CN109085133A - One kind being based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The measuring device and its measurement method of concentration - Google Patents
One kind being based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The measuring device and its measurement method of concentration Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
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- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/359—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using near infrared light
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- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
Abstract
The invention discloses a kind of measuring devices based on the modified off-axis integrated chamber atmospheric CH_4 concentration of real-time reflectivity, are based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity the invention also discloses above-mentioned4The measurement method of apparatus for measuring concentration.Present invention employs carry out atmosphere CH based on the modified off-axis integrated chamber output spectrum method of real-time reflectivity4The measurement of concentration, CH of this method without using known concentration before testing4Standard gas demarcates the reflectance ratio of high reflected mirror of off-axis integrated chamber, real-time calibration is carried out to reflectance ratio of high reflected mirror in actual measurement environment, it can avoid albedo measurement deviation caused by being changed as test environment, reduce the gas concentration measurement deviation as caused by reflectivity changes, systematic survey stability is improved, the method for the present invention can be suitable for atmosphere CH4The real-time monitoring of concentration.
Description
Technical field
The present invention relates to one kind to be based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The measuring device of concentration, also
It is related to the measurement method of above-mentioned measuring device, belongs to field of optical measuring technologies.
Background technique
CH4It is to cause one of predominant gas of greenhouse effects, although concentration is very low in an atmosphere (about 1.8ppmv),
It is CO to the effect of greenhouse effects225 times, and its concentration is being increased every year with 1.1% speed, is become in global climate
Key player is play in warm.Quickly, the trace CH in real time, in accurate measurements lower atmosphere4Content is to analysis atmospheric methane
Source, reduction discharge of methane, reduction global warming track are significant.Benefit from the development of laser light source, a variety of high sensitivity
Spectrographic technique is maturely applied to atmosphere CH4Gasmetry, including the output of cavity ring-down spectroscopy (CRDS) method, off-axis integrated chamber
Spectrum (OA-ICOS) method etc..Wherein, OA-ICOS has high sensitivity and robustness, and compared with CRDS, anti-interference ability is more
By force, more suitable for outer field measurement, to be widely used in atmosphere CH4Detection and analysis.
Existing off-axis integrated chamber measuring system atmospheric sounding CH4When, it needs to demarcate the reflectivity of high reflective mirror, mesh
Preceding common calibration mode is the CH for using known concentration before testing4Standard gas demarcates reflectivity.However due to reality
The component and CH of air to be measured in site environment4The component of standard gas is different, and may change at any time, completely according to calibration mode
The reflectance measurement of acquisition can have certain deviation, and the measured deviation of reflectivity will cause CH4Concentration measurement generates inclined
Difference.More seriously when testing environmental change, reflectivity is changed correspondingly, and uses CH4The reflectivity of standard gas calibration is one
A definite value, this will cause the systematic survey stability to decline.On the other hand, due to atmosphere CH4Concentration is in ppmv magnitude, the concentration
The CH of magnitude4Standard gas prepares complicated and concentration itself there are certain error, and CH4Standard gas higher cost, calibration process are cumbersome.
Therefore, a kind of CH without using known concentration before testing is developed4Standard gas demarcates reflectivity, and can carry out to reflectivity real-time
Modified off-axis integrated chamber atmosphere CH4The measuring device and its measurement method of concentration are particularly important.
Summary of the invention
Goal of the invention: technical problem to be solved by the invention is to provide one kind to be based on the modified off-axis product of real-time reflectivity
Divide chamber atmosphere CH4The measuring device of concentration.
The present invention also technical problems to be solved are to provide above-mentioned based on the modified off-axis integrated chamber atmosphere of real-time reflectivity
CH4The measurement method of apparatus for measuring concentration, this method can reduce the gas concentration measurement deviation as caused by reflectivity changes, improve
The measurement stability of system is suitable for atmosphere CH4The real-time monitoring of concentration.
