CN108106645A - Fiber grating sensing demodulation apparatus and method based on the reference of hydrogen cyanide absorbing wavelength - Google Patents
Fiber grating sensing demodulation apparatus and method based on the reference of hydrogen cyanide absorbing wavelength Download PDFInfo
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- LELOWRISYMNNSU-UHFFFAOYSA-N hydrogen cyanide Chemical compound N#C LELOWRISYMNNSU-UHFFFAOYSA-N 0.000 title claims abstract description 74
- 239000000835 fiber Substances 0.000 title claims abstract description 61
- 238000000034 method Methods 0.000 title claims abstract description 27
- 239000013307 optical fiber Substances 0.000 claims abstract description 79
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 40
- 239000001257 hydrogen Substances 0.000 claims abstract description 40
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 40
- 230000003287 optical effect Effects 0.000 claims abstract description 14
- 238000012545 processing Methods 0.000 claims abstract description 12
- 238000000862 absorption spectrum Methods 0.000 claims abstract description 11
- 238000010521 absorption reaction Methods 0.000 claims description 30
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- 230000006641 stabilisation Effects 0.000 abstract description 5
- 238000011105 stabilization Methods 0.000 abstract description 5
- 238000000605 extraction Methods 0.000 abstract description 4
- 230000009102 absorption Effects 0.000 description 25
- 238000010586 diagram Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 4
- JMANVNJQNLATNU-UHFFFAOYSA-N oxalonitrile Chemical compound N#CC#N JMANVNJQNLATNU-UHFFFAOYSA-N 0.000 description 4
- 230000003595 spectral effect Effects 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- BJQHLKABXJIVAM-UHFFFAOYSA-N bis(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 239000002131 composite material Substances 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
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- 230000011514 reflex Effects 0.000 description 2
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- 239000002360 explosive Substances 0.000 description 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/268—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light using optical fibres
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/28—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with deflection of beams of light, e.g. for direct optical indication
- G01D5/285—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with deflection of beams of light, e.g. for direct optical indication using a movable mirror
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/28—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with deflection of beams of light, e.g. for direct optical indication
- G01D5/30—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with deflection of beams of light, e.g. for direct optical indication the beams of light being detected by photocells
Abstract
The invention discloses a kind of fiber grating sensing demodulation apparatus and method based on the reference of hydrogen cyanide absorbing wavelength, which includes wideband light source (1), tunable F P wave filters (2), optical fiber level-one beam splitter (3), optical fiber circulator (4), optical fibre optical grating sensing array (5), fiber secondary beam splitter (6), optical fiber cyaniding hydrogen chamber (7), faraday rotator mirror (8), photodetector array (9), data collecting card (10), processing unit (11)；Using hydrogen cyanide absorption spectrum feature, the absolute reference wavelength of temperature stabilization is obtained by the absworption peak for extracting absorption spectrum, effectively improves Wavelength demodulation stability.Compared with prior art, the present invention realizes the fiber grating demodulation of temperature stabilization；It need not increase that other hardware are i.e. extractable to obtain absolute reference wavelength, it is simple in structure and at low cost；Reduce the extraction difficulty of absolute reference wavelength；Demodulation accuracy is improved, the demodulation accuracy under constant ambient temperature is in 2pm.
Description
Technical field
The invention belongs to fiber grating sensing technology fields, demodulate and fill more particularly to a kind of optical fiber grating sensing high stable
It puts and demodulation method.
Background technology
Fiber grating sensing system be using light as carrier, optical fiber for medium, using with light footpath it is thin, it is corrosion-resistant, multiplexing
The system that the fiber-optic grating sensor for the advantages that ability is strong, electromagnetism interference realizes sensing measurement.Fiber-optic grating sensor it is anti-
Ejected wave is grown related with the physical parameters such as the ess-strain, vibration, the temperature and pressure that are acted on sensor, passes through measurement sensor
Reflection wavelength can measure the physical parameter acted on sensor.Compared to traditional sensing technology, optical fiber grating sensing skill
Art has the characteristics that wide measurement range, high-precision and high-resolution, in harsh rings such as strong electromagnetic, inflammable and explosive or thermal vacuums
Advantage is had more under border.
