CN110749872A - Coherent differential absorption laser radar and method for detecting gas concentration - Google Patents
Coherent differential absorption laser radar and method for detecting gas concentration Download PDFInfo
- Publication number
- CN110749872A CN110749872A CN201810813114.6A CN201810813114A CN110749872A CN 110749872 A CN110749872 A CN 110749872A CN 201810813114 A CN201810813114 A CN 201810813114A CN 110749872 A CN110749872 A CN 110749872A
- Authority
- CN
- China
- Prior art keywords
- laser
- signal
- transmitted
- light
- transmitting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000010521 absorption reaction Methods 0.000 title claims abstract description 66
- 230000001427 coherent effect Effects 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims description 19
- 238000001514 detection method Methods 0.000 claims abstract description 37
- 238000012545 processing Methods 0.000 claims abstract description 19
- 230000010355 oscillation Effects 0.000 claims abstract description 11
- 230000035559 beat frequency Effects 0.000 claims description 20
- 239000013307 optical fiber Substances 0.000 claims description 4
- 230000035945 sensitivity Effects 0.000 abstract description 5
- 230000005855 radiation Effects 0.000 abstract description 4
- 239000007789 gas Substances 0.000 description 56
- 238000010586 diagram Methods 0.000 description 7
- 238000000862 absorption spectrum Methods 0.000 description 6
- 238000001228 spectrum Methods 0.000 description 4
- 230000003321 amplification Effects 0.000 description 3
- 230000008033 biological extinction Effects 0.000 description 3
- 238000000295 emission spectrum Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000003199 nucleic acid amplification method Methods 0.000 description 3
- 230000003595 spectral effect Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- 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
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/88—Lidar systems specially adapted for specific applications
Abstract
The invention provides a coherent differential absorption laser radar, comprising: the device comprises a first adjustable continuous wave laser, a second adjustable continuous wave laser, a beam splitter, an acousto-optic modulator, a laser amplifier, a circulator, a transmitting and receiving telescope, a coupler, a balance detector, a collecting card and a digital signal processing system. The invention determines two required laser wavelengths by selecting a proper absorption line of a gas molecule to be detected in the middle infrared, then divides a local oscillation light and a signal light by a beam splitter, and finally performs frequency combination respectively by a coupler and adopts a balance detector for detection to obtain the concentration of the gas molecule. The detection sensitivity is improved due to the higher absorption section coefficient and smaller background radiation of the middle infrared part gas, the direct detection is replaced by coherent detection, the influence of low quantum efficiency on the detection precision is reduced, the utilization rate of echo signals is improved, and the performance of the differential absorption laser radar is improved.
Description
Technical Field
The invention relates to the technical field of laser radars, in particular to a coherent differential absorption laser radar and a method for detecting gas concentration.
Background
The laser radar technology has attracted wide attention from the birth of lasers, and is applied to military, meteorological and atmospheric monitoring and other aspects by virtue of the characteristics of strong anti-interference capability, high precision and the like. Laser radars of different structures and different purposes are emerging continuously. The differential absorption radar is an important application of the laser radar, and the differential absorption radar is applied to a plurality of aspects such as atmospheric pollutant monitoring at present.
Most gas molecules have characteristic absorption lines, and a dark line left in the spectrum due to selective absorption of the gas molecules is an absorption line. The air pollution detection by differential absorption laser radar selects the wavelength of the characteristic absorption spectrum line of the gas molecule to be detected as the wavelength lambda of the emitted laseronWhen the laser beam with the wavelength is transmitted in the atmosphere, the laser beam and gas molecules generate strong resonance absorption and attenuate, and the concentration information of the gas in the atmosphere can be inverted by measuring the attenuation degree of the laser beam. In order to eliminate the influence of other substances in the atmosphere and factors such as the absorption of optical instruments on the wavelength and instrument parameters on the measurement precision, the wavelength lambda which is very close to the central wavelength of the absorption line of the gas to be measured and just shifts out of the absorption line is also required to be selectedoffThe principle of synchronous measurement as a reference beam is called differential absorption principle.
Two beams of laser lambda with different wavelengthsonAnd λoffThe equation for the echo detected after passing through the atmosphere is:
in the formula Pon/of(fR) is the received echo power from the R-R + Δ R high atmospheric segment, P0(lambda) is the power of the transmitted laser beam,. DELTA.R is the range resolution, k (lambda) is the system receiving efficiency constant, R is the detection distance, A is the effective area of the receiving telescope, β is the backscattering coefficient of the probe light in the atmosphere, α (lambda, R) is the extinction coefficient except for the gas to be measured, N (R) is the concentration of the gas to be measured, and σ (lambda) is the corresponding absorption cross-section, sinceλonAnd λoffClose, approximate is β (lambda)on)＝β(λof)f，α(λon,r)＝α(λoff,r)，k(λon)＝k(λoff). The formula (1) and the formula (2) are divided (i.e. the main factor of atmospheric change is eliminated), and logarithm and differential operation are performed on two sides to obtain an expression for calculating the concentration of the gas to be measured, wherein the expression is as follows:
in classical differentially absorbing radars, λonCorresponding to the peak, λ, of the absorption spectrum of the gas to be measuredoffCorresponding to the valleys of the absorption spectrum of the gas to be measured. In practice, for gases with infrared absorption spectra, the spectral lines are very narrow (0.2 cm)-1)，λonAnd λoffMay correspond to the same wavelength, but the bandwidth of the emission spectrum differs significantly, e.g. λ on1/10(0.02 cm) with light emission spectrum width smaller than or equal to the absorption spectrum line width of the gas to be measured-1) It is strongly absorbed; and λoffThe light emission spectrum width is more than 10 times (2 cm) of the absorption spectrum line width-1) It is absorbed very little, i.e. the effective absorption cross section is small.
Laser radars can be classified into coherent detection and direct detection according to the detection principle. Coherent detection amplifies weak signals in a mode of coherent beat frequency of laser atmosphere echo signals and local oscillator laser, and then processes beat frequency signals subsequently to achieve detection concentration. Direct detection utilizes a frequency discriminator to convert Doppler shift information into relative change of energy so as to detect the atmospheric wind speed. In the edge technology, besides the two interferometers, high-resolution frequency discriminators such as a molecular absorption line interferometer, a Michelson interferometer, a grating, a prism, a Mach-Zehnder interferometer and the like can be adopted. In the infrared band, the application of direct detection in the mid-infrared band is limited due to the low quantum efficiency of the photoelectric detector made of the existing material. In coherent detection, due to the amplification effect of the local oscillation light, the device has higher quantum efficiency, higher sensitivity, better performance and better measurement precision. Therefore, the coherent differential absorption laser radar in the middle infrared band is provided to realize accurate detection of gas.
Disclosure of Invention
The invention aims to provide a coherent differential absorption laser radar and a method for detecting gas concentration by using the coherent differential absorption laser radar.
In view of the above, the present application provides a coherent differential absorption lidar comprising: the device comprises a first adjustable continuous wave laser, a second adjustable continuous wave laser, a beam splitter, an acousto-optic modulator, a laser amplifier, a circulator, a transmitting and receiving telescope, a coupler, a balance detector, an acquisition card and a digital signal processing system;
the first tunable continuous wave laser is used for emitting a laser beam with a wavelength of lambdaonThe second tunable continuous wave laser is used for emitting the first laser with the wavelength of lambdaoffThe wavelength of the first laser and the lambda of the gas to be measuredonThe wavelength is the same, and the second laser wavelength is the same as the lambda of the gas to be measuredoffThe wavelengths are the same;
the first laser and the second laser are simultaneously transmitted to the beam splitter, signal light of the beam splitter is transmitted to the acousto-optic modulator, pulse light of the acousto-optic modulator is transmitted to the laser amplifier, an amplified signal of the laser amplifier is transmitted to the circulator, a signal of the circulator is transmitted to the transmitting and receiving telescope, an echo signal of the transmitting and receiving telescope is transmitted to the circulator, a signal of the circulator and local oscillator light of the beam splitter are transmitted to the coupler, a beat frequency signal of the coupler is transmitted to the balance detector, a signal of the balance detector is transmitted to the acquisition card, and a signal of the acquisition card is transmitted to the digital signal processing system.
Preferably, the first laser, the second laser, the signal light, the pulsed light, the amplified signal, the echo signal, the local oscillator light, the beat signal, and the signal may be transmitted through a carrier.
Preferably, the carrier is one or both of an optical fiber and space light.
The application also provides a method for detecting the gas concentration by using the coherent differential absorption laser radar, which comprises the following steps:
the wavelength of the gas to be measured emitted from the first tunable continuous wave laser is lambdaonThe wavelength of the gas to be measured emitted from the second tunable continuous wave laser is lambdaoffTwo laser beams emit local oscillation light and signal light through the beam splitter;
transmitting the signal light to an acousto-optic modulator to be modulated into pulse light, transmitting the pulse light to a laser amplifier, and amplifying the energy into an amplified signal; the amplified signal is transmitted to a transmitting and receiving telescope through a circulator and is transmitted to the atmosphere to act on the atmosphere, and a backscattering signal is obtained;
receiving the backward scattering signal by a transmitting and receiving telescope to form an echo signal, and transmitting the echo signal and the local oscillator light to a coupler for beat frequency through a circulator to form a beat frequency signal;
and transmitting the beat frequency signal to a balance detector for detection, and then sequentially processing the beat frequency signal by a collecting card and a digital signal processing system to obtain the concentration of the gas to be detected.
