CN109100325A - A kind of gas concentration measuring method based on spectral absorption second harmonic feature extraction - Google Patents

A kind of gas concentration measuring method based on spectral absorption second harmonic feature extraction Download PDF

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CN109100325A
CN109100325A CN201810618427.6A CN201810618427A CN109100325A CN 109100325 A CN109100325 A CN 109100325A CN 201810618427 A CN201810618427 A CN 201810618427A CN 109100325 A CN109100325 A CN 109100325A
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周宾
王红
王一红
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Southeast University
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    • 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
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Abstract

本发明公开了一种基于光谱吸收率二次谐波特征提取的气体浓度测量方法，该方法通过建立适合于任意调制系数下的考虑福伊特线型的光谱吸收率二次谐波峰高‑峰宽特征关系，实现了利用谐波特征计算积分吸光度，从而获得气体参数信息；同时在该方法实施过程中采用对数处理技术，直接消除了剩余幅度调制对谐波信号畸变的影响，提高了测量精度；本发明测量方法无需进行复杂的最小二乘迭代拟合计算且只需要进行一次滤波处理，降低了对硬件系统的要求；在无法获得完整谐波信号时仍可较精确的提取波形特征点信息，测量下限更低；无需利用数据库中自展宽系数、各种其他组分的碰撞展宽系数、温度依赖指数等过多的参数，减小对数据库参数的依赖性，应用范围更广。

The invention discloses a gas concentration measurement method based on the second harmonic feature extraction of spectral absorptivity. The method establishes the peak height of the second harmonic of spectral absorptivity considering the Voith line shape under any modulation coefficient. The characteristic relationship of peak width realizes the calculation of integral absorbance by using harmonic characteristics, so as to obtain gas parameter information; at the same time, logarithmic processing technology is used in the implementation process of this method, which directly eliminates the influence of residual amplitude modulation on harmonic signal distortion, and improves the Measurement accuracy; the measurement method of the present invention does not need to perform complex least squares iterative fitting calculations and only needs to perform one filtering process, which reduces the requirements for the hardware system; when the complete harmonic signal cannot be obtained, the waveform features can still be extracted more accurately point information, the lower measurement limit is lower; there is no need to use too many parameters in the database such as self-broadening coefficient, collision broadening coefficient of various other components, temperature dependence index, etc., reducing the dependence on database parameters and wider application range.

Description

A kind of gas concentration measuring method based on spectral absorption second harmonic feature extraction
Technical field
The present invention relates to a kind of gas concentration measuring methods based on spectral absorption second harmonic feature extraction, belong to sharp Optical absorption spectra technical field.
Background technique
Tunable diode laser absorption spectroscopy techniques (tunable diode laser absorption Spectroscopy, TDLAS) because the multi-parameters on-line measurement such as concentration of component, temperature, pressure and speed may be implemented, And has the characteristics that highly sensitive, Fast Time Response and non-contact, have in detection and the combustion diagnosis field of trace gas Wide application prospect.
In order to reduce influence of the noise to measurement result, signal-to-noise ratio is improved, frequently with wavelength tune on signal detecting method Spectrum (WMS) method processed, wherein second-harmonic detection is the most commonly used.Frequency-modulated spectroscopy is when actual quantification measures, measurement As a result it generally requires to demarcate by calibrating gas, however due to the component of under test gas in actual field environment and calibrating gas Component is different, and may change at any time, and the gas concentration measurement obtained completely according to calibration mode can have certain mistake Difference.In order to solve this problem, researcher has developed a series of non-calibrating WMS methods, and main includes being based on Hitran number According to the harmonic analysis method of library emulation and WMS-2f/1f waveform fitting etc..However the harmonic wave point based on the emulation of Hitran database Analysis method needs accurate line parameters (for example, collision broadening coefficient, the temperature-independent from ceofficient of spread, various other components refer to Number etc.) and laser modulation characterisitic parameter, measurement result be affected by line parameters.WMS-2f/1f waveform fitting method It without more line parameters, is widely used in the measurement of gas parameter in recent years, however this method needs to carry out greatly The iterative fitting of amount calculates, and needs to carry out the filtering processing of multiple harmonic, and calculation amount is larger, to hardware and fitting algorithm requirement It is higher.More seriously when absorption is weaker or measurement environment is more severe, influenced by background variation and residual amplitude modulation, Harmonic wave form signal is obtained it is difficult to extract complete, WMS-2f/1f waveform fitting method can not be applied at this time.On the other hand, due to humorous The information being richly stored in wave signal line style about spectral absorption also can extract light from the wave character of harmonic signal Spectrum absorptivity is to realize the measurement of gas parameter.However existing waveshape feature abstraction spectral absorption method is often only applicable in Frequency analysis under the small index of modulation or lorentzian curve, measurement noise is relatively low, and application range is limited.Therefore, develop A kind of signal-to-noise ratio is high, and independent of spectral line data library parameter, and the non-calibrating WMS method being suitable under any index of modulation is especially It is important.
Summary of the invention
Technical problem to be solved by the invention is to provide a kind of gas based on spectral absorption second harmonic feature extraction Bulk concentration measurement method, the gas concentration measuring method signal-to-noise ratio is high, independent of spectral line data library parameter, and is suitable for any The gas concentration measurement of non-calibrating Wavelength modulation spectroscopy under the index of modulation.
In order to solve the above technical problems, the technical scheme adopted by the invention is as follows:
A kind of gas concentration measuring method based on spectral absorption second harmonic feature extraction, the measurement method include with Lower step:
Step 1, laser modulates optical maser wavelength, photodetector while scanning absorption line with high frequency sinusoidal signal The background light intensity signal I of no absorption is measured respectively0With the transmitted light intensity signal I for having absorptiont；
Step 2, interference peak-to-peak signal of the measurement laser after solid etalon, and freely composing according to the solid etalon Time domain light intensity signal is converted into frequency domain light intensity signal by spacing FSR, to obtain the variation relation V of laser scanning relative wavenumbers (t) and the size a of modulation depth；
Step 3, transmitted light intensity signal I measurement obtainedtWith background light intensity signal I0Logarithm process is carried out, spectrum is obtained Absorptivity signal alpha (v)；
Step 4, locking phase filtering processing is carried out to spectral absorption signal alpha (v), obtains its corresponding second harmonic signal Hα；
Step 5, second harmonic signal H is calculated using peak-seeking algorithmαCenter peak heightsCombining laser scanning phase Second harmonic signal H is calculated to the variation relation V (t) of wave numberαIn the secondary lobe width Λ of frequency domain；
Step 6, it establishes under any index of modulation, the corresponding second harmonic signal H of spectral absorption α (v)αCenter peak height DegreeAnd secondary lobe width Λ and integrated absorbance A and absorption line Lorentz broadening λLRelationship；
Step 7, absorption line Lorentz broadening λ is initializedL=λL0, it is absorbed spectral line according to known temperature computation Gauss broadens λG, in conjunction with the modulation depth a that measurement obtains, theoretical secondary lobe width Λ is calculated0；
Step 8, the theoretical secondary lobe width Λ that the secondary lobe width Λ and step 7 that judgment step 5 obtains are obtained0Whether meet with The lower condition of convergence:
In formula, s is preset convergence threshold；
If satisfied, the Lorentz broadening λ for the spectral line that is then absorbedL=λL0, the harmonic wave center peak heights that are obtained in conjunction with step 5Integrated absorbance A is calculated, integrated absorbance A calculation formula is as follows:
If not satisfied, then updating λL0=λnew, return step 7；Wherein, λnewIt is the new of used optimization algorithm generation Value, optimization algorithm can be randomly selected from algorithmic function each in MATLAB, and the function selected can generate a random new value；
Step 9, the concentration value of gas, the calculating of gas concentration value are calculated according to the integrated absorbance A being calculated Formula is as follows:
In formula, P is gas stagnation pressure, and S (T) is that the spectral line line under temperature T is strong, and L is to absorb optical length.
Wherein, in step 3, the expression formula of logarithm process are as follows:
α (v)=- ln (It/I0)=A φ (v)
In formula: ItAnd I0Respectively laser transmitted light intensity and laser light incident light intensity；A is integrated absorbance；φ (v) is line style Function.