Fiber grating sensing demodulation method mainly has interferometric demodulation, linear edge filter demodulation, matched filtering demodulation, tunable F-
The technologies such as the demodulation of P wave filters, scan laser demodulation.Tunable TEA CO2 laser demodulation can realize height in wide spectral range
Speed, high-precision demodulate, and are common fiber grating sensing demodulation methods, are realized by the inverse piezoelectric effect of PZT in wide scope
Length scanning, and PZT is sluggish, creep and the characteristics such as non-linear prevent transmission peak wavelength and driving voltage from keeping linear well
Degree and repeatability, thus demodulation accuracy can be influenced.In order to correct the nonlinear effect, it is necessary to the true of F-P tunable optic filters
Real centre wavelength carries out dynamic calibration.Currently used calibration tool has fiber grating, etalon etc., however these calibration tools
Under varying temperature environment, the reference wavelength that is provided due to fiber grating and etalon can with environment temperature changes and changing causes to solve
Adjust error larger.Therefore F-P tunable optic filters are not suitable for the test occasion of variation of ambient temperature.
Optical fiber gas chamber can be provided not with the absolute reference wavelength of variation of ambient temperature, therefore gas chamber can be utilized to absorb ripple
The long F-P tunable optic filters centre wavelength to etalon calibration carries out secondary correction, such as patent《Based on composite wavelength reference
Fiber grating sensing demodulation device and method》(application number：2015103149934) the composite wavelength reference disclosed by.To sum up institute
It states, tunable TEA CO2 laser demodulation method demodulation accuracy is poor, while hardware cost is higher, it is difficult to work as applied to actual test
In.
The content of the invention
In order to overcome, tunable TEA CO2 laser transmission peak wavelength caused by environment alternating temperature and driving voltage are non-thread in the prior art
Property deteriorate influence to fiber grating sensor wavelength demodulation stability, the present invention proposes a kind of based on hydrogen cyanide absorbing wavelength to join
The fiber grating sensing demodulation apparatus and method examined, using hydrogen cyanide absorption spectrum feature, by the absorption for extracting absorption spectrum
Peak obtains the absolute reference wavelength of temperature stabilization, effectively improves Wavelength demodulation stability, realizes a kind of temperature stabilization and structure
Simple fiber grating demodulation device and its demodulation method.
A kind of fiber grating sensing demodulation device based on the reference of hydrogen cyanide absorbing wavelength of the present invention, the device include width
Band light source 1, tunable TEA CO2 laser 2, optical fiber level-one beam splitter 3, optical fiber circulator 4, optical fibre optical grating sensing array 5, optical fiber two
Grade beam splitter 6, optical fiber cyaniding hydrogen chamber 7, faraday rotator mirror 8, photodetector array 9, data collecting card 10, processing
Unit 11；Wherein：
The light that wideband light source 1 is sent exports frequency sweep by a tunable TEA CO2 laser 2 by voltage control scanning and swashs
Light, the sweeping laser exported is by optical fiber level-one beam splitter 3 by 70:30 are divided into two parts light, are passed wherein 70% light reaches
Feel link, 30% light reaches wavelength reference link；The light of arrival Inductive links enters fiber secondary beam splitter 6 and is divided into 8 beams, often
Shu Guangjun is sent sweeping laser to Fiber Bragg Grating Sensor Array 5 by an optical fiber circulator 4, and the sensor senses external world is to be measured
Parameter is simultaneously encoded into the centre wavelength of fiber grating reflected light, and reflected light signal is sent by optical fiber circulator 4 to light again
Electric explorer 9；The light for reaching wavelength reference link enters optical fiber cyaniding hydrogen chamber 7, optical fiber cyaniding hydrogen by optical fiber circulator 4
Room 7 opposite side connection faraday rotator mirror 8, under 8 reflex of faraday rotator mirror, light passes twice through optical fiber cyanogen
Change hydrogen chamber 7, then by being sent again by optical fiber circulator 4 to photodetector array 9, photodetector array 9 will be all
Optical signal be transformed into electric signal and sent through data collecting card 10 to processing unit 11 and be demodulated.
