All-solid-state three-wavelength four-channel ozone and aerosol detection laser radar system

Abstract

The utility model discloses an all-solid-state three-wavelength four-channel ozone and aerosol detection laser radar system, which relates to the technical field of laser radar in the field of environmental monitoring and comprises a three-wavelength laser transmitting module, a telescope echo signal receiving module, a subsequent light path module and a high-speed signal acquisition and control module. The three-wavelength laser transmitting module is respectively connected with the telescope echo signal receiving module and the subsequent light path module, and the telescope echo signal receiving module is connected with the high-speed signal acquisition and control module through the subsequent light path module. The solid Raman laser technology and the laser frequency doubling technology are applied to generate two beams of ultraviolet light capable of performing differential inversion analysis on ozone, so that information such as concentration distribution and spatial evolution of the ozone can be obtained, and the visible light generated after the action of the Raman crystal can be used for performing inversion analysis on aerosol; and distribution and evolution information of fine particles and aerosol in the atmosphere can be obtained.

Description

Technical Field

[0001] This utility model relates to the field of lidar technology in environmental monitoring, specifically to a solid-state three-wavelength four-channel lidar system for detecting ozone and aerosols. Background Technology

[0002] Lidar is an active remote sensing technology that detects atmospheric parameters (such as temperature, water vapor, wind, ozone, and the optical properties of aerosols) by receiving light scattering signals from atmospheric atoms, molecules, and aerosols. Lidar possesses unique technological advantages such as long detection range, high coherence, and high spatiotemporal resolution, and has become an indispensable tool in the fields of ozone, aerosol, and atmospheric research.

[0003] Lidar combines traditional radar technology with modern laser technology, serving as a powerful supplement to conventional ground-based monitoring techniques. It can be used to continuously monitor the vertical distribution and rapid changes of atmospheric ozone and aerosols, and to analyze the composition and spatiotemporal evolution of aerosols. Lidar data can provide information such as the structure and spatiotemporal evolution of the atmospheric boundary layer (PBL), ozone concentration, vertical profiles and temporal evolution characteristics of atmospheric aerosol (dust) extinction coefficients, cloud height and multi-layer cloud structure, atmospheric visibility, and PM2.5 and PM10 concentrations. Simultaneously, lidar can monitor the diffusion patterns of urban air pollutants such as industrial smoke emissions, monitor weather processes such as haze and dust storms, and achieve precise source identification of atmospheric aerosols, providing crucial technical support for scientific and precise governance.

[0004] However, most current ozone monitoring lidar systems use ultraviolet differential absorption schemes, employing high-power ultraviolet light sources. To ensure sufficient output power and good environmental adaptability, these lidar designs are often excessively large and heavy, with complex structures and poor portability. Light sources using gas as the gain medium are difficult to assemble and have poor stability, making them unsuitable for extended use as mature industrial products. Furthermore, traditional lidar systems often only detect a single atmospheric component; detecting multiple atmospheric parameters requires the coordinated operation of multiple lidar units.

[0005] No effective solutions have yet been proposed to address the problems in the relevant technologies. Utility Model Content

[0006] To address the problems in related technologies, this invention proposes an all-solid-state three-wavelength four-channel ozone and aerosol detection lidar system to overcome the aforementioned technical problems in existing related technologies.

[0007] Therefore, the specific technical solution adopted by this utility model is as follows:

[0008] The all-solid-state three-wavelength four-channel ozone and aerosol detection lidar system includes a three-wavelength laser emission module, a telescope echo signal receiving module, a follow-up optical path module, and a high-speed signal acquisition and control module.

[0009] Among them, the three-wavelength laser emission module is connected to the high-speed signal acquisition and control module, the telescope echo signal receiving module is connected to the subsequent optical path module, and the subsequent optical path module is connected to the high-speed signal acquisition and control module.

[0010] Furthermore, the three-wavelength laser emission module consists of a laser, a first Raman resonator, a second Raman resonator, a first frequency doubling cavity, a second frequency doubling cavity, a first polarizing beam splitter prism, and a beam pointing adjustment system. The beam pointing adjustment system consists of a first dichroic mirror, a second dichroic mirror, a first reflecting mirror, a second reflecting mirror, and a half-wave plate.

[0011] Furthermore, the subsequent optical path module consists of a third dichroic mirror, a fourth dichroic mirror, a first filter, a second filter, a third filter, a fourth filter, a second polarizing beam splitter, a first photomultiplier tube assembly, a second photomultiplier tube assembly, a third photomultiplier tube assembly, and a fourth photomultiplier tube assembly.

[0012] Furthermore, the high-speed signal acquisition and control module consists of an acquisition module, a control submodule, and an industrial control computer module; and the acquisition module, control submodule, and industrial control computer module maintain communication connections in sequence, with the acquisition module and industrial control computer module maintaining a communication connection.

[0013] The beneficial effects of this utility model are as follows:

[0014] 1. This invention utilizes solid-state Raman laser technology and laser frequency doubling technology to generate two beams of ultraviolet light capable of differential inversion analysis of ozone, which can obtain information such as ozone concentration distribution and spatial evolution. In addition, the visible light generated after passing through the Raman crystal can also be used for inversion analysis of aerosols, which can obtain information on the distribution and evolution of fine particulate matter and aerosols in the atmosphere.

[0015] 2. The all-solid-state three-wavelength four-channel ozone and aerosol detection lidar system of this utility model can detect information such as ozone concentration and distribution, extinction coefficient, backscattering coefficient, boundary layer height, and vertical profile of ozone and aerosol concentration in the atmosphere.

[0016] 3. This utility model greatly reduces the size and weight of the lidar system, realizes the coordinated detection of ozone and aerosols, greatly improves the functional performance requirements of the radar, and achieves synchronous real-time detection of multiple atmospheric environmental parameters.

[0017] 4. By further reducing noise and optimizing the signal, and utilizing the absorption differences of ozone at different wavelengths, the telescope receives the light echo signals generated by the interaction between 280nm and 295nm laser pulses and ozone. After signal detection, the echo signal profile of the probed atmosphere is obtained. Then, through data inversion algorithm processing, optical characteristic parameters of ozone components in the atmosphere, such as ozone concentration and distribution, can be obtained. Similarly, by using a radar telescope to receive the Mie scattering light signal generated by aerosols on the laser transmission path at 560nm laser, and then based on the lidar equation algorithm inversion, the spatiotemporal distribution of aerosol concentration in the atmosphere and related data products such as extinction coefficient, backscattering coefficient, and boundary layer height can be obtained.

[0018] 5. After the radar prototype equipment is built using this utility model, the overall radar equipment weighs no more than 60kg, and its length, width, and height are no more than 1m, 0.5m, and 0.5m respectively. It can be used for directional, scanning, and mobile detection of ozone, aerosols, and particulate matter. Through actual detection and observation, the radar's optimal detection range for ozone exceeds 3km, and the detection range for aerosols exceeds 5km. The inversion data, such as the absolute value of component concentration and the time evolution trend, shows good consistency with the data from national control stations. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is one of the structural schematic diagrams of an all-solid-state three-wavelength four-channel ozone and aerosol detection lidar system according to an embodiment of the present invention;

[0021] Figure 2 This is the second structural schematic diagram of the all-solid-state three-wavelength four-channel ozone and aerosol detection lidar system according to an embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of the structure of the three-wavelength laser emission module in the all-solid-state three-wavelength four-channel ozone and aerosol detection lidar system according to an embodiment of the present invention.

[0023] In the picture:

[0024] 1. Three-wavelength laser emitting module; 101. Laser; 102. First Raman resonator; 103. Second Raman resonator; 104. First frequency doubling cavity; 105. Second frequency doubling cavity; 106. First polarizing beam splitter prism; 107. First dichroic mirror; 108. First reflecting mirror; 109. Second dichroic mirror; 110. Second reflecting mirror; 111. Third reflecting mirror; 112. Half-wave plate; 2. Telescope echo signal receiving module; 3. Subsequent optical path module; 301. Third dichroic mirror... 302. Dichroic mirror; 303. First filter; 304. Second filter; 305. Third filter; 306. Fourth filter; 307. Second polarizing beam splitter; 308. First photomultiplier tube assembly; 309. Second photomultiplier tube assembly; 310. Third photomultiplier tube assembly; 311. Fourth photomultiplier tube assembly; 4. High-speed signal acquisition and control module; 401. Acquisition module; 402. Control submodule; 403. Industrial computer module. Detailed Implementation

[0025] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are usually used to represent similar components.

[0026] According to an embodiment of the present invention, an all-solid-state three-wavelength four-channel ozone and aerosol detection lidar system is provided.

[0027] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Figure 1 As shown, the all-solid-state three-wavelength four-channel ozone and aerosol detection lidar system according to an embodiment of the present invention includes a three-wavelength laser emitting module 1, a telescope echo signal receiving module 2, a follow-up optical path module 3, and a high-speed signal acquisition and control module 4.

[0028] Among them, the three-wavelength laser emission module 1 is connected to the high-speed signal acquisition and control module 4, the telescope echo signal receiving module 2 is connected to the follow-up optical path module 3, and the follow-up optical path module 3 is connected to the high-speed signal acquisition and control module 4.

[0029] Using the above technical solution, this utility model utilizes a three-wavelength laser emitting module 1 to provide three different wavelengths of laser light for radar detection. After collimation and beam expansion, the laser beam pointing adjustment system can achieve automatic or manual control of the laser pointing. The laser used in this utility model is a pulsed laser. It can achieve the screening and separation of multi-channel atmospheric echo signals, and achieve independent and efficient extraction of signals of different wavelengths or polarizations. It can achieve photoelectric conversion of echo signals. The high-speed acquisition system and industrial control computer system can achieve high-speed acquisition and analysis of signals.

[0030] Furthermore, it should be noted that the three-wavelength laser emitting module 1 can simultaneously output laser beams with wavelengths of 560nm, 295nm, and 280nm. The telescope echo signal receiving module 2 can simultaneously receive atmospheric echo signals of these three wavelengths, which then enter the subsequent optical path after passing through the collimating lens group. The subsequent optical path module 3 can simultaneously acquire the three-wavelength signals. After beam splitting, the atmospheric echo signals of each band enter the corresponding detectors for photoelectric conversion, and then are connected to the high-speed signal acquisition module for acquisition. The industrial control computer module 403 processes the signals obtained by the radar system to obtain radar inversion maps, and obtains information such as atmospheric ozone concentration and distribution, extinction coefficient, backscattering coefficient, boundary layer height, and vertical profiles of ozone and aerosol concentrations.

[0031] In addition, the telescope echo signal receiving module 2 consists of a Cassegrain telescope, which can receive most radar echo signals and transmit the signals to the subsequent optical path system.

[0032] In one embodiment, the three-wavelength laser emitting module 1 is composed of a laser 101, a first Raman resonator 102 and a second Raman resonator 103, a first frequency doubling cavity 104, a second frequency doubling cavity 105, and a beam pointing adjustment system. The beam pointing adjustment system is composed of a first dichroic mirror 107, a first reflector 108, a second dichroic mirror 109, a second reflector 110, a third reflector 111, and a half-wave plate 112. Thus, the three-wavelength laser emitting module 1 provides three different wavelengths of laser light required for radar detection. After collimation and beam expansion, the beam pointing adjustment system can realize automatic or manual control of the laser pointing. The laser used in this invention is a pulsed laser.

[0033] It should be noted that the laser is a pulsed laser that can output a narrow pulse width laser with a wavelength of 532nm and adjustable repetition rate. The beam pointing adjustment system consists of three piezoelectric electric adjustment frames and reflectors bonded to them, which reflect the three laser beams respectively. By applying different voltages to the electric adjustment frames through the control box, the two-dimensional deflection motion of the mirrors can be adjusted, thereby realizing the adjustment and control of the laser beam output direction.

[0034] The stimulated Raman scattering resonator (first Raman resonator 102 and second Raman resonator 103) consists of a resonator, a Raman nonlinear crystal, and a temperature control module. The resonator is a plano-concave cavity and uses solid-state Raman laser technology. The stimulated Raman scattering resonator is a dual-cavity system that can convert 532nm laser light into 560nm first-order light and 590nm second-order light, respectively. The double frequency doubling cavity consists of two independent frequency doubling cavities that can frequency double the 560nm first-order light and 590nm second-order light into 280nm ultraviolet light and 295nm ultraviolet light, respectively.

[0035] The multi-channel beam shaping section consists of concave lenses, convex lenses, cylindrical lenses, and reflectors. By adjusting the positions of the lenses, the laser beam shaping is optimized, reducing the laser divergence angle. The beam pointing adjustment system consists of three piezoelectric electric adjustment frames and reflectors bonded to them, which reflect the three laser beams respectively. By applying different voltages to the electric adjustment frames through the control box, the two-dimensional deflection motion of the lenses can be adjusted, thereby achieving the adjustment and control of the laser beam emission direction.

[0036] In one embodiment, the aforementioned follower optical path module 3 is composed of a third dichroic mirror 301, a fourth dichroic mirror 302, a first filter 303, a second filter 304, a third filter 305, a fourth filter 306, a second polarizing beam splitter prism 307, and a first photomultiplier tube assembly 308, a second photomultiplier tube assembly 309, a third photomultiplier tube assembly 310, and a fourth photomultiplier tube assembly 311, thereby achieving the screening and separation of multi-channel atmospheric echo signals and realizing the independent and efficient extraction of signals of different wavelengths or polarizations.

[0037] It should be noted that the filters (first filter 303, second filter 304, third filter 305, and fourth filter 306) are all ultra-narrowband filters, and the extinction ratio of the first polarizing beam splitter 106 and the second polarizing beam splitter 307 is greater than 1000:1.

[0038] In this embodiment, the high-speed signal acquisition and control module 4 comprises an acquisition module 401, a control submodule 402, and an industrial computer module 403. The acquisition module 401, control submodule 402, and industrial computer module 403 are sequentially connected in communication, with the acquisition module 401 and the industrial computer module 403 maintaining a communication connection. This enables the acquisition and control of echo signals, allowing the high-speed acquisition system and the industrial computer system to achieve high-speed signal acquisition and analysis.

[0039] In addition, it should be noted that the all-solid-state three-wavelength four-channel ozone and aerosol detection lidar system is designed to weigh no more than 60kg, and its length, width and height are no more than 1m, 0.5m and 0.5m respectively. It can be used for directional, scanning and mobile detection of ozone and aerosols.

[0040] To facilitate understanding of the above-mentioned technical solutions of this utility model, the working principle or operation method of this utility model in actual process will be described in detail below.

[0041] In practical applications, the laser emits a 532nm pulsed laser beam. After passing through a half-wave plate 112 and a first polarizing beam splitter prism 106, the beam is split into two paths, which pass through a first Raman resonator 102 and a second reflector 110 and a second Raman resonator 103, respectively. After the optical path is adjusted, the first Raman resonator 102 and the second Raman resonator 103 output 560nm first-order Stokes light and 590nm second-order Stokes light, respectively. After passing through the frequency doubling crystals of the first frequency doubling cavity 104 and the second frequency doubling cavity 105, respectively, 280nm and 295nm deep ultraviolet light are generated. At this time, four wavelengths of laser light, namely 560nm, 590nm, 280nm and 295nm, can be stably emitted.

[0042] The first frequency doubling cavity 104 can output 560nm and 280nm lasers. These lasers are separated by the first dichroic mirror 107, which separates the transmitted 560nm light from the reflected 280nm light. The 280nm light is then reflected by the first reflecting mirror 108 before being output. The second frequency doubling cavity 105 can output 590nm and 295nm lasers. These lasers are separated by the second dichroic mirror, which separates the transmitted 590nm light from the reflected 295nm light. The 295nm light is then reflected by the second reflecting mirror 110 before being output. By absorbing the 590nm band with a light absorber, only the 560nm, 280nm, and 295nm laser bands required by the radar can be output.

[0043] The optical signal entering the subsequent optical path system passes through the third dichroic mirror 301, splitting into a transmitted 560nm visible light signal and reflected 280nm and 295nm ultraviolet light signals. The transmitted visible light signal then passes through the second polarizing beam splitter prism 307 to obtain a 560nm parallel polarization channel and a 560nm vertical polarization channel. The reflected ultraviolet light signal passes through the fourth dichroic mirror 302 to separate the transmitted 295nm light signal and the reflected 280nm light signal. A third filter 305 and a second filter 304 are placed before the second photomultiplier tube assembly 309 and the third photomultiplier tube assembly 310 of the 560nm parallel and vertical polarization channels, a 280nm fourth filter 306 is placed before the fourth photomultiplier tube assembly 311 of the 280nm channel, and a 295nm first filter 303 is placed before the first photomultiplier tube assembly 308 of the 295nm channel, thus obtaining four radar signal channels.

[0044] The Raman nonlinear crystal used in this invention is a strontium tungstate crystal, and the frequency doubling crystal is a BBO crystal.

[0045] Strontium tungstate crystals can be grown using the Czochralski method, which offers a short growth cycle, large size, and good optical quality. This crystal is a novel, high-performance solid Raman material with advantages such as non-hygroscopicity, good mechanical properties, wide transmission band, high optical damage threshold, narrow Raman spectral lines, large scattering cross-section, and high gain coefficient. The strontium tungstate crystal used in this invention has a size of 6*6*50mm.

[0046] BBO crystal is an excellent nonlinear negative uniaxial crystal with a wide operating wavelength range of 400nm to 3500nm. It also exhibits high frequency doubling efficiency, good transmittance, optical uniformity, and damage threshold. BBO crystals are commonly used as frequency doubling crystals in the second, third, fourth, and fifth harmonics of lasers. The BBO crystal used in this invention has a size of 4*4*12mm and is coated with high-transmittance films of 560nm and 280nm, and 590nm and 295nm, respectively.

[0047] The telescope used in this invention is a Cassegrain telescope with an aperture of 150mm and a receiving field of view of 0.6mrad. Both the primary and secondary mirrors are coated with specific wavelengths of 560nm, 280nm, and 295nm.

[0048] The filters used in this invention are all ultra-narrow band filters.

[0049] The photomultiplier tube assembly used in this invention is an analog photomultiplier tube assembly.

[0050] This invention relates to a fully solid-state, three-wavelength, four-channel ozone and aerosol detection lidar system that can simultaneously emit three-wavelength laser signals and receive four types of echo signals, enabling simultaneous detection of ozone composition and aerosol distribution in the atmosphere.

[0051] Solid-state Raman laser technology is a laser technology that utilizes the stimulated Raman scattering effect of solid-state Raman nonlinear crystals to convert the original laser wavelength to obtain a new wavelength laser output. It is an effective means of obtaining new wavelength lasers.

[0052] Laser frequency doubling technology, also known as second harmonic generation technology, is the earliest nonlinear optical effect discovered in the laboratory. When laser light passes through a frequency doubling crystal, the wavelength is halved and the frequency is doubled.

[0053] In summary, by utilizing the above-mentioned technical solution of this utility model, which employs solid-state Raman laser technology and laser frequency doubling technology to generate two beams of ultraviolet light capable of differential inversion analysis of ozone, information such as ozone concentration distribution and spatial evolution can be obtained. Furthermore, the visible light generated after passing through a Raman crystal can also be used for aerosol inversion analysis, providing information on the distribution and evolution of fine particulate matter and aerosols in the atmosphere. This utility model's all-solid-state, three-wavelength, four-channel ozone and aerosol detection lidar system can detect the ozone concentration and distribution, extinction coefficient, backscattering coefficient, boundary layer height, ozone, and aerosols in the atmosphere. Information such as concentration vertical profiles; this utility model greatly reduces the size and weight of the lidar system, realizes the coordinated detection of ozone and aerosols, greatly improves the functional performance requirements of the radar, and achieves synchronous real-time detection of multiple atmospheric environmental parameters; by further reducing noise and optimizing the signal, and utilizing the absorption difference of ozone at different wavelengths, the telescope receives the light echo signals generated by the interaction between 280nm and 295nm band laser pulses and ozone, obtains the echo signal profile of the detected atmosphere through signal detection, and then obtains the optical characteristic parameters of ozone components in the atmosphere, such as ozone concentration and distribution, through data inversion algorithm processing. Similarly, by using a radar telescope to receive the Mie scattering signal of a 560nm laser from aerosols along the laser transmission path, and then using the lidar equation algorithm for inversion, the spatiotemporal distribution of aerosol concentration in the atmosphere and related data products such as extinction coefficient, backscattering coefficient, and boundary layer height can be obtained. After building a radar prototype using this invention, the overall radar equipment weighs no more than 60kg, and its length, width, and height are no more than 1m, 0.5m, and 0.5m respectively. It can be used for directional, scanning, and mobile detection of ozone, aerosols, and particulate matter. Through actual detection and observation, the radar's optimal detection range for ozone exceeds 3km, and the detection range for aerosols exceeds 5km. The inversion data, such as the absolute value of component concentration and its temporal evolution trend, shows good consistency with the data from national control stations.

[0054] In this utility model, unless otherwise explicitly specified and limited, the terms "installation", "setting", "connection", "fixing", "screw connection", etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0055] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A fully solid-state, three-wavelength, four-channel lidar system for detecting ozone and aerosols, characterized in that, It includes a three-wavelength laser emission module (1), a telescope echo signal receiving module (2), a follow-up optical path module (3), and a high-speed signal acquisition and control module (4); The three-wavelength laser emission module (1) is connected to the high-speed signal acquisition and control module (4), the telescope echo signal receiving module (2) is connected to the follow-up optical path module (3), and the follow-up optical path module (3) is connected to the high-speed signal acquisition and control module (4).

2. The all-solid-state three-wavelength four-channel ozone and aerosol detection lidar system according to claim 1, characterized in that, The three-wavelength laser emission module (1) consists of a laser (101), a first Raman resonator (102) and a second Raman resonator (103), a first frequency doubling cavity (104), a second frequency doubling cavity (105), a first polarization beam splitter prism (106), and a beam pointing adjustment system.

3. The all-solid-state three-wavelength four-channel ozone and aerosol detection lidar system according to claim 2, characterized in that, The beam pointing adjustment system consists of a first dichroic mirror (107), a first reflecting mirror (108), a second dichroic mirror (109), a second reflecting mirror (110), a third reflecting mirror (111), and a half-wave plate (112).

4. The all-solid-state three-wavelength four-channel ozone and aerosol detection lidar system according to claim 3, characterized in that, The subsequent optical path module (3) consists of a third dichroic mirror (301), a fourth dichroic mirror (302), a first filter (303), a second filter (304), a third filter (305), a fourth filter (306), a second polarizing beam splitter prism (307), and a first photomultiplier tube assembly (308), a second photomultiplier tube assembly (309), a third photomultiplier tube assembly (310), and a fourth photomultiplier tube assembly (311).

5. The all-solid-state three-wavelength four-channel ozone and aerosol detection lidar system according to claim 4, characterized in that, The high-speed signal acquisition and control module (4) consists of an acquisition module (401), a control submodule (402), and an industrial control computer module (403); and the acquisition module (401), the control submodule (402), and the industrial control computer module (403) maintain communication connection in sequence, and the acquisition module (401) and the industrial control computer module (403) maintain communication connection.

Images