All-solid-state tropospheric and stratospheric ozone sounding lidar system

Abstract

The application relates to the technical field of laser radar, and discloses a full-solid-state troposphere and stratosphere ozone detection laser radar system which comprises a pump light generation module, a solid-state ultraviolet laser module, a wavelength real-time monitoring module, a return light signal receiving module and a signal collection and storage module. The pump light generation module is used for generating an ultraviolet laser beam; the solid-state ultraviolet laser module divides the ultraviolet laser beam into four detection lasers which respectively form a differential absorption wavelength pair for detecting stratosphere ozone and a differential absorption wavelength pair for detecting troposphere ozone; the wavelength real-time monitoring module is used for monitoring the frequencies of the four detection lasers in real time; the return light signal receiving module is used for receiving backscattering return light signals of the detection lasers at different altitudes and converting the backscattering return light signals into electric signals; and the signal collection and storage module is used for collecting the electric signals and storing the electric signals as digital signals. The full-solid-state design of the system is realized through the optical parametric oscillation technology when four narrow-band laser ozone detection wavelengths are generated, the ozone concentrations in the stratosphere and the troposphere can be simultaneously detected, and continuous observation can be realized in the daytime and at night.

Description

Technical Field

[0001] This invention relates to the field of lidar technology, specifically to an all-solid-state lidar system for detecting ozone in the troposphere and stratosphere. Background Technology

[0002] In the atmosphere, ozone is generally divided into tropospheric ozone and stratospheric ozone. Tropospheric ozone accounts for about 10% of the total ozone and actively participates in many chemical processes in the troposphere as a strong oxidant. Tropospheric ozone is harmful to humans, animals, and plants. Stratospheric ozone, on the other hand, accounts for a larger proportion of the total ozone. Due to its strong absorption of ultraviolet light, it plays an important role in protecting humans and the environment from ultraviolet radiation in the stratosphere.

[0003] Differential absorption lidar is an advanced technology suitable for repeatable measurement of the vertical distribution of atmospheric ozone gas concentration. It involves simultaneously or alternately emitting two laser beams (one pair or other pairs) with different ozone absorption cross-sections into the atmosphere. A receiving telescope receives the backscattered echo signals from these two laser beams scattered by the atmospheric medium. A photomultiplier tube converts the optical signals into electrical signals, which are then acquired by a high-speed data acquisition card and stored as digital signals. The ozone concentration along the path of the paired laser beams can then be calculated. However, currently common differential absorption ozone lidar typically uses a Raman tube to generate Raman lasers of corresponding wavelengths as the detection wavelength pair. This approach suffers from problems such as low solid-state integration, inflexible selection of detection wavelengths within a certain range, low energy conversion efficiency, short detection range, and difficulty in achieving continuous day and night observation. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an all-solid-state tropospheric and stratospheric ozone detection lidar system.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A fully solid-state tropospheric and stratospheric ozone detection lidar system includes:

[0007] Pump light generation module, used to generate an ultraviolet laser beam with a wavelength of 355nm;

[0008] The solid-state ultraviolet laser module uses optical parametric oscillation (OPO) technology to split the ultraviolet laser beam into four probe lasers, one of which is used to obtain wavelengths of [missing information]. The stratospheric ozone concentration detection laser is directly emitted into the atmosphere of the target object to detect the stratospheric ozone concentration; the remaining three channels are allocated to obtain wavelengths of... , and The three adjustable wavelength ozone concentration detection lasers are emitted into the atmosphere of the target object; and The differential absorption wavelength pair that constitutes the detection of stratospheric ozone concentration, and The differential absorption wavelength pair is used to detect the concentration of ozone in the troposphere;

[0009] The wavelength real-time monitoring module is used to monitor the frequency of the four detection lasers in real time.

[0010] The echo signal receiving module is used to receive the backscattered echo signals of the probe laser at different heights and convert them into electrical signals;

[0011] The signal acquisition and storage module is used to acquire the electrical signal and store it as a digital signal, while also storing the data transmitted back by the wavelength real-time monitoring module.

[0012] In one embodiment, the pump light generation module includes a YAG laser and a frequency doubling crystal; the 1064nm wavelength laser emitted from the YAG laser is tripled by the frequency doubling crystal to generate a 355nm wavelength ultraviolet laser beam.

[0013] In one embodiment, the frequency-doubling crystal in the pump light generation module includes a Type-I LBO second harmonic crystal and a Type-II LBO third harmonic crystal; wherein the Type-I LBO second harmonic crystal is used to double the frequency of the 1064nm wavelength laser output from the YAG laser to generate a 532nm wavelength second harmonic green laser, with the remaining portion being a 1064nm wavelength laser; the Type-II LBO third harmonic crystal is used to sum the frequency of the 532nm wavelength green laser and the remaining 1064nm wavelength laser to generate a 355nm wavelength third harmonic ultraviolet laser beam.

[0014] In one embodiment, the solid-state ultraviolet laser module includes a beam splitter, a reflector, three sets of optical parametric oscillators, a frequency doubling crystal, a Fabry-Perot interferometer, and a laser beam expander.

[0015] The beam splitter is used to divide the energy of the 355nm ultraviolet laser beam output by the pump light generation module into four paths according to the detection height requirements. Except for one path which is directly emitted into the atmosphere of the target object, the remaining three laser beams enter the optical parametric oscillator.