Wherein, linear function φ (v) is the convolution of lorentzian curve function and Gaussian lineshape function, using Fu Yite line style Function description, approximate expression are as follows:
φ (v)=cLφL(v)+cGφG(v)
In formula: φLAnd φGRespectively lorentzian curve function and Gaussian lineshape function；cLAnd cGRespectively Lorentz broadening λLλ is broadened with GaussGWeight coefficient；v0For laser line centre frequency；λ is the full width at half maximum of absorption line；cL、cGWith λ's Calculation formula is as follows:
D=(λL-λG)/(λL+λG)
cL=0.6818817+0.6129331d-0.1838439d2-0.1156844d3
cG=0.3246017-0.6182531d+0.1768139d2+0.1210944d3
Second harmonic central peak height and secondary lobe small peak are extracted in the width of frequency domain as characteristic quantity, and establishes and is suitable for Under any index of modulation, the corresponding second harmonic signal H of spectral absorption α (v)αCenter peak heights and secondary lobe width Λ with Integrated absorbance A and absorption line Lorentz broadening λLRelationship；
Wherein, the corresponding second harmonic signal H of spectral absorption α (v)αCenter peak heightsWith integrated absorbance A and Absorption line Lorentz broadening λLRelational expression are as follows:
In formula, I1For 1 rank modified Bessel function of the first kind, parameter m, cL、cGCalculation formula it is as follows:
D=(λL-λG)/(λL+λG)
cL=0.6818817+0.6129331d-0.1838439d2-0.1156844d3
cG=0.3246017-0.6182531d+0.1768139d2+0.1210944d3
M=2a/ λ；
Wherein, the corresponding second harmonic signal H of spectral absorption α (v)αSecondary lobe width Λ and integrated absorbance A and suction Receive spectral line Lorentz broadening λLRelational expression are as follows:
In formula, r=cG/cL, p1=1.966194179, p2=0.390933340, p3=3.093996758, p4= 0.388999538, p5=0.806546476, p6=-0.289132222, p7=-1.775513203, p8=0.017671096, p9=1.041510614, p10=-0.146221523, p11=-1.073806845.
Wherein, in step 9, the strong S of spectral line line (T) is varied with temperature and is indicated using following formula:
In formula, h is Planck constant, and h is the light velocity in vacuum, and k is Boltzmann constant, and E is low-level energy, T0= 296K is reference temperature, v0For core frequency, the calculation method of partition function value when Q (T) is temperature T, E and Q (T) is logical Inquiry HITRAN2016 database is crossed to obtain.
The utility model has the advantages that the spectral absorption that this method is suitable for the consideration Voigt line style under any index of modulation is secondary Harmonic wave peak height-peak width feature extraction, while logarithm process technology is used, measuring signal is handled, has been reached and WMS-2f/ 1f the same light intensity normalizes effect, and the result that logarithm process obtains is unrelated with laser intensity modulation parameter, directly eliminates The influence that residual amplitude modulation distorts to harmonic signal, improves measurement accuracy；Measurement method of the present invention and WMS-2f/1f wave Shape approximating method is compared, and without carrying out complicated least-squares iteration the Fitting Calculation and only needing once to be filtered, is dropped The low requirement to hardware system, and wave character point information still can be accurately extracted when complete harmonic signal can not be obtained, it surveys It is lower to measure lower limit；Without using in database from ceofficient of spread, the collision broadening coefficient of various other components, temperature-independent index Etc. excessive parameter, reduce the dependence to database parameter, application range is wider.
Detailed description of the invention
Fig. 1 is the flow chart of gas concentration measuring method of the present invention；
The comparison for the harmonic wave that Fig. 2 obtains for the fitting result of WMS-2f/1f waveform fitting method with measurement method of the present invention Figure；
Fig. 3 is that difference is matched under gas concentration, the concentration measurement figure of two kinds of gas concentration measuring methods；
Fig. 4 is different under gas concentration, and the relative error of two kinds of gas concentration measuring method measurements compares.
Specific embodiment
Technical scheme of the present invention is further explained with reference to the accompanying drawing.
Fig. 1 is the flow chart of measurement method of the present invention, as shown in Figure 1, the present invention is based on spectral absorption second harmonic spies The gas concentration measuring method extracted is levied, is specifically comprised the following steps:
Step 1, the background light intensity signal I of no absorption is measured respectively0With the transmitted light intensity signal I for having absorptiont:
Laser modulates optical maser wavelength while scanning absorption line with high frequency sinusoidal signal, and photodetector is surveyed respectively Measure the background light intensity signal I without absorption0With the transmitted light intensity signal I for having absorptiont；
Step 2, measurement laser goes out the relationship between frequency and time of light:
Interference peak-to-peak signal of the laser after solid etalon is measured, and spacing is freely composed according to the solid etalon Time domain light intensity signal is converted into frequency domain light intensity signal by FSR, thus obtain laser scanning relative wavenumbers variation relation V (t) and The size a of modulation depth；
Step 3, spectral absorption α (v) is calculated:
The transmitted light intensity signal I that measurement is obtainedtWith background light intensity signal I0Logarithm process is carried out, spectral absorption is obtained Signal alpha (v)=- ln (It/I0)=A φ (v)；
Step 4, analysis obtains the second harmonic signal H of spectral absorption signalα:
Spectral absorption signal alpha (v) is handled using digital servo-control process, obtains the x-component and y comprising second harmonic signal Component:
x2f=α (v) cos (4 π fmt) y2f=α (v) sin (4 π fmt)
In formula, fmFor modulating frequency, x2f、y2fIt is the corresponding x-component of spectral absorption signal alpha (v), y-component respectively；
Then low-pass filtered device extracts the second harmonic X-component and Y-component of each signal:
X2f=lowpass filter (x2f) Y2f=lowpass filter (y2f)
The second harmonic of spectral absorption signal alpha (v) is shown below；
Step 5, analysis obtains spectral absorption signal second harmonic signal HαCenter peak heights and secondary lobe width:
Second harmonic signal H is calculated using peak-seeking algorithmαCenter peak heightsCombining laser scanning relative wavenumbers Variation relation V (t) second harmonic signal H is calculatedαIn the secondary lobe width Λ of frequency domain；
Step 6, it establishes under any index of modulation, the corresponding second harmonic signal H of spectral absorption α (v)αCenter peak height DegreeAnd secondary lobe width Λ and integrated absorbance A and absorption line Lorentz broadening λLRelationship:
The corresponding second harmonic signal H of spectral absorption α (v)αCenter peak heightsWith integrated absorbance A and absorption spectra Line Lorentz broadening λLRelationship expression formula are as follows:
In formula, I1For 1 rank modified Bessel function of the first kind, parameter m, cL、cGCalculation formula it is as follows:
D=(λL-λG)/(λL+λG)
cL=0.6818817+0.6129331d-0.1838439d2-0.1156844d3
cG=0.3246017-0.6182531d+0.1768139d2+0.1210944d3
M=2a/ λ
The corresponding second harmonic signal H of spectral absorption α (v)αSecondary lobe width Λ and integrated absorbance A and absorption line Lorentz broadening λLRelationship expression formula are as follows:
R=c in formulaG/cL, parameter pi(i=1,2 ..., value 11) it is as shown in table 1:
1 parameter p of tableiValue
Step 7, harmonic wave secondary lobe width theoretical value Λ is calculated0:
Firstly the need of initialization absorption line Lorentz broadening λL=λL0；
λ is broadened according to the Gauss that absorption line can be calculated in known temperatureG, calculation formula is as follows:
λG=7.1623 × 10-7v0(T/M)1/2
In formula, M is the molal weight of under test gas；
In conjunction with the modulation depth a that measurement obtains, and utilize the corresponding second harmonic of spectral absorption α (v) of step 6 foundation Signal HαSecondary lobe width Λ and integrated absorbance A and absorption line Lorentz broadening λLRelationship theoretical harmonic wave can be calculated Secondary lobe width Λ0；
Step 8, the theoretical secondary lobe width Λ that the secondary lobe width Λ and step 7 that judgment step 5 obtains are obtained0Whether meet with The lower condition of convergence:
In formula, ε is preset convergence threshold；
If satisfied, the Lorentz broadening λ for the spectral line that is then absorbedL=λL0, the harmonic wave center peak heights that are obtained in conjunction with step 5Integrated absorbance A can be calculated, integrated absorbance A calculation formula is as follows:
If not satisfied, then updating λL0=λnew, return step 7；Wherein, λnewIt is the new of used optimization algorithm generation Value, optimization algorithm can arbitrarily be chosen from algorithmic function each in MATLAB, and the function selected can generate a random new value.
Step 9, gas concentration value is calculated:
It can be calculated as follows to obtain gas concentration value according to integrated absorbance A:
In formula, P is gas stagnation pressure, and S (T) is that the spectral line line under temperature T is strong, and L is to absorb optical length.
Absorption line strengths S (T) variation with temperature can indicate are as follows:
In formula, h is Planck constant, and h is the light velocity in vacuum, and k is Boltzmann constant, and E is low-level energy, T0= 296K is reference temperature, v0For core frequency, the calculation method of partition function value when Q (T) is temperature T, E and Q (T) can To be found in HITRAN2016 database.
Embodiment 1
Below with CH4Molecule 6046.95cm-4Spectral line carries out CH4The measurement of volumetric concentration, CH4Be respectively as follows: with gas concentration 2.10×10-2、1.57×10-2、1.05×10-2、5.28×10-3、2.08×10-3、1.10×10-3、5.01×10-4、2.54 ×10-4.Harmonic wave comparison result such as Fig. 2 that the fitting result of WMS-2f/1f waveform fitting method and measurement method of the present invention obtain It is shown.As shown in Figure 2, work as CH4(> 1.10 × 10 when volumetric concentration is higher-3), WMS-2f/1f waveform is complete and regression criterion compared with It is small.But with CH4Volumetric concentration reduces, and measurement signal-to-noise ratio reduction causes WMS-2f/1f waveform that obvious distortion occurs, at this time WMS- 2f/1f waveform fitting method is unsuitable to be used to calculate CH4Volumetric concentration.It is different from WMS-2f/1f waveform fitting method, this Invention does not need complete shape information based on spectral absorption second harmonic feature extracting method, it is only necessary to extract second harmonic Signal HαCentral peak height and the characteristic informations such as harmonic wave width.Actually due to HαThe noise of harmonic wave at centre-height Than highest, and other peak heights are to HαThe influence of width is little, therefore method proposed by the present invention has higher signal-to-noise ratio.Even if Work as CH4Volumetric concentration is 2.54 × 10-4When, HαHarmonic wave still has obvious peak height-peak width feature.Different CH4With gas concentration Under, two methods measurement of concetration surveys result as shown in figs. 34.Work as CH4Volumetric concentration is greater than 2.08 × 10-3When, two methods are surveyed Amount relative deviation is respectively less than 2%, (the < 1.10 × 10 when concentration further decreases-3), with measurement signal-to-noise ratio reduction, two kinds The measured deviation of method all becomes larger, but the measurement result of harmonic characteristic extracting method of the present invention is closer to gas concentration.
As can be seen that using method proposed by the present invention without carrying out complicated least-squares iteration the Fitting Calculation and only needing It is once filtered, reduces the requirement to hardware system；It still can be accurate when complete harmonic signal can not be obtained Wave character point information is extracted, measurement lower limit is lower；Without using in database from ceofficient of spread, the collision of various other components The excessive parameters such as ceofficient of spread, temperature-independent index, reduce the dependence to database parameter, and application range is wider.Measurement As a result more accurate, compared with WMS-2f/1f waveform fitting method, the present invention proposes that the calculated result of method is more credible.

Claims (6)

1.一种基于光谱吸收率二次谐波特征提取的气体浓度测量方法，其特征在于，该测量方法包括以下步骤：1. A gas concentration measurement method based on spectral absorptance second harmonic feature extraction, characterized in that the measurement method may further comprise the steps: 步骤1，激光器在扫描吸收谱线的同时以高频正弦信号调制激光波长，光电探测器分别测量无吸收的背景光强信号I0和有吸收的透射光强信号It；Step 1, the laser modulates the laser wavelength with a high-frequency sinusoidal signal while scanning the absorption line, and the photodetector measures the background light intensity signal I 0 without absorption and the transmitted light intensity signal I t with absorption; 步骤2，测量激光经过固体标准具后的干涉峰信号，并根据该固体标准具的自由谱间距FSR，将时域光强信号转换成频域光强信号，从而得到激光扫描相对波数的变化关系V(t)和调制深度的大小a；Step 2: Measure the interference peak signal after the laser passes through the solid etalon, and convert the light intensity signal in the time