CN109115720A - A kind of long measurement method simultaneously with gas concentration of the effective journey of multi-way gas absorption cell - Google Patents
A kind of long measurement method simultaneously with gas concentration of the effective journey of multi-way gas absorption cell Download PDFInfo
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Abstract
The present invention provides a kind of effective journey of multi-way gas absorption cell the long measurement method simultaneously with gas concentration, is related to absorption spectrum detection technique field.Specifically includes the following steps: tunable laser laser output beam enters multi-way gas absorption cell, under test gas is filled in gas absorption cell；Laser output wavelength is tuned, incident intensity and output intensity is measured, obtains gas absorption spectra；Using the relationship of line absorption line style and pressure, pressure in regulating gas pond obtains the gas absorption spectrum line under different pressure.The present invention can measure the long gas concentration in gas cell of effective journey of gas absorption cell under different pressure simultaneously, without being calibrated before measuring to gas absorption cell effective journey length, avoid influence of the sample gas concentration error to measurement result, accuracy is high, present system structure is simple simultaneously, it is easy to build adjusting, it is easy to operate.
Description
Technical field
The present invention relates to absorption spectrum detection technique fields, and in particular to a kind of effective journey of multi-way gas absorption cell is long and gas
Bulk concentration while measurement method.
Background technique
Absorption spectroscopy techniques are widely used in polluted gas detection, industrial exhaust gas monitoring, medical diagnosis, national defence peace
Congruent field.Spectral technique has the advantages that detection sensitivity is high, and minimum detection limit can reach ppb-ppt magnitude, may be implemented
Trace gas composition detection in industrial process gas, oral cavity sample gas and environmental pollution gas.Since each molecule has its spy
" fingerprint " feature having has strong selectivity to the absorption of light, and the response time is fast, and a wide range of scene prison in real time may be implemented
It surveys.Absorption spectrum detection sensitivity and effective journey length that absorbs are proportional, and spy can be improved by increasing effective journey length that absorbs
Survey sensitivity.Using multi-pass reflection-absorption pond, it can effectively increase absorption path-length.Multi-pass absorption cell is using light in gas
The principle of multiple roundtrip in body pond, increase effectively absorption journey is long, usually absorption path-length can be increased hundred times.Often
Primary event, light pass through gas cell by different optical paths.
When carrying out atmosphere measurement detection of gas using absorption spectroscopy techniques, need to carry out instrument to absorb the long calibration of journey.Often
Calibration mode is that it is long to be finally inversed by gas absorption journey using calibrating gas and absorption spectrum known to concentration.Use this method
If it is reasonable that the gas cell calibrated, which effectively absorbs journey length large error occur, because being difficult to obtain the accurate Standard Gases of concentration
Body, in addition some gases itself belong to viscous gas, though to pond inner wall plate teflon material may also can in inner wall or
It is lost at air inlet, so that there are deviations for intracavitary standard gas concentration and configuration concentration, causes calibration result inaccurate.
Summary of the invention
In view of the shortcomings of the prior art, the present invention provides, a kind of effective journey of multi-way gas absorption cell is long to be surveyed simultaneously with gas concentration
Amount method can measure the long gas concentration in gas cell of effective journey of gas absorption cell under different pressure simultaneously, be not necessarily to
Gas absorption cell effective journey length to be calibrated before measurement, avoids influence of the sample gas concentration error to measurement result, accuracy is high,
Present system structure is simple simultaneously, is easy to build adjusting, easy to operate.
In order to achieve the above object, technical solution of the present invention is achieved by the following technical programs:
A kind of long measurement method simultaneously with gas concentration of the effective journey of multi-way gas absorption cell, comprising the following steps:
Step 1: laser light incident is transmitted to being equipped in the gas absorption cell of high reflectance hysteroscope from gas absorption cell
The laser come gathers on infrared detector, and optical signal is converted to electric signal by infrared detector, simultaneously by data collecting card record
It is input in data processing system and is handled and stored, obtain output signal；
Step 2: the wavelength of tuning laser, obtains the laser of different frequency, data collecting card records entering under each frequency ν
Light intensity is penetrated, output intensity I (ν)=I under each frequency ν is calculated0(ν) exp [- α (ν) L], wherein L is optical absorption length,
α (ν) is that there are also the relationships of absorption cross-section σ (ν) and concentration N by absorption coefficient, absorption coefficient (ν) and integrated absorption cross-section S (T) are as follows:
WhereinIt is normalized molecular absorption line line style, meets:
It is related to the concentration N and pressure P of gas is absorbed, and the value of integrated absorption cross-section S (T) passes through HITRAN infrared spectroscopy
Database obtains；
Step 3: incident intensity and output intensity are measured by infrared detector or spectrometer, system is controlled by pressure
Pressure in system control gas absorption cell, during this, the concentration N for absorbing gas is remained unchanged, and obtains a series of following sides
Journey group:
Step 4: being utilized to accurately extract the information of the absorption the journey long L and gas concentration N that include in detectable signal
Multiple Non Linear Regression algorithm constructs objective function:
When objective function u is minimized, N and L at this time are the optimal solution of equation group, can be obtained the long L of effective journey and
The value of gas concentration N.
Preferably, laser is projected by the broad tuning narrow linewidth quantum cascade laser of high light beam quality in the first step, laser
For tunable TEM00 mould, frequency tuning range can cover one complete absorption peak of under test gas, and its line width does not influence
Absorption line wire width measuring.
Preferably, the plano-concave that gas absorption cell is identical by two pieces of radius of curvature in the first step, highly reflecting films are plated in concave surface is high
Reflecting mirror is constituted.
Preferably, under test gas is filled in the first step into gas absorption cell, under test gas enters after being filtered
In gas absorption cell, the pressure using pressure control system control gas absorption cell is stablized, and pressure control system includes flow control
Device, pressure control device and vacuum pump processed.
Preferably, enter in gas absorption cell after the collimated mirror collimation of laser in the first step, then line focus lens gather
On infrared detector.
Preferably, in second step by the wavelength control unit of quantum cascade laser come the output wavelength of tuning laser, and
And optical output signal amplitude is kept to stablize, obtain the laser of different frequency.
Preferably, the gas absorption spectra for drawing out absorption coefficient α (ν) and ν according to data measured in second step is bent
Line, and processing is fitted to the curve.
Preferably, the gas absorption spectra under different pressure is obtained according to data measured in third step.
The present invention provides a kind of effective journey of multi-way gas absorption cell the long measurement method simultaneously with gas concentration, with the prior art
It is compared to advantage:
(1) present invention can measure gas under different pressure using the line style of absorption line gas and the relationship of pressure simultaneously
The long gas concentration in gas cell of effective journey of body absorption cell, without utilizing known concentration before carrying out gas concentration measurement
Calibrating gas calibrates gas absorption cell effective journey length, avoids influence of the sample gas concentration error to measurement result, accuracy
It is high；
(2) present system structure is simple, is easy to build adjusting, easy to operate, brings greatly just to researcher
Benefit.
Detailed description of the invention
Fig. 1 is measuring device system diagram of the present invention；
Fig. 2 is the gas absorption spectra figure in the embodiment of the present invention under different pressure.
In figure: 1 filter, 2 data processing systems, 3 wavelength control units, 4 flow controllers, 5 data collecting cards, 6 laser,
7 collimating mirrors, 8 gas absorption cells, 9 condenser lenses, 10 infrared detectors, 11 pressure controllers, 12 vacuum pumps.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below with reference to the embodiment of the present invention pair
Technical solution in the embodiment of the present invention is clearly and completely described, it is clear that described embodiment is a part of the invention
Embodiment, instead of all the embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art are not making wound
Every other embodiment obtained under the premise of the property made labour, shall fall within the protection scope of the present invention.
Embodiment:
A kind of long measurement method simultaneously with gas concentration of the effective journey of multi-way gas absorption cell, comprising the following steps:
Step 1: being incident on laser 6 in the gas absorption cell 8 equipped with high reflectance hysteroscope, transmitted from gas absorption cell 8
Laser 6 out gathers on infrared detector 10, and optical signal is converted to electric signal by infrared detector 10, by data collecting card
5 record and are input in data processing system 2 and are handled and stored, and obtain output signal；
Step 2: the wavelength of tuning laser 6, obtains the laser 6 of different frequency, data collecting card 5 is recorded under each frequency ν
Output intensity I (ν)=I under each frequency ν is calculated in incident intensity0(ν) exp [- α (ν) L], wherein L is that optical absorption is long
Degree, α (ν) are that there are also the relationships of absorption cross-section σ (ν) and concentration N by absorption coefficient, absorption coefficient (ν) and integrated absorption cross-section S (T)
Are as follows:
WhereinIt is normalized molecular absorption line line style, meets:
It is related to the concentration N and pressure P of gas is absorbed, and the value of integrated absorption cross-section S (T) passes through HITRAN infrared spectroscopy
Database obtains；
Step 3: incident intensity and output intensity are measured by infrared detector 10 or spectrometer, controlled by pressure
System controls the pressure in gas absorption cell 8, and during this, the concentration N for absorbing gas is remained unchanged, and obtains following a series of
Equation group:
Step 4: being utilized to accurately extract the information of the absorption the journey long L and gas concentration N that include in detectable signal
Multiple Non Linear Regression algorithm constructs objective function:
When objective function u is minimized, N and L at this time are the optimal solution of equation group, can be obtained the long L of effective journey and
The value of gas concentration N.
Wherein, laser 6 is projected by the broad tuning narrow linewidth quantum cascade laser of high light beam quality in the first step, laser 6
For tunable TEM00 mould, frequency tuning range can cover one complete absorption peak of under test gas, and its line width does not influence
Absorption line wire width measuring；The plano-concave that gas absorption cell 8 is identical by two pieces of radius of curvature in the first step, highly reflecting films are plated in concave surface
High reflection mirror is constituted；Under test gas is filled in the first step into gas absorption cell 8, under test gas enters after the filtering of filter 1
In gas absorption cell 8, the pressure using pressure control system control gas absorption cell 8 is stablized, and pressure control system includes flow
Controller 4, pressure control device 11 and vacuum pump 12；Enter gas absorption cell 8 after the collimated mirror 7 of laser 6 collimation in the first step
It is interior, then line focus lens 9 gather on infrared detector 10；Pass through the wavelength control unit 3 of quantum cascade laser in second step
Carry out the output wavelength of tuning laser 6, and optical output signal amplitude is kept to stablize, obtains the laser of different frequency；Second step
The middle gas absorption spectra curve that absorption coefficient α (ν) Yu ν are drawn out according to data measured, and the curve is fitted
Processing；The gas absorption spectra under different pressure is obtained according to data measured in third step.
It is illustrated in figure 2 in gas absorption cell 8 and is filled with N2When O Standard Gases, absorbed according to the gas that data measured is fitted
Spectrum, the main component of Standard Gases is by N2And N2O composition, changes the wavelength of laser 6, i.e., the frequency v of laser 6 is in 2188.6-
2189.0cm-1In the range of, gas under different pressure P to laser 6 mainly there are three absorption peak, the frequency of laser 6 as seen from the figure
Rate v is in 2188.68cm-1、2188.76cm-1And 2188.93cm-1Near when, gas is larger to the absorption intensity of laser 6, i.e.,
Absorption coefficient α (ν) is larger, and when gas pressure intensity P is bigger, the line width of absorption peak is wider.
It should be noted that, in this document, relational terms such as first and second and the like are used merely to a reality
Body or operation are distinguished with another entity or operation, are deposited without necessarily requiring or implying between these entities or operation
In any actual relationship or order or sequence.Moreover, the terms "include", "comprise" or its any other variant are intended to
Non-exclusive inclusion, so that the process, method, article or equipment including a series of elements is not only wanted including those
Element, but also including other elements that are not explicitly listed, or further include for this process, method, article or equipment
Intrinsic element.In the absence of more restrictions, the element limited by sentence "including a ...", it is not excluded that
There is also other identical elements in process, method, article or equipment including the element.
The above embodiments are merely illustrative of the technical solutions of the present invention, rather than its limitations；Although with reference to the foregoing embodiments
Invention is explained in detail, those skilled in the art should understand that: it still can be to aforementioned each implementation
Technical solution documented by example is modified or equivalent replacement of some of the technical features；And these modification or
Replacement, the spirit and scope for technical solution of various embodiments of the present invention that it does not separate the essence of the corresponding technical solution.
Claims (8)
1. a kind of long measurement method simultaneously with gas concentration of the effective journey of multi-way gas absorption cell, which is characterized in that including following step
It is rapid:
Step 1: laser (6) is incident on the gas absorption cell (8) equipped with high reflectance hysteroscope Nei, it is saturating from gas absorption cell (8)
The laser (6) shot out gathers on infrared detector (10), and optical signal is converted to electric signal by infrared detector (10), by counting
It records and is input in data processing system (2) according to capture card (5) and handled and stored, obtain output signal；
Step 2: the wavelength of tuning laser (6), obtains the laser (6) of different frequency, data collecting card (5) is recorded under each frequency ν
Incident intensity, output intensity I (ν)=I under each frequency ν is calculated0(ν) exp [- α (ν) L], wherein L is optical absorption
Length, α (ν) are that there are also the passes of absorption cross-section σ (ν) and concentration N by absorption coefficient, absorption coefficient (ν) and integrated absorption cross-section S (T)
System are as follows:
WhereinIt is normalized molecular absorption line line style, meets:
It is related to the concentration N and pressure P of gas is absorbed, and the value of integrated absorption cross-section S (T) passes through HITRAN ir data
Library obtains；
Step 3: incident intensity and output intensity are measured by infrared detector (10) or spectrometer, system is controlled by pressure
Pressure in system control gas absorption cell (8), during this, the concentration N for absorbing gas is remained unchanged, and is obtained following a series of
Equation group:
Step 4: in order to accurately extract the information of the absorption the journey long L and gas concentration N that include in detectable signal, utilization is polynary
Nonlinear regression algo constructs objective function:
When objective function u is minimized, N and L at this time is the optimal solution of equation group, and the long L of effective journey and gas can be obtained
The value of concentration N.
2. a kind of long measurement method simultaneously with gas concentration of the effective journey of multi-way gas absorption cell according to claim 1,
Be characterized in that: laser (6) is projected by the broad tuning narrow linewidth quantum cascade laser of high light beam quality in the first step, laser (6)
For tunable TEM00 mould, frequency tuning range can cover one complete absorption peak of under test gas, and its line width does not influence
Absorption line wire width measuring.
3. a kind of long measurement method simultaneously with gas concentration of the effective journey of multi-way gas absorption cell according to claim 1,
It is characterized in that: the plano-concave high reflection that gas absorption cell (8) is identical by two pieces of radius of curvature in the first step, highly reflecting films are plated in concave surface
Mirror is constituted.
4. a kind of long measurement method simultaneously with gas concentration of the effective journey of multi-way gas absorption cell according to claim 1,
It is characterized in that: being filled under test gas in the first step into gas absorption cell (8), under test gas enters after filter (1) is filtered
In gas absorption cell (8), stablized using the pressure of pressure control system control gas absorption cell (8), pressure control system includes
Flow controller (4), pressure control device (11) and vacuum pump (12).
5. a kind of long measurement method simultaneously with gas concentration of the effective journey of multi-way gas absorption cell according to claim 1,
It is characterized in that: entering in gas absorption cell (8) after laser (6) collimated mirror (7) collimation in the first step, then line focus lens (9)
It gathers on infrared detector (10).
6. a kind of long measurement method simultaneously with gas concentration of the effective journey of multi-way gas absorption cell according to claim 1,
It is characterized in that: by the wavelength control unit of quantum cascade laser (3) come the output wavelength of tuning laser (6) in second step, and
And optical output signal amplitude is kept to stablize, obtain the laser (6) of different frequency.
7. a kind of long measurement method simultaneously with gas concentration of the effective journey of multi-way gas absorption cell according to claim 1,
It is characterized in that: drawing out the gas absorption spectra curve of absorption coefficient α (ν) Yu ν in second step according to data measured, and right
The curve is fitted processing.
8. a kind of long measurement method simultaneously with gas concentration of the effective journey of multi-way gas absorption cell according to claim 1,
It is characterized in that: the gas absorption spectra under different pressure being obtained according to data measured in third step.
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| CN110146455A (en) * | 2019-05-27 | 2019-08-20 | 安徽大学 | Laser spectrum gas concentration measuring method based on deep learning |
| CN111781165A (en) * | 2019-04-04 | 2020-10-16 | 深圳米字科技发展有限公司 | Simultaneous analysis of H in natural gas2O and CO2Laser detection method of content |
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