[0016] The reflector is used to change the direction of laser transmission in the horizontal direction and to emit the probe laser into the atmosphere of the target object in the vertical direction;

[0017] The optical parametric oscillator uses a 355nm ultraviolet laser beam to generate three signal lasers of different wavelengths, with wavelengths of [missing information]. ;

[0018] The frequency doubling crystal is a nonlinear birefringent Type-I BBO crystal, used to frequency double three laser signals of different wavelengths, outputting a second harmonic ultraviolet laser, thereby generating a differential absorption wavelength pair for detecting tropospheric ozone concentration. The corresponding two ozone concentration detection lasers, and the wavelength is Stratospheric ozone concentration detection laser;

[0019] The Fabry-Perot interferometer is used to narrow the linewidth of three ozone concentration detection lasers;

[0020] The laser beam expander is a transmission-type achromatic beam expander used to expand the narrowed linewidth ozone concentration detection laser output from the Fabry-Perot interferometer and then emit it into the atmosphere of the target object.

[0021] In one embodiment, the optical parametric oscillator includes an optical resonant cavity and two nonlinear optical crystals. The optical resonant cavity includes a plane mirror and a concave mirror, and the two nonlinear optical crystals are placed between the plane mirror and the concave mirror. After passing through the optical resonant cavity, a 355nm ultraviolet laser beam generates a signal laser in the wavelength range of 560nm to 630nm and idler light in the wavelength range of 830nm to 970nm. The plane mirror has an anti-reflective coating with a wavelength of 830nm to 970nm on the incident light side to filter the idler light, and a partially reflective coating with a wavelength of 560nm to 630nm on the emitting light side to enable light oscillation and amplification. The concave mirror has a partially reflective coating with a wavelength of 560nm to 630nm on the incident light side and an anti-reflective coating with a wavelength of 830nm to 970nm on the emitting light side to filter the idler light.

[0022] In one embodiment, both nonlinear optical crystals are nonlinear birefringent Type-I BBO crystals, which are placed symmetrically between the plane mirror and the concave mirror.

[0023] Using a 355nm ultraviolet laser beam as the pump light, the refractive index of the nonlinear optical crystal for different wavelengths is altered by changing the angle between the optical axis of the nonlinear optical crystal and the incident pump light, thereby achieving phase matching and generating the signal laser required for detecting different ozone concentrations. The wavelength of the pump light... Wavelength of the signal laser wavelength of idle frequency light Between ;

[0024] Wherein, the generation wavelength is The phase matching angle satisfied by the signal laser is The generated wavelength is The phase matching angle satisfied by the signal laser is The generated wavelength is The phase matching angle satisfied by the signal laser is ;in, No two of them are equal.

[0025] In one embodiment, the echo optical signal receiving module includes a receiving telescope, a beam splitter, a transmission optical fiber, a chopping optical disc, a follow-up optical path, and a photomultiplier tube.

[0026] In one embodiment, the receiving telescope has an aperture of 1m and is used to receive wavelengths of... and The backscattered echo signal of the stratospheric ozone concentration detection laser, and the wavelength of and The backscattered echo signal of the laser used for detecting tropospheric ozone concentration; the receiving telescope also needs to receive the wavelength of The stratospheric ozone concentration detection laser excited by the laser has wavelengths of... The nitrogen Raman backscattered echo signal.

[0027] In one embodiment, the beam-splitting optical path includes a collimating lens, a dichroic mirror, a beam splitter (2:8), and a converging lens, used to split the backscattered echo light signals of six different wavelengths received by the receiving telescope to each transmission fiber; the wavelength is and The backscattered echo signal is split into two backscattered echo signals with higher and lower energy by a beam splitter (2:8). The backscattered echo signal with higher energy is used to detect the ozone concentration in the upper troposphere and needs to be cut by a chopping optical disc. The backscattered echo signal with lower energy is used to detect the ozone concentration in the lower troposphere and does not need to be cut by a chopping optical disc, but is directly connected to the subsequent optical path through the transmission optical fiber.

[0028] In one embodiment, the chopping disc is used to provide the main timing of the lidar system and to chop off backscattered light signals from the air below 5,000 meters when detecting ozone concentration in the stratosphere and upper troposphere, thereby avoiding photomultiplier tube saturation.

[0029] In one embodiment, the follow-up optical path includes a collimating lens, a filter, and a converging lens; multiple wavelengths of backscattered echo light signals collected by the receiving telescope are transmitted to the follow-up optical path through different transmission optical fibers; the optical platform composed of the collimating lens, filter, and converging lens in the follow-up optical path extracts the backscattered echo light signals and converts them into electrical signals through a photomultiplier tube.

[0030] In one embodiment, the subsequent optical path may further include a filter with a bandwidth of 0.15 nm and a Fabry-Perot interferometer for adjusting the wavelength of... The backscattered echo signal of the stratospheric ozone concentration detection laser is used to suppress solar background photon noise, enabling the lidar system to reach the top of the stratosphere during daytime observations.

[0031] In one embodiment, the signal acquisition and storage module includes an acquisition device and a storage hard disk, used to acquire the electrical signal output by the echo optical signal receiving module and quickly store it as a digital signal for the application scenario of long-term continuous observation of the radar system day and night. The signal acquisition and storage module is also used to store the data of the wavelength real-time monitoring module, and the data stored on the hard disk is used to invert the ozone concentration profile and perform data analysis.