domain into the light intensity signal in the frequency domain according to the free spectral spacing FSR of the solid etalon, so as to obtain the change relationship of the relative wave number of the laser scanning V(t) and the magnitude a of the modulation depth; 步骤3，对测量得到的透射光强信号It与背景光强信号I0进行对数处理，得到光谱吸收率信号α(v)；Step 3, logarithmic processing is carried out to the measured transmitted light intensity signal I t and the background light intensity signal I 0 to obtain the spectral absorptance signal α(v); 步骤4，对光谱吸收率信号α(v)进行锁相滤波处理，得到其对应的二次谐波信号Hα；Step 4, performing phase-locked filtering on the spectral absorptance signal α(v) to obtain its corresponding second harmonic signal H α ; 步骤5，利用寻峰算法计算得到二次谐波信号Hα的中心峰高度结合激光扫描相对波数的变化关系V(t)计算得到二次谐波信号Hα在频域的旁瓣宽度Λ；Step 5, using the peak-finding algorithm to calculate the central peak height of the second harmonic signal H α The sidelobe width Λ of the second harmonic signal H α in the frequency domain is calculated by combining the change relationship V(t) of the relative wave number of the laser scanning; 步骤6，建立任意调制系数下，光谱吸收率α(v)对应的二次谐波信号Hα的中心峰高度及旁瓣宽度Λ与积分吸光度A和吸收谱线洛伦兹展宽λL的关系；Step 6, establish the central peak height of the second harmonic signal H α corresponding to the spectral absorptivity α(v) under any modulation coefficient And the relationship between side lobe width Λ and integrated absorbance A and absorption line Lorentz broadening λ L ; 步骤7，初始化吸收谱线洛伦兹展宽λL＝λL0，根据已知的温度计算得到吸收谱线的高斯展宽λG，结合测量得到的调制深度a，计算得到理论旁瓣宽度Λ0；Step 7, initialize the Lorentz broadening of the absorption line λ L = λ L0 , calculate the Gaussian broadening λ G of the absorption line according to the known temperature, and calculate the theoretical sidelobe width Λ 0 in combination with the measured modulation depth a; 步骤8，判断步骤5得到的旁瓣宽度Λ和步骤7得到的理论旁瓣宽度Λ0是否满足以下收敛条件：Step 8, whether the theoretical side lobe width Λ obtained by judging the side lobe width Λ that step 5 obtains and step 7 satisfies the following convergence conditions: 式中，ε为预先设定的收敛阈值；In the formula, ε is the preset convergence threshold; 若满足，则得到吸收谱线的洛伦兹展宽λL＝λL0，结合步骤5得到的谐波中心峰高度计算出积分吸光度A，积分吸光度A计算公式如下：If it is satisfied, the Lorentz broadening of the absorption line λ L =λ L0 is obtained, combined with the harmonic center peak height obtained in step 5 Calculate the integral absorbance A, and the calculation formula of the integral absorbance A is as follows: 若不满足，则更新λL0＝λnew，返回步骤7；其中，λnew是所采用的优化算法产生的新值，优化算法可从MATLAB中各算法函数中随机选取，选出的函数会产生一个随机的新值；If not satisfied, update λ L0 = λ new and return to step 7; wherein, λ new is the new value generated by the optimization algorithm adopted, the optimization algorithm can be randomly selected from each algorithm function in MATLAB, and the selected function will generate a random new value; 步骤9，根据计算得到的积分吸光度A计算得到气体的浓度值，气体浓度值的计算公式如下：Step 9, calculate the concentration value of the gas according to the calculated integral absorbance A, the calculation formula of the gas concentration value is as follows: 式中，P为气体总压，S(T)为温度T下的谱线线强，L为吸收光程长。In the formula, P is the total gas pressure, S(T) is the spectral line intensity at temperature T, and L is the absorption path length. 2.根据权利要求1所述的基于光谱吸收率二次谐波特征提取的气体浓度测量方法，其特征在于：步骤3中，对数处理的表达式为：2. the gas concentration measuring method based on spectral absorptivity second harmonic feature extraction according to claim 1, is characterized in that: in step 3, the expression of logarithmic processing is: α(v)＝-ln(It/I0)＝Aφ(v)α(v)=-ln(I t /I 0 )=Aφ(v) 式中：It和I0分别为激光透射光强和激光入射光强；A为积分吸光度；φ(v)为线型函数。In the formula: I t and I 0 are the laser transmitted light intensity and laser incident light intensity, respectively; A is the integral absorbance; φ(v) is a linear function. 3.