CN108981953A - A kind of laser absorption spectrum temp measuring method and system based on interference modulations principle - Google Patents
A kind of laser absorption spectrum temp measuring method and system based on interference modulations principle Download PDFInfo
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Abstract
The present invention provides a kind of laser absorption spectrum temp measuring method and system based on interference modulations principle, and element used includes laser generating unit, Mach once moral fibre optic interferometer, photoelectric detection unit and data processing unit etc..Wherein, by Mach-Zehnder interferometer after laser signal generates, under test gas is then passed through, data are acquired by photodetector and is uploaded to data processing unit processing.The mapping for absorbing light intensity data and relative wavenumbers and absorbing light intensity data is extracted from measurement data, fitting obtains the initial value of baseline and absorption spectrum parameter, and it is modified by iteration, absorptivity is integrated according to modified absorption spectrum parameter calculation, tested gas temperature is calculated by the integral absorptivity of a plurality of spectral line.Optical system structure of the present invention is simple, no movable member and can inhibit background radiation noise, and overall effect is prominent, applied widely, high reliablity, is with a wide range of applications.
Description
(1) technical field
The present invention proposes a kind of laser absorption spectrum temp measuring method and system based on interference modulations principle, in particular to one
The Mach of etalon and light intensity modulator once moral fibre optic interferometer kind is multiplexed in measuring system, by laser modulation technique application
In field of temperature measurement.
(2) background technique
Gas parameter measurement method based on laser absorption spectrum is as a kind of quick, high sensitivity non-cpntact measurement side
Method has obtained development at full speed, is a kind of effective method in temperature and concentration measurements field, is widely used in burning
Diagnosis, Combustion System etc., application potential is huge, and prospect is considerable.
The measurement method of typical monochromatic light road absorption spectrum is divided into direct absorption process (DAS, Direct Absorption
) and wavelength modulation method (WMS, Wavelength Modulation Spectroscopy) Spectroscopy.Two absorption spectras
The monochromatic light road laser absorption spectroscopy of line is used to obtain mean temperature and concentration of component of the flow field along laser path.Such as X.Liu
With J.B.Jeffries in 2006 in " Applied Physics B " (Applied Physics B) 469-478 pages of phase hair of volume 82 the 3rd
Entitled " for measuring the development of the Adjustable Diode laser sensor of combustion turbine exhaustion temperature " (the Development of of table
a tunable diode laser sensor for measurements of gas turbine exhaust
Temperature it) in a text, is verified in the large scale industry gas turbine for generator, along the mean temperature of laser path
It is converted to by the ratio of the two water absorption line measurement absorbances near infrared region, and is developing multi-thread strategy to solve unevenness
The problem of even Temperature Distribution.DAS method is widely used in low-temp low-pressure measurement.However, such as M.A.Bolshov and
Yu.A.Kuritsyn is in 2015 in " spectrochemistry journal B atomic spectroscopy " (Spectrochimica Acta Part B
Atomic Spectroscopy) the 106th 45-66 pages of the phase entitled " tunable two pole used as combustion diagnosis technology delivered
Pipe laser spectrum tech " (Tunable diode laser spectroscopy as a technique for
Combustion diagnostics) in a text, there is the heat of needle position misalignment caused by such as light scatters, test cabinet in DAS method
The transmitting of structure, optical standard have the problems such as effect.For the dynamic mistake of the measurement process of hot environment, especially hot conditions
In journey measurement, the radiation energy (density) of infrared band increases with temperature and is increased, when temperature reaches 1000K, due to hot spoke
Ambient noise caused by penetrating can not be ignored as small noise.
In WMS method, be superimposed upon on ramp sweep waveform at a slow speed using high frequency sinusoidal signal, modulate laser wavelength and
Intensity.As Gregory B.Rieker and Jay B.Jeffries in 2009 in " Application Optics " (Applied Optics)
The phase page 5546 of volume 48 the 29th entitled " the calibration-free wavelength modulation method of the measurement gas temperature and concentration suctions in harsh environment delivered
Receive spectral technique " (Calibration-free wavelength-modulation spectroscopy for
Measurements of gas temperature and concentration in harsh environments) text
In, in contrast to direct absorption process, in supersonic airstream in carbon dioxide measurement, WMS-2f method is promoted in terms of signal-to-noise ratio
4 times.As Alexander Klein and Oliver Witzel in 2014 in " sensor " (Sensors) o. 11th of volume 14
21497-21513 pages of entitled " quickly, the direct absorption process of time-sharing multiplex and the wavelength modulation method laser absorption spectrum skill delivered
Art " (Rapid, time-division multiplexed, direct absorption-and wavelength
Modulation-spectroscopy) in a text, show after obtaining experiment measurement, the final result of WMS is needed by suitable
Complicated computation modeling and fitting algorithm obtains.As Guojie Tu and Fengzhong Dong in 2015 in " IEEE sensor
Periodical " 3535-3542 pages of the phase of volume 15 the 6th of (IEEE Sensors Journal) deliver it is entitled " tunable under condition of normal pressure
The random noise and long term drift of diode laser absorption spectroscopic system are analyzed " (Analysis of Random Noise and
Long-Term Drift for Tunable Diode Laser Absorption Spectroscopy System at
Atmospheric Pressure) in a text, it is indicated that in harsh industrial environment, the difference of pressure and temperature is to absolute absorption
Spectral half-width brings uncertain factor, to reduce the applicability of long-term sensor deployment.It is realized in the TDLAS of early stage
In, generally use external optical chopper or lithium niobate amplitude modulaor.Such as James R.P.Bain and Michael Lengden
In 2015 in " IEEE sensor periodical " (IEEE sensors journal) 1-1 pages of the phase entitled " base delivered of volume 16 the 3rd
Restore the method for absolute absorption wire shaped using modulation method outside balance detection in tunable diode laser technology " (Recovery
of Absolute Absorption Line Shapes in Tunable Diode Laser Spectroscopy using
External Amplitude Modulation with Balanced Detection) in a text, it is indicated that typical optics is cut
The modulating frequency of wave device generally can reach kHz, and the modulating frequency of lithium niobate amplitude modulaor can reach MHz, but laser need to be made to reach
A part of light intensity is lost to polarization state, and the light channel structure needed is more complicated compared with traditional direct absorption process.
As Y Deguchi and M Noda in 2002 in " bacteriology periodical " (Journal of Bacteriology)
2637-2641 pages of the phase of volume 190 the 7th entitled " the laser diagnostics skill that temperature and the species concentration monitoring of industrial application use delivered
Art " (Industrial applications of temperature and species concentration
Monitoring using laser diagnostics) in a text, interferometer no matter in DAS method or WMS method all
Ensure the synchronization of optical frequency as etalon.
Based on background above, a kind of laser absorption spectrum temp measuring method and system based on interference modulations has been invented herein,
Uniform temperature is measured by single light path bispectrum line, etalon data are obtained by an optical path simultaneously and absorption spectra is believed
Breath.On the basis of relative simplicity system structure, the modulation of light intensity is realized, has inhibition to make ambient noise to a certain extent
With, and realize the measurement of temperature.
(3) summary of the invention
The core technology of gas temperature measurer based on laser absorption spectroscopy is how accurately to mention from laser signal
Take out absorption spectrum information.The general gas temp measuring system based on laser absorption spectroscopy is required to an independent optical path
It uses as etalon, is changed with time relationship with extracting relative wavenumbers, optical system is complex.
The present invention proposes a kind of absorption spectrum temp measuring system based on interference modulations and the spectrum reconstruction method based on iteration,
Mach once moral fibre optic interferometer as intensity modulation device while be multiplexed with etalon, it is no longer necessary to an independent optical path conduct
Etalon uses, and simplifies optical system and can inhibit ambient noise.
Element used includes: laser generating unit, Mach once moral fibre optic interferometer, photoelectric detection unit and data processing list
Member etc..
The technical solution adopted by the present invention is that: laser is become after Mach once moral fibre optic interferometer by collimating mirror
Parallel spatial light is acquired after tested gas by photodetector.By the way that acquisition measuring signal is demodulated and is fitted
The initial parameter values of spectroscopic data and base-line data are obtained, then it is modified by iterative process, obtain spectrum simulation ginseng
Several end values.It is acquired by the fitting parameter of spectroscopic data and integrates absorptivity, and is resolved and obtained the temperature value of tested gas.
