Near space all-altitude environment multi-element laser radar detection platform

Abstract

The application provides a near-space full-altitude environment multi-element laser radar detection platform, constructs a trinity structure of "common basic support + atmospheric composition detection + meteorological multi-element detection", solves a multi-device data fusion problem through a unified optical reference and a time synchronization mechanism, improves the spatiotemporal consistency of detection data, realizes high-precision collaborative detection of "full altitude and multi-element", breaks through the capability limitation of a single platform and a dispersed networking scheme, constructs an efficient multi-source heterogeneous data processing architecture, meets the real-time storage, analysis and visualization needs of massive data, improves the reliability and expandability of the equipment, realizes all-weather unattended operation, and supports flexible expansion of subsequent functional modules.

Description

Technical Field

[0001] This invention belongs to the field of remote sensing technology, specifically relating to a near-space full-elevation environment multi-element lidar detection platform. Background Technology

[0002] Near space (typically referring to the airspace 20-100 km above the ground) is a crucial region connecting aviation and aerospace. Accurate detection of its environmental parameters (such as atmospheric composition, temperature, humidity, density, and wind field) is of strategic significance for national security, aerospace vehicle design, weather forecasting, and global climate change research. Currently, mainstream international near-space exploration technