CN206740648U - A kind of NO2The device of concentration distribution detection - Google Patents
A kind of NO2The device of concentration distribution detection Download PDFInfo
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- CN206740648U CN206740648U CN201720641036.7U CN201720641036U CN206740648U CN 206740648 U CN206740648 U CN 206740648U CN 201720641036 U CN201720641036 U CN 201720641036U CN 206740648 U CN206740648 U CN 206740648U
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Abstract
The utility model belongs to laser spectrum tech application field, and in particular to a kind of NO2The device of concentration distribution detection.By the vertical 90 degree of placements of first laser device and second laser, second laser is rotated by 90 ° the polarization state of the transmitting laser beam of second laser by half-wave plate so that the polarization state of the transmitting laser beam of first laser device and second laser is vertical direction；After this, the laser beam that first laser device and second laser are sent synthesizes light beam via the polarization spectroscope of 45 degree of placements, then is transmitted into after being collimated by laser beam emitting device in air；The backscatter signal for the laser beam being transmitted into air is collected via laser receiver, after bandpass filter filters out the atmospheric background signal, is imaged onto on a tilted-putted imaging sensor.Using apparatus and method of the present utility model, system architecture is greatly simplified, reduces system cost, improves the stability of system.
Description
Technical field
The utility model belongs to laser spectrum tech application field, and in particular to a kind of NO2The device of concentration distribution detection.
Background technology
Laser radar (Light Detection and Ranging, Lidar) technology is that a kind of active optical remote sensing is visited
Survey technology, it has uniqueness in height/spatial resolution, detectivity, antijamming capability and monitoring etc. in real time
Advantage.Since laser comes out, American-European countries begins to laser radar technique being applied in atmosphere environment supervision.Difference is inhaled
Laser radar (DIAL) technology of receipts is a kind of special shape in laser radar technique.DIAL technologies are directed to the absorption of gas with various
Spectral line, from large-scale pulsed laser successively into air launch different wave length laser pulse (a branch of wavelength is located at gas to be measured
The big position of body absorption intensity such as absworption peak, is designated as λon；Other a branch of wavelength is located at the small position of under test gas absorption intensity
For example paddy is absorbed, it is designated as λoff), and detect, analyze its backscatter signal so as to obtain under test gas concentration in an atmosphere point
Cloth.Currently, the DIAL technologies of main flow depend on into air launch nanosecond order light pulse, and passage time differentiate
Mode detects the backscatter signal in different distance, so as to finally realize atmospheric gas (such as NO2) concentration detection.DIAL
Technology is due to possessing distance resolution and with unique advantage.It is big using the detection of pulsed DIAL technology
During gas dusty gas, requirement harshness of the system to light source is, it is necessary to tunable dual wavelength, high pulse energy, narrow linewidth and stability
Good nanosecond order (10-100ns) light-pulse generator, this is exactly the main bugbear of field puzzlement international academic community and the current world
The focus of research, and limit the main reason of its commercial applications.
First technology [1] (Ryoichi Toriumi, Hideo Tai, Nobuo Takeuchi, " Tunable solid-
state blue laser differentialabsorption lidar system for NO2 monitoring,”
Opt.Eng.35 (8) 2371-2375,1996) in, by Nd:YAG laser pumping Ti:Sapphire lasers and use and frequency
Mode produce near 450nm tunable pulse type laser output.The laser pulse being transmitted into air, looked in the distance by receiving
The backscatter signal that mirror is collected and differentiated by photomultiplier detection range.Enter eventually through difference absorption spectrum analytic approach
Row data analysis, obtain NO in air2Concentration distribution.In the art, the atmospheric laser radar signal in different distance
It is to be parsed by the time of light pulse return laser light reception device or detector.This method light source, photodetection structure are answered
It is miscellaneous, stability is poor, with high costs, it is difficult to practical application.
First technology [2] (Shunxing Hu, et.al., " A new differential absorption lidar
for NO2measurements uing Raman-shifted technique,”Chinese Optics Letters 1(8)
435-437,2003) in, using Nd:YAG laser difference pumping D2And CH4The mode of gas cell, produce 395.60nm and
396.82nm pulse lasers export, and using similar to signal detection is carried out by the way of first technology [1], finally realize in air
NO2The detection of concentration distribution.But still there is light source in this method, photodetection is complicated, stability is poor, with high costs,
The problem of being difficult to practical application.
Utility model content
The utility model provides a kind of NO2The apparatus and method of concentration distribution detection, effectively overcome NO in background technology2It is dense
Degree distribution detects faced light source, photodetection is complicated, stability is poor, with high costs, it is difficult to the bottleneck such as practical application
Problem.
The technical solution of the utility model：
A kind of NO2Concentration distribution detection device, it is characterised in that the device include first laser device, second laser,
Half-wave plate, polarization spectroscope, laser beam emitting device, laser receiver, bandpass filter and imaging sensor, first laser device
90 degree of placements vertical with second laser, second laser make the polarization of the transmitting laser beam of second laser by half-wave plate
State is rotated by 90 °, and the polarization state of the transmitting laser beam of first laser device and second laser is vertical direction；First laser device
Light beam is synthesized via the polarization spectroscope of 45 degree of placements with the laser beam that second laser is sent, then is filled by Laser emission
It is transmitted into after putting collimation in air.
The backscatter signal for the laser beam being transmitted into air is collected via laser receiver, by bandpass filter
After piece filters out the atmospheric background signal, it is imaged onto on a tilted-putted imaging sensor；Meeting the bar of Sharpe image-forming principle
Under part, imaging sensor carries out blur-free imaging to the laser beam being transmitted into air, and different pixels correspond to different distance
Upper laser beam imaging, realize the Range resolution detection to the backscatter signal intensity of air.
Described imaging sensor, laser receiver and laser beam emitting device meets following relation：Imaging sensor institute
The optical axis position where plane, lens (or parabolic mirror etc.) the place plane of laser receiver and laser beam emitting device
Put (namely light path where transmitting light beam) three to intersect, meet Scheimpflug image-forming principles (Sharpe image-forming principle).
Described first laser device and second laser are diode laser, and its operation wavelength passes through temperature and driving electricity
Flow control, wavelength is respectively locked at NO2The larger and smaller part of absorption intensity, claims respectively on absorption line (300-600nm)
Be λonAnd λoffWavelength；λ is contrasted by analyzingonWavelength and λoffThe intensity P of the atmospheric backscatter optical signal of wavelengthon, Poff,
Calculate the NO in air2Concentration distribution.
Described laser beam emitting device is made up of lens or lens group.
The operation wavelength of the transmission peak wavelength of described bandpass filter and first laser device and second laser matches,
First laser device and second laser can be allowed to launch laser beam wavelength identical optical signal and pass through.
Described laser receiver is made up of lens or lens group, or is made up of reflective imaging system.
Described image sensor can be array image sensor or linear array image sensor.
The beneficial effects of the utility model：
The utility model NO2The apparatus and method of concentration distribution detection, using imaging sensor as photodetector, and
The distance point of the back scattering optical signal of the light beam to being transmitted into air is realized under conditions of Sharpe image-forming principle is met
Distinguish detection, it is very big to simplify system architecture, reduce system requirements.The bar of high-power nanosecond order light-pulse generator is not being needed
Under part, using continuous optical diode laser as light source, pass through adjustment work temperature so that its wavelength is located at NO respectively2's
On absworption peak and absorption paddy, the differential absorbing detection of Range resolution is realized.Using this technical scheme, system is greatly simplified
Structure, system cost is reduced, improve the stability of system.
Brief description of the drawings
Fig. 1 is that the geometrical relationship for needing to meet between laser beam emitting device, laser receiver and imaging sensor three is put down
Face figure, namely Sharpe image-forming principle schematic diagram.
Fig. 2 (a) is NO2Absorption spectra line chart of the gas in the range of 300-600nm；First laser device and second laser
Operation wavelength is located at NO2In the range of absorption spectra at different absorption intensities.
Fig. 2 (b) is NO2Gas absorption spectrum line partial enlarged drawing and λonAnd λoffWavelength relative position schematic diagram.First laser
The operation wavelength of device and second laser is located at NO2In the range of absorption spectra at different absorption intensities.
Fig. 3 is NO2The installation drawing of concentration distribution detection.
In figure：1 first laser device；2 second lasers；3 half-wave plates；4 polarization spectroscopes；
5 laser beam emitting devices；6 laser receivers；7 bandpass filters；8 imaging sensors.
Embodiment
Below in conjunction with the accompanying drawings and technical scheme, specific embodiment of the present utility model is further illustrated.
Embodiment
A kind of NO2The method of concentration distribution detection, step are as follows：
A, first laser device and the temperature and driving current of second laser are controlled, wavelength is output it and is locked in respectively
NO2Larger (the λ of absorption intensity on gas absorption spectrum lineon) and smaller part (λoff), the wavelength of first laser device and second laser
Design standard is：NO2Gas is in λonAnd λoffThere is different absorption intensities on two wavelength.
B, the output beam of first laser device and second laser is coupled into light beam by polarization spectroscope, this Shu Guang
Beam is transmitted among air after being collimated via laser beam emitting device.Wherein the polarization state of the output beam of second laser is by half-wave
Piece realizes 90 degree of rotations.
C, the driving current of second laser is arranged to 0 or less than operation threshold after, close second laser；Control the
One laser drive current launches laser beam to operation threshold is higher than, and the duration of laser beam is designated as T1, is transmitted into big
After first laser device laser beam in gas is via the particulate matter back scattering in air, collected by laser receiver, via
After bandpass filter filters out the atmospheric background signal, then photodetection realized by imaging sensor, the signal intensity that is recorded (if
For array image sensor, it is necessary to which the image pixel intensities that vertical direction is imaged with laser beam are added up) it is λonWavelength it is big
Gas backscatter signal intensity P1；
D, first laser device driving current is arranged to 0 or less than operation threshold after, close first laser device；Control second
Laser drive current launches laser beam, duration and the first laser in step C of laser beam to operation threshold is higher than
The launch time of device is identical (T1), and the second laser laser beam being transmitted into air dissipates backward via the particulate matter in air
After penetrating, collected by laser receiver, after filtering out the atmospheric background signal via bandpass filter, then light realized by imaging sensor
Electrical resistivity survey is surveyed, and the signal intensity recorded is (if array image sensor, it is necessary to the picture for vertical direction being imaged with laser beam
Plain intensity is added up) it is λoffThe atmospheric backscatter signal intensity P2 of wavelength.
E, first laser device driving current is arranged to 0 or less than operation threshold after, close first laser device；Second is swashed
Light device driving current be arranged to 0 or less than operation threshold after, close second laser；Laser receiver collects the atmospheric background letter
Number, imaging sensor gathers the atmospheric background signal, recorded to carry out photodetection with the identical time (T1) in step C
Signal intensity (if array image sensor, it is necessary to the image pixel intensities that vertical direction is imaged with laser beam are added up)
For P3；
F, P1-P3, P2-P3 are calculated and respectively obtains first laser device (λonWavelength) and second laser (λoffWavelength) it is big
Gas backscatter signal intensity PonAnd Poff。
G, repeat step C-F takes n times P to n times (N can be random natural number)onAnd PoffThe average value of signal is designated as respectively
Pon-avgAnd Poff-avg；
H, system calibration：System known fixed object of adjusting the distance is measured, and noted down by fixed object reflection
Laser beam is in the position of image sensor.According to geometry image-forming principle, image sensor pixel and measurement distance can be calculated
Between relation.