In order to solve the above technical problems, the technical scheme adopted by the invention is as follows:
One kind being based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The measuring device of concentration, including two-way detection
The optical signal of optical path and signal processing module, two-way detection optical path is transmitted to signal processing mould by corresponding photodetector respectively
It is handled in block；First via detection optical path successively includes function generator I, laser controller I, Distributed Feedback Laser I, light collimation
Device, resonant cavity, condenser lens and photodetector I are filled with air to be measured in resonant cavity；Function generator I occurs signal and gives
Laser controller I, laser controller I are controlled Distributed Feedback Laser I and are swashed while scanning absorption line with high frequency sinusoidal signal modulation
Optical wavelength, off-axis incident is into resonant cavity after optical collimator collimates for the laser that Distributed Feedback Laser I is issued, and incident laser is through to be measured
After air absorbs, signal received by photodetector I after coming out line focus lens focus from resonant cavity, photodetector I will adopt
The optical signal collected is converted into electric signal transmission into signal processing module；It successively includes function generator that second tunnel, which detects optical path,
II, laser controller II, Distributed Feedback Laser II, with reference to absorption cell and photodetector II, with reference to being filled with sky to be measured in absorption cell
Gas；Function generator II occurs signal and laser controller II, laser controller II is given to control Distributed Feedback Laser II in scanning absorption spectra
Optical maser wavelength is modulated with high frequency sinusoidal signal while line, the laser that Distributed Feedback Laser II is issued is transmitted to by optical fiber with reference to absorption
The entrance port in pond comes out from reference absorption cell and is received by photodetector II after the air to be measured in reference absorption cell absorbs
Collected optical signal is converted into electric signal transmission into signal processing module by signal, photodetector II.
It wherein, further include being made of with pneumatic module premix barrel, flow controller and aspiration pump with pneumatic module；Premix barrel one
End is connect with inlet end, and the premix barrel other end is connect with resonant cavity and with reference to the air inlet of absorption cell respectively；Resonant cavity and reference
The gas outlet of absorption cell passes through connecting pipe respectively and connect with aspiration pump, and flow controller is equipped in connecting pipe.
Wherein, the Distributed Feedback Laser I is 1653.7nmDFB laser, and Distributed Feedback Laser II is 1391.7nmDFB laser
Device.
Wherein, air to be measured is respectively fed to detect in resonant cavity and reference absorption cell by premix barrel.
It is above-mentioned to be based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The measurement method of the measuring device of concentration, packet
Include following steps:
Step 1, the Distributed Feedback Laser I in two-way detection optical path and Distributed Feedback Laser II are respectively while scanning absorption line
Optical maser wavelength is modulated with high frequency sinusoidal signal, the laser of sending is visited by photoelectricity respectively after being each passed through resonant cavity and reference absorption cell
It surveys device I and photodetector II and receives signal, photodetector I measurement obtains resonant cavity background light intensity signal and transmitted light intensity letter
Number, photodetector II measurement is obtained with reference to absorption cell background light intensity signal and transmitted light intensity signal；
Step 2, the reference absorption cell background light intensity signal and transmitted light intensity signal step 1 obtained carries out at locking phase filtering
Reason obtains its corresponding button background first harmonic normalization second harmonic signal, extracts the H with reference to absorption cell2O absorbs peak height
Spend measured value；
Step 3, according to known atmospheric temperature, pressure, the reference absorption cell obtained with reference to absorption pond length and measurement
Background light intensity signal obtains different H in conjunction with 2016 database of HITRAN2The corresponding emulation of O concentration refers to absorption cell transmitted light
Strong signal is filtered through locking phase, obtains its corresponding button background first harmonic normalization second harmonic signal, extracts H2O
Absorption peak height value establishes different H2O concentration and H2The database of O absorption peak height value substitutes into step 2 with reference to absorption cell
H2O absorption peak height measurements obtain real-time H2O concentration measurement；
Step 4, resonant cavity background light intensity signal and transmitted light intensity signal are subjected to locking phase filtering processing, it is corresponding obtains its
It detains background first harmonic and normalizes second harmonic signal, extract the H of resonant cavity2O absorption peak height measurements and CH4Absorption peak
Height measurements；
Step 5, according to known atmospheric temperature, pressure, Resonant Intake System, real-time H2It O concentration measurement and measures
Resonant cavity background light intensity signal obtains the corresponding emulation resonant cavity transmitted light of different reflectivity in conjunction with 2016 database of HITRAN
Strong signal is filtered through locking phase, obtains its corresponding button background first harmonic normalization second harmonic signal, extracts H2O
Absorption peak height value, establishes different reflectivity and H2The database of O absorption peak height value substitutes into the H of resonant cavity in step 42O inhales
It receives peak heights measured value and obtains real-time reflectance measurement；
Step 6, it according to known atmospheric temperature, pressure, Resonant Intake System, real-time reflectance measurement and measures humorous
Vibration chamber background light intensity signal obtains different CH in conjunction with 2016 database of HITRAN4The corresponding emulation resonant cavity transmitted light of concentration
Strong signal is filtered through locking phase, obtains its corresponding button background first harmonic normalization second harmonic signal, extracts CH4
Absorption peak height value establishes different CH4Concentration and CH4The database of absorption peak height value substitutes into the CH of resonant cavity in step 44It inhales
It receives peak heights measured value and obtains real-time CH4Concentration measurement.
The utility model has the advantages that big present invention employs being carried out based on the modified off-axis integrated chamber output spectrum method of real-time reflectivity
Gas CH4The measurement of concentration, CH of this method without using known concentration before testing4Standard gas is anti-to the high reflective mirror of off-axis integrated chamber
The rate of penetrating is demarcated, and carries out real-time calibration to reflectance ratio of high reflected mirror in actual measurement environment, can avoid being changed by test environment
Caused by albedo measurement deviation, reduce the gas concentration measurement deviation as caused by reflectivity changes, improve systematic survey stablize
Property, the method for the present invention can be suitable for atmosphere CH4The real-time monitoring of concentration.
Detailed description of the invention
Fig. 1 is that the present invention is based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The system of apparatus for measuring concentration is former
Reason figure；
Fig. 2 is that the present invention is based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The flow chart of concentration measuring method；
Fig. 3 is using measuring device of the present invention to atmosphere CH4The result figure of measurement of concetration.
Specific embodiment
Below in conjunction with the drawings and specific embodiments, technical scheme is described further.
As shown in Figure 1, the present invention is based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The measuring device of concentration,
Optical path and signal processing module 4 are detected including two-way, the optical signal of two-way detection optical path is passed by corresponding photodetector respectively
It transports in signal processing module 4 and is handled；The first via detection optical path successively include function generator I8, laser controller I9,
Distributed Feedback Laser I10, optical collimator 11, resonant cavity 12, condenser lens 13 and photodetector I18, in resonant cavity 12 filled with to
Survey air；Function generator I8 occurs signal and laser controller I9, laser controller I9 control Distributed Feedback Laser I10 is given to scan
Optical maser wavelength is modulated with high frequency sinusoidal signal while absorption line, the laser that Distributed Feedback Laser I10 is issued is quasi- through optical collimator 11
For off-axis incident into resonant cavity 12, incident laser comes out line focus lens 13 after air to be measured absorption, from resonant cavity 12 after straight
Signal is received by photodetector I18 after focusing, collected optical signal is converted into electric signal transmission extremely by photodetector I18
In signal processing module 4；It successively includes function generator II5, laser controller II6, Distributed Feedback Laser that second tunnel, which detects optical path,
II7, with reference to absorption cell 17 and photodetector II3, with reference to being filled with air to be measured in absorption cell 17；Function generator II5 hair
Raw signal gives laser controller II6, laser controller II6 to control Distributed Feedback Laser II7 while scanning absorption line with high frequency
Sinusoidal signal modulation optical maser wavelength, the laser that Distributed Feedback Laser II7 is issued are transmitted to the entrance port with reference to absorption cell 17 by optical fiber,
After the air to be measured in reference absorption cell 17 absorbs, is come out from reference absorption cell 17 and signal, light are received by photodetector II3
Collected optical signal is converted into electric signal transmission into signal processing module 4 by electric explorer II3；Wherein, Distributed Feedback Laser
I10 is 1653.7nmDFB laser, and Distributed Feedback Laser II7 is 1391.7nmDFB laser；1653.7nmDFB laser can expire
Foot scans 6046.95cm simultaneously-1Locate CH4Absorption line and 6047.79cm-1Locate H2The absorption line of O, it is synchronous to realize reflectivity
Calibration and CH4The measurement of concentration；H in an atmosphere2O concentration is higher, selects H2O is in 7185.60cm-1The absorption line at place can be
It realizes under the conditions of shorter absorption light path to its density real-time monitoring.The probe source used in actual measurement is not limited to
1653.7nm Distributed Feedback Laser and 1391.7nmDFB laser.
The present invention is based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The measuring device of concentration further includes distribution group
Part is made of with pneumatic module premix barrel 14, flow controller 15 and aspiration pump 16；14 one end of premix barrel and external inlet end connect
It connects, 14 other end of premix barrel is connect with resonant cavity 12 and with reference to the air inlet of absorption cell 17 respectively；Resonant cavity 14 and reference absorb
The gas outlet in pond 17 passes through connecting pipe 2 respectively and connect with aspiration pump 16, and flow controller 15 is equipped in connecting pipe 2,
Air to be measured in environment is extracted by aspiration pump 16, flow controller group 15 controls extraction flow, and air to be measured is mixed through premix barrel 14
After conjunction, respectively enters resonant cavity 12 and detected with reference to absorption cell 17.
Signal occurs for function generator II5 to laser controller II6 control Distributed Feedback Laser II7 in scanning absorption line
Optical maser wavelength is modulated with high frequency sinusoidal signal simultaneously, the laser of sending is transmitted to the entrance port with reference to absorption cell 17 by optical fiber, passes through
After air to be measured absorbs, is come out from reference absorption cell 17 and signal is received by photodetector II3；Function generator I8 hair simultaneously
Raw signal, which is modulated to laser controller I9 control Distributed Feedback Laser I10 while scanning absorption line with high frequency sinusoidal signal, to swash
Optical wavelength, off-axis incident is into resonant cavity 12 after optical collimator 11 for the laser of sending, after air to be measured absorption, from resonant cavity
12, which come out line focus lens 13, focuses, and receives signal by photodetector I18, and two photodetectors turn two ways of optical signals
Electric signal transmission to signal processing module 4 is changed into be handled.
As shown in Fig. 2, the present invention is based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The measurement method of concentration,
Include the following steps:
Step 1, by the central temperature and electric current of laser controller II6 control 1391.7nmDFB laser, make laser
Center wavelength of light is in λ out1Near (7185.60cm-1), function generator II5 output frequency is fsSinusoidal scanning signal superposition
Frequency is fmHigh frequency sinusoidal modulated signal the output wavelength of the Distributed Feedback Laser is tuned, the laser of output is passed by optical fiber
It transports to reference in absorption cell 17, photodetector II3 is measured respectively with reference to absorption cell 17N2Background light intensity signalAnd transmission
Light intensity signalSimultaneously by the central temperature and electric current of laser controller I9 control 1653.7nmDFB laser, make laser
Device goes out center wavelength of light in λ2(6047.35cm-1) near, function generator I8 output frequency is fsSinusoidal scanning signal it is folded
Adding frequency is fmHigh frequency sinusoidal modulated signal the output wavelength of the Distributed Feedback Laser is tuned, the laser of output is through light standard
For off-axis incident into resonant cavity 12, photodetector I18 measures resonant cavity 12N respectively after straight device 11 collimates2Background light intensity signalWith transmitted light intensity signal IM(v)；λ1For H2O measures the wavelength of spectral line, λ2For CH4Measure spectral line (6046.95cm-1) with it is attached
Nearly H2O absorption line (6047.79cm-1) intermediate wavelength；
Step 2,17 background light intensity signal of absorption cell will be referred toWith transmitted light intensity signalCarry out locking phase filtering
Processing obtains its corresponding button background first harmonic normalization second harmonic signalIt extracts with reference to absorption cell
H2O absorption peak height measurements
In formula (1),For convolution symbol, F is filter function, and t is time, fmFor modulating frequency, Respectively background light intensityThe X and Y-direction component of corresponding first harmonic and second harmonic； Respectively transmitted light intensityThe X and Y-direction component of corresponding first harmonic and second harmonic； Respectively transmitted light intensityWith background light intensityThe absolute value of corresponding first harmonic signal,For transmitted light intensityCorresponding button background first harmonic normalizes second harmonic signal；
Step 3, according to Beer-Lambert law, absorptivity k (v1) be expressed as
In formula, p is gas pressure intensity,For atmosphere H2O concentration, L are with reference to absorption pond length, and S (T) is that absorption line exists
The intensity of spectral line when temperature T, T are gas temperature (being obtained by temperature and humidity measuring instrument HMT333 real-time monitoring), φ (v1) it is to absorb
The linear function of spectral line is described using Voigt line style, and the line parameters in linear function are provided by HITRAN2016 database；
It can must be emulated by formula (2) and refer to absorption cell transmitted light intensityAre as follows:
Establish different H2O concentrationCorresponding emulation refers to absorption cell transmitted light intensityIt willWithInto
The identical locking phase filtering processing of row step 2 obtains its corresponding button background first harmonic normalization second harmonic signalExtract H2O absorption peak height valueIt establishesWithDatabase, substitute into?
