A Ozone Differential Absorption Lidar System and a Method for Detecting Atmospheric Ozone Distribution

Abstract

The present invention relates to the field of atmospheric ozone detection, in particular to an ozone differential absorption laser radar system and an atmospheric ozone distribution detection method, wherein the ozone differential absorption laser radar system comprises: a laser emitting device, wherein the laser emitting device emits a laser beam of a first wavelength; a wavelength conversion device, wherein the laser beam of the first wavelength generates a laser beam of a second wavelength and a laser beam of a third wavelength respectively after passing through the wavelength conversion device; and a laser receiving device, wherein the laser receiving device receives an echo signal, wherein the echo signal is obtained by backscattering of the laser beam of the first wavelength, the laser beam of the second wavelength and the laser beam of the third wavelength through the atmosphere. The radar system provided by the present invention has simple technology, low cost and convenient maintenance.

Description

Technical Field

[0001] The present invention relates to the field of atmospheric ozone detection, in particular to an ozone differential absorption laser radar system and an atmospheric ozone distribution detection method Background Art

[0002] Although ozone plays an important role in protecting humans and the environment in the stratosphere, if its concentration increases in the troposphere, it will cause serious harm to humans, animal and plant growth and the ecological environment. It also plays an important role in tropospheric photochemistry, atmospheric environmental quality and ecological environment. Differential absorption lidar technology has become an effective means of detecting atmospheric ozone distribution due to its advantages such as high spatial resolution, fast real-time and large dynamic range.

[0003] At present, lasers are usually used to emit laser light sources to pump gases (such as hydrogen, deuterium, CO2) Raman tubes to generate corresponding Raman lasers of different wavelengths. After beam expansion and collimation, Raman lasers and laser light sources are emitted into the atmosphere. After atmospheric attenuation, they are scattered and absorbed by particles in the atmosphere. Differential absorption is formed by using the different absorption degrees of Raman lasers of different wavelengths by ozone. After scattering and absorption by atmospheric particles and ozone, the backscattered laser is extinguished by the atmosphere again on the return journey, and then received by the receiving optical system, photoelectrically converted by the photodetector, and finally the echo signal is collected. The spatial distribution information of ozone concentration can be obtained using the differential absorption algorithm. Systems based on tunable laser light sources or OPO tuning technology are usually technically complex, costly, and inconvenient to maintain. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide an ozone differential absorption lidar system and an atmospheric ozone distribution detection method, aiming to solve at least one problem in the prior art.

[0005] The first aspect of the present invention proposes an ozone differential absorption laser radar system, comprising: a laser emitting device, the laser emitting device emitting a laser beam of a first wavelength; a wavelength conversion device, the laser beam of the first wavelength passing through the wavelength conversion device generates a laser beam of a second wavelength and a laser beam of a third wavelength respectively; a laser receiving device, the laser receiving device receiving an echo signal, the echo signal is obtained by the laser beam of the first wavelength, the laser beam of the second wavelength and the laser beam of the third wavelength backscattered through the atmosphere. The radar system provided by the present invention is simple in technology, low in cost and easy to maintain.

[0006] Optionally, the laser emitting device comprises: a laser, the laser emitting a laser beam of a first wavelength, the first wavelength being 266 nm. The present invention uses a 266 nm laser, which has the advantage of being mature in technology and easy to implement.

[0007] Optionally, the laser wavelength conversion device includes: a Raman tube, after the laser beam of the first wavelength passes through the Raman tube, a laser beam of a second wavelength and a laser beam of a third wavelength are generated respectively; the second wavelength is 287nm, and the third wavelength is 299nm. The present invention uses a 266nm laser to pump the Raman tube to generate laser beams with wavelengths of 287nm and 299nm. This method is relatively direct, simple, reliable and safe to generate Raman lasers.

[0008] Optionally, the ozone differential absorption laser radar system further comprises: a telescope, the telescope receives the echo signal and outputs the received echo signal to the laser receiving device. The present invention is more conducive to the reception of echo signals by using a telescope.

[0009] Optionally, the ozone differential absorption laser radar system further includes a beam expander, a first reflector, and a second reflector, and the composite laser beam after passing through the beam expander, the first reflector, and the second reflector is coaxially arranged with the telescope; or the composite laser beam after passing through the beam expander, the first reflector, and the second reflector is off-axis arranged with the telescope; the composite laser beam includes a laser beam of the first wavelength, a laser beam of the second wavelength, and a laser beam of the third wavelength. The present invention adopts a coaxial transmission and reception method to minimize the radar blind area and improve the use value of radar data; or adopts an off-axis method to reduce the influence of near-field echo saturation.

[0010] Optionally, the echo signal includes a first echo signal, a second echo signal and a third echo signal; the first echo signal, the second echo signal and the third echo signal are respectively obtained by backscattering of a laser beam of a first wavelength, a laser beam of a second wavelength and a laser beam of a third wavelength through the atmosphere.

[0011] Optionally, the laser receiving device includes: a first detector, which receives the first echo signal; a second detector, which receives the second echo signal; a third detector, which receives the second echo signal; a fourth detector, which receives the third echo signal; and a fifth detector, which receives the third echo signal.

[0012] Optionally, the ozone differential absorption laser radar system further comprises: an aperture, a first lens and a first filter, wherein the aperture, the first lens and the first filter are sequentially arranged on the light exit side of the telescope. The present invention can form a collimated light beam by using the aperture, the first lens and the first filter combination to form the echo signal received by the telescope.

[0013] Optionally, the ozone differential absorption laser radar system further includes: a first dichroic mirror, a second dichroic mirror, a first beam splitter and a second beam splitter; the light incident side of the first dichroic mirror is arranged on the light exit side of the first filter; the light incident side of the second dichroic mirror is arranged on the light exit side of the first dichroic mirror, and the first detector is arranged on the light exit side of the first dichroic mirror; the first beam splitter and the second beam splitter are respectively arranged on the light exit side of the second dichroic mirror; the second detector, the third detector, the fourth detector and the fifth detector are respectively arranged on the light exit side of the first beam splitter and the second beam splitter. The first beam splitter and the second beam splitter of the present invention split the echo signals of 287nm and 299nm, which can avoid the influence of the easy saturation of the echo signals.

[0014] The second aspect of the present invention proposes a method for detecting atmospheric ozone distribution, comprising: providing a laser emitting device, which emits a laser beam of a first wavelength; providing a wavelength conversion device, which generates a laser beam of a second wavelength and a laser beam of a third wavelength after the laser beam of the first wavelength passes through the wavelength conversion device; providing a laser receiving device, which receives an echo signal, and the echo signal is obtained by backscattering of the laser beam of the first wavelength, the laser beam of the second wavelength and the laser beam of the third wavelength through the atmosphere. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of an embodiment of an ozone differential absorption laser radar system of the present invention;

[0016] Figure 2 It is a schematic diagram of another embodiment of the ozone differential absorption laser radar system of the present invention;

[0017] Figure 3 The present invention is a flow chart of an embodiment of a method for detecting atmospheric ozone distribution. DETAILED DESCRIPTION

[0018] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly and comprehensively understood.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0020] The specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details do not need to be adopted to implement the present invention. In other examples, in order to avoid confusing the present invention, known circuits, software or methods are not specifically described.

[0021] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "in one embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or subcombination. In addition, it should be understood by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale.

[0022] Problems with existing solutions: (1) Systems based on tunable laser light sources or OPO tuning technology are usually technically complex, costly, and inconvenient to maintain; (2) Solid-state lasers are usually used to pump hydrogen or deuterium-based Raman tubes to generate Raman light, which may not only cause complex optical path structures and high pump source power requirements, but also cause safety issues with the gas itself; (3) Since the transmitting and receiving optical axes are relatively close (off-axis) or use a coaxial structure, the near-field echo signal is easily saturated, affecting the measurement.

[0023] Based on this, the present application hopes to provide a solution that can solve the above-mentioned technical problems, the details of which will be described in the subsequent embodiments.