根据权利要求2所述的基于光谱吸收率二次谐波特征提取的气体浓度测量方法，其特征在于：线型函数φ(v)是洛伦兹线型函数和高斯线型函数的卷积，采用福伊特线型函数描述，其近似表达式如下：3. the gas concentration measuring method based on spectral absorptivity second harmonic feature extraction according to claim 2, is characterized in that: linear function φ (v) is the volume of Lorentz linear function and Gaussian linear function The product is described by the Voith linear function, and its approximate expression is as follows: φ(v)＝cLφL(v)+cGφG(v)φ(v)＝c L φ L (v)+c G φ G (v) 式中：φL和φG分别为洛伦兹线型函数和高斯线型函数；cL和cG分别为洛伦兹展宽λL和高斯展宽λG的权重系数；v0为激光谱线中心频率；λ为吸收谱线的半高全宽；cL、cG和λ的计算公式如下：In the formula: φ L and φ G are the Lorentzian line shape function and Gaussian line shape function respectively; c L and c G are the weight coefficients of Lorentz broadening λ L and Gaussian broadening λ G respectively; v 0 is the laser spectral line Center frequency; λ is the full width at half maximum of the absorption line; the calculation formulas of c L , c G and λ are as follows: d＝(λL-λG)/(λL+λG)d=(λ L -λ G )/(λ L +λ G ) cL＝0.6818817+0.6129331d-0.1838439d2-0.1156844d3 c L ＝0.6818817+0.6129331d-0.1838439d 2 -0.1156844d 3 cG＝0.3246017-0.6182531d+0.1768139d2+0.1210944d3 c G ＝0.3246017-0.6182531d+0.1768139d 2 +0.1210944d 3 4.根据权利要求1所述的基于光谱吸收率二次谐波特征提取的气体浓度测量方法，其特征在于：步骤6中，光谱吸收率α(v)对应的二次谐波信号Hα的中心峰高度与积分吸光度A和吸收谱线洛伦兹展宽λL的关系表达式为：4. the gas concentration measuring method based on spectral absorptivity second harmonic feature extraction according to claim 1, is characterized in that: in step 6, the corresponding second harmonic signal H of spectral absorptivity α (v) central peak height The relationship expression with the integrated absorbance A and the Lorentz broadening λ L of the absorption line is: 式中，I1为第一类1阶变形贝塞尔函数，参数m、cL、cG的计算公式如下：In the formula, I 1 is the first-order deformed Bessel function of the first kind, and the calculation formulas of parameters m, c L and c G are as follows: d＝(λL-λG)/(λL+λG)d=(λ L -λ G )/(λ L +λ G ) cL＝0.6818817+0.6129331d-0.1838439d2-0.1156844d3 c L ＝0.6818817+0.6129331d-0.1838439d 2 -0.1156844d 3 cG＝0.3246017-0.6182531d+0.1768139d2+0.1210944d3 c G ＝0.3246017-0.6182531d+0.1768139d 2 +0.1210944d 3 m＝2a/λ。m=2a/λ. 5.根据权利要求1所述的基于光谱吸收率二次谐波特征提取的气体浓度测量方法，其特征在于：步骤6中，光谱吸收率α(v)对应的二次谐波信号Hα的旁瓣宽度Λ与积分吸光度A和吸收谱线洛伦兹展宽λL的关系表达式为：5. the gas concentration measuring method based on spectral absorptivity second harmonic feature extraction according to claim 1, is characterized in that: in step 6, the corresponding second harmonic signal H of spectral absorptivity α (v) The relational expressions of the side lobe width Λ and the integral absorbance A and the Lorentzian broadening λ L of the absorption line are: 式中，r＝cG/cL，p1＝1.966194179，p2＝0.390933340，p3＝3.093996758，p4＝0.388999538，p5＝0.806546476，p6＝-0.289132222，p7＝-1.775513203，p8＝0.017671096，p9＝1.041510614，p10＝-0.146221523，p11＝-1.073806845。In the formula, r=c G /c L , p 1 =1.966194179, p 2 =0.390933340, p 3 =3.093996758, p 4 =0.388999538, p 5 =0.806546476, p 6 =-0.289132222, p 7 5,p 7 = -13203 =0.017671096, p 9 =1.041510614, p 10 =-0.146221523, p 11 =-1.073806845. 6.根据权利要求1所述的基于光谱吸收率二次谐波特征提取的气体浓度测量方法，其特征在于：步骤9中，谱线线强S(T)随温度变化采用下式表示：6. the gas concentration measurement method based on spectral absorptivity second harmonic feature extraction according to claim 1, is characterized in that: in step 9, spectral line intensity S (T) adopts following formula expression with temperature change: 式中，h为Planck常数，h为真空中光速，k为Boltzmann常数，E为低能级能量，T0＝296K为参考温度，v0为谱线中心频率，Q(T)为温度T时的配分函数值，E及Q(T)的计算方法通过查询HITRAN2016数据库得到。In the formula, h is Planck’s constant, h is the speed of light in vacuum, k is Boltzmann’s constant, E is the low-level energy, T 0 =296K is the reference temperature, v 0 is the center frequency of the spectral line, and Q(T) is the temperature at T The partition function value, the calculation method of E and Q(T) are obtained by querying the HITRAN2016 database.