During calculating and outputting laser relative wavenumbers data respectively by acquisition data and absorb light intensity data, the solution of use
It is as follows to calculate method and step:
Step 1, the laser signal that module generation occurs for laser first pass around Mach-Zehnder interferometer and obtain intensity modulation wave
The measuring signal of long scan then passes through measurand, is finally acquired by photodetector, and form is such as in principle for acquisition signal
Shown in formula (1),
Wherein, IMZIIt (t) is that photodetector collects the measurement data changed over time, I0It (t) is generated by laser
Laser signal without the light intensity data before Mach-Zehnder interferometer and measurand, vFSRIt is the free spectrum model of interferometer
Enclose (FSR, Free spectral range), A, B, φ0Be by the Mach parameter that once moral fibre optic interferometer self structure determines,
When the interferometer used is fixed, these parameters are constant, and v (t) is output laser relative wavenumbers data, and α (v (t)) is tested
The absorption spectra of object；；
Step 2, according to acquisition data calculation output laser relative wavenumbers data v (t), by Mach-Zehnder interferometer and
The laser signal of measurand is as shown in (1) formula, and laser relative wavenumbers data can resolve to obtain by light intensity data, in laser
For signal strength twice between extreme point, wave number variation is a Free Spectral Range；In order under limited sampling number more
The accurate position for extracting extreme point, when extracting relative wavenumbers data with the following method, to IMZI(t) signal carries out high-pass filtering,
Its cutoff frequency is laser signal scan frequency；Record the zero crossing of filtered signal, the midpoint of every two adjacent zero crossing
Position is extreme point position；Relative wavenumbers representated by data point where two extreme points differ a Free Spectral Range,
This makes it possible to obtain the relative wavenumbers data v (t) of data laser；
Step 3 demodulates acquisition data, and be absorbed light intensity data: by relative wavenumbers data v (t) generation of laser
Enter (1), obtains the mapping relations of relative wavenumbers v and measurement data, such as (2) formula
According to the Free Spectral Range v of Mach-Zehnder interferometerFSR, the signal as described in (3) formula can be provided
By (2) (3) simultaneous, available absorption light intensity data I (t) after quadrature demodulation is carried out, as shown in (4) formula
Wherein I0(t) be by laser generate laser signal enter Mach-Zehnder interferometer before light intensity signal, Ibase
(t) it is and I0(t) directly proportional signal is in data processing base-line data ideally, and α (v (t)) is tested
The absorption spectra of object.
Baseline parameter and absorption spectrum parameter are obtained by way of fitting in solution process, and are fitted by iterated revision
As a result, calculating the temperature value of tested gas in turn, the calculation method of use includes the following steps:
Step 1 determines mathematical model used in being fitted in various process, according to light intensity data is absorbed, passes through minimum
Two modes for multiplying fitting estimate the fitting parameter of baseline, are fitted using cubic polynomial to baseline, obtain the fitting of baseline
Parameter group ParaBase0, the model used is such as shown in (5)
Wherein, fitting parameter group ParaBase0For the polynomial parameters of fitting.Then, it is obtained based on Bill's Lambert law
The data α (t) of absorptivity, such as shown in (6)
The relative wavenumbers data v (t) of laser is substituted into, be absorbed modal data α (v), and is fitted on this basis, adopts
Model such as (7) is shown,
Wherein, A is the integral absorptivity of absorption spectra, φvIt (v) is Voigt line style spread function.Due to Voigt line style letter
Number calculates the calculating comprising convolution point, therefore can not directly obtain its analytic solutions, can only be solved by numerical value calculating, be
Quickly the absorption coefficient and Voigt line style halfwidth at core are obtained, use the simplified model as shown in (8),
Wherein, v0For absorption spectra center wave number, Δ vCFor collision broadening line half-width, Δ vDFor dopplerbroadening spectral line half
Width, Δ vVFor Voigt linear function line half-width, can be acquired by empirical equation (9), φv(v0) it is that Voigt linear function is being composed
Value at line centre frequency can be acquired by (10), (11) and (12).
Therefore, when being fitted with simplified absorption spectrum model (7) to absorption spectra data, absorption spectra parameter ParaSpec0
It needs to include A, Δ vC、ΔvDAnd v0Four parameters.
It regard α (v) as initial data, is fitted using absorption spectrum fitting model (7), the fitting ginseng for the spectrum that is absorbed
Number ParaSpec0。
Step 2, using the fitting parameter of the baseline of acquisition and absorption spectrum as initial value, according to absorption light intensity data I
(t) with using baseline fitting parameter ParaBasei-1The base-line data I being calculatedbasefitting(i-1)(t) it is divided by and basis
(6) absorption spectra data α is acquiredi(t)；
Step 3, by absorption spectra data αi(t) with the relative wavenumbers data v (t) of laser, be absorbed spectrum and laser
Relative wavenumbers between mapping αi(v), it absorbs spectrum model (7) to be fitted absorption spectra data, be absorbed spectrum parameter
ParaSpeci；
Step 4, to absorb light intensity data as fit object, according to absorption spectrum parameter ParaSpeciWith relative wavenumbers pair
The mapping v (t) for absorbing light intensity data, is fitted baseline to obtain parameter ParaBasei, and the absorption light intensity data I of fittingi
(t)；
Step 5 judges to absorb light intensity data I (t) and its fitting data Ii(t) residuals squares SiWith with last residual error
The opposite variation of quadratic sum, when variable quantity is greater than 0.1%, return step two, otherwise, the fitting of absorption spectrum after output amendment
Parameter ParaSpeciWith the fitting parameter ParaBase of baselinei；
Step 6 obtains integral absorptivity according to absorption spectrum parameter, is carried out by the integral absorptivity of a plurality of absorption spectra
Resolving obtains tested gas temperature.
The present invention has the advantages that in the present invention by multiplexing Mach once moral fibre optic interferometer as etalon and light intensity tune
Device processed, measurement process only need an optical path, and abbreviation is based on tunable absorption spectroscopy techniques using direct absorption process thermometric
System structure；By multiplexing Mach, once moral fibre optic interferometer is directly being absorbed as etalon and light intensity modulator in the present invention
Intensity modulation has been carried out on the basis of method thermometric, has inhibiting effect to ambient noise to a certain extent；In computation, with
The spectrum parameter and baseline parameter obtained using baseline fitting method carries out fitting result by way of iteration as initial value
Amendment, obtains more accurate spectrum parameter, reduces systematic error.
(4) Detailed description of the invention
Fig. 1 is single-pathway laser absorption spectrum temp measuring system structure chart；
Fig. 2 is that absorption signal changes with time after demodulating；
Fig. 3 is the relationship of relative wavenumbers at any time；
Fig. 4 emulates data and compares the relationship of result before and after iteration.
(5) specific embodiment
In the present embodiment, the measurand gas for giving a uniform temperature, demonstrates this method by numerical simulation
Validity.
The present invention will be further described below with reference to the drawings:
In Fig. 1, semiconductor laser with tunable control module (1), semiconductor laser with tunable (2) collectively constitute sharp
Light generating unit, by optical fiber, once moral fibre optic interferometer (3) is connected with Mach, by collimating mirror (4) by the transmission light in optical fiber
It is transformed into collimated light (directional light), it is right by data acquisition module (7) by photodetector (6) after passing through tested gas (5)
Measurement data is acquired and uploads, and carries out follow-up data by data processing unit (8) and handles to obtain final calculation result.
In simulation process, the environment setting of emulation is as follows, and absorption target is hydrone, molar concentration 0.5%, temperature
298K, pressure 1atm, absorption distance 80cm.The parameter A=B=0.5, v of the Mach used once moral fibre optic interferometerFSR=
0.01cm-1, the center wave number of selected absorption spectra is respectively 7183.89cm-1、7185.59cm-1。
Step 1 occurs module by laser and issues laser, by being become after Mach once moral fibre optic interferometer by collimating mirror
Spatial light passes through region to be measured, receives by detector, obtains absorption signal all the way, signal form such as (1) is shown, system knot
Structure is as shown in Figure 1；
Step 2 according to acquisition data reconstruction relative wavenumbers and absorbs the mapping relations between light intensity data, first to IMZI
(t) signal high-pass filtering, cutoff frequency are laser signal scan frequency；Then, its zero crossing, every two adjacent mistake are recorded
The midpoint of zero point is extreme point position；Relative wavenumbers representated by data point where two extreme points differ a freedom
Spectral region (FSR) our available relative wavenumbers and absorbs the mapping relations v (t) between light intensity data accordingly, as a result such as
Shown in Fig. 2.
Step 3 calculates light intensity absorption data according to detectable signal, firstly, according to relative wavenumbers and absorbing light intensity data
Between mapping relations v (t), be coordinately transformed, obtain as shown in (2)
According to the Free Spectral Range v of Mach-Zehnder interferometerFSR, the form of reference signal can be provided as described in (3) formula
Available absorption light intensity data identical with traditional direct absorption process measuring signal after being demodulated, such as (4)
Shown in formula
I (t)=I0(t)·α(v(t)) (4)
Wherein I0(t) be by laser generate laser signal enter Mach-Zehnder interferometer before light intensity signal, α (v
It (t)) is the absorption spectra of measurand, as a result as shown in Figure 3.
Step 4 is resolved and is corrected to baseline parameter and absorption spectrum parameter by iterative process.Pass through base first
The mode of line fitting obtains the estimated value of the fitting parameter of baseline and absorption spectra, then with the quasi- of the baseline of estimation and absorption spectrum
Parameter is closed as initial value.Wherein, center wave number 7183.89cm-1Spectrum simulation initial parameter value ParaSpec7183-0's
ΔvC、ΔvD, A and v0It is 0.1860,0.1860,0.0113 and 0.0838 respectively, baseline fitting initial parameter value
ParaBase7183-0=[0,0,0.0003,3.9044]；Center wave number is 7185.59cm-1Spectrum simulation initial parameter value
ParaSpec7185-0Δ vC、ΔvD, A and v0It is 0.5162,0.5162,0.0973 and 0.1952 respectively, at the beginning of baseline fitting parameter
Initial value ParaBase7185-0=[0,0,0.0003,3.8880]；
Step 5 starts iterative process, according to absorption light intensity data and uses baseline fitting parameter ParaBaseiIt calculates
To base-line data be divided by and negative logarithm taken to be absorbed spectroscopic data；Later, Voigt function is carried out to absorption spectra data to intend
It closes, be absorbed spectrum parameter ParaSpeci；Secondly, to absorb light intensity data as fit object, according to absorption spectrum parameter
ParaSpeciWith relative wavenumbers to the mapping v (t) for absorbing light intensity data, baseline is fitted to obtain parameter ParaBasei, and
The absorption light intensity data I of fittingi(t)；Finally, judgement absorbs light intensity data I (t) and its fitting data Ii(t) residuals squares Si
The opposite variation with last residual sum of squares (RSS), when variable quantity is greater than 0.1%, return continue the first step of iterative process after
It is continuous to be fitted, otherwise it is assumed that this process has restrained, the fitting parameter ParaSpec of absorption spectrum after output amendmentiAnd baseline
Fitting parameter ParaBasei.Wherein, center wave number 7183.89cm-1Absorption spectrum fitting parameter iteration experienced 186 times,
Spectrum simulation parameter ParaSpec7183-186Δ vC、ΔvD, A and v0It is 0.0117,0.1055,0.0047 and 0.0841 respectively,
Baseline fitting parameter value ParaBase7183-186=[- 1.0848e-14,2.1269e-10,0.0003,3.8971], center wave number
For 7185.59cm-1Absorption spectrum fitting parameter iteration experienced 290 times, spectrum simulation parameter value ParaSpec7185-290Δ
vC、ΔvD, A and v0It is 0.0716,0.1928,0.0240 and 0.1980 respectively, baseline fitting parameter value ParaBase7185-290=
[-6.10e-15,9.21e-11,2.95e-4,3.8837]；
Integral absorptivity is obtained according to absorption spectrum parameter, is resolved to obtain by the integral absorptivity of a plurality of absorption spectra
Tested gas temperature, the absorption spectra initial value resolved and the comparison by the absorption spectra after iterated revision are as shown in Figure 4.If
Determining temperature is 298K, and resolving temperature is 299.9K.
Above to the description of the present invention and embodiments thereof, it is not limited to which this, is only reality of the invention shown in attached drawing
Apply one of mode.Without departing from the spirit of the invention, it without creating designs similar with the technical solution
Structure or embodiment, the category scope of the present invention.
Claims (3)
1. laser absorption spectrum temp measuring method and system based on interference modulations principle, including laser generating unit, Mach Zeng De
Fibre optic interferometer, photoelectric detection unit and data processing unit etc., which is characterized in that laser signal passes through after being generated by generation module
Crossing Mach, once moral fibre optic interferometer completes intensity modulated, acquires data by photoelectric detection unit after measurand, and by its
It is uploaded to data processing unit, in data handling procedure, is calculated respectively by acquisition data and absorb light intensity data and opposite wave
Number absorb light intensity data between mapping relations, then by way of fitting according to absorb light intensity data in approximation without absorption
Part calculate the estimated value of baseline parameter, resolve to obtain and absorb according to relative wavenumbers and the mapping relations for absorbing between light intensity data
The estimated value of spectrum parameter, and the estimated value of baseline and absorption spectrum parameter being modified by way of iteration, according to repairing
Absorption spectrum parameter after just obtains corresponding integral absorptivity of the spectral line under measured target environment, integrates and inhales in conjunction with a plurality of spectral line
Yield calculates the temperature value of tested gas.
2. the laser absorption spectrum temp measuring method and system according to claim 1 based on interference modulations principle, feature
It is: calculates and outputs laser relative wavenumbers data and absorption light intensity data respectively by acquiring data, include the following steps,
The laser signal that module generates occurs for step 1, laser first pass around Mach-Zehnder interferometer and obtain intensity modulation wavelength to sweep
The measuring signal retouched then passes through measurand, is finally acquired by photodetector, acquires signal form such as formula in principle
(1) shown in,
Wherein, IMZIIt (t) is that photodetector collects the measurement data changed over time, I0It (t) is swashing by laser generation
Optical signal is without the light intensity data before Mach-Zehnder interferometer and measurand, vFSRIt is the Free Spectral Range of interferometer
(FSR, Free spectral range), A, B, φ0Be by the Mach parameter that once moral fibre optic interferometer self structure determines, when
These parameters are constant when the interferometer used is fixed, and v (t) is output laser relative wavenumbers data, and α (v (t)) is tested pair
The absorption spectra of elephant；；
Step 2 by Mach-Zehnder interferometer and is tested according to acquisition data calculation output laser relative wavenumbers data v (t)
The laser signal of object is as shown in (1) formula, and laser relative wavenumbers data can resolve to obtain by light intensity data, in laser signal
For intensity twice between extreme point, wave number variation is a Free Spectral Range；In order to more accurate under limited sampling number
Extract extreme point position, extract relative wavenumbers data when with the following method, to IMZI(t) signal carries out high-pass filtering, section
Only frequency is laser signal scan frequency；Record the zero crossing of filtered signal, the midpoint of every two adjacent zero crossing
As extreme point position；Relative wavenumbers representated by data point where two extreme points differ a Free Spectral Range, thus
The relative wavenumbers data v (t) of data laser can be obtained；
Step 3 demodulates acquisition data, and be absorbed light intensity data: the relative wavenumbers data v (t) of laser is substituted into
(1), the mapping relations of relative wavenumbers v and measurement data, such as (2) formula are obtained
According to the Free Spectral Range v of Mach-Zehnder interferometerFSR, the signal as described in (3) formula can be provided
By (2) (3) simultaneous, available absorption light intensity data I (t) after quadrature demodulation is carried out, as shown in (4) formula
Wherein I0(t) be by laser generate laser signal enter Mach-Zehnder interferometer before light intensity signal, Ibase(t)
It is and I0(t) directly proportional signal is in data processing base-line data ideally, and α (v (t)) is tested pair
The absorption spectra of elephant.