[0032] Compared with the prior art, the beneficial technical effects of the present invention are:

[0033] The all-solid-state ozone differential absorption lidar system of this invention can utilize a high-pulse-energy laser and achieve an all-solid-state design by generating four narrow-band laser detection wavelengths through optical parametric oscillation technology. This enables simultaneous detection of stratospheric and tropospheric ozone concentrations and allows the lidar system to conduct continuous observations during both day and night. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the all-solid-state tropospheric and stratospheric ozone detection lidar system in an embodiment of the present invention;

[0035] Figure 2 This is a diagram showing the internal structure of the all-solid-state tropospheric and stratospheric ozone detection lidar system in an embodiment of the present invention.

[0036] In the picture:

[0037] 1. High-pulse-energy laser; 2. Type-I LBO frequency-second crystal; 3. Type-II LBO frequency-third crystal; 4. Mirror; 5. Beam splitter one; 6. Beam splitter two; 7. Beam splitter three; 8. Plane mirror one; 801, incident light side of the plane mirror; 802, exit light side of the plane mirror; 9. Nonlinear birefringent Type-I BBO crystal one; 10. Nonlinear birefringent Type-I BBO crystal two; 11. Concave mirror one; 1101, incident light side of concave mirror one; 1102, exit light side of concave mirror one; 12. Concave mirror two; 13. Beam splitter four; 14. Fabry-Perot interferometer one; 15. Laser beam expander one; 16. Mirror one; 17. Wavelength meter one; 18. Beam splitter five; 19. Laser beam expander two; 20. Wavelength meter two; 2 1. Plane mirror 2; 2101, Incident light side of plane mirror 2; 2102, Outgoing light side of plane mirror 2; 22. Reflector 2; 23. Nonlinear birefringent Type-I BBO crystal 3; 24. Nonlinear birefringent Type-I BBO crystal 4; 25. Concave mirror 2; 2501, Incident light side of concave mirror 2; 2502, Outgoing light side of concave mirror 2; 26. Frequency doubling crystal 2; 27. Beam splitter 6; 28. Fabry-Perot interferometer 2; 29. ​​Laser beam expander 3; 30. Reflector 3; 31. Wavelength meter 3; 32. Plane mirror 3; 3201, Incident light side of plane mirror 3; 3202, Outgoing light side of plane mirror 3; 33. Nonlinear birefringent type-I BBO crystal 4; 5. Type-I refractive BBO crystal; 34. Type-I nonlinear birefringent BBO crystal; 35. Concave mirror; 3501. Incident light side of concave mirror; 3502. Outgoing light side of concave mirror; 36. Frequency doubling crystal; 37. Beam splitter; 38. Fabry-Perot interferometer; 39. Laser beam expander; 40. Mirror; 41. Wavemeter; 42. Receiving telescope; 43. Collimating lens; 44. Dichroic mirror; 45. Dichroic mirror; 46. Beam splitter; 47. Converging lens; 48. Transmission fiber; 49. Collimating lens; 50. Filter; 51. Converging lens; 52. Photomultiplier tube; 53. Converging lens. 54. Transmission fiber optic cable II; 55. Collimating lens III; 56. Filter II; 57. Converging lens X; 58. Photomultiplier tube II; 59. Beam splitter II; 60. Converging lens III; 61. Transmission fiber optic cable III; 62. Collimating lens IV; 63. Filter III; 64. Converging lens XI; 65. Photomultiplier tube III; 66. Converging lens IV; 67. Transmission fiber optic cable IV; 68. Collimating lens V; 69. Filter IV; 70. Converging lens XII; 71. Photomultiplier tube IV; 72. Dichroic mirror III; 73. Dichroic mirror IV; 74. Converging lens V; 75. Transmission fiber optic cable V; 76. Collimating lens VI; 77. Filter V; 78. Fabry-Perot interferometer IV; 79. Converging lens XIII;80. Photomultiplier tube 5; 81. Converging lens 6; 82. Transmission fiber 6; 83. Collimating lens 7; 84. Filter 6; 85. Converging lens 14; 86. Photomultiplier tube 6; 87. Dichroic mirror 5; 88. Converging lens 7; 89. Transmission fiber 7; 90. Collimating lens 8; 91. Filter 7; 92. Converging lens 15; 93. Photomultiplier tube 7; 94. Converging lens 8; 95. Transmission fiber 8; 96. Collimating lens 9; 97. Filter 8; 98. Fabry-Perot interferometer 5; 99. Converging lens 16; 100. Photomultiplier tube 8; 101. Chopper optical disc; 102. Signal cable; 103. High-speed acquisition device; 104. High-capacity storage hard disk. Detailed Implementation

[0038] A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0039] This invention provides an all-solid-state differential absorption lidar system for simultaneous all-weather tropospheric and stratospheric detection. For example... Figure 1 As shown, the above-mentioned all-solid-state tropospheric and stratospheric ozone detection lidar system includes: a pump light generation module S1, a solid-state ultraviolet laser module S2, a wavelength real-time monitoring module S3, an echo light signal receiving module S4, and a signal acquisition and storage module S5.

[0040] Pump light generation module S1 is used to provide high-quality and high-pulse-energy beams required for nonlinear optics.

[0041] Solid-state ultraviolet laser module S2 is used to generate two tunable, narrow-linewidth ozone concentration detection lasers for tropospheric ozone detection using optical parametric oscillation technology (the wavelengths of these two lasers are...). and This consists of a differential absorption wavelength pair for detecting tropospheric ozone concentration, and two narrow-linewidth ozone concentration detection lasers for detecting stratospheric ozone (the wavelengths of these two lasers are...). and The system consists of a differential absorption wavelength pair for detecting stratospheric ozone concentration, and is designed and implemented as a fully solid-state system to simultaneously detect stratospheric and tropospheric ozone.