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Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109959637A (en) * 2019-04-04 2019-07-02 中南大学 Method and device for suppressing etalon effect for detection of residual oxygen in glass vials
CN109991189A (en) * 2019-04-04 2019-07-09 东南大学 A fixed-point wavelength-modulated gas concentration measurement device based on wavenumber drift correction and its measurement method
CN111829980A (en) * 2020-07-23 2020-10-27 安徽农业大学 A detection system and method for linear nonlinear correction based on harmonic technology
CN112213283A (en) * 2020-09-15 2021-01-12 江苏方天电力技术有限公司 Gas concentration measuring method
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CN113252601A (en) * 2021-05-13 2021-08-13 清华大学 Multi-component substance detection method and device based on wavelength modulation spectrum technology
CN113627319A (en) * 2021-08-09 2021-11-09 中南大学 Approximate gas concentration signal classification method based on harmonic amplitude passing probability
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CN114062312A (en) * 2021-10-24 2022-02-18 中南大学 A lock-in amplification method and system in TDLAS gas detection
CN114235741A (en) * 2021-11-10 2022-03-25 华南理工大学 A TDLAS-based gas concentration measurement method and system
CN114295581A (en) * 2021-12-31 2022-04-08 厦门大学 Gas concentration detection method and device insensitive to DFB laser wavelength characteristic
CN114397273A (en) * 2021-12-31 2022-04-26 南京星空低碳科技中心(有限合伙) Gas concentration measuring device and method based on second harmonic and fourth harmonic combination
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CN115015113A (en) * 2022-05-05 2022-09-06 东南大学 Spectral gas parameter measurement method and device based on signal power spectrum analysis
CN115792136A (en) * 2023-01-28 2023-03-14 清华大学合肥公共安全研究院 Gas concentration detection method and device, terminal equipment and storage medium
CN117092064A (en) * 2023-06-28 2023-11-21 中南大学 Calibration-free harmonic signal demodulation method based on logarithmic method
CN117740183A (en) * 2023-12-18 2024-03-22 大连理工大学 Synchronous detection method for modulating TDLAS temperature and concentration under short-optical-path weak absorption
CN118150519A (en) * 2024-03-28 2024-06-07 四川大学 Laser absorption spectrum multi-gas parameter measurement method based on deep learning

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102914515A (en) * 2012-07-29 2013-02-06 安徽皖仪科技股份有限公司 Method for extracting low-concentration signals of laser gas analyzer
CN103868885A (en) * 2014-03-27 2014-06-18 清华大学 Composite multi-harmonic-based online gas concentration measurement method
CN105388120A (en) * 2015-11-25 2016-03-09 山西大学 WMRF new model-based calibration-free wavelength modulation spectrum gas detection method
US20160139043A1 (en) * 2014-09-29 2016-05-19 Zyomed Corp. Systems and methods for generating and using projector curve sets for universal calibration for noninvasive blood glucose and other measurements
US20160174845A1 (en) * 2006-04-13 2016-06-23 Ivana Ledesma Apparatus for the non-invasive measurement of tissue function and metabolism by determination of steady-state fluorescence anisotropy
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
CN107247034A (en) * 2017-05-24 2017-10-13 东南大学 A kind of bifrequency wavelength modulator approach based on absorption spectroscopy techniques

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160174845A1 (en) * 2006-04-13 2016-06-23 Ivana Ledesma Apparatus for the non-invasive measurement of tissue function and metabolism by determination of steady-state fluorescence anisotropy
CN102914515A (en) * 2012-07-29 2013-02-06 安徽皖仪科技股份有限公司 Method for extracting low-concentration signals of laser gas analyzer
CN103868885A (en) * 2014-03-27 2014-06-18 清华大学 Composite multi-harmonic-based online gas concentration measurement method
US20160139043A1 (en) * 2014-09-29 2016-05-19 Zyomed Corp. Systems and methods for generating and using projector curve sets for universal calibration for noninvasive blood glucose and other measurements
CN105388120A (en) * 2015-11-25 2016-03-09 山西大学 WMRF new model-based calibration-free wavelength modulation spectrum gas detection method
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
CN107247034A (en) * 2017-05-24 2017-10-13 东南大学 A kind of bifrequency wavelength modulator approach based on absorption spectroscopy techniques

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
YUYAN LIU: "Simple empirical analytical approximation to the voigt profile", 《OPTICAL SOCIETY OF AMERICA》 *
熊涌泉 等: "基于波长调制光谱技术的免标定单线测量法", 《光学学报》 *

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