3. the laser absorption spectrum temp measuring method and system according to claim 1 based on interference modulations principle, feature
Be: solution process obtains baseline parameter and absorption spectrum parameter by way of fitting, and passes through iterated revision fitting result,
And then the temperature value of tested gas is calculated, solution process includes the following steps,
Step 1 estimates the fitting parameter of baseline, using three times according to light intensity data is absorbed by way of least square fitting
Multinomial is fitted baseline, obtains the fitting parameter group ParaBase of baseline0, the model used is such as shown in (5)
Wherein, fitting parameter group ParaBase0For the polynomial parameters of fitting.Then, it is absorbed rate based on Bill's Lambert law
Data α (t), such as shown in (6)
The relative wavenumbers data v (t) of laser is substituted into, be absorbed modal data α (v), and is fitted on this basis, use
Model such as (7) is shown,
Wherein, A is the integral absorptivity of absorption spectra, φvIt (v) is Voigt line style spread function.Since Voigt linear function calculates
Calculating comprising convolution point, therefore its analytic solutions can not be directly obtained, it can only be solved by numerical value calculating, in order to quick
The absorption coefficient and Voigt line style halfwidth at core are obtained, the simplified model as shown in (8) is used,
Wherein, v0For absorption spectra center wave number, Δ vCFor collision broadening line half-width, Δ vDFor dopplerbroadening line half-width, Δ
vVFor Voigt linear function line half-width, can be acquired by empirical equation (9), φv(v0) it is Voigt linear function in core
Value at frequency can be acquired by (10), (11) and (12).
Therefore, when being fitted with simplified absorption spectrum model (7) to absorption spectra data, absorption spectra parameter ParaSpec0It needs to wrap
Include A, Δ vC、ΔvDAnd v0Four parameters.
It regard α (v) as initial data, is fitted using absorption spectrum fitting model (7), the fitting parameter for the spectrum that is absorbed
ParaSpec0。
Step 2, using the fitting parameter of the baseline of acquisition and absorption spectrum as initial value, according to absorb light intensity data I (t) with
Use the fitting parameter ParaBase of baselinei-1The base-line data I being calculatedbasefitting(i-1)(t) it is divided by and is asked according to (6)
Obtain absorption spectra data αi(t)；
Step 3, by absorption spectra data αi(t) and the relative wavenumbers data v (t) of laser, the phase of be absorbed spectrum and laser
To the mapping α between wave numberi(v), it absorbs spectrum model (7) to be fitted absorption spectra data, be absorbed spectrum parameter
ParaSpeci；
Step 4, to absorb light intensity data as fit object, according to absorption spectrum parameter ParaSpeciWith relative wavenumbers to absorption
The mapping v (t) of light intensity data is fitted baseline to obtain parameter ParaBasei, and the absorption light intensity data I of fittingi(t)；
Step 5 judges to absorb light intensity data I (t) and its fitting data Ii(t) residuals squares SiWith with last residuals squares
The opposite variation of sum, when variable quantity is greater than 0.1%, return step two, otherwise, the fitting parameter of absorption spectrum after output amendment
ParaSpeciWith the fitting parameter ParaBase of baselinei；
Step 6 obtains integral absorptivity according to absorption spectrum parameter, is resolved by the integral absorptivity of a plurality of absorption spectra
Obtain tested gas temperature.
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| CN112798550A (en) * | 2021-04-14 | 2021-05-14 | 四川大学 | Wide-measurement-range laser absorption spectrum combustion diagnosis method |
| CN113176222A (en) * | 2021-06-09 | 2021-07-27 | 复旦大学 | Gas concentration inversion method based on direct absorption spectrum |
| CN113252204A (en) * | 2021-04-01 | 2021-08-13 | 北京航空航天大学 | Laser absorption spectrum temperature measurement method based on amplitude modulation |
| CN113358160A (en) * | 2021-07-08 | 2021-09-07 | 天津大学 | Atmospheric data measuring method and system |
| CN113390826A (en) * | 2021-05-28 | 2021-09-14 | 中国科学院力学研究所 | Integral absorbance measurement error estimation method for sight line non-uniform absorption spectrum measurement |
| CN114993987A (en) * | 2022-05-16 | 2022-09-02 | 北京航空航天大学 | Temperature and gas concentration measuring method and system based on absorption spectrum amplitude modulation |
| CN117747008A (en) * | 2024-02-07 | 2024-03-22 | 山东省科学院激光研究所 | Baseline fitting and noise reduction method and system for gas laser absorption spectrum |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102680020A (en) * | 2012-05-16 | 2012-09-19 | 清华大学 | Gas parameter online measurement method based on wavelength modulation spectroscopy |
| CN103557886A (en) * | 2013-10-29 | 2014-02-05 | 东南大学 | Method for simultaneously measuring distribution of high-temperature gas two-dimensional transient temperature field and concentration field based on hyper spectrum |
| JP2014085301A (en) * | 2012-10-26 | 2014-05-12 | Nippon Telegr & Teleph Corp <Ntt> | Light intensity measurement device for wavelength sweeping light source |
| US20170212366A1 (en) * | 2016-01-21 | 2017-07-27 | Sumitomo Electric Industries, Ltd. | Optical transceiver implementing erbium doped fiber amplifier |
| CN107219190A (en) * | 2017-05-05 | 2017-09-29 | 东南大学 | A kind of non-calibrating gas parameter measuring method based on triangular modulation |
-
2018
- 2018-10-24 CN CN201811235909.XA patent/CN108981953B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102680020A (en) * | 2012-05-16 | 2012-09-19 | 清华大学 | Gas parameter online measurement method based on wavelength modulation spectroscopy |
| JP2014085301A (en) * | 2012-10-26 | 2014-05-12 | Nippon Telegr & Teleph Corp <Ntt> | Light intensity measurement device for wavelength sweeping light source |
| CN103557886A (en) * | 2013-10-29 | 2014-02-05 | 东南大学 | Method for simultaneously measuring distribution of high-temperature gas two-dimensional transient temperature field and concentration field based on hyper spectrum |
| US20170212366A1 (en) * | 2016-01-21 | 2017-07-27 | Sumitomo Electric Industries, Ltd. | Optical transceiver implementing erbium doped fiber amplifier |
| CN107219190A (en) * | 2017-05-05 | 2017-09-29 | 东南大学 | A kind of non-calibrating gas parameter measuring method based on triangular modulation |
Non-Patent Citations (4)
| Title |
|---|
| ALEXANDER KLEIN 等: "Rapid, Time-Division Multiplexed, Direct Absorption- and Wavelength Modulation-Spectroscopy", 《SENSORS》 * |
| 杨阳 等: "基于波长调制谐波信号主峰拟合的气体浓度测量方法", 《北京航空航天大学学报》 * |
| 王广宇 等: "二极管激光吸收传感器测量超声速流场的温度和速度", 《光学学报》 * |
| 陈亚婧 等: "多谱线 TDLAS 测温中谱线选择的实验研究", 《电子测量与仪器学报》 * |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110031198B (en) * | 2019-04-25 | 2020-11-10 | 上海工程技术大学 | Energy-considered strain load spectrum compiling method |
| CN110031198A (en) * | 2019-04-25 | 2019-07-19 | 上海工程技术大学 | A kind of alternating load spectrum preparation method considering energy |
| CN111239072A (en) * | 2019-11-25 | 2020-06-05 | 中国航空工业集团公司北京长城计量测试技术研究所 | Method for accurately measuring temperature of combustion gas |
| CN113252204A (en) * | 2021-04-01 | 2021-08-13 | 北京航空航天大学 | Laser absorption spectrum temperature measurement method based on amplitude modulation |
| CN112798550A (en) * | 2021-04-14 | 2021-05-14 | 四川大学 | Wide-measurement-range laser absorption spectrum combustion diagnosis method |
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| CN113176222A (en) * | 2021-06-09 | 2021-07-27 | 复旦大学 | Gas concentration inversion method based on direct absorption spectrum |
| CN113358160A (en) * | 2021-07-08 | 2021-09-07 | 天津大学 | Atmospheric data measuring method and system |
| CN113358160B (en) * | 2021-07-08 | 2022-05-17 | 天津大学 | Atmospheric data measuring method and system |
| CN114993987A (en) * | 2022-05-16 | 2022-09-02 | 北京航空航天大学 | Temperature and gas concentration measuring method and system based on absorption spectrum amplitude modulation |
| CN114993987B (en) * | 2022-05-16 | 2024-04-30 | 北京航空航天大学 | Temperature and gas concentration measuring method and system based on absorption spectrum amplitude modulation |
| CN117747008A (en) * | 2024-02-07 | 2024-03-22 | 山东省科学院激光研究所 | Baseline fitting and noise reduction method and system for gas laser absorption spectrum |
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