I, with reference to the relation between the image sensor and measurement distance obtained in step F, according to atmospheric laser radar side
Journey (such as formula 1 or its variation), can ask for NO2Gas concentration distribution C (z)：
Wherein, σ (λon) it is NO2Gas is in λonAbsorption cross-section or equivalent absorption section at wavelength, σ (λoff) it is NO2Gas
In λoffAbsorption cross-section or equivalent absorption section at wavelength, z is distance,It is the differentiating operator adjusted the distance.
Claims (5)
- A kind of 1. NO2The device of concentration distribution detection, it is characterised in that the device includes first laser device, second laser, half Wave plate, polarization spectroscope, laser beam emitting device, laser receiver, bandpass filter and imaging sensor, first laser device and The vertical 90 degree of placements of second laser, second laser make the polarization state of the transmitting laser beam of second laser by half-wave plate It is rotated by 90 °, the polarization state of the transmitting laser beam of first laser device and second laser is vertical direction；First laser device and The laser beam that second laser is sent synthesizes light beam via the polarization spectroscope of 45 degree of placements, then by laser beam emitting device It is transmitted into after collimation in air；The backscatter signal for the laser beam being transmitted into air is collected via laser receiver, is filtered by bandpass filter After the atmospheric background signal, it is imaged onto on a tilted-putted imaging sensor；Under conditions of Sharpe image-forming principle is met, Imaging sensor carries out blur-free imaging to the laser beam being transmitted into air, and different pixels correspond to laser in different distance Light beam is imaged, and realizes the Range resolution detection to the backscatter signal intensity of air.
- 2. device according to claim 1, it is characterised in that described imaging sensor, laser receiver and laser Emitter meets following relation：Plane, the lens place plane of laser receiver and Laser emission where imaging sensor Optical axis position three where device is intersected, and meets Sharpe image-forming principle.
- 3. device according to claim 2, it is characterised in that first laser device and second laser are diode laser Device, its operation wavelength are controlled by temperature and driving current, and wavelength is respectively locked at into NO2Absorption intensity is larger on absorption line And smaller part, it is referred to as λonAnd λoffWavelength；λ is contrasted by analyzingonWavelength and λoffThe atmospheric backscatter light letter of wavelength Number intensity Pon, Poff, calculate air NO2Concentration distribution.
- 4. device according to claim 3, it is characterised in that described laser beam emitting device is by lens or lens group structure Into；Described laser receiver is made up of lens, lens group or reflective imaging system.
- 5. device according to claim 4, it is characterised in that described imaging sensor is array image sensor or line Array image sensor.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108761486A (en) * | 2018-05-16 | 2018-11-06 | 大连理工大学 | New pattern laser radar system based on Scheimpflug principles |
| WO2021122885A1 (en) | 2019-12-20 | 2021-06-24 | Centre National De La Recherche Scientifique (Cnrs) | System and method for detecting and quantifying gaseous constituents in the atmosphere |
| CN113075684A (en) * | 2021-04-06 | 2021-07-06 | 浙江师范大学 | Novel Sas atmosphere laser radar based on TDLAS technology |
-
2017
- 2017-06-05 CN CN201720641036.7U patent/CN206740648U/en active Active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108761486A (en) * | 2018-05-16 | 2018-11-06 | 大连理工大学 | New pattern laser radar system based on Scheimpflug principles |
| CN108761486B (en) * | 2018-05-16 | 2021-02-19 | 泛测（北京）环境科技有限公司 | Laser radar system based on Scheimpflug principle |
| WO2021122885A1 (en) | 2019-12-20 | 2021-06-24 | Centre National De La Recherche Scientifique (Cnrs) | System and method for detecting and quantifying gaseous constituents in the atmosphere |
| CN113075684A (en) * | 2021-04-06 | 2021-07-06 | 浙江师范大学 | Novel Sas atmosphere laser radar based on TDLAS technology |
| CN113075684B (en) * | 2021-04-06 | 2023-09-19 | 浙江师范大学 | Novel sand's atmosphere laser radar based on TDLAS technology |
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