The fiber grating sensing demodulation method based on the reference of hydrogen cyanide absorbing wavelength of the present invention, the detailed process of this method
It is as follows：
1st, the light that wideband light source 1 is sent is by a tunable TEA CO2 laser 2 by voltage control scanning, in triangle
Ripple or the lower output narrow-band frequency-sweeping laser of sawtooth voltage driving, by optical fiber level-one beam splitter 3 by two parts light is divided into, wherein one
Part light reaches Inductive links, and another part light reaches wavelength reference link；
2nd step, the light of arrival Inductive links enter fiber secondary beam splitter 6 and are divided into N beams, pass through an optical fiber per Shu Guangjun
Circulator 4 send narrow-band frequency-sweeping laser to fiber-optic grating sensor 5, and sensor senses are extraneous to be measured and are encoded into optical fiber
In the centre wavelength of optical grating reflection light, reflected light signal is sent by optical fiber circulator 4 to photodetector array 9 again；
3rd step, the light of arrival wavelength reference link enter optical fiber cyaniding hydrogen chamber 7, optical fiber cyaniding by optical fiber circulator
Hydrogen chamber's 7 opposite side connection faraday rotator mirror 8, the transmitted light of optical fiber cyaniding hydrogen chamber 7 are reflected by Faraday rotation
Mirror 8 is again introduced into optical fiber cyaniding hydrogen chamber 7 and carries out double absorption after reflecting, the transmitted light after double absorption passes through fiber annular again
Device 4 is sent to photodetector array 9, and all optical signals are transformed into electric signal through data collecting card by photodetector array 9
10 send to processing unit 11 and are demodulated；
4th step, scanning light source unevenness cause to obtain most after removing baseline ingredient there are baseline in hydrogen cyanide absorption spectrum
Whole hydrogen cyanide absorption line；
5th step carries out peak-seeking to the gas absworption peak for removing baseline ingredient, then carries out first-order difference to peak position,
Position, that is, R0 and P1 Absorption Lines of difference result maximum, using R0 the and P1 Absorption Lines of hydrogen cyanide gas as lambad labeling, accordingly
The mark zero point that automatic identification lambad labeling position is calculated as wavelength provides reference respectively in this, as initial position to both sides
Wavelength；Peak-seeking, and the sampled point-wavelength provided according to optical fiber cyaniding hydrogen chamber are carried out to the fiber grating sensing signal collected
Relation obtains the centre wavelength value of fiber grating sensing signal.
Compared with prior art, the present invention has following good effect：
1st, the fiber grating demodulation device proposed by the present invention based on the reference of hydrogen cyanide absorbing wavelength utilizes optical fiber hydrogen cyanide
Gas chamber provides absolute reference wavelength, by feat of cyaniding hydrogen chamber absorption line from the excellent of the such environmental effects such as temperature, impact
Point so that demodulating equipment can be applied in the severe operating environments such as alternating temperature, high/low temperature.Based on the reference of hydrogen cyanide absorbing wavelength
Fiber grating demodulation device in quick changeable temperature process (2.4 DEG C/min), the wavelength stability that demodulates ± 2.5pm with
It is interior, realize the fiber grating demodulation of temperature stabilization.
2nd, the characteristics of present invention does not absorb interval not etc. by using hydrogen cyanide gas absorption spectrum extracts characteristic wavelength, nothing
It need to increase that other hardware are i.e. extractable to obtain absolute reference wavelength, it is simple in structure and at low cost.Light is directly extracted after baseline is removed
Fine cyaniding hydrogen chamber absworption peak reduces the extraction difficulty of absolute reference wavelength；Using cubic spline interpolation to tunable filter
Ripple device nonlinear calibration can improve demodulation accuracy, and the demodulation accuracy under constant ambient temperature is in 2pm
Description of the drawings
Fig. 1 is the fiber grating demodulation apparatus structure schematic diagram based on the reference of hydrogen cyanide absorbing wavelength of the present invention；
Fig. 2 removes the spectrum before and after baseline for cyaniding hydrogen chamber absorption spectrum；
Fig. 3 is cyaniding hydrogen chamber absorption spectrum lambad labeling schematic diagram；
Fig. 4 is cyaniding hydrogen chamber absworption peak peak extraction schematic diagram；
Reference numeral：1st, wideband light source, 2, tunable TEA CO2 laser, 3, optical fiber level-one beam splitter, 4, circulator, 5, light
Fine grating sensing array, 6, fiber secondary beam splitter, 7, cyaniding hydrogen chamber, 8, faraday rotator mirror, 9, photodetector,
10th, data collecting card, 11, computer processing unit.
Specific embodiment
Embodiments of the present invention are described in further detail below in conjunction with attached drawing.
Fiber grating demodulation device provided by the invention based on the reference of hydrogen cyanide absorbing wavelength includes 11 parts,
In：
Wideband light source 1, for providing wide spectrum optical for system, including C-band ASE light sources, C+L wave band ASE light sources and SLD light
Source, power is in 0.1mW~40mW；
Tunable TEA CO2 laser 2, for by filtering out wavelength change from wideband light source to the adjusting of its driving voltage
Narrow spectral signal, so as to form the output of the tunable laser of high stability, the spectrum width of tunable TEA CO2 laser 10pm~
400pm, free spectral limit are 90nm~200nm；
Optical fiber level-one beam splitter 3, for input light to be divided according to a certain percentage, including planar waveguide-type fiber beam splitting
Device, fused biconical taper formula fiber optic splitter；
Fiber optical circulator 4, the light for fiber secondary beam splitter to be come out are sent to sensor link and collect reflection letter
Number light when light source power is more than 1mW, uses fiber coupler to substitute to reduce system cost；
Optical fibre optical grating sensing array 5 for perceiving extraneous parameter variation to be measured, and is encoded into fiber grating back wave
In length；
Fiber secondary beam splitter 6 swashs for the tunable laser of output to be divided into the scanning identical with shape is composed of N beams light intensity
Light, N values are selected from one in 2,4,8,16,32,64,128；
Cyaniding hydrogen chamber 7, for providing absolute wavelength reference, inside is filled with hydrogen cyanide gas；
Faraday rotator mirror 8, for by being connected to cyaniding hydrogen chamber one side, for by the transmission of cyaniding hydrogen chamber
Light is reflected so that is effectively absorbed light path and is doubled；
Photodetector array 9, for the optical signal of sensing passage and reference channel to be converted into voltage analog signal；
Data collecting card 10, for gathering the voltage analog signal obtained by photodetector array；
Computer processing unit 11, using computer or embedded computing system, for being tested sensor fibre grating
Wavelength is demodulated.
Invention also provides it is a kind of based on hydrogen cyanide absorbing wavelength reference fiber grating demodulation method, this method
Detailed process is as follows：
1st, the light that wideband light source is sent is by a tunable TEA CO2 laser by voltage driving scanning, in triangular wave
Or the output sweeping laser of sawtooth voltage driving periodical, it is divided into two parts light by optical fiber level-one beam splitter, wherein one
Part light reaches Inductive links, and another part light reaches wavelength reference link；
2nd, the light of arrival Inductive links enters fiber secondary beam splitter and is divided into N beams, passes through a fiber optic loop per Shu Guangjun
Shape device send sweeping laser to fiber-optic grating sensor, the extraneous parameter to be measured of sensor senses and to be encoded into fiber grating anti-
It penetrates in the centre wavelength of light, reflected light signal is sent by optical fiber circulator to photodetector again；
3rd, the light for reaching wavelength reference link is sent sweeping laser to optical fiber cyaniding hydrogen chamber, cyanogen by optical fiber circulator
Change hydrogen chamber's opposite side connection faraday rotator mirror, the transmitted light of cyaniding hydrogen chamber is reflected by faraday rotator mirror
After be again introduced into cyaniding hydrogen chamber and carry out second and absorb, the transmitted light after double absorption is sent to photoelectricity by optical fiber circulator and visited
Survey device, all optical signals are transformed into electric signal and are sent through data collecting card to processing unit by photodetector array to be solved
It adjusts；
4th, wideband light source causes scanning light source uneven phenomenon occur after tunable TEA CO2 laser high-velocity scanning,
It in turn results in there are baseline in hydrogen cyanide absorption line, by obtaining final hydrogen cyanide absorption line after removing baseline ingredient.
Going the method for baseline includes filter method, Empirical mode decomposition etc.；
5th, there are a series of apparent absorption lines, wherein R0 absorptions in the range of 1525-1565nm for hydrogen cyanide gas
Line wavelength is 1541.7528nm, and P1 Absorption Lines absorbing wavelength is 1543.1142nm, and at intervals of 1.3614nm, and remaining is absorbed
Wavelength interval is both less than 0.9nm, significantly less than the interval between R0 and P1 Absorption Lines, therefore using R0 and P1 Absorption Lines as wavelength
Mark.
6th, peak-seeking is carried out to the hydrogen cyanide absorption spectrum for removing baseline ingredient, a jump then is carried out to peak position
Point, position, that is, R0 and P1 Absorption Lines of difference result maximum, accordingly can automatic identification lambad labeling position calculated as wavelength
Zero point is marked, reference wavelength is provided respectively to both sides in this, as initial position；To the fiber grating sensing signal that collects into
Row peak-seeking, and demodulate to obtain in fiber grating sensing signal according to sampled point-wavelength relationship that optical fiber cyaniding hydrogen chamber provides
Cardiac wave long value.
