 sense light at setting height
The Fresnel reflection of fine end face 12.Strength Changes by monitoring each Fresnel reflecting peak can monitor whether testing liquid reaches
To corresponding 13 height of setting liquid level.
Beat frequency interference signal demodulating method based on above-mentioned point type liquid level sensor specifically includes several steps
The first step, using optical heterodyne detection technique, to backscatter signal along sensor fibre (Rayleigh scattering and Fresnel
Reflection) it is acquired with the interference signal after reference arm generation beat frequency interference.
Second step, the beat signal acquired using computer to the first step carry out non-uniform Fast Fourier and convert to be passed
Corresponding beat frequency frequency spectrum along photosensitive fibre.
Third step carries out drop point processing to beat frequency frequency spectrum, it is therefore an objective to reduce entire spectrum number strong point, accelerate operation speed
Degree.
4th step is smoothed beat frequency spectrum signal, improves the difference of Fresnel reflection peak value and ambient noise.
Convenient for accurately finding the position of each reflection peak.
5th step carries out peak-seeking calculating to beat frequency frequency spectrum.It includes all reflection peaks for finding entire spectrogram that peak-seeking, which calculates,
Transverse and longitudinal coordinate, i.e. distance and peak value size.The transverse and longitudinal coordinates of calculated all Fresnel reflections and preservation, as local ginseng
Examine value.
6th step, peak value magnitude difference compare.Data of every acquisition, it is poor to carry out with the Local Reference Number that step 5 saves
Value calculates.When the peak value size and Local Reference Number peak value magnitude difference of this acquisition data are greater than given threshold (given threshold
Depending on testing liquid refractive index, since Fresnel reflecting peak strength difference whether liquid level to be measured is contacted with sensor fibre end face can
Up to 10dB, therefore given threshold range is very wide, and measurement accuracy is high) when, otherwise it is 0 that return, which judges numerical value 1,.All binary systems
Number constitutes truth table.
Truth table data corresponding to each reflection peak are sent to slave computer by the 7th step.The corresponding instruction of slave computer control
Lamp and warning device
As it will be easily appreciated by one skilled in the art that accompanying drawings and embodiments described herein are only to illustrate the technology of the present invention
Scheme rather than its limitations, it is all do not depart from the present invention program spirit and principle within it is made it is any modification, equivalent replacement and
Improve etc., it should all cover within the scope of the technical scheme claimed by the invention.
Claims (5)
1. the point type liquid level sensor device based on optical frequency domain reflection technology, which is characterized in that including linear frequency sweep laser, light
Fine beam splitter, optical fiber circulator, sensing module, fiber coupler, photodetector, data collecting card, computer and alarm electricity
Road；Wherein:
The sweeping laser that the linear frequency sweep laser exports is divided into two-way by the fiber optic splitter, is all the way signal light, separately
It is all the way reference light；Signal light enters the optical fiber circulator, and reference light enters the fiber coupler；
The sensing module is connect by single mode optical fiber with the optical fiber circulator, and signal light enters the sensing by single mode optical fiber
Module；The sensing module includes fiber optic splitter, more sensor fibres, and the tail end end face of every sensor fibre is through transverse cuts
Smooth, the tail end of each sensor fibre is placed in the container of different set liquid level, and the end face of every sensor fibre is located at prepare liquid
Each setting liquid level of position；Signal light enters sensor fibre by the fiber optic splitter, in each sensor fibre
The Fresnel reflection signal that tail end endface generates returns along road and through being coupled into single mode optical fiber, single-mode optics at fiber optic splitter
Backreflected signals light in fibre imports the fiber coupler by the optical fiber circulator, with reference light in the optical fiber coupling
Beat frequency interference occurs at clutch, generates beat frequency interference signal；
The beat frequency interference signal is converted electric signal by the photodetector；
The data collecting card acquires the beat frequency interference signal in electric signal by multichannel simultaneously；
The computer and the linear frequency sweep laser, the data collecting card carry out data communication, and control described linear
Frequency swept laser and the data collecting card, which also carries out processing analysis to beat frequency interference signal, and sends data to
The warning circuit；
The warning circuit data that computer issues based on the received, control instructions lamp and alarm.
2. point type liquid level sensor device as described in claim 1, which is characterized in that the fiber optic splitter will be described linear
The sweeping laser of frequency swept laser output is divided into 50:50 two-way.