[0024] See also Figure 1 and Figure 2 The present application scheme describes in detail an ozone differential absorption lidar system, which specifically includes:

[0025] A laser emitting device 23, wherein the laser emitting device 23 emits a laser beam of a first wavelength. In an optional embodiment, the laser emitting device 23 includes a laser, wherein the laser emits a laser beam of a first wavelength, wherein the first wavelength is 266 nm. Furthermore, the laser may include but is not limited to a 266 nm solid-state laser; in one or some other embodiments, the laser may also be other types of lasers, which are not listed here one by one.

[0026] A wavelength conversion device 24, wherein the wavelength conversion device 24 generates a laser beam of a second wavelength and a laser beam of a third wavelength respectively through the laser beam of the first wavelength; in an optional embodiment, the laser wavelength conversion device 24 includes: a Raman tube, wherein the laser beam of the first wavelength generates a laser beam of a second wavelength and a laser beam of a third wavelength respectively after passing through the Raman tube; the second wavelength is 287nm, and the third wavelength is 299nm. The present invention uses a 266nm solid laser to pump a CO2 Raman tube, thereby generating laser beams of wavelengths 287nm and 299nm. This method of generating Raman lasers is relatively direct, simple, reliable and safe.

[0027] A laser receiving device receives an echo signal, wherein the echo signal is obtained by backscattering of the laser beam of the first wavelength, the laser beam of the second wavelength, and the laser beam of the third wavelength through the atmosphere.

[0028] In an optional embodiment, the echo signal includes a first echo signal, a second echo signal and a third echo signal; the first echo signal, the second echo signal and the third echo signal are respectively obtained by backscattering of a laser beam of a first wavelength, a laser beam of a second wavelength and a laser beam of a third wavelength through the atmosphere.

[0029] In an optional embodiment, the laser receiving device may include: a first detector 18, the first detector 18 receives the first echo signal; a second detector 19, the second detector 19 receives the second echo signal; a third detector 20, the third detector 20 receives the second echo signal; a fourth detector 21, the fourth detector 21 receives the third echo signal; a fifth detector 22, the fifth detector 22 receives the third echo signal. Furthermore, the first detector 18 includes a 266nm laser detector, the second detector 19 includes a 287nm laser detector, the third detector 20 includes a 287nm laser detector, the fourth detector 21 includes a 299nm laser detector, and the fifth detector 22 includes a 299nm laser detector.

[0030] In an optional embodiment, the ozone differential absorption laser radar system further includes a telescope 1, the telescope 1 receives the echo signal, and outputs the received echo signal laser receiving device to the laser receiving device. Furthermore, the telescope 1 includes a primary mirror 28 and a secondary mirror 29, and the primary mirror 28 and the secondary mirror 29 can be coaxially arranged. In one embodiment, the telescope 1 can be a Cassegrain telescope, and in another implementation, the telescope 1 can also be other types of telescopes, which will not be repeated here.

[0031] Please see again Figure 1In an optional embodiment, the ozone differential absorption laser radar system further includes a beam expander 27, a first reflector 25 and a second reflector 26. The composite laser beam after passing through the beam expander 27, the first reflector 25 and the second reflector 26 is coaxially arranged with the telescope 1, and the composite laser beam includes the laser beam of the first wavelength, the laser beam of the second wavelength and the laser beam of the third wavelength. When coaxially arranged, the light entrance side of the beam expander 27 is arranged at the light exit side of the Raman tube, and the beam expander 27 is arranged outside the telescope 1, the light entrance side of the first reflector 25 is arranged at the light exit side of the beam expander 27, the light entrance side of the second reflector 26 is arranged at the light exit side of the first reflector 25, and the second reflector 26 is arranged on the secondary mirror 29 of the telescope 1. In the actual application process, the 266nm solid laser emits a 266nm laser beam into the Raman tube, and generates 287nm and 299nm Raman lasers through the Raman frequency shift effect. Laser beams of three wavelengths, 266nm, 287nm and 299nm, are emitted from the Raman tube, enter the beam expander 27, are expanded and collimated, and are reflected by the first reflector 25 and the second reflector 26, and are emitted into the atmosphere. The present invention adopts the coaxial transmission and reception mode to reduce the radar blind area as much as possible and improve the use value of radar data.