Embodiment 1：Fiber grating sensing demodulation device based on the reference of hydrogen cyanide absorbing wavelength
As shown in Figure 1, the tunable TEA CO2 laser 2 that the light that wideband light source 1 is sent is scanned by one by voltage control,
Sweeping laser is exported under triangular wave or sawtooth voltage driving, 70 are pressed by optical fiber level-one beam splitter 3:30 are divided into two parts
Light, wherein 70% light reaches Inductive links, 30% light reaches wavelength reference link；The light for reaching Inductive links enters optical fiber
Two level beam splitter 6 is divided into 8 beams, is sent sweeping laser to fiber-optic grating sensor 5 by an optical fiber circulator 4 per Shu Guangjun,
The extraneous parameter to be measured of sensor senses is simultaneously encoded into the centre wavelength of fiber grating reflected light, and reflected light signal passes through again
Optical fiber circulator is sent to photodetector 9；The light for reaching wavelength reference link enters optical fiber cyaniding hydrogen by optical fiber circulator
Room 7, optical fiber cyaniding hydrogen chamber opposite side connection faraday rotator mirror 8, under faraday rotator mirror reflex, light
Optical fiber cyaniding hydrogen chamber is passed twice through, then by being sent again by optical fiber circulator to photodetector 9, photodetector array
It all optical signals is transformed into electric signal is sent through data collecting card 10 to processing unit 11 and is demodulated.
Embodiment 2：Fiber grating sensing demodulation method based on the reference of hydrogen cyanide absorbing wavelength
The demodulating process of the above-mentioned fiber grating sensing demodulation device based on the reference of hydrogen cyanide absorbing wavelength is as follows：
Wideband light source in Fig. 1 is by a tunable TEA CO2 laser by voltage control scanning, in triangular wave or sawtooth
The lower output sweeping laser of wave voltage driving, 70 are pressed by optical fiber level-one beam splitter:30 are divided into two parts light, wherein 70% light arrives
Up to Inductive links, 30% light reaches wavelength reference link；The light of arrival Inductive links enters fiber secondary beam splitter and is divided into N
Beam is sent sweeping laser to fiber-optic grating sensor by an optical fiber circulator per Shu Guangjun, and the sensor senses external world is to be measured
Parameter is simultaneously encoded into the centre wavelength of fiber grating reflected light, and reflected light signal is sent by optical fiber circulator to photoelectricity again
Detector；The light for reaching wavelength reference link enters optical fiber cyaniding hydrogen chamber by optical fiber circulator, is inhaled by hydrogen cyanide gas
The faraday rotator mirror that transmitted light after receipts is connected into air inlet chamber opposite side, light carry out anti-in faraday rotator mirror
Optical fiber cyaniding hydrogen chamber is again introduced into after penetrating and carries out double absorption, is then sent again by optical fiber circulator to photodetector, light
All optical signals are transformed into electric signal and are sent through data collecting card to processing unit by electric explorer array to be demodulated.
Optical fiber cyaniding hydrogen chamber is divided into two steps as the method for wavelength reference：First, wideband light source is filtered by tunable F-P
Scanning light source is caused uneven phenomenon occur after ripple device high-velocity scanning, is in turn resulted in hydrogen cyanide absorption line there are baseline, because
, by obtaining final hydrogen cyanide absorption line after removing baseline ingredient, hydrogen cyanide absorption spectrum removes the schematic diagram before and after baseline for this
As shown in Figure 2.Going the method for baseline includes filter method, Empirical mode decomposition etc.；Second, to the hydrogen cyanide after baseline is gone to absorb
Spectral line carries out peak-seeking, then carries out first-order difference to peak position.R0 Absorption Lines wavelength is 1541.7528nm, and P1 Absorption Lines are inhaled
Receipts wavelength is 1543.1142nm, is both less than between R0 and P1 Absorption Lines at intervals of 1.3614nm, remaining absorbing wavelength interval
0.9nm, therefore using R0 and P1 Absorption Lines as lambad labeling, preferable hydrogen cyanide absorption line and lambad labeling schematic diagram as schemed
Shown in 3.Difference result here is significantly greater than other absorption lines, accordingly can automatic identification lambad labeling position, made with this
Reference wavelength is provided respectively to both sides for initial position.Peak-seeking is carried out to the fiber grating sensing signal collected, and according to light
Sampled point-wavelength relationship that fine cyaniding hydrogen chamber provides demodulates to obtain the centre wavelength value of fiber grating sensing signal.