Preferably, the method is used for detecting gas in a middle infrared band of 3.0-10.6 microns.
Preferably, the gas to be detected is CO2、SO2Or CH4。
The application provides a coherent differential absorption lidar, it includes: the device comprises a first adjustable continuous wave laser, a second adjustable continuous wave laser, a beam splitter, an acousto-optic modulator, a laser amplifier, a circulator, a transmitting and receiving telescope, a coupler, a balance detector, an acquisition card and a digital signal processing system; the coherent gas concentration detection mode is realized by utilizing the beam splitter, the coupler and the balance detector, the detection mode is obtained through a difference frequency signal of local oscillation light and signal light, and a middle infrared detector is not needed, so that the sensitivity of gas concentration detection is improved; on the other hand, the gas concentration is detected in a wave band of 3-10.6 μm, the solar background radiation is low in the wave band, and the absorption section coefficient of each gas molecule is high, so that the gas detection with higher precision can be realized.
Drawings
FIG. 1 is a schematic connection diagram of a 3.0-10.6 μm coherent differential absorption laser radar according to the present invention;
FIG. 2 is a simulated initial signal of a coherent differential absorption lidar in accordance with the present invention;
FIG. 3 is a coherent inversion power spectrum of a coherent differential absorption lidar according to the present invention;
FIG. 4 is a CNR diagram corresponding to the coherent differential absorption laser radar provided by the present invention;
FIG. 5 shows CO2Absorption profile from 760nm to 6000 nm;
FIG. 6 shows SO2Absorption profile from 760nm to 6000 nm;
FIG. 7 is CH4Absorption profile from 760nm to 6000 nm.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
The invention provides a coherent differential absorption laser radar, aiming at a method for detecting gas concentration by using a traditional differential absorption laser radar, wherein the coherent differential absorption laser radar is used for detecting gas concentration and has higher sensitivity; specifically, the embodiment of the invention discloses a coherent differential absorption laser radar, which comprises: the device comprises a first adjustable continuous wave laser, a second adjustable continuous wave laser, a beam splitter, an acousto-optic modulator, a laser amplifier, a circulator, a transmitting and receiving telescope, a coupler, a balance detector, an acquisition card and a digital signal processing system;
the first tunable continuous wave laser is used for emitting a laser beam with a wavelength of lambdaonThe second tunable continuous wave laser is used for emitting the first laser with the wavelength of lambdaoffThe wavelength of the first laser and the lambda of the gas to be measuredonThe wavelength is the same as that of the second laser wavelengthLambda of gasoffThe wavelengths are the same;
the first laser and the second laser are simultaneously transmitted to the beam splitter, signal light of the beam splitter is transmitted to the acousto-optic modulator, pulse light of the acousto-optic modulator is transmitted to the laser amplifier, an amplified signal of the laser amplifier is transmitted to the circulator, a signal of the circulator is transmitted to the transmitting and receiving telescope, an echo signal of the transmitting and receiving telescope is transmitted to the circulator, a signal of the circulator and local oscillator light of the beam splitter are transmitted to the coupler, a beat frequency signal of the coupler is transmitted to the balance detector, a signal of the balance detector is transmitted to the acquisition card, and a signal of the acquisition card is transmitted to the digital signal processing system.
As shown in fig. 1, fig. 1 is a schematic connection diagram of a coherent differential absorption lidar of the present application, where (1) is a first tunable continuous wave laser, (2) is a second tunable continuous wave laser, (3) is a beam splitter, (4) is an acousto-optic modulator, (5) is a laser amplifier, (6) is a circulator, (7) is a transmitting-receiving telescope, (8) is a coupler, (9) is a balanced detector, (10) is an acquisition card, and (11) is a digital signal processing system, which are all devices conventional in the art, in the present application, the beam splitter (3), the coupler (8), and the balanced detector (9) are used in coherent detection for the first time, a coherent detection method composed of the beam splitter (3), the coupler (8), and the balanced detector (9) is used, the beam splitter divides laser light into local oscillator light and signal light, and backscattered light and local oscillator light after the signal light exits to the atmosphere beats at the coupler, by detecting with a balanced detector, the gas concentration is obtained through coherent detection, and the precision is improved.
In the coherent differential absorption lidar, the transmission of signals or laser can be directly transmitted in a space light mode, can also be transmitted in an optical fiber mode, and can also be transmitted in a mode of combining the two carriers; the optical fiber is well known to those skilled in the art, and the present application is not particularly limited thereto.
