阅读说明：本技术 一种分段扫描激光气体吸收谱拼接获取较宽谱的方法 (Method for acquiring wider spectrum by splicing segmented scanning laser gas absorption spectrum ) 是由 姚强 张施令 李新田 赫树开 钱进 刘晓波 颜相连 何洁 齐汝宾 于 2021-08-05 设计创作，主要内容包括：一种分段扫描激光气体吸收谱拼接获取较宽谱的方法,具体包括以下步骤：(一)、扫描采集激光器电流调谐特性数据和温度调谐特性数据；(二)、根据激光器电流调谐特性数据和温度调谐特性数据,结合数据拟合算法建立激光器调谐特性模型；(三)、采集得到激光器正常工作下的m组分段气体吸收信号；(四)、将建立的调谐特性模型应用于步骤(三)中采集得到的m组分段气体吸收信号,得到m组分段吸收谱；(五)、利用吸收谱拼接整合算法将m组分段吸收谱拼接整合为一组较宽气体吸收全谱。本发明通过激光器调谐特性模型对若干组分段气体吸收信号进行数据处理,得到若干组分段吸收谱,将各组分段吸收谱拼接成较宽的吸收谱。(A method for acquiring a wider spectrum by splicing a segmented scanning laser gas absorption spectrum specifically comprises the following steps: scanning and acquiring laser current tuning characteristic data and temperature tuning characteristic data; establishing a laser tuning characteristic model by combining a data fitting algorithm according to the laser current tuning characteristic data and the temperature tuning characteristic data; acquiring m component section gas absorption signals under the normal working of the laser; applying the established tuning characteristic model to the m-component section gas absorption signals acquired in the step (III) to obtain m-component section absorption spectra; and fifthly, splicing and integrating the m component absorption spectra into a group of wider gas absorption full spectra by using an absorption spectrum splicing and integrating algorithm. According to the invention, data processing is carried out on a plurality of component section gas absorption signals through a laser tuning characteristic model to obtain a plurality of component section absorption spectrums, and the component section absorption spectrums are spliced into a wider absorption spectrum.)

1. A method for acquiring a wider spectrum by splicing a segmented scanning laser gas absorption spectrum is characterized by comprising the following steps: the method specifically comprises the following steps:

scanning and acquiring laser current tuning characteristic data and temperature tuning characteristic data;

establishing a laser tuning characteristic model by combining a data fitting algorithm according to the laser current tuning characteristic data and the temperature tuning characteristic data;

acquiring m component section gas absorption signals under the normal working of the laser;

(IV) applying the established tuning characteristic model to the m-component section gas absorption signals acquired in the step (III) to obtain m-component section absorption spectraA _j（λ _jk），j=1, 2,···m; k=1, 2,···q）；

(V) splicing and integrating the m component absorption spectra into a group of wider gas absorption full spectra by using an absorption spectrum splicing and integrating algorithmA（λ _k’），k’=1, 2,···p，p>q）。

2. The method for acquiring a wider spectrum by segmented scanning laser gas absorption spectrum splicing according to claim 1, wherein the method comprises the following steps: the step (one) is specifically as follows: measuring emission spectra of the laser at each driving current and each working temperature by using a spectrometer to obtain current tuning characteristic data of the laser at each specific working temperature (namely, scanning and acquiring to obtain a driving current and output wavelength data pair: (I _i，λ _i) I =1, 2, · · n) and temperature tuning characteristic data of the laser at each specific drive current (i.e. scanning and acquiring working temperature and output wavelength data pair: (i.e. scanning and acquiring)T _i，λ _i），i=1、 2、···n）。

3. The segmented scanning laser gas absorption spectrum splicing method for acquiring a wider spectrum according to claim 2, wherein the method comprises the following steps: the step (II) is specifically as follows: establishing a laser tuning characteristic model through a data fitting algorithm according to the laser current tuning characteristic data and the temperature tuning characteristic data obtained in the step (I), wherein the data fitting algorithm comprises a linear fitting algorithm and a nonlinear fitting algorithm, the linear fitting algorithm is a first-order polynomial fitting algorithm based on a least square method, the nonlinear fitting algorithm is a second-order polynomial fitting algorithm based on the least square method, and the tuning characteristic model comprises the step of modeling the current tuning characteristic data at each specific working temperature to obtain the current tuning characteristic model at the specific working temperatureλ（I) Modeling the temperature tuning characteristic data under each specific driving current to obtain a temperature tuning characteristic model under the specific driving currentλ（T) The method also comprises a comprehensive tuning characteristic model which simultaneously considers two parameters of the driving current and the working temperatureλ（I，T）。

4. The segmented scanning laser gas absorption spectrum splicing method for acquiring a wider spectrum according to claim 3, wherein the method comprises the following steps: the step (III) is specifically as follows: the laser with the established current tuning characteristic model, temperature tuning characteristic model or comprehensive tuning characteristic model is applied to a laser gas analyzer or any other instrument or experimental system based on laser absorption spectrum technology, a gas to be detected is tested, the driving current (or working temperature) of the laser is set to be a fixed value, then the working temperature (or driving current) is scanned, a group of segmented gas absorption signals are acquired, then the set value of the driving current (or working temperature) of the laser is changed, then the working temperature (or driving current) is repeatedly scanned, another group of segmented gas absorption signals are acquired, the operation process is repeated, m groups of corresponding segmented gas absorption signals are acquired, and the selection principle of the number m is as follows: the number of parameters is set to cover the maximum range allowed by normal operation of the laser and overlap the wavelengths of the absorption spectra of the gas segments obtained, and the sweep range of the other parameter is set to be less than or equal to the maximum allowed range for normal light emission of the laser (e.g., when the operating temperature is set to a fixed value, the drive current sweep range can be set to be from the threshold current to the maximum allowed current at the operating temperature).

5. The segmented scanning laser gas absorption spectrum splicing method for acquiring a wider spectrum according to claim 4, wherein the method comprises the following steps: the absorption spectrum splicing and integrating algorithm in the step (V) specifically comprises the following steps: firstly, filtering m groups of segmental absorption spectrums, then integrating abscissa data (wavelength) and ordinate data (absorption spectrums) of m groups of data after filtering, and finally filtering;

wherein the abscissa data is integrated to calculate respectively the abscissa minimum interval delta in the segmented absorption spectrum dataλ _jJ =1, 2, · · m, the minimum value of which is taken to be ΔλThen the smallest wavelength data from the abscissa data of the m-component segmented absorption spectrumλ _j1Starting up to maximum wavelength dataλ _jpSearching and calculating a difference of less than 0.5 delta from the wavelengthλAll other sets of wavelength data ofλ _jk(j =1, 2,. m, j ≠ j; k =1, 2,. q), the average value of the wavelength data is taken as the value of the abscissa position, the average value of the absorption spectrum data corresponding to the wavelength data is taken as the ordinate value (absorption spectrum value) of the abscissa position (wavelength position), and the full spectrum abscissa data series after splicing and integration is obtainedλ _k’K' =1, 2, · · p, and the full spectrum ordinate seriesA _k’Finally obtain a wider full spectrumA（λ _k’）。

Technical Field

The invention relates to the technical field of non-contact gas concentration detection, in particular to a method for acquiring a wider spectrum by splicing a segmented scanning laser gas absorption spectrum.

Background

The tunable semiconductor laser absorption spectrum (TDLAS) technology is combined with the tunable characteristic of a semiconductor laser and the absorption characteristic of gas molecules to energy light with specific wavelength, and the semiconductor laser is widely applied to the concentration detection of non-contact gas by virtue of the advantages of high sensitivity, short response time and the like.

However, the semiconductor laser has a narrow gas absorption spectrum obtained by single drive current scanning at a fixed working temperature, and a wider absorption spectrum range of the gas to be measured can be obtained by changing the working temperature of the laser. At present, no related technology adopts the combination of the driving current and the working temperature to be applied to the concentration detection of the non-contact gas.