[0042] The wavelength real-time monitoring module S3 is used to monitor the frequency of the narrow-linewidth ozone concentration detection laser output by the solid-state ultraviolet laser module S2 in real time to prevent frequency drift.

[0043] The echo signal receiving module S4 is used to classify and receive the backscattered echo signals of ozone concentration detection lasers at different emission energies and target altitudes. It also uses a combination of an ultra-narrow band filter and a Fabry-Perot interferometer to suppress solar background photon noise during the day, so as to achieve all-day observation of the lidar system.

[0044] The signal acquisition and processing module S5 is used to acquire the electrical signal output by the photomultiplier tube at high speed, convert it into a digital signal for storage, and also store the data returned by the wavelength real-time monitoring module.

[0045] Figure 2 The internal structure of an all-solid-state tropospheric and stratospheric ozone detection lidar system is shown. Figure 2 In this context, SHG stands for Type-I LBO second harmonic crystal, THG stands for Type-II LBO third harmonic crystal, and PMT stands for photomultiplier tube.

[0046] In one embodiment, the pump light generation module S1 includes a high-pulse-energy laser 1 and a frequency-doubling crystal. The 1064nm wavelength laser emitted from the high-pulse-energy laser 1 is tripled by the frequency-doubling crystal to generate a high-quality, high-energy 355nm wavelength short-wavelength ultraviolet laser beam. This short-wavelength ultraviolet laser beam is subsequently allocated the laser energy required to detect the stratosphere, serving as one beam in the stratospheric ozone concentration detection laser, with a wavelength of [missing information]. After being expanded by a laser beam expander, the laser beam is directly emitted into the atmosphere of the target object. The energy of the remaining three beams is allocated to pump the solid-state ultraviolet laser module S2, thereby generating another stratospheric ozone concentration detection laser (with a wavelength of...). ), and two other tropospheric ozone concentration detection lasers (corresponding wavelengths) and (This is a differential absorption wavelength pair for detecting tropospheric ozone concentration). Among them, the high-pulse energy laser 1 adopts a high-power YAG high-pulse energy laser.

[0047] In one embodiment, the frequency doubling crystal in the pump light generation module S1 includes a Type-I LBO second harmonic crystal (SHG) 2 and a Type-II LBO third harmonic crystal (THG) 3. The Type-I LBO second harmonic crystal 2 is used to double the frequency of the 1064nm wavelength laser output from the high pulse energy laser 1 to generate a 532nm wavelength second harmonic green laser. The Type-II LBO third harmonic crystal 3 is used to sum the frequency of the 532nm wavelength second harmonic green laser and the remaining 1064nm wavelength laser to generate a 355nm wavelength third harmonic ultraviolet laser. After the laser direction is changed by the reflector 4, it is used as the pump light input of the solid-state ultraviolet laser module S2.

[0048] In one embodiment, the solid-state ultraviolet laser module S2 includes beam splitters (beam splitter 5, beam splitter 6, beam splitter 7, beam splitter 4, beam splitter 5, beam splitter 6, beam splitter 7, beam splitter 8, beam splitter 9, beam splitter 10, beam splitter 11, beam splitter 12, beam splitter 13, beam splitter 14, beam splitter 15, beam splitter 16, beam splitter 16, beam splitter 17, beam splitter 18, beam splitter 18, beam splitter 19 ... Besides the stratospheric ozone concentration detection laser with wavelength 1, the other three ozone concentration detection lasers have wavelengths of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 ... Used to form a differential absorption wavelength pair for detecting stratospheric ozone concentration ( ) and the differential absorption wavelength pair for detecting tropospheric ozone concentration ( The laser beam is expanded by laser beam expander 15, laser beam expander 29, laser beam expander 39, and laser beam expander 439 to reduce the laser divergence angle and emit it into the atmosphere of the target object for ozone concentration detection.

[0049] In an optional embodiment, beam splitters 1 (5), 2 (6), and 3 (7) are used to divide the energy of the 355nm wavelength short-wave ultraviolet laser beam output by the pump light generation module S1 into four paths according to different detection heights; beam splitters 4 (13), 5 (18), 6 (27), and 7 (37) have a beam splitting ratio of 99:1, which are used to separate weak energy laser beams so that the ozone concentration detection laser frequency output by the solid-state ultraviolet laser module S2 can be monitored in real time by wavelength meters 1 (17), 2 (20), 3 (31), and 4 (41).

[0050] In one embodiment, the optical parametric oscillator in the solid-state ultraviolet laser module S2 consists of an optical resonant cavity and two nonlinear optical crystals. The optical resonant cavity is composed of plane mirrors (plane mirror 8, plane mirror 21, and plane mirror 32 in the three optical parametric oscillators) and concave mirrors (concave mirror 11, concave mirror 25, and concave mirror 35 in the three optical parametric oscillators). The two nonlinear optical crystals are nonlinear birefringent Type-I BBO crystals (the two nonlinear birefringent Type-I BBO crystals in the first optical parametric oscillator are nonlinear birefringent...). Type-I BBO crystal 1 (9), Nonlinear birefringent Type-I BBO crystal 2 (10), and two other nonlinear birefringent Type-I BBO crystals in the second group of optical parametric oscillators (Type-I BBO crystal 3 (23) and Type-I BBO crystal 4 (24) respectively), and two other nonlinear birefringent Type-I BBO crystals in the third group of optical parametric oscillators (Type-I BBO crystal 5 (33) and Type-I BBO crystal 6 (34) respectively). These nonlinear birefringent Type-I BBO crystals are placed between a plane mirror and a concave mirror. The optical parametric oscillator uses a 355nm ultraviolet laser beam to generate three ozone concentration detection laser signal lasers. The wavelengths of the three signal lasers are respectively... .