3. a kind of point type liquid level sensor measurement method based on claims 1 or 2, which comprises the following steps:
Linear scan laser issues the laser of optical maser wavelength periodicity linear change, and laser enters fiber optic splitter and is divided into two-way
Light, it is all the way reference light that light, which is signal light, all the way；
Reference light is directly coupled into an input terminal in fiber coupler；
Signal light enters optical fiber circulator and is transferred to single mode optical fiber, enters sensing module, each sensing by single mode optical fiber
The Fresnel reflection signal that the tail end endface of optical fiber generates is returned along road, and coupling is combined into single-mode optics at fiber optic splitter
Fibre, the backreflected signals light in single mode optical fiber import the fiber coupler by the optical fiber circulator, exist with reference light
Beat frequency interference occurs at the fiber coupler, generates beat frequency interference signal；
Beat frequency interference signal is converted to electric signal through photodetector, is acquired by data collecting card, is quick Fu by computer
In leaf transformation obtain the spectrum information of beat signal.
4. a kind of beat frequency interference signal demodulating method of the point type liquid level sensor based on claims 1 or 2, which is characterized in that
The following steps are included:
Non-uniform Fast Fourier is carried out to the beat frequency interference signal of acquisition and converts to obtain corresponding beat frequency frequency along sensor fibre
Spectrum；
Drop point processing is carried out to beat frequency frequency spectrum；
Beat frequency spectrum signal is smoothed, the difference of Fresnel reflection peak value and ambient noise is improved；
Peak-seeking calculating is carried out to beat frequency frequency spectrum, it includes the transverse and longitudinal coordinate for finding all reflection peaks of entire spectrogram that peak-seeking, which calculates,
That is distance and peak value size, the transverse and longitudinal coordinates of calculated all Fresnel reflections and preservation, as Local Reference Number；
Data of every acquisition carry out difference calculating with the Local Reference Number of preservation, when this acquisition data peak value size with
When Local Reference Number peak value magnitude difference is greater than given threshold, otherwise it is 0 that return, which judges numerical value 1, and all binary numbers constitute true
It is worth table；
Truth table data corresponding to each reflection peak are sent to warning circuit, warning circuit controls corresponding indicator light and report
Alert device is alarmed.
5. according to the method described in claim 4, it is characterized in that, before and after liquid level is contacted with sensor fibre end face, with the biography
Step evolution jump occurs for the intensity for feeling the corresponding beat frequency interference signal of fiber end face, dry by analyzing the sensor fibre end face beat frequency
The variation of signal is related to judge whether testing liquid has reached setting liquid level.
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| CN108507981B (en) * | 2018-04-11 | 2020-09-22 | 南京大学 | Silicon-based waveguide back reflection sensing device based on OFDR (optical frequency domain reflectometry) and measuring method thereof |
| CN109060721A (en) * | 2018-08-06 | 2018-12-21 | 佛山科学技术学院 | A kind of index sensor based on micro-nano fiber and end face reflection |
| CN111595246B (en) * | 2020-07-24 | 2020-10-30 | 武汉昊衡科技有限公司 | Wavelength division multiplexer channel length measuring device and method |
| CN113252142B (en) * | 2021-05-18 | 2022-04-19 | 西南科技大学 | Non-contact measurement system and method for liquor level in closed container |
| CN113701853B (en) * | 2021-07-09 | 2022-12-27 | 北京航天控制仪器研究所 | Real-time liquid level measurement and analysis method based on distributed optical fiber liquid level sensor |
| CN113834599B (en) * | 2021-08-25 | 2023-06-27 | 深圳大学 | Energy sensing system and method based on optical frequency domain reflection measurement technology |
| CN113959943B (en) * | 2021-09-22 | 2024-03-19 | 武汉雷施尔光电信息工程有限公司 | Cavitation share measuring system and method of planar optical fiber probe sensor |
| CN114234818B (en) * | 2021-12-17 | 2023-09-22 | 中国计量科学研究院 | Laser interferometry displacement measurement system and method |
| CN116519088B (en) * | 2023-07-03 | 2023-10-17 | 深圳市柏金科技有限公司 | Passive wading sensor, detection method and liquid level measurement system |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105067103A (en) * | 2015-08-31 | 2015-11-18 | 上海交通大学 | Vibration detection device and method based on optical frequency domain reflectometer |
| CN106248175A (en) * | 2016-10-09 | 2016-12-21 | 深圳市迈测科技股份有限公司 | Laser fiber fluid level measuring instrument and measuring method |
| CN106595807A (en) * | 2016-11-22 | 2017-04-26 | 中国科学院西安光学精密机械研究所 | Long-distance passive liquid level sensor based on distributed optical fiber |
-
2017
- 2017-08-09 CN CN201710673698.7A patent/CN107515033B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105067103A (en) * | 2015-08-31 | 2015-11-18 | 上海交通大学 | Vibration detection device and method based on optical frequency domain reflectometer |
| CN106248175A (en) * | 2016-10-09 | 2016-12-21 | 深圳市迈测科技股份有限公司 | Laser fiber fluid level measuring instrument and measuring method |
| CN106595807A (en) * | 2016-11-22 | 2017-04-26 | 中国科学院西安光学精密机械研究所 | Long-distance passive liquid level sensor based on distributed optical fiber |
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