[0032] Please see again Figure 2 In another optional embodiment, the composite laser beam after passing through the beam expander 27, the first reflector 25 and the second reflector 26 is set off-axis from the telescope 1; the composite laser beam includes the laser beam of the first wavelength, the laser beam of the second wavelength and the laser beam of the third wavelength. When set off-axis, the beam expander 27 is set inside the telescope 1; the light entrance side of the first reflector 25 is set at the light exit side of the Raman tube, the light entrance side of the second reflector 26 is set at the light exit side of the first reflector 25, and the light entrance side of the beam expander 27 is set at the light exit side of the second reflector 26. In actual application, a 266nm solid laser emits a 266nm laser beam into the Raman tube, and generates 287nm and 299nm Raman lasers through the Raman frequency shift effect. Laser beams of three wavelengths, 266nm, 287nm and 299nm, are emitted from the Raman tube, reflected by the first reflector 25 and the second reflector 26, enter the beam expander 27, and are emitted into the atmosphere after being expanded and collimated by the beam expander 27. The present invention adopts the off-axis mode of emission and reception to reduce the influence of near-field echo saturation.

[0033] In an optional embodiment, the ozone differential absorption lidar system further includes: an aperture 2, a first lens 3 and a first filter 4, and the aperture 2, the first lens 3 and the first filter 4 are sequentially arranged on the light-emitting side of the telescope 1. The backscattered echo signals of three wavelengths are returned and received by the telescope 1, and the echo signals are reflected by the primary mirror 28 and the secondary mirror 29 inside the telescope 1, and are focused on the center of the aperture 2. The telescope 1 limits the received field of view through the aperture 2. The divergent light beam after passing through the aperture 2 is received and collimated by the first lens 3, and the collimated light beam is filtered by the first filter 4. Further, the first filter 4 may include but is not limited to a neutral density filter, and the first lens 3 may include but is not limited to a field of view lens.

[0034] In an optional embodiment, the ozone differential absorption laser radar system further includes: a first dichroic mirror 5, a second dichroic mirror 8, a first beam splitter 10 and a second beam splitter 12; the light incident side of the first dichroic mirror 5 is arranged at the light exit side of the first filter 4; the light incident side of the second dichroic mirror 8 is arranged at the light exit side of the first dichroic mirror 5, and the first detector 18 is arranged at the light exit side of the first dichroic mirror 5; the first beam splitter 10 and the second beam splitter 12 are respectively arranged at the light exit side of the second dichroic mirror 8; the second detector 19, the third detector 20, the fourth detector 21 and the fifth detector 22 are respectively arranged at the light exit side of the first beam splitter 10 and the second beam splitter 12. The first beam splitter 10 and the second beam splitter 12 of the present invention split the echo signals of 287nm and 299nm, which can avoid the influence of the easy saturation of the echo signals.

[0035] After the collimated light beam passes through the first filter 4, it is split by the first dichroic mirror 5, wherein the reflected part is a light beam containing a wavelength of 266nm, which is filtered by the second filter 6 to obtain a single light beam with a wavelength of 266nm, and finally focused by the second lens 13 onto the first detector 18 corresponding to 266nm, where the main signal is the Mie scattering echo signal with a wavelength of 266nm, which is used to invert the optical parameter profile of atmospheric aerosols. In addition, the light of the transmitted part of the light split by the first dichroic mirror 5 contains light beams with wavelengths of 287nm and 299nm, which are filtered out by the third filter 7 to remove the redundant background signal, and then split by the second dichroic mirror 8. Furthermore, the second filter 6 includes but is not limited to an interference filter, the third filter 7 includes but is not limited to a bandpass filter, and the second lens 13 includes but is not limited to a focusing lens.

[0036] The present invention can respectively include the following two methods when receiving the light beam with a wavelength of 287nm and the light beam with a wavelength of 299nm in the echo signal:

[0037] Using direct receiving method (i.e. Figure 1 or Figure 2 The reflected part of the light split by the first dichroic mirror 5 is a light beam with a wavelength of 287nm, which is filtered by the fourth filter 9 to obtain a single light beam with a wavelength of 287nm. The light beam is focused by the third lens 14 onto the second detector 19 of 287nm, which is mainly a Mie scattering echo signal with a wavelength of 287nm, and is used for differential absorption inversion of ozone concentration distribution. The fourth filter 9 includes but is not limited to an interference filter, and the third lens 14 includes but is not limited to a focusing lens.