Fig. 4 is gas absworption peak peak extraction schematic diagram, and using Gauss curve fitting during less than normal pressure, optionally greater than normal pressure when adopts
Use Lorentz fit.
Claims (2)
1. a kind of fiber grating sensing demodulation device based on the reference of hydrogen cyanide absorbing wavelength, which is characterized in that the device includes
Wideband light source (1), tunable TEA CO2 laser (2), optical fiber level-one beam splitter (3), optical fiber circulator (4), optical fiber grating sensing battle array
Arrange (5), fiber secondary beam splitter (6), optical fiber cyaniding hydrogen chamber (7), faraday rotator mirror (8), photodetector array
(9), data collecting card (10), processing unit (11)；Wherein：
The light that wideband light source (1) is sent exports frequency sweep by a tunable TEA CO2 laser (2) by voltage control scanning and swashs
Light, the sweeping laser exported is by optical fiber level-one beam splitter (3) by 70:30 are divided into two parts light, wherein 70% light reaches
Inductive links, 30% light reach wavelength reference link；The light of arrival Inductive links enters fiber secondary beam splitter (6) and is divided into 8
Beam is sent sweeping laser to Fiber Bragg Grating Sensor Array (5), sensor sense by an optical fiber circulator (4) per Shu Guangjun
Know extraneous parameter to be measured and be encoded into the centre wavelength of fiber grating reflected light, reflected light signal passes through fiber annular again
Device (4) is sent to photodetector (9)；The light for reaching wavelength reference link enters optical fiber cyaniding hydrogen by optical fiber circulator (4)
Room (7), optical fiber cyaniding hydrogen chamber (7) opposite side connection faraday rotator mirror (8) are anti-in faraday rotator mirror (8)
It penetrates under effect, light passes twice through optical fiber cyaniding hydrogen chamber (7), then by being sent again by optical fiber circulator (4) to photodetection
All optical signals are transformed into electric signal and are sent through data collecting card (10) to processing by device array (9), photodetector array (9)
Unit (11) is demodulated.
2. a kind of fiber grating sensing demodulation side based on the reference of hydrogen cyanide absorbing wavelength according to claim 1 described device
Method, it is characterised in that the detailed process of this method is as follows：
The tunable TEA CO2 laser (2) that the light that (1) step, wideband light source (1) are sent is scanned by one by voltage control,
Triangular wave or the lower output narrow-band frequency-sweeping laser of sawtooth voltage driving, by optical fiber level-one beam splitter (3) by being divided into two parts light,
A portion light reaches Inductive links, and another part light reaches wavelength reference link；
(2) step, the light of arrival Inductive links enter fiber secondary beam splitter (6) and are divided into N beams, pass through an optical fiber per Shu Guangjun
Circulator (4) send narrow-band frequency-sweeping laser to fiber-optic grating sensor (5), and sensor senses are extraneous to be measured and are encoded into
In the centre wavelength of fiber grating reflected light, reflected light signal is sent by optical fiber circulator (4) to photodetector array again
(9)；
(3) step, the light of arrival wavelength reference link enter optical fiber cyaniding hydrogen chamber (7), optical fiber cyaniding by optical fiber circulator
Hydrogen chamber (7) opposite side connection faraday rotator mirror (8), the transmitted light of optical fiber cyaniding hydrogen chamber (7) are revolved by faraday
Turn to be again introduced into optical fiber cyaniding hydrogen chamber (7) progress double absorption after speculum (8) reflects, the transmitted light after double absorption is led to again
It crosses optical fiber circulator (4) to send to photodetector array (9), all optical signals are transformed into electricity by photodetector array (9)
Signal send to processing unit (11) through data collecting card (10) and is demodulated；
(4) step, scanning light source unevenness cause to obtain finally after removing baseline ingredient there are baseline in hydrogen cyanide absorption spectrum
Hydrogen cyanide absorption line；
(5) step carries out peak-seeking to the gas absworption peak for removing baseline ingredient, and first-order difference is then carried out to peak position, poor
Position, that is, R0 and P1 Absorption Lines of point result maximum, using R0 the and P1 Absorption Lines of hydrogen cyanide gas as lambad labeling, accordingly oneself
The mark zero point that dynamic identification lambad labeling position is calculated as wavelength, reference wave is provided in this, as initial position respectively to both sides
It is long；Peak-seeking is carried out to the fiber grating sensing signal collected, and the sampled point-wavelength provided according to optical fiber cyaniding hydrogen chamber closes
System obtains the centre wavelength value of fiber grating sensing signal.
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