To real-time H2O concentration measurement
Step 4, by resonant cavity background light intensity signalWith transmitted light intensity signal IM(v) the identical locking phase of step 2 is carried out
Filtering processing obtains its corresponding button background first harmonic normalization second harmonic signalThe H2O for extracting resonant cavity inhales
Receive peak heights measured valueWith CH4 absorption peak height measurements
Step 5, by the basic theories of off-axis integrated chamber it is found that resonant cavity background light intensity signalBelieve with transmitted light intensity
Number IM(v) relationship are as follows:
In formula, R is the reflectivity of resonant cavity high reflective mirror, is above Resonant Intake System (it is identical to absorb pond length with reference), α (v)
For absorption coefficient, α (v) is expressed as
α (ν)=pxS (T) φ (v) (5)
In formula, x is gas concentration, by formula (4) and (5), can must emulate resonant cavity transmitted light intensity signal IS(v) are as follows:
Establish different reflectivity RSCorresponding emulation resonant cavity transmitted light intensity signal IS(v), by IS(v) andIt is walked
Rapid 2 identical locking phase filtering processing, obtains its corresponding button background first harmonic normalization second harmonic signalIt extracts
H2O absorption peak height valueEstablish RSWithDatabase, substitute intoObtain real-time reflectance measurement Rr；
Step 6, different CH4 concentration are established by formula (6)Corresponding emulation resonant cavity transmitted light intensity signal IS(v), by IS
(v) andThe identical locking phase filtering processing of step 2 is carried out, it is secondary humorous to obtain its corresponding button background first harmonic normalization
Wave signalExtract CH4 absorption peak height valueIt establishesWithDatabase, substitute intoObtain CH4
Concentration measurement
Real-time H in atmosphere2Shown in (a) in O concentration measurement such as Fig. 3, scan frequency 50Hz carried out for 500 periods
H is provided after average2O concentration measurement, within the 600s testing time, atmosphere H2O concentration slowly fluctuates, and fluctuation of concentration ±
Within 0.5%, the real-time reflectivity R that is calculatedrShown in (b) in measurement result such as Fig. 3, average reflectance RfFor
0.99501, standard deviation is 1.2 × 10-4, real-time CH in the atmosphere that is calculated4Concentration measurement is as shown such as (c) in Fig. 3,
Atmosphere CH4Mean concentration measured value is 1.821ppmv, and standard deviation 0.024ppmv, i.e. relative deviation are 1.31%, the time
Resolution ratio is 10s.And use average reflectance RfCH in the atmosphere being calculated4For concentration results also in Fig. 3 (c), what is obtained is big
Gas CH4Mean concentration measured value is 1.820ppmv, and standard deviation 0.052ppmv, i.e. relative deviation are 2.86%.By above-mentioned
As a result it is found that using real-time reflectivity RrThe CH being calculated4Concentration results relative deviation is smaller, and stability is more preferable, effectively subtracts
Lack by reflectivity changes bring measured deviation, which may be implemented atmosphere CH4Concentration it is quick, real-time, stable
Measurement.
Claims (5)
1. one kind is based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The measuring device of concentration, it is characterised in that: including
Two-way detects optical path and signal processing module, and the optical signal of two-way detection optical path is transmitted to letter by corresponding photodetector respectively
It is handled in number processing module；It successively includes function generator I, laser controller I, Distributed Feedback Laser that the first via, which detects optical path,
I, optical collimator, resonant cavity, condenser lens and photodetector I；Function generator I occurs signal and gives laser controller I, laser
Controller I controls Distributed Feedback Laser I and modulates optical maser wavelength, Distributed Feedback Laser while scanning absorption line with high frequency sinusoidal signal
The laser that I is issued after optical collimator collimates into resonant cavity, inhale off-axis incident through the air to be measured in resonant cavity by incident laser
After receipts, from resonant cavity come out line focus lens focus after by photodetector I receive signal, photodetector I will be collected
Optical signal is converted into electric signal transmission into signal processing module；Second tunnel detection optical path successively includes function generator II, swashs
Optical controller II, Distributed Feedback Laser II, with reference to absorption cell and photodetector II；Function generator II occurs signal and gives laser control
Device II processed, laser controller II control Distributed Feedback Laser II and modulate laser while scanning absorption line with high frequency sinusoidal signal
Wavelength, the laser that Distributed Feedback Laser II is issued is transmitted to the entrance port with reference to absorption cell by optical fiber, through to be measured in reference absorption cell
It after air absorbs, is come out from reference absorption cell and signal is received by photodetector II, photodetector II believes collected light
Number electric signal transmission is converted into signal processing module.