[0051] The 355nm ultraviolet laser beam, after passing through the optical resonant cavity, generates a signal laser in the wavelength range of 560nm~630nm and idler light in the wavelength range of 830nm~970nm. An anti-reflective coating of 830nm~970nm is deposited on the incident light side 801 of plane mirror 8, the incident light side 2101 of plane mirror 21, and the incident light side 3201 of plane mirror 32 to filter the idler light. A partially reflective coating of 560nm~630nm wavelength is deposited on the exit light side 802 of plane mirror 8, the exit light side 2102 of plane mirror 21, and the exit light side 3202 of plane mirror 32 to enable the signal laser to oscillate and amplify. Two nonlinear birefringent Type-I BBO crystals are placed symmetrically in a cross shape to compensate for walk-off loss caused by walk-off angle and improve light conversion efficiency. Concave mirror 11 (incident light side 1101), concave mirror 25 (incident light side 2501), and concave mirror 35 (incident light side 3501) are coated with a 560nm~630nm partial reflective coating. Concave mirror 11 (outcident light side 1102), concave mirror 25 (outcident light side 2502), and concave mirror 35 (outcident light side 3502) are coated with an 830~970nm anti-reflective coating, which is also used to filter idler light.

[0052] In an optional embodiment, an optical parametric oscillator composed of a plane mirror 8, a nonlinear birefringent Type-I BBO crystal 9, a nonlinear birefringent Type-I BBO crystal 10, and a concave mirror 11, together with a frequency-harmonic crystal 12, generates... A wavelength-dependent laser for detecting ozone concentration; an optical resonant cavity composed of a plane mirror 21, a nonlinear birefringent Type-I BBO crystal 23, a nonlinear birefringent Type-I BBO crystal 4 24, and a concave mirror 25, and a frequency doubling crystal 26, generating... A wavelength-dependent laser for detecting ozone concentration; an optical resonant cavity composed of a plane mirror (32), a nonlinear birefringent Type-I BBO crystal (53), a nonlinear birefringent Type-I BBO crystal (634), and a concave mirror (35), and a frequency doubling crystal (36), generating... Ozone concentration detection laser at a specific wavelength; and The differential absorption wavelength pair for detecting tropospheric ozone concentration.

[0053] In one embodiment, two nonlinear birefringent Type-I BBO crystals are symmetrically placed crosswise within a single optical resonator in the solid-state ultraviolet laser module S2. By changing the angle between the optical axis of the nonlinear birefringent Type-I BBO crystal and the incident pump light, the refractive index of the nonlinear birefringent Type-I BBO crystal for different wavelength beams can be changed to achieve phase matching and generate the signal laser required for detecting different ozone concentrations, wherein the pump light... Signal laser and leisure frequency light The wavelength relationship between them satisfies .

[0054] In an optional embodiment, the wavelength generated by the cross-symmetrically placed nonlinear birefringent Type-I BBO crystal 9 and nonlinear birefringent Type-I BBO crystal 10 is... The signal laser satisfies a phase matching angle of . The wavelength generated by the cross-symmetrically placed nonlinear birefringent Type-I BBO crystals 323 and 424 is... The signal laser satisfies a phase matching angle of . The wavelength generated by the cross-symmetrically placed nonlinear birefringent Type-I BBO crystals 5.33 and 6.34 is... The signal laser satisfies a phase matching angle of . The ozone concentration detection laser of different wavelengths can be flexibly selected by adjusting the angle (phase matching angle) between the incident pump light and the optical axis of the nonlinear birefringent Type-I BBO crystal; among which, , , .

[0055] In one embodiment, the frequency doubling crystals 12, 26, and 36 in the solid-state ultraviolet laser module S2 are nonlinear birefringent Type I BBO crystals. The half-frequency signal laser output from the optical parametric oscillator is injected into the frequency doubling crystals to satisfy the Brewster angle. Nonlinear optical techniques are used to optimize the three wavelengths... The signal laser is processed to output second harmonic ultraviolet laser, thereby achieving frequency doubling and outputting... Ozone concentration detection laser at specific wavelengths.

[0056] In one embodiment, the Fabry-Perot interferometer 14, Fabry-Perot interferometer 28, and Fabry-Perot interferometer 38 in the solid-state ultraviolet laser module S2 are used to narrow the linewidth of the ozone concentration detection laser, thereby improving its coherence and spectral purity.

[0057] In one embodiment, the laser beam expander 15, laser beam expander 29, laser beam expander 39, and laser beam expander 49 in the solid-state ultraviolet laser module S2 are used to respectively convert the outputs of the Fabry-Perot interferometer 14, Fabry-Perot interferometer 28, and Fabry-Perot interferometer 38 into the laser beams. The wavelength is for ozone concentration detection laser, and The stratospheric ozone concentration detection laser beam is expanded and emitted into the atmosphere of the target object. Each laser beam expander is a transmission-type achromatic beam expander, which provides the same magnification for the four detection lasers of the lidar system and can also reduce the laser divergence angle to meet the receiving field of view of the telescope.

[0058] In one embodiment, the wavelength real-time monitoring module S3 is used to monitor the laser frequency of the four probe lasers to prevent absorption errors caused by wavelength drift from affecting the intensity of the backscattered echo light signal, so as to ensure the system's high stability and high frequency accuracy laser output.

[0059] In one embodiment, the echo light signal receiving module S4 includes a receiving telescope 42, a beam splitting optical path, transmission optical fibers (transmission optical fiber 1 48, transmission optical fiber 2 54, transmission optical fiber 3 61, transmission optical fiber 4 67, transmission optical fiber 5 75, transmission optical fiber 6 82, transmission optical fiber 7 89, and transmission optical fiber 8 95, respectively), a chopping optical disc 101, a follow-up optical path, and photomultiplier tubes (photomultiplier tube 1 52, photomultiplier tube 2 58, photomultiplier tube 3 65, photomultiplier tube 4 71, photomultiplier tube 5 80, photomultiplier tube 6 86, photomultiplier tube 7 93, and photomultiplier tube 8 100, respectively), used to receive and split the backscattered echo light signals of ozone concentration detection lasers with different emission energies and different target altitudes (stratospheric and tropospheric), and convert the optical signals received by the follow-up optical path into electrical signals through the photomultiplier tubes.

[0060] In one embodiment, the echo optical signal receiving module S4 has a receiving telescope 42 with a diameter of 1m, used to receive wavelengths of... and The backscattered echo signal and wavelength of the laser used for stratospheric ozone concentration detection are as follows: and In addition to the backscattered echo signal from the ozone concentration detection laser, the 1m aperture telescope also needs to receive wavelengths of... The stratospheric ozone concentration detection laser excited by the laser has wavelengths of... The nitrogen Raman backscattered echo signal.

[0061] In one embodiment, the beam splitting optical path in the echo signal receiving module S4 includes a collimating lens 43, dichroic mirrors (dichroic mirror 44, dichroic mirror 45, dichroic mirror 72, dichroic mirror 73, dichroic mirror 87, etc.), a beam splitter (with a splitting ratio of 2:8, including beam splitter 46, beam splitter 59) and a converging lens (converging lens 47, converging lens 53, converging lens 60, converging lens 46, converging lens 54, converging lens 61, converging lens 78, converging lens 84, etc.), which are used to split the six different wavelength echo signals received by the receiving telescope to each transmission optical fiber.

[0062] In one embodiment, the beam splitter in the echo signal receiving module S4 is configured to receive wavelengths from the receiving telescope 42. The backscattered echo signal from the tropospheric ozone concentration detection laser, after being collimated by collimating lens 43 and split into two wavelengths by dichroic mirror 44, is then separated by dichroic mirror 45. The echo optical signals are separated, among which and The wavelength echo signal light is then split into two beams of high energy (80%) and low energy (20%) by beam splitter 2 59 and beam splitter 1 46, respectively. The stronger echo signal light is focused by converging lens 4 66 and converging lens 2 53 to transmission fiber 4 67 and transmission fiber 2 54 for detecting ozone concentration in the upper troposphere, and needs to be fed through chopper optical disc 101. The weaker echo signal light is focused by converging lens 3 60 and converging lens 1 47 to transmission fiber 3 61 and transmission fiber 1 48 for detecting ozone concentration in the lower troposphere, and does not need to be fed through chopper optical disc 101 but is directly fed through the transmission fiber into the subsequent optical path.

[0063] In one embodiment, the beam splitter in the echo signal receiving module S4 is configured to receive wavelengths from the receiving telescope 42. The backscattered echo signal from the stratospheric ozone concentration detection laser also includes the corresponding excitation generated at a wavelength of The nitrogen Raman backscattered echo signal, after being collimated by collimating lens 43 and separated into two wavelengths by dichroic mirror 44, is transmitted through dichroic mirror 72. and A beam of light of a certain wavelength, reflected and A beam of light of wavelength, in which the reflected light... and The wavelength beam is separated by a dichroic mirror 4.73. Stratospheric ozone concentration detection wavelength and its corresponding The nitrogen Raman backscattered signal wavelengths are separated and converged by converging lenses 5.74 and 6.81 respectively to transmission optical fibers 5.75 and 6.82, requiring a chopping disc 101 for transmission; the transmitted signal... and The wavelength beam is separated by the dichroic mirror 5.87. Stratospheric ozone concentration detection wavelength and its corresponding The nitrogen Raman backscattered signal wavelengths are separated and converged by focusing lens 894 and focusing lens 788 to transmission fiber 895 and transmission fiber 789, respectively, and also need to pass through chopping optical disc 101.

[0064] In one embodiment, the chopping optical disc 101 in the echo optical signal receiving module S4 is used to provide the main timing of the lidar system while chopping off strong backscattered light signals at low altitudes, thereby preventing photomultiplier tubes 1 52, 2 58, 3 65, 4 71, 5 80, 6 86, 7 93, and 8 100 from receiving saturation, thus protecting the detector.

[0065] In one embodiment, the follow-up optical path in the echo optical signal receiving module S4 includes collimating lenses (collimating lens 2 49, collimating lens 3 55, collimating lens 4 62, collimating lens 5 68, collimating lens 6 76, collimating lens 7 83, collimating lens 8 90, and collimating lens 9 96, respectively), filters (filter 1 50, filter 2 56, filter 3 63, filter 4 69, filter 5 77, filter 6 84, filter 7 91, and filter 8 97, respectively), and converging lenses (converging lens 9 51 and converging lens 10 57, respectively). Converging lenses 11 (64), 12 (70), 13 (79), 14 (85), 15 (92), and 16 (99) are used to transmit the backscattered echo light signals of multiple wavelengths split from the beam splitter through transmission fibers 1 (48), 2 (54), 3 (61), 4 (67), 5 (75), 6 (82), 7 (89), and 8 (95) to the optical platform of the subsequent optical path. After collimation and filtering to extract the effective signals, they facilitate photoelectric conversion by the photomultiplier tubes of each channel.

[0066] In one embodiment, the photomultiplier tubes in the echo optical signal receiving module S4 are used to receive the echo signal light after subsequent optical path processing and convergence. Among them, photomultiplier tube 1 52, photomultiplier tube 2 58, photomultiplier tube 3 65, photomultiplier tube 4 71, photomultiplier tube 5 80, photomultiplier tube 6 86, photomultiplier tube 7 93, and photomultiplier tube 8 100 respectively receive the echo signal light converged by converging lens 9 51, converging lens 10 57, converging lens 11 64, converging lens 12 70, converging lens 13 79, converging lens 14 85, converging lens 15 92, and converging lens 16 99, and convert the optical signal into an electrical signal, which is then transmitted to the signal acquisition and storage module S5 through the signal cable 102.

[0067] In a preferred embodiment, filters 5 (77) and 8 (97) in the subsequent optical path are 0.15nm ultra-narrow bandpass filters, and Fabry-Perot interferometers 4 (78) and 5 (98) are added for observation during the day to filter wavelengths of... The backscattered echo signal of the stratospheric ozone concentration detection laser is used to suppress solar background photon noise, enhance the target signal to improve the signal-to-noise ratio, and enable the lidar system to reach the top of the stratosphere at the observation altitude during the day, achieving synchronous detection of the troposphere and stratosphere all day long.

[0068] In one embodiment, the signal acquisition and storage module S5 includes a high-speed acquisition device 103 and a large-capacity storage hard disk 104. The high-speed acquisition device 103 is used to acquire the electrical signals output by photomultiplier tubes 1-52, 2-58, 3-65, 4-71, 5-80, 6-86, 7-93, and 8-100 into digital signals at high speed, which determines the spatial resolution distance of the lidar system. The large-capacity storage hard disk 104 is used to store the digital signals and is suitable for the application scenario of long-term continuous observation of the lidar system day and night. It is also used to store the data of the wavelength real-time monitoring module S3. The data stored on the hard disk can be used for subsequent inversion and analysis of the ozone concentration profile.

[0069] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0070] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0072] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A fully solid-state lidar system for detecting ozone in the troposphere and stratosphere, characterized in that, include: Pump light generation module, used to generate an ultraviolet laser beam with a wavelength of 355nm; The solid-state ultraviolet laser module uses optical parametric oscillation (OPO) technology to split the ultraviolet laser beam into four probe lasers, one of which is used to obtain wavelengths of [missing information]. The stratospheric ozone concentration detection laser is directly emitted into the atmosphere of the target object to detect the stratospheric ozone concentration; the remaining three channels are allocated to obtain wavelengths of... , and The three adjustable-wavelength ozone concentration detection lasers are emitted into the atmosphere of the target object; and The differential absorption wavelength pair that constitutes the detection of stratospheric ozone concentration, and The system comprises a differential absorption wavelength pair for detecting tropospheric ozone concentration; the solid-state ultraviolet laser module includes a beam splitter, a reflector, three sets of optical parametric oscillators, a frequency doubling crystal, a Fabry-Perot interferometer, and a laser beam expander; the beam splitter divides the 355nm ultraviolet laser beam output from the pump light generation module into four paths according to the detection altitude requirements. One path is directly emitted into the atmosphere of the target object, while the remaining three paths enter the optical parametric oscillators; the reflector changes the laser transmission direction horizontally and vertically directs the detection laser into the atmosphere of the target object; the optical parametric oscillators utilize the 355nm ultraviolet laser beam to generate three signal lasers of different wavelengths, with wavelengths of... The frequency doubling crystal is a nonlinear birefringent Type-I BBO crystal, used to frequency double three different wavelength signal lasers, outputting a second harmonic ultraviolet laser, thereby generating a differential absorption wavelength pair for detecting tropospheric ozone concentration. The corresponding two ozone concentration detection lasers, and the wavelength is The system includes a stratospheric ozone concentration detection laser; a Fabry-Perot interferometer is used to narrow the linewidth of the three ozone concentration detection lasers; and a transmission-type achromatic beam expander is used to expand the ozone concentration detection laser output from the Fabry-Perot interferometer after narrowing the linewidth before transmitting it into the atmosphere of the target object. The wavelength real-time monitoring module is used to monitor the frequency of the four detection lasers in real time. The echo signal receiving module is used to receive the backscattered echo signals of the probe laser at different heights and convert them into electrical signals; The signal acquisition and storage module is used to acquire the electrical signal and store it as a digital signal, while also storing the data transmitted back by the wavelength real-time monitoring module.

2. The all-solid-state tropospheric and stratospheric ozone detection lidar system according to claim 1, characterized in that, The pump light generation module includes a YAG laser and a frequency doubling crystal; the 1064nm wavelength laser emitted from the YAG laser is tripled by the frequency doubling crystal to generate a 355nm wavelength ultraviolet laser beam.