The application also provides a method for detecting gas concentration by using the coherent differential absorption laser radar, which specifically comprises the following steps:
the wavelength of the gas to be measured emitted from the first tunable continuous wave laser is lambdaonThe wavelength of the gas to be measured emitted from the second tunable continuous wave laser is lambdaoffTwo laser beams emit local oscillation light and signal light through the beam splitter;
transmitting the signal light to an acousto-optic modulator to be modulated into pulse light, transmitting the pulse light to a laser amplifier, and amplifying the energy into an amplified signal; the amplified signal is transmitted to a transmitting and receiving telescope through a circulator and is transmitted to the atmosphere to act on the atmosphere, and a backscattering signal is obtained;
receiving the backward scattering signal by a transmitting and receiving telescope to form an echo signal, and transmitting the echo signal and the local oscillator light to a coupler for beat frequency through a circulator to form a beat frequency signal;
and transmitting the beat frequency signal to a balance detector for detection, and then sequentially processing the beat frequency signal by a collecting card and a digital signal processing system to obtain the concentration of the gas to be detected.
The gas detection is carried out in the intermediate infrared band of 3.0-10.6 microns, a plurality of molecular absorption spectral lines with larger absorption section coefficients exist in the band, detection of more trace gases can be realized, and the detectability is better. FIG. 5 shows CO2Absorption characteristic diagram from 760nm to 6000nm, and SO in FIG. 62Absorption profile from 760nm to 6000nm, FIG. 7 is CH4From the absorption characteristic diagram of 760nm to 6000nm, SO is shown2The absorption cross-sectional coefficient at 4.0 μm is 100 times that at 2.5 μm, CO2The absorption cross-sectional coefficient at 4.3 μm is 100 times that at 2.7 μm, 1000 times that at 2.0 μm, 10000 or more at 4.8 μm, CH4The absorption section coefficient at 3.3 μm is 100 times that at 2.4 μm and 1.6 μm; therefore, the detection method provided by the application can realize detection on all gases in mid-infrared bands, and has higher sensitivity in the bands by utilizing coherent differential absorption laser radar to detect the gases.
In the specific process of detecting the gas concentration, the method firstly emits lambda from the adjustable continuous wave lasers (1) and (2) respectivelyonAnd λoffTwo lasers of different wavelengths, whereinonSelected within the absorption peak of the gas molecule, lambdaoffThe gas concentration is detected by the two lasers with different wavelengths outside the absorption peak of the gas molecule, so that the gas concentration detection accuracy is high. As shown in fig. 2, fig. 2 is a diagram of an initial signal of the simulation. The two beams of laser with different wavelengths are divided into local oscillator light and signal light through the beam splitter, and the local oscillator light, the signal light, the subsequent signal and the laser are two beams.
According to the invention, after the local oscillator light and the signal light are obtained, the signal light is modulated into pulse light through the acoustic optical modulator, then the pulse light with two wavelengths is subjected to energy amplification through the laser amplifier, and is input into the transmitting and receiving telescope through the circulator to be transmitted to the atmosphere, and the laser light emitted from the transmitting and receiving telescope is subjected to the action of the atmosphere to obtain a back scattering signal which is received by the transmitting and receiving telescope. Because the absorption cross sections of the two laser beams with different wavelengths are different, two different echo signals can be generated after atmospheric extinction, and the obtained echo signals are used as the basis of calculation to calculate the gas concentration.
The echo signals are transmitted to the coupler through the circulator, meanwhile, the two laser local oscillation lights with different wavelengths beat frequencies with the corresponding echo signals respectively, the two beat frequency signals enter the balance detector to be detected, and finally, the two beat frequency signals are processed through the acquisition card and the digital signal processing system, and inversion of the molecular concentration is achieved through coherence. Fig. 3 is a power spectrum of coherent inversion, and fig. 4 is a corresponding CNR diagram, from which the gas concentration is obtained by the calculation of equation (3).
The invention determines two required laser wavelengths by selecting a proper absorption line of a gas molecule to be detected in the middle infrared, then divides local oscillation light and signal light by a beam splitter, respectively combines frequencies by a coupler, and detects by a balance detector. Compare traditional differential absorption lidar, the coherent differential absorption lidar main advantage that this application provided is: (1) a plurality of molecular absorption spectral lines with larger absorption section coefficients exist in the wavelength range of 3.0-10.6 microns, so that more trace gases can be detected, and the detection performance is better; (2) according to the solar radiation spectrum, the solar background radiation in the middle infrared band is small, and the gas detection is more accurate; (3) the system is safe for human eyes by using invisible infrared light of human eyes, compared with ultraviolet light and visible light wave bands; (4) the coherent detection is used, the direct detection is relatively carried out, the structure is simple, and the cost is low.
For further understanding of the present invention, the method for detecting gas concentration by coherent differential absorption lidar provided by the present invention is described in detail below with reference to the following examples, and the scope of the present invention is not limited by the following examples.
Examples
A coherent differential absorption laser radar based on 3.0-10.6 μm, comprising: adjustable continuous wave lasers (1) and (2), a beam splitter (3), an acousto-optic modulator (AOM) (4), a laser amplifier (amplifier) (5), a circulator (circular) (6), a transmitting and receiving telescope (7), a coupler (8), a balance detector (9), an acquisition card (10) and a digital signal processing system (11); the adjustable continuous wave lasers (1) and (2) are connected with a beam splitter (3), the beam splitter divides laser into local oscillation light and emergent laser, and the emergent laser is connected with an acousto-optic modulator (4); the acousto-optic modulator (4) is connected with a laser amplifier (5), the laser amplifier (5) is connected with a circulator (6), the circulator (6) is connected with a transmitting and receiving telescope (7), a signal returned by the transmitting and receiving telescope (7) is connected with a coupler (8) through the circulator (6), the coupler (8) is connected with a balance detector (9), the balance detector (9) is connected with an acquisition card (10), and the acquisition card (10) is connected with a digital signal processing system (11);
the method comprises the following specific steps:
the method comprises the following steps: the adjustable continuous wave lasers (1) and (2) respectively emit lambdaon、λoffThe laser with two different wavelengths is divided into local oscillation light and signal light by a beam splitter (3); signal light is modulated into pulse light through the AOM (4), energy amplification is carried out on the two wavelengths through the amplifier (5), and the pulse light is input into the transmitting and receiving telescope (7) through the circulator (6) and is transmitted into the atmosphere;
step two: emergent laser is acted by atmosphere, an obtained backscattering signal is received by a transmitting-receiving telescope (7), two different echo signals can be generated after atmospheric extinction due to different absorption sections of two lasers with different wavelengths, the echo signals pass through a circulator (6) and a coupler (8), the two laser local oscillation lights with different wavelengths beat with the corresponding echo signals respectively, the two beat signals enter a balance detector (9) for detection, and finally the two beat signals are processed by an acquisition card (10) and a digital signal processing system (11), and inversion of gas molecule concentration is realized through coherence, so that the gas concentration is obtained.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (6)
1. A coherent differential absorption lidar comprising: the device comprises a first adjustable continuous wave laser, a second adjustable continuous wave laser, a beam splitter, an acousto-optic modulator, a laser amplifier, a circulator, a transmitting and receiving telescope, a coupler, a balance detector, an acquisition card and a digital signal processing system;
the first tunable continuous wave laser is used for emitting a laser beam with a wavelength of lambdaonThe second tunable continuous wave laser is used for emitting the first laser with the wavelength of lambdaoffThe wavelength of the first laser and the lambda of the gas to be measuredonThe wavelength is the same, and the second laser wavelength is the same as the lambda of the gas to be measuredoffThe wavelengths are the same;
the first laser and the second laser are simultaneously transmitted to the beam splitter, signal light of the beam splitter is transmitted to the acousto-optic modulator, pulse light of the acousto-optic modulator is transmitted to the laser amplifier, an amplified signal of the laser amplifier is transmitted to the circulator, a signal of the circulator is transmitted to the transmitting and receiving telescope, an echo signal of the transmitting and receiving telescope is transmitted to the circulator, a signal of the circulator and local oscillator light of the beam splitter are transmitted to the coupler, a beat frequency signal of the coupler is transmitted to the balance detector, a signal of the balance detector is transmitted to the acquisition card, and a signal of the acquisition card is transmitted to the digital signal processing system.
2. The coherent differential absorption lidar of claim 1, wherein the first laser, the second laser, the signal light, the pulsed light, the amplified signal, the echo signal, the local oscillator light, the beat signal, and the signal are transmittable over a carrier.
3. The coherent differential absorption lidar of claim 2, wherein the carrier is one or both of an optical fiber and spatial light.
4. A method for detecting gas concentration using the coherent differential absorption lidar according to any of claims 1 to 3, comprising the steps of:
the wavelength of the gas to be measured emitted from the first tunable continuous wave laser is lambdaonThe wavelength of the gas to be measured emitted from the second tunable continuous wave laser is lambdaoffTwo laser beams emit local oscillation light and signal light through the beam splitter;
transmitting the signal light to an acousto-optic modulator to be modulated into pulse light, transmitting the pulse light to a laser amplifier, and amplifying the energy into an amplified signal; the amplified signal is transmitted to a transmitting and receiving telescope through a circulator and is transmitted to the atmosphere to act on the atmosphere, and a backscattering signal is obtained;
receiving the backward scattering signal by a transmitting and receiving telescope to form an echo signal, and transmitting the echo signal and the local oscillator light to a coupler for beat frequency through a circulator to form a beat frequency signal;
and transmitting the beat frequency signal to a balance detector for detection, and then sequentially processing the beat frequency signal by a collecting card and a digital signal processing system to obtain the concentration of the gas to be detected.
5. The method of claim 4, wherein the method performs gas detection in the mid-infrared band of 3.0 μm to 10.6 μm.
6. The method of claim 4, wherein the gas to be measured is CO2、SO2Or CH4。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810813114.6A CN110749872A (en) | 2018-07-23 | 2018-07-23 | Coherent differential absorption laser radar and method for detecting gas concentration |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810813114.6A CN110749872A (en) | 2018-07-23 | 2018-07-23 | Coherent differential absorption laser radar and method for detecting gas concentration |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN110749872A true CN110749872A (en) | 2020-02-04 |
Family
ID=69275097
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810813114.6A Pending CN110749872A (en) | 2018-07-23 | 2018-07-23 | Coherent differential absorption laser radar and method for detecting gas concentration |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110749872A (en) |
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112268871A (en) * | 2020-11-24 | 2021-01-26 | 西南技术物理研究所 | Method for simultaneously measuring concentration of various polluted gases in atmosphere |
| CN112285741A (en) * | 2020-09-25 | 2021-01-29 | 中国科学院上海技术物理研究所 | Composition of micro-pulse laser radar for detecting troposphere atmospheric temperature vertical profile |
| CN112630746A (en) * | 2020-12-01 | 2021-04-09 | 北京遥感设备研究所 | Pulse Doppler laser radar for long-distance target measurement |
| CN112924985A (en) * | 2021-03-16 | 2021-06-08 | 中国科学技术大学 | Mixed type laser radar for Mars atmosphere detection |
| CN113109838A (en) * | 2021-04-23 | 2021-07-13 | 北京聚恒博联科技有限公司 | Coherent wind lidar capable of carrying out water vapor differential absorption measurement |
| CN113433570A (en) * | 2021-07-15 | 2021-09-24 | 北京遥测技术研究所 | Atmospheric carbon dioxide concentration detection differential absorption laser radar system |
| CN113721226A (en) * | 2021-08-31 | 2021-11-30 | 深圳市镭神智能系统有限公司 | Frequency modulation continuous wave laser radar |
| CN114578319A (en) * | 2022-05-06 | 2022-06-03 | 武汉镭晟科技有限公司 | Fiber laser module for free space gas remote sensing laser radar |
| CN114637030A (en) * | 2022-05-18 | 2022-06-17 | 南京信息工程大学 | Dual-polarization receiving gas detection laser radar and gas detection method |
| CN115015966A (en) * | 2022-08-04 | 2022-09-06 | 南京信息工程大学 | Gas detection laser radar based on wide-spectrum light source |
| CN115128639A (en) * | 2022-09-01 | 2022-09-30 | 中国科学技术大学 | Differential absorption laser radar capable of adjusting seed optical power in real time |
| CN115290599A (en) * | 2022-10-08 | 2022-11-04 | 青岛镭测创芯科技有限公司 | Laser radar system for measuring concentration of greenhouse gas |
| CN115356281A (en) * | 2022-10-20 | 2022-11-18 | 哈尔滨翰奥科技有限公司 | Mixed gas multi-parameter measurement method based on infrared broadband light source |
| JP7205010B1 (en) * | 2022-06-20 | 2023-01-16 | 三菱電機株式会社 | Lidar with wavelength locking |
| CN116609796A (en) * | 2023-07-20 | 2023-08-18 | 青岛镭测创芯科技有限公司 | Water vapor coherent differential absorption laser radar system |
| WO2023174165A1 (en) * | 2022-03-18 | 2023-09-21 | 华为技术有限公司 | Coherent receiving device, coherent transmitting device and coherent communication system |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060011840A1 (en) * | 2002-09-10 | 2006-01-19 | Bryce David J | Coherent differential absorption lidar (dial) |
| CN1918466A (en) * | 2003-12-19 | 2007-02-21 | Itt制造企业公司 | System and method for remote quantitative detection of fluid leaks from a natural gas or oil pipeline |
| CN101493406A (en) * | 2008-11-04 | 2009-07-29 | 中国人民解放军电子工程学院 | Atmospheric air carbon dioxide long distance laser coherent detecting device based on differential absorption |
| CN103946716A (en) * | 2011-12-21 | 2014-07-23 | 三菱电机株式会社 | Laser radar device |
| CN104237898A (en) * | 2014-10-07 | 2014-12-24 | 西南石油大学 | Natural gas leakage telemetering laser radar |
| CN104596996A (en) * | 2015-01-06 | 2015-05-06 | 香港理工大学深圳研究院 | Gas detection method and gas detection system based on hollow-core optical fiber photothermal effect |
| CN105334519A (en) * | 2015-09-12 | 2016-02-17 | 盐城师范学院 | Laser radar system for simultaneously detecting multiple atmospheric parameters at high precision on the basis of three-channel F-P etalon |
| CN106970392A (en) * | 2017-05-31 | 2017-07-21 | 南京先进激光技术研究院 | High sensitivity gaseous contamination detecting laser radar system |
| CN107807367A (en) * | 2017-11-02 | 2018-03-16 | 南京牧镭激光科技有限公司 | A kind of coherent wind laser radar apparatus |
| CN108088801A (en) * | 2017-12-07 | 2018-05-29 | 电子科技大学 | Laser NDT device based on 90 ° of optical mixer units |
-
2018
- 2018-07-23 CN CN201810813114.6A patent/CN110749872A/en active Pending
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060011840A1 (en) * | 2002-09-10 | 2006-01-19 | Bryce David J | Coherent differential absorption lidar (dial) |
| CN1918466A (en) * | 2003-12-19 | 2007-02-21 | Itt制造企业公司 | System and method for remote quantitative detection of fluid leaks from a natural gas or oil pipeline |
| CN101493406A (en) * | 2008-11-04 | 2009-07-29 | 中国人民解放军电子工程学院 | Atmospheric air carbon dioxide long distance laser coherent detecting device based on differential absorption |
| CN103946716A (en) * | 2011-12-21 | 2014-07-23 | 三菱电机株式会社 | Laser radar device |
| CN104237898A (en) * | 2014-10-07 | 2014-12-24 | 西南石油大学 | Natural gas leakage telemetering laser radar |
| CN104596996A (en) * | 2015-01-06 | 2015-05-06 | 香港理工大学深圳研究院 | Gas detection method and gas detection system based on hollow-core optical fiber photothermal effect |
| CN105334519A (en) * | 2015-09-12 | 2016-02-17 | 盐城师范学院 | Laser radar system for simultaneously detecting multiple atmospheric parameters at high precision on the basis of three-channel F-P etalon |
| CN106970392A (en) * | 2017-05-31 | 2017-07-21 | 南京先进激光技术研究院 | High sensitivity gaseous contamination detecting laser radar system |
| CN107807367A (en) * | 2017-11-02 | 2018-03-16 | 南京牧镭激光科技有限公司 | A kind of coherent wind laser radar apparatus |
| CN108088801A (en) * | 2017-12-07 | 2018-05-29 | 电子科技大学 | Laser NDT device based on 90 ° of optical mixer units |
Non-Patent Citations (2)
| Title |
|---|
| 文东旭等: "红外激光外差气体分析仪信号分析", 《光学学报》 * |
| 陶小红等: "大气CO2相干探测激光雷达系统性能分析", 《量子电子学报》 * |
Cited By (27)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112285741B (en) * | 2020-09-25 | 2022-07-08 | 中国科学院上海技术物理研究所 | Micro-pulse laser radar for detecting vertical profile of troposphere atmospheric temperature |
| CN112285741A (en) * | 2020-09-25 | 2021-01-29 | 中国科学院上海技术物理研究所 | Composition of micro-pulse laser radar for detecting troposphere atmospheric temperature vertical profile |
| CN112268871B (en) * | 2020-11-24 | 2024-01-26 | 西南技术物理研究所 | Method for simultaneously measuring concentration of various polluted gases in atmosphere |
| CN112268871A (en) * | 2020-11-24 | 2021-01-26 | 西南技术物理研究所 | Method for simultaneously measuring concentration of various polluted gases in atmosphere |
| CN112630746A (en) * | 2020-12-01 | 2021-04-09 | 北京遥感设备研究所 | Pulse Doppler laser radar for long-distance target measurement |
| CN112630746B (en) * | 2020-12-01 | 2023-09-15 | 北京遥感设备研究所 | Pulse Doppler laser radar for measuring long-distance target |
| CN112924985A (en) * | 2021-03-16 | 2021-06-08 | 中国科学技术大学 | Mixed type laser radar for Mars atmosphere detection |
| CN112924985B (en) * | 2021-03-16 | 2023-11-17 | 中国科学技术大学 | Mixed laser radar for Mars atmospheric detection |
| CN113109838A (en) * | 2021-04-23 | 2021-07-13 | 北京聚恒博联科技有限公司 | Coherent wind lidar capable of carrying out water vapor differential absorption measurement |
| CN113433570A (en) * | 2021-07-15 | 2021-09-24 | 北京遥测技术研究所 | Atmospheric carbon dioxide concentration detection differential absorption laser radar system |
| CN113433570B (en) * | 2021-07-15 | 2022-11-01 | 北京遥测技术研究所 | Atmospheric carbon dioxide concentration detection differential absorption laser radar system |
| CN113721226A (en) * | 2021-08-31 | 2021-11-30 | 深圳市镭神智能系统有限公司 | Frequency modulation continuous wave laser radar |
| WO2023174165A1 (en) * | 2022-03-18 | 2023-09-21 | 华为技术有限公司 | Coherent receiving device, coherent transmitting device and coherent communication system |
| CN114578319B (en) * | 2022-05-06 | 2022-08-09 | 武汉镭晟科技有限公司 | Fiber laser module for free space gas remote sensing laser radar |
| CN114578319A (en) * | 2022-05-06 | 2022-06-03 | 武汉镭晟科技有限公司 | Fiber laser module for free space gas remote sensing laser radar |
| CN114637030A (en) * | 2022-05-18 | 2022-06-17 | 南京信息工程大学 | Dual-polarization receiving gas detection laser radar and gas detection method |
| WO2023248265A1 (en) * | 2022-06-20 | 2023-12-28 | 三菱電機株式会社 | Lidar having wavelength lock function |
| JP7205010B1 (en) * | 2022-06-20 | 2023-01-16 | 三菱電機株式会社 | Lidar with wavelength locking |
| CN115015966A (en) * | 2022-08-04 | 2022-09-06 | 南京信息工程大学 | Gas detection laser radar based on wide-spectrum light source |
| CN115015966B (en) * | 2022-08-04 | 2022-10-28 | 南京信息工程大学 | Gas detection laser radar based on wide-spectrum light source |
| CN115128639A (en) * | 2022-09-01 | 2022-09-30 | 中国科学技术大学 | Differential absorption laser radar capable of adjusting seed optical power in real time |
| CN115290599B (en) * | 2022-10-08 | 2023-01-24 | 青岛镭测创芯科技有限公司 | Laser radar system for measuring concentration of greenhouse gas |
| CN115290599A (en) * | 2022-10-08 | 2022-11-04 | 青岛镭测创芯科技有限公司 | Laser radar system for measuring concentration of greenhouse gas |
| CN115356281B (en) * | 2022-10-20 | 2023-02-07 | 中国科学院新疆理化技术研究所 | Mixed gas multi-parameter measurement method based on infrared broadband light source |
| CN115356281A (en) * | 2022-10-20 | 2022-11-18 | 哈尔滨翰奥科技有限公司 | Mixed gas multi-parameter measurement method based on infrared broadband light source |
| CN116609796A (en) * | 2023-07-20 | 2023-08-18 | 青岛镭测创芯科技有限公司 | Water vapor coherent differential absorption laser radar system |
| CN116609796B (en) * | 2023-07-20 | 2023-11-10 | 青岛镭测创芯科技有限公司 | Water vapor coherent differential absorption laser radar system |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110749872A (en) | Coherent differential absorption laser radar and method for detecting gas concentration | |
| US10866319B2 (en) | Stray-light tolerant lidar measurement system and stray-light tolerant lidar measurement method | |
| CN106772438B (en) | A kind of laser radar system of round-the-clock accurate measurement atmospheric temperature and aerosol parameters | |
| US7349094B2 (en) | Laser radar apparatus having multiple output wavelengths | |
| JP2008002815A (en) | Wavelength variable pulse light generator, and optical tomographic measuring instrument using the same | |
| WO2021000359A1 (en) | Dispersion gating-based atmospheric composition measurement laser radar | |
| CN110441792B (en) | Rayleigh scattering laser radar system capable of measuring wind and temperature simultaneously and related calibration method | |
| CN107290063B (en) | Seawater temperature measuring method and system | |
| CN111122500A (en) | Gas concentration remote sensing detection device and method based on coherent detection method | |
| CN105974396A (en) | Speed measurement method and system based on double etalons | |
| JP4018799B2 (en) | Method and apparatus for measuring concentration of absorption component of scattering medium | |
| Abdelazim et al. | Development and operational analysis of an all-fiber coherent Doppler lidar system for wind sensing and aerosol profiling | |
| Sun et al. | Comparison of IPDA lidar receiver sensitivity for coherent detection and for direct detection using sine-wave and pulsed modulation | |
| CN111208084A (en) | Optical fiber gas concentration remote sensing detection device and method based on coherent detection method | |
| CN211528208U (en) | Optical fiber gas concentration remote sensing detection device based on coherent detection method | |
| CN110456383B (en) | Molecular scattering coherent laser radar system | |
| Chen et al. | Coherent high-spectral-resolution lidar for the measurement of the atmospheric Mie–Rayleigh–Brillouin backscatter spectrum | |
| CN115290599B (en) | Laser radar system for measuring concentration of greenhouse gas | |
| CN114295583B (en) | Coherent measurement device for greenhouse gas | |
| Totems et al. | Advanced signal processing methods for pulsed laser vibrometry | |
| CN112882062B (en) | Space based CO 2 Flux laser detection device | |
| CN112799099A (en) | Near-infrared all-fiber water vapor differential absorption laser radar | |
| Stephen et al. | Oxygen spectroscopy laser sounding instrument for remote sensing of atmospheric pressure | |
| CN116337777B (en) | Broadband photoacoustic spectrum measurement system and method based on single optical comb | |
| CN112904308B (en) | Laser radar system and method for detecting cloud phase state and cloud water content |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20200204 |