2. according to claim 1 be based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The measuring device of concentration,
It is characterized by also including pneumatic module is matched, it is made of with pneumatic module premix barrel, flow controller and aspiration pump；Premix barrel one end
It is connect with inlet end, the premix barrel other end is connect with resonant cavity and with reference to the air inlet of absorption cell respectively；Resonant cavity and reference are inhaled
The gas outlet of receives pond passes through connecting pipe respectively and connect with aspiration pump, and flow controller is equipped in connecting pipe.
3. according to claim 1 be based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The measuring device of concentration,
It is characterized by: the Distributed Feedback Laser I is 1653.7nmDFB laser, Distributed Feedback Laser II is 1391.7nmDFB laser.
4. according to claim 2 based on CH in the modified off-axis integrated chamber atmosphere of real-time reflectivity4The measurement of concentration fills
It sets, it is characterised in that: air to be measured is respectively fed to detect in resonant cavity and reference absorption cell by premix barrel.
5. a kind of described in claim 1 based on the modified off-axis integrated chamber atmosphere CH of real-time reflectivity4The measuring device of concentration
Measurement method, which comprises the steps of:
Step 1, the Distributed Feedback Laser I in two-way detection optical path and Distributed Feedback Laser II are respectively while scanning absorption line with height
Frequency sinusoidal signal modulation optical maser wavelength, the laser of sending are each passed through after resonant cavity and reference absorption cell respectively by photodetector
I and photodetector II receives signal, and photodetector I measurement obtains resonant cavity background light intensity signal and transmitted light intensity signal,
Photodetector II measurement is obtained with reference to absorption cell background light intensity signal and transmitted light intensity signal；
Step 2, the reference absorption cell background light intensity signal and transmitted light intensity signal step 1 obtained carries out locking phase filtering processing,
Its corresponding button background first harmonic normalization second harmonic signal is obtained, the H with reference to absorption cell is extracted2O absorbs peak heights
Measured value；
Step 3, according to known atmospheric temperature, pressure, the reference absorption cell background obtained with reference to absorption pond length and measurement
Light intensity signal obtains different H in conjunction with 2016 database of HITRAN2The corresponding emulation of O concentration is believed with reference to absorption cell transmitted light intensity
Number, it is filtered through locking phase, obtains its corresponding button background first harmonic normalization second harmonic signal, extract H2O absorbs
Peak height angle value establishes different H2O concentration and H2The database of O absorption peak height value substitutes into step 2 and refers to the H of absorption cell2O inhales
It receives peak heights measured value and obtains real-time H2O concentration measurement；
Step 4, resonant cavity background light intensity signal and transmitted light intensity signal are subjected to locking phase filtering processing, obtain its corresponding button back
Scape first harmonic normalizes second harmonic signal, extracts the H of resonant cavity2O absorption peak height measurements and CH4Absorb peak heights
Measured value；
Step 5, according to known atmospheric temperature, pressure, Resonant Intake System, real-time H2O concentration measurement and the resonant cavity measured
Background light intensity signal obtains the corresponding emulation resonant cavity transmitted light intensity letter of different reflectivity in conjunction with 2016 database of HITRAN
Number, it is filtered through locking phase, obtains its corresponding button background first harmonic normalization second harmonic signal, extract H2O absorbs
Peak height angle value, establishes different reflectivity and H2The database of O absorption peak height value substitutes into the H of resonant cavity in step 42O absorption peak
Height measurements obtain real-time reflectance measurement；
Step 6, according to known atmospheric temperature, pressure, Resonant Intake System, real-time reflectance measurement and the resonant cavity measured
Background light intensity signal obtains different CH in conjunction with 2016 database of HITRAN4The corresponding emulation resonant cavity transmitted light intensity letter of concentration
Number, it is filtered through locking phase, obtains its corresponding button background first harmonic normalization second harmonic signal, extract CH4It absorbs
Peak height angle value establishes different CH4Concentration and CH4The database of absorption peak height value substitutes into the CH of resonant cavity in step 44Absorption peak
Height measurements obtain real-time CH4Concentration measurement.
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