3. The all-solid-state tropospheric and stratospheric ozone detection lidar system according to claim 2, characterized in that, The frequency-doubling crystals in the pump light generation module include Type-I LBO second-harmonic crystals and Type-II LBO third-harmonic crystals. The Type-I LBO second-harmonic crystal is used to double the frequency of the 1064nm wavelength laser output from the YAG laser to generate a 532nm wavelength second-harmonic green laser, with the remaining 1064nm wavelength laser. The Type-II LBO third-harmonic crystal is used to combine the 532nm wavelength green laser and the remaining 1064nm wavelength laser to generate a 355nm wavelength third-harmonic ultraviolet laser beam.

4. The all-solid-state tropospheric and stratospheric ozone detection lidar system according to claim 1, characterized in that, The optical parametric oscillator includes an optical resonant cavity and two nonlinear optical crystals. The optical resonant cavity includes a plane mirror and a concave mirror, and the two nonlinear optical crystals are placed between the plane mirror and the concave mirror. After passing through the optical resonant cavity, a 355nm ultraviolet laser beam generates a signal laser in the wavelength range of 560nm~630nm and idler light in the wavelength range of 830nm~970nm. The incident light side of the plane mirror is coated with an anti-reflection coating with a wavelength of 830nm~970nm to filter the idler light. The emitting light side of the plane mirror is coated with a partially reflective coating with a wavelength of 560nm~630nm to enable the light to oscillate and amplify. The incident light side of the concave mirror is coated with a partially reflective coating with a wavelength of 560nm~630nm, and the emitting light side of the concave mirror is coated with an anti-reflection coating with a wavelength of 830nm~970nm to filter the idler light.

5. A fully solid-state tropospheric and stratospheric ozone detection lidar system according to claim 4, characterized in that, Both nonlinear optical crystals are nonlinear birefringent Type-I BBO crystals, and are placed symmetrically between the plane mirror and the concave mirror. Using a 355nm ultraviolet laser beam as the pump light, the refractive index of the nonlinear optical crystal for different wavelengths is altered by changing the angle between the optical axis of the nonlinear optical crystal and the incident pump light, thereby achieving phase matching and generating the signal laser required for detecting different ozone concentrations. The wavelength of the pump light... Wavelength of the signal laser wavelength of idle frequency light Between ; Wherein, the generation wavelength is The phase matching angle satisfied by the signal laser is The generated wavelength is The phase matching angle satisfied by the signal laser is The generated wavelength is The phase matching angle satisfied by the signal laser is ;in, No two of them are equal.

6. The all-solid-state tropospheric and stratospheric ozone detection lidar system according to claim 1, characterized in that, The echo optical signal receiving module includes a receiving telescope, a beam splitter, a transmission optical fiber, a chopping optical disc, a follow-up optical path, and a photomultiplier tube.

7. A fully solid-state tropospheric and stratospheric ozone detection lidar system according to claim 6, characterized in that, The receiving telescope has an aperture of 1m and is used to receive wavelengths of... and The backscattered echo signal of the stratospheric ozone concentration detection laser, and the wavelength of and The backscattered echo signal of the laser used for detecting tropospheric ozone concentration; the receiving telescope also needs to receive the wavelength of The stratospheric ozone concentration detection laser excited by the laser has wavelengths of... The nitrogen Raman backscattered echo signal.

8. A fully solid-state tropospheric and stratospheric ozone detection lidar system according to claim 6, characterized in that, The beam-splitting optical path includes a collimating lens, a dichroic mirror, a beam splitter, and a converging lens, used to split the backscattered echo light signals of six different wavelengths received by the receiving telescope into various transmission optical fibers; the beam splitter has a splitting ratio of 2:8 and a wavelength of... and The backscattered echo signal is split into two backscattered echo signals with higher and lower energy by a beam splitter. The backscattered echo signal with higher energy is used to detect the ozone concentration in the upper troposphere and needs to be cut by a chopping optical disc. The backscattered echo signal with lower energy is used to detect the ozone concentration in the lower troposphere and does not need to be cut by a chopping optical disc, but is directly connected to the subsequent optical path through the transmission optical fiber.

9. A fully solid-state tropospheric and stratospheric ozone detection lidar system according to claim 6, characterized in that, The chopping disc is used to provide the main timing of the lidar system and to chop off backscattered light signals from the air below 5,000 meters when detecting ozone concentration in the stratosphere and upper troposphere, thereby avoiding the photomultiplier tube from becoming saturated.

10. A fully solid-state tropospheric and stratospheric ozone detection lidar system according to claim 6, characterized in that, The subsequent optical path includes a collimating lens, a filter, and a converging lens. Backscattered echo light signals of multiple wavelengths collected by the receiving telescope are transmitted to the subsequent optical path through different transmission optical fibers. The optical platform composed of the collimating lens, filter, and converging lens in the subsequent optical path extracts the backscattered echo light signals and converts them into electrical signals through a photomultiplier tube.

11. A fully solid-state tropospheric and stratospheric ozone detection lidar system according to claim 10, characterized in that, The subsequent optical path also includes a filter with a bandwidth of 0.15 nm and a Fabry-Perot interferometer, used for adjusting the wavelength of... Backscattered echo light signals from stratospheric ozone concentration detection lasers are used to suppress solar background photon noise.

12. A fully solid-state tropospheric and stratospheric ozone detection lidar system according to claim 1, characterized in that, The signal acquisition and storage module includes an acquisition device and a storage hard disk. It is used to acquire the electrical signal output by the echo optical signal receiving module and store it as a digital signal at an acquisition frequency in the MHz range. This is used for the application scenario of continuous all-day observation of the radar system. The signal acquisition and storage module is also used to store the data of the wavelength real-time monitoring module. The data stored on the hard disk is used to invert the ozone concentration profile and perform data analysis.

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