Disclosure of Invention

The invention aims to provide a method for acquiring a wider spectrum by splicing a segmented scanning laser gas absorption spectrum.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for acquiring a wider spectrum by splicing a segmented scanning laser gas absorption spectrum specifically comprises the following steps:

scanning and acquiring laser current tuning characteristic data and temperature tuning characteristic data;

establishing a laser tuning characteristic model by combining a data fitting algorithm according to the laser current tuning characteristic data and the temperature tuning characteristic data;

acquiring m component section gas absorption signals under the normal working of the laser;

(IV) applying the established tuning characteristic model to the m-component section gas absorption signals acquired in the step (III) to obtain m-component section absorption spectraA _j（λ _jk），j=1, 2,···m; k=1, 2,···q）；

(V) splicing and integrating the m component absorption spectra into a group of wider gas absorption full spectra by using an absorption spectrum splicing and integrating algorithmA（λλ _k’），k’=1, 2,···p，p>q）。

The step (one) is specifically as follows: measuring emission spectra of the laser at each driving current and each working temperature by using a spectrometer to obtain current tuning characteristic data of the laser at each specific working temperature (namely, scanning and acquiring to obtain a driving current and output wavelength data pair: (I _i，λ _i) I =1, 2, · · n) and temperature tuning characteristic data of the laser at each specific drive current (i.e. scanning and acquiring working temperature and output wavelength data pair: (i.e. scanning and acquiring)T _i，λ _i），i=1、 2、···n）。

The step (II) is specifically as follows: establishing a laser tuning characteristic model through a data fitting algorithm according to the laser current tuning characteristic data and the temperature tuning characteristic data obtained in the step (I), wherein the data fitting algorithm comprises a linear fitting algorithm and a nonlinear fitting algorithm, the linear fitting algorithm is a first-order polynomial fitting algorithm based on a least square method, the nonlinear fitting algorithm is a second-order polynomial fitting algorithm based on the least square method, and the tuning characteristic model comprises the step of modeling the current tuning characteristic data at each specific working temperature to obtain the current tuning characteristic model at the specific working temperatureλ（I) Modeling the temperature tuning characteristic data under each specific driving current to obtain a temperature tuning characteristic model under the specific driving currentλ（T) The method also comprises a comprehensive tuning characteristic model which simultaneously considers two parameters of the driving current and the working temperatureλ（I，T）。

The step (III) is specifically as follows: the laser with the established current tuning characteristic model, temperature tuning characteristic model or comprehensive tuning characteristic model is applied to a laser gas analyzer or any other instrument or experimental system based on laser absorption spectrum technology, a gas to be detected is tested, the driving current (or working temperature) of the laser is set to be a fixed value, then the working temperature (or driving current) is scanned, a group of segmented gas absorption signals are acquired, then the set value of the driving current (or working temperature) of the laser is changed, then the working temperature (or driving current) is repeatedly scanned, another group of segmented gas absorption signals are acquired, the operation process is repeated, m groups of corresponding segmented gas absorption signals are acquired, and the selection principle of the number m is as follows: the number of parameters is set to cover the maximum range allowed by normal operation of the laser and overlap the wavelengths of the absorption spectra of the gas segments obtained, and the sweep range of the other parameter is set to be less than or equal to the maximum allowed range for normal light emission of the laser (e.g., when the operating temperature is set to a fixed value, the drive current sweep range can be set to be from the threshold current to the maximum allowed current at the operating temperature).