[0038] Use 9:1 split receiving mode (i.e. Figure 1 or Figure 2 (including the part in the dotted frame): the reflected part split by the second dichroic mirror 8 is a light beam containing a wavelength of 287nm, which is filtered by the fourth filter 9 to obtain a single light beam with a wavelength of 287nm, and then split by the first beam splitter 10 to obtain a light beam with a transmission and reflection energy ratio of 9:1, respectively. The light beams are focused by the third lens 14 and the fourth lens 15 to the corresponding 287nm second detector 19 and the third detector 20, respectively. Here, it is mainly the Mie scattering echo signal with a wavelength of 287nm, which is used for differential absorption inversion of ozone concentration distribution. Wherein, the first beam splitter 10 includes but is not limited to a 9:1 beam splitter, and the fourth lens 15 includes but is not limited to a focusing lens.

[0039] Using direct receiving method (i.e. Figure 1 or Figure 2 The transmission part split by the second dichroic mirror 8 is a light beam with a wavelength of 299 nm, which is filtered by the fifth filter 11 to obtain a single light beam with a wavelength of 299 nm. The light beam is focused by the fifth lens 16 onto the fourth detector 21 with a wavelength of 299 nm. Here, it is mainly a Mie scattering echo signal with a wavelength of 299 nm, which is used for differential absorption inversion of ozone concentration distribution. The fifth filter 11 is an interference filter, and the fifth lens 16 and the sixth lens 17 are both focusing lenses.

[0040] Use 9:1 split receiving mode (i.e. Figure 1 or Figure 2(including the part in the dotted frame): the transmission part split by the second dichroic mirror 8 is a light beam containing a wavelength of 299nm, which is filtered by the fourth filter 9 to obtain a single light beam with a wavelength of 299nm, and then split by the second beam splitter 12 to obtain a light beam with a transmission and reflection energy ratio of 9:1, respectively. The light beams are focused by the fifth lens 16 and the sixth lens 17 to the corresponding 299nm fourth detector 21 and the fifth detector 22, respectively. Here, it is mainly the Mie scattering echo signal with a wavelength of 299nm, which is used for differential absorption inversion of ozone concentration distribution. Wherein, the second beam splitter 12 includes but is not limited to a 9:1 beam splitter.

[0041] The ozone differential absorption lidar system proposed in the present invention utilizes the backscattering measurement and ozone differential absorption principle to invert the spatial distribution information of ozone through the ozone absorption characteristic algorithm. A 9:1 beam splitter is used to split the 287nm and 299nm echo signals, and the energy ratio algorithm can avoid the influence of the echo signal being easily saturated.

[0042] See also Figure 3 The present application scheme describes in detail a method for detecting atmospheric ozone distribution, which is applicable to the ozone differential absorption laser radar system in the aforementioned embodiment of the present invention. Specifically, the method for detecting atmospheric ozone distribution includes:

[0043] S1, providing a laser emitting device, wherein the laser emitting device emits a laser beam of a first wavelength.

[0044] In an optional embodiment, the laser emitting device includes a laser, and the laser emits a laser beam of a first wavelength, and the first wavelength is 266nm. Furthermore, the laser may include but is not limited to a 266nm solid laser; in one or some other embodiments, the laser may also be other types of lasers, which are not listed here one by one.

[0045] S2, providing a wavelength conversion device, wherein the laser beam of the first wavelength generates a laser beam of a second wavelength and a laser beam of a third wavelength after passing through the wavelength conversion device;

[0046] In an optional embodiment, the laser wavelength conversion device includes: a Raman tube, after the laser beam of the first wavelength passes through the Raman tube, a laser beam of a second wavelength and a laser beam of a third wavelength are generated respectively; the second wavelength is 287nm, and the third wavelength is 299nm. The present invention uses a 266nm solid laser to pump the CO2 Raman tube, thereby generating laser beams with wavelengths of 287nm and 299nm. Using this method to generate Raman lasers is relatively direct, simple, reliable and safe.