The absorption spectrum splicing and integrating algorithm in the step (V) specifically comprises the following steps: firstly, filtering m groups of segmental absorption spectrums, then integrating abscissa data (wavelength) and ordinate data (absorption spectrums) of m groups of data after filtering, and finally filtering;

wherein the abscissa data is integrated to calculate respectively the abscissa minimum interval delta in the segmented absorption spectrum dataλ _jJ =1, 2, · · m, the minimum value of which is taken to be ΔλThen the smallest wavelength data from the abscissa data of the m-component segmented absorption spectrumλ _j1Starting up to maximum wavelength dataλ _jpSearching and calculating a difference of less than 0.5 delta from the wavelengthλAll other sets of wavelength data ofλ _jk(j =1, 2,. m, j ≠ j; k =1, 2,. q), the average value of the wavelength data is taken as the value of the abscissa position, the average value of the absorption spectrum data corresponding to the wavelength data is taken as the ordinate value (absorption spectrum value) of the abscissa position (wavelength position), and the full spectrum abscissa data series after splicing and integration is obtainedλ _k’K' =1, 2, · · p, and the full spectrum ordinate seriesA _k’Finally obtain a wider full spectrumA（λ _k’）。

Compared with the prior art, the invention has outstanding substantive characteristics and remarkable progress, and particularly, the invention utilizes the TDLAS technology, establishes a laser tuning characteristic model by testing the relation between the output wavelength of a laser and the working temperature and the driving current, tests the gas to be detected by using the laser, collects gas absorption signals of a plurality of component sections of the laser, processes the data of the gas absorption signals of each component section by the established tuning characteristic model to obtain a plurality of component section absorption spectrums, and then integrates and splices the component section absorption spectrums to obtain a wider gas absorption full spectrum, so that the gas absorption peak value can be obtained, and the laser under the gas absorption peak value is adopted to detect the optimal concentration of the gas to be detected.

According to the invention, data processing is carried out on a plurality of component section gas absorption signals through a laser tuning characteristic model to obtain a plurality of component section absorption spectrums, and the component section absorption spectrums are spliced into a wider gas absorption full spectrum.

Drawings

Fig. 1 is a block diagram of the working principle of the present invention.

Fig. 2 is a graph of ICL laser output wavelength versus drive current for different specific operating temperatures of the present invention.

Fig. 3 is a graph of ICL laser output wavelength versus operating temperature for different specific drive currents of the present invention.

Fig. 4 is a plot of drive current versus output wavelength for an ICL laser of the present invention at 35 c.

FIG. 5 is a plot of operating temperature versus output wavelength for an 80mA ICL laser in accordance with the present invention.

Fig. 6 is a plot of operating temperature and drive current versus output wavelength for an ICL laser of the present invention.

FIG. 7 is SO at 25 ℃ for an ICL laser of the present invention₂F₂Absorption spectrum.

FIG. 8 shows SO at 30 ℃ for an ICL laser of the present invention₂F₂Absorption spectrum.

FIG. 9 is SO at 35 ℃ for an ICL laser of the present invention₂F₂Absorption spectrum.

FIG. 10 is SO at 40 ℃ for an ICL laser of the present invention₂F₂Absorption spectrum.

FIG. 11 is SO at different temperatures for ICL lasers of the present invention₂F₂Complete high-precision absorption spectrum.

FIG. 12 is a SO generated by scan splicing of ICL lasers of the present invention at different temperatures₂F₂The absorption spectrum from 3612 nm to 3624 nm is compared with that in the HITRAN database.

Detailed Description

The embodiments of the present invention are further described below with reference to the drawings.

As shown in fig. 1 to 12, a method for acquiring a wider spectrum by splicing a segmented scanning laser gas absorption spectrum specifically includes the following steps:

scanning and acquiring laser current tuning characteristic data and temperature tuning characteristic data;

establishing a laser tuning characteristic model by combining a data fitting algorithm according to the laser current tuning characteristic data and the temperature tuning characteristic data;

acquiring m component section gas absorption signals under the normal working of the laser;

(IV) applying the established tuning characteristic model to the m-component section gas absorption signals acquired in the step (III) to obtain m-component section absorption spectraA _j（λ _jk），j=1, 2,···m; k=1, 2,···q）；

(V) splicing and integrating the m component absorption spectra into a group of wider gas absorption full spectra by using an absorption spectrum splicing and integrating algorithmA（λ _k’），k’=1, 2,···p，p>q）。

The laser emitted by the ICL laser has the characteristic of narrow line width, and the output wavelength of the ICL laser has the characteristic of changing along with the change of the working temperature and the driving current, which is the basis of the TDLAS technology, so that the embodiment combines a wavelength meter to test the relationship between the output wavelength of the ICL laser and the working temperature and the driving current, wherein the working temperature range of the ICL laser is 20 ℃ to 40 ℃, and the driving current range is 40 mA to 120 mA.

The step (one) is specifically as follows: the temperature controller of the ICL laser was set to 5 temperature gradients: the current driver of the ICL laser was set to 9 drive current gradients at 20 ℃, 25 ℃, 30 ℃, 35 ℃ and 40 ℃ at each temperature gradient: 40 mA, 50 mA, 60 mA, 70 mA, 80mA, 90 mA, 100 mA, 110 mA and 120 mA, and a wavelength meter is utilized to collect the output wavelength of the ICL laser corresponding to different driving currents at each specific temperature and the output wavelength of the ICL laser corresponding to different temperatures at each specific driving current, so as to obtain the current tuning characteristic data of the ICL laser at each specific working temperature (namely, the driving current and output wavelength data pairs are obtained by scanning and collecting) ((I _i，λ _i) I =1, 2, · · n) and temperature tuning characteristic data of the ICL laser at each specific drive current (i.e. scan acquisition of working temperature versus output wavelength data pair: (i.e. scan acquisition of the operating temperature versus output wavelength data pairT _i，λ _i），i=1、 2、···n）。

The step (II) is specifically as follows: processing the current tuning characteristic data of the ICL laser at each specific working temperature, and taking the driving current as an abscissa and the output wavelength as an ordinate to obtain a relation curve graph of the output wavelength and the driving current of the ICL laser at different specific working temperatures, as shown in FIG. 2; similarly, the temperature tuning characteristic data of the ICL laser under each specific driving current is processed, and the relationship curve of the ICL laser output wavelength and the working temperature under different specific driving currents is obtained by taking the working temperature as the abscissa and the output wavelength as the ordinate, as shown in fig. 3;

it can be observed from fig. 2 that the relationship between the output wavelength and the driving current of the ICL laser is nonlinear, and taking the operating temperature of the ICL laser at 35 ℃ as an example, the output wavelength values corresponding to different driving currents injected into the ICL laser are shown in table 1:

TABLE 1, 35 ℃ ICL laser drive current and output wavelength correspondence table

With drive current of ICL laserIOutputting the wavelength as abscissa dataλCarrying out nonlinear fitting on the ordinate data to establish a current tuning characteristic modelλ（I) The nonlinear fitting algorithm is:

（1）

in the formula (1), the reaction mixture is,k ₁ 、k ₂ andC ₁ are all constants;

FIG. 4 shows a fitting curve of the drive current and the output wavelength of an ICL laser at 35 deg.Ck ₁ =0.0002741，k ₂ =0.05572，C ₁ =3613, thus obtaining drive current of ICL laser at 35 DEG CIAnd output wavelengthλThe relational expression between them is:

（2）

goodness of fit R in FIG. 4²0.9999, indicating the current tuning characteristic model of the drive current and output wavelength of the ICL laserλ（I) The goodness of fit is very high;

it can be observed from fig. 3 that the relationship between the output wavelength of the ICL laser and the operating temperature is linear, and taking the drive current of the ICL laser at 80mA as an example, the output wavelength values of the ICL laser corresponding to different operating temperatures are shown in table 2:

TABLE 2, 80mA ICL laser working temperature and output wavelength corresponding table

Operating temperature of ICL laserTOutputting the wavelength as abscissa dataλLinear fitting is carried out for the ordinate data, and a temperature tuning characteristic model is establishedλ（T) The linear fitting algorithm is:

（3）

in the formula (3)k ₃ AndC ₂ are all constants;

FIG. 5 shows a fitting curve of the operating temperature and the output wavelength of the ICL laser at 80mAk ₃ =0.3514， C ₂ =3607, thus obtaining the operating temperature of the ICL laser at 80mATAnd output wavelengthλThe relational expression between them is:

（4）

goodness of fit R in FIG. 5²0.9999, indicating the temperature tuning characteristic model of the operating temperature and the output wavelength of the ICL laserλ（T) The goodness of fit is high;

from the above analysis, an integrated tuning characteristic model can be establishedλ（I，T) Output wavelength of ICL laserλAnd operating temperatureTAnd a drive currentIThe formed relation is as follows:

（5）

the measured data is substituted into formula (5) for fitting, and the wavelength is outputλAs Z coordinate data, operating temperatureTFor y coordinate data, drive currentIFor x-coordinate data, the fit is shown in figure 6,k ₁ =0.00026，k ₂ =0.0503，k ₂ =0.3355，C ₃ =3601, goodness of fit R²0.998, and the comprehensive tuning characteristic model of the working temperature, the driving current and the output wavelength of the ICL laser is establishedλ（I，T) The goodness of fit is high.

The step (III) is specifically as follows: firstly, setting an ICL laser current driver, setting the driving current to be 80mA, setting the voltage-current conversion ratio to be 200 mA/V gear, setting the output waveform of a signal generator to be sawtooth wave with the frequency of 10 Hz, and then respectively setting N₂And SO₂F₂Gas is introduced into the optical path cell (N)₂As background gas), adjusting the working temperature of ICL laser to 25 deg.C, 30 deg.C, 35 deg.C, and 40 deg.C in sequence, and collecting background and SO at different temperatures₂F₂The signal is absorbed.

The step (IV) is specifically as follows: collecting the background and SO at different temperatures₂F₂Deducting background signal in absorption signal, and modeling temperature tuning characteristicλ（T) Application to SO₂F₂Absorption of the signal to give ISO at 25 ℃ of CL laser₂F₂Absorption spectrum (FIG. 7), SO at 30 deg.C of ICL laser₂F₂Absorption spectrum (FIG. 8), SO at 35 deg.C of ICL laser₂F₂Absorption spectrum (FIG. 9), SO at 40 deg.C of ICL laser₂F₂Absorption spectrum (fig. 10).

The step (V) is specifically as follows: SO at 25 ℃ of ICL laser₂F₂Absorption spectrum (FIG. 7), SO at 30 deg.C of ICL laser₂F₂Absorption spectrum (FIG. 8), SO at 35 deg.C of ICL laser₂F₂Absorption spectrum (FIG. 9), SO at 40 deg.C of ICL laser₂F₂Integrating and splicing abscissa data and ordinate data of the absorption spectrogram (figure 10) to obtain SO of the ICL laser at different temperatures₂F₂Complete high-precision absorption spectrum (FIG. 11) with SO measured by spectrometer and found in HITRAN database₂F₂The absorption spectrum resolution is all 0.5 cm^-1Left and right, lower resolution, SO formed by scanning and splicing ICL laser at different temperatures₂F₂The absorption spectrum at 3612 nm-3624 nm is compared with that in HITRAN database, as shown in FIG. 12, the left side in FIG. 12 is SO formed by scanning and splicing ICL laser at different temperatures₂F₂The absorption spectrum from 3612 nm to 3624 nm, the absorption spectrum at the right side in FIG. 12 in HITRAN database, and SO formed by scanning and splicing ICL laser at different temperatures₂F₂The resolution of absorption spectrum between 3612 nm and 3624 nm is obviously raised, and according to SO₂F₂The complete high-precision absorption spectrogram can know the SO₂F₂Two absorption peaks exist in an absorption spectrum from 3612 nm to 3624 nm, and the peak value of the absorption peak at 3619.3nm is the most powerful, SO that the absorption spectrum for SO₂F₂The concentration detection is best performed by using a strong absorption peak at 3619.3 nm.

The above embodiments are merely to illustrate rather than to limit the technical solutions of the present invention, and although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that; modifications and equivalents may be made thereto without departing from the spirit and scope of the invention and it is intended to cover in the claims the invention as defined in the appended claims.