[0047] S3, providing a laser receiving device, wherein the laser receiving device receives an echo signal, wherein the echo signal is obtained by backscattering of the laser beam of the first wavelength, the laser beam of the second wavelength, and the laser beam of the third wavelength through the atmosphere.

[0048] In an optional embodiment, the echo signal includes a first echo signal, a second echo signal and a third echo signal; the first echo signal, the second echo signal and the third echo signal are respectively obtained by backscattering of a laser beam of a first wavelength, a laser beam of a second wavelength and a laser beam of a third wavelength through the atmosphere.

[0049] In an optional embodiment, the laser receiving device includes: a first detector, the first detector receives the first echo signal; a second detector, the second detector receives the second echo signal; a third detector, the third detector receives the second echo signal; a fourth detector, the fourth detector receives the third echo signal; a fifth detector, the fifth detector receives the third echo signal. Furthermore, the first detector includes a 266nm laser detector, the second detector includes a 287nm laser detector, the third detector includes a 287nm laser detector, the fourth detector includes a 299nm laser detector, and the fifth detector includes a 299nm laser detector.

[0050] In another optional embodiment, the atmospheric ozone distribution detection method further includes:

[0051] S4, providing a telescope, the telescope receives the echo signal, and outputs the received echo signal to the laser receiving device.

[0052] In an optional embodiment, the telescope includes a primary mirror and a secondary mirror, and the primary mirror and the secondary mirror can be coaxially arranged. In one embodiment, the telescope can adopt a Cassegrain telescope, and in another embodiment, the telescope can also adopt other types of telescopes, which will not be repeated here.

[0053] S5, providing a collimator, a first reflector and a second reflector, each passing through the collimator.

[0054] In one embodiment, the composite laser beam behind the first reflecting mirror and the second reflecting mirror is coaxially arranged with the telescope, and the composite laser beam includes the laser beam of the first wavelength, the laser beam of the second wavelength and the laser beam of the third wavelength.

[0055] When coaxially arranged, the light entrance side of the beam expander is arranged at the light exit side of the Raman tube, the beam expander is arranged outside the telescope, the light entrance side of the first reflector is arranged at the light exit side of the beam expander, the light entrance side of the second reflector is arranged at the light exit side of the first reflector, and the second reflector is arranged on the secondary mirror of the telescope. In actual application, a 266nm solid laser emits a 266nm laser beam into the Raman tube, and generates 287nm and 299nm Raman lasers through the Raman frequency shift effect. Laser beams of three wavelengths of 266nm, 287nm, and 299nm are emitted from the Raman tube, enter the beam expander, are expanded and collimated, and then are reflected by the first reflector and the second reflector and emitted into the atmosphere. The present invention adopts a coaxial transmission and reception method to minimize the radar blind area and improve the use value of radar data.

[0056] In another optional embodiment, the composite laser beam after passing through the beam expander, the first reflector and the second reflector is set off-axis with the telescope; the composite laser beam includes the laser beam of the first wavelength, the laser beam of the second wavelength and the laser beam of the third wavelength. When set off-axis, the beam expander is set inside the telescope; the light entrance side of the first reflector is set at the light exit side of the Raman tube, the light entrance side of the second reflector is set at the light exit side of the first reflector, and the light entrance side of the beam expander is set at the light exit side of the second reflector. In the actual application process, a 266nm solid laser emits a 266nm laser beam into the Raman tube, and generates 287nm and 299nm Raman lasers through the Raman frequency shift effect. The laser beams of three wavelengths of 266nm, 287nm and 299nm are emitted from the Raman tube, reflected by the first reflector and the second reflector, enter the beam expander, are expanded and collimated, and then emitted into the atmosphere. The present invention adopts the off-axis mode of transmitting and receiving to reduce the influence of near-field echo saturation.

[0057] S6, providing an aperture, a first lens and a first filter, wherein the aperture, the first lens and the first filter are sequentially arranged on the light exit side of the telescope.

[0058] In an optional embodiment, backscattered echo signals of three wavelengths are returned and received by the telescope. The echo signals are reflected by the primary mirror and the secondary mirror inside the telescope and focused on the center of the aperture, and the telescope limits the received field of view through the aperture. The divergent light beam after passing through the aperture is received and collimated by the first lens, and the collimated light beam is filtered by the first filter. Further, the first filter may include but is not limited to a neutral density filter, and the first lens includes but is not limited to a field of view lens.

[0059] S7, provide a first dichroic mirror, a second dichroic mirror, a first beam splitter, and a second beam splitter.

[0060] In an optional embodiment, the light entrance side of the first dichroic mirror is arranged at the light exit side of the first filter; the light entrance side of the second dichroic mirror is arranged at the light exit side of the first dichroic mirror, and the first detector is arranged at the light exit side of the first dichroic mirror; the first beam splitter and the second beam splitter are respectively arranged at the light exit side of the second dichroic mirror; the second detector, the third detector, the fourth detector and the fifth detector are respectively arranged at the light exit side of the first beam splitter and the second beam splitter. The first beam splitter and the second beam splitter of the present invention split the echo signals of 287nm and 299nm, which can avoid the influence of easy saturation of the echo signals.

[0061] After the collimated light beam passes through the first filter, it is split by the first dichroic mirror, wherein the reflected part is a light beam containing a wavelength of 266nm, which is filtered by the second filter to obtain a single light beam with a wavelength of 266nm, and finally focused by the second lens onto the corresponding first detector of 266nm, where the main signal is the Mie scattering echo signal with a wavelength of 266nm, which is used to invert the optical parameter profile of atmospheric aerosols. In addition, the light of the transmitted part in the light split by the first dichroic mirror contains light beams with wavelengths of 287nm and 299nm, which are filtered out by the third filter to remove the redundant background signal, and then split by the second dichroic mirror. Furthermore, the second filter includes but is not limited to an interference filter, the third filter includes but is not limited to a bandpass filter, and the second lens includes but is not limited to a focusing lens.

[0062] The present invention can respectively include the following two methods when receiving the light beam with a wavelength of 287nm and the light beam with a wavelength of 299nm in the echo signal:

[0063] Using a direct receiving method: the reflected part of the light split by the first dichroic mirror is a light beam containing a wavelength of 287nm, which is filtered by the fourth filter to obtain a single light beam with a wavelength of 287nm, and the light beam is focused by the third lens onto the second detector of 287nm, where the main signal is the Mie scattering echo signal with a wavelength of 287nm, which is used for differential absorption inversion of ozone concentration distribution. The fourth filter includes but is not limited to an interference filter, and the third lens includes but is not limited to a focusing lens.

[0064] Using a 9:1 splitting receiving method: the reflected part of the light split by the second dichroic mirror is a light beam containing a wavelength of 287nm, which is filtered by the fourth filter to obtain a single light beam with a wavelength of 287nm, and then split by the first beam splitter to obtain light beams with a transmission and reflection energy ratio of 9:1. The light beams are focused by the third lens and the fourth lens to the corresponding 287nm second detector and third detector, respectively. Here, it is mainly the Mie scattering echo signal with a wavelength of 287nm, which is used for differential absorption inversion of ozone concentration distribution. Wherein, the first beam splitter includes but is not limited to a 9:1 beam splitter, and the fourth lens includes but is not limited to a focusing lens.

[0065] Using a direct receiving method: the transmission part of the light split by the second dichroic mirror is a light beam with a wavelength of 299nm, which is filtered by the fifth filter to obtain a single light beam with a wavelength of 299nm. The light beam is focused by the fifth lens to the fourth detector of 299nm, where the main signal is the Mie scattering echo signal with a wavelength of 299nm, which is used for differential absorption inversion of ozone concentration distribution. Among them, the fifth filter is an interference filter, and the fifth lens and the sixth lens are both focusing lenses.

[0066] Use 9:1 splitting receiving mode: the transmission part split by the second dichroic mirror is a beam containing a wavelength of 299nm, which is filtered by the fifth filter to obtain a single beam of 299nm wavelength, and then split by the second beam splitter to obtain beams with a transmission and reflection energy ratio of 9:1. The beams are focused by the fifth lens and the sixth lens to the corresponding 299nm fourth detector and fifth detector, which are mainly Mie scattering echo signals with a wavelength of 299nm, and are used for differential absorption inversion of ozone concentration distribution. Wherein, the second beam splitter includes but is not limited to a 9:1 beam splitter,

[0067] The atmospheric ozone distribution detection method proposed in the present invention utilizes the backscattering measurement and ozone differential absorption principle to invert the spatial distribution information of ozone through the ozone absorption characteristic algorithm. A 9:1 beam splitter is used to split the 287nm and 299nm echo signals, and the energy ratio algorithm can avoid the influence of the echo signal being easily saturated.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. An ozone differential absorption laser radar system, characterized in that: include: A laser emitting device, wherein the laser emitting device emits a laser beam of a first wavelength; a wavelength conversion device, wherein the laser beam of the first wavelength generates a laser beam of a second wavelength and a laser beam of a third wavelength respectively after passing through the wavelength conversion device; A laser receiving device, wherein the laser receiving device receives an echo signal, wherein the echo signal is obtained by backscattering of the laser beam of the first wavelength, the laser beam of the second wavelength, and the laser beam of the third wavelength through the atmosphere; the echo signal includes a first echo signal, a second echo signal, and a third echo signal; The laser emitting device comprises a laser, and the laser emits a laser beam of a first wavelength, wherein the first wavelength is 266 nm; The wavelength conversion device comprises a Raman tube, and the laser beam of the first wavelength generates a laser beam of the second wavelength and a laser beam of the third wavelength respectively after passing through the Raman tube; the second wavelength is 287nm, and the third wavelength is 299nm; The ozone differential absorption laser radar system further includes a telescope, which receives the echo signal and outputs the received echo signal to the laser receiving device; The laser receiving device comprises: a first detector, the first detector receives the first echo signal; a second detector, the second detector receives the second echo signal; a third detector, the third detector receives the second echo signal; a fourth detector, the fourth detector receives the third echo signal; a fifth detector, the fifth detector receives the third echo signal; The ozone differential absorption laser radar system further includes a beam expander, a first reflector, and a second reflector. The composite laser beam after passing through the beam expander, the first reflector, and the second reflector is coaxially arranged with the telescope; or the composite laser beam after passing through the beam expander, the first reflector, and the second reflector is off-axis arranged with the telescope; the composite laser beam includes a laser beam of the first wavelength, a laser beam of the second wavelength, and a laser beam of the third wavelength; The ozone differential absorption laser radar system further includes: an aperture, a first lens and a first filter, wherein the aperture, the first lens and the first filter are sequentially arranged on the light exit side of the telescope; The ozone differential absorption lidar system also includes: a first dichroic mirror, a second dichroic mirror, a first beam splitter and a second beam splitter; the light incident side of the first dichroic mirror is arranged on the light exit side of the first filter; the light incident side of the second dichroic mirror is arranged on the light exit side of the first dichroic mirror, and the first detector is arranged on the light exit side of the first dichroic mirror; the first beam splitter and the second beam splitter are respectively arranged on the light exit side of the second dichroic mirror; the second detector, the third detector, the fourth detector and the fifth detector are respectively arranged on the light exit sides of the first beam splitter and the second beam splitter, and the transmission and reflection splitting ratio of the first beam splitter and the second beam splitter is 9:

1.

2. A method for detecting atmospheric ozone distribution, characterized in that: include: Providing a laser emitting device, wherein the laser emitting device emits a laser beam of a first wavelength; Providing a wavelength conversion device, wherein the laser beam of the first wavelength generates a laser beam of a second wavelength and a laser beam of a third wavelength respectively after passing through the wavelength conversion device; Providing a laser receiving device, the laser receiving device receives an echo signal, the echo signal is obtained by backscattering of the laser beam of the first wavelength, the laser beam of the second wavelength, and the laser beam of the third wavelength through the atmosphere; The atmospheric ozone distribution detection method is applicable to the ozone differential absorption lidar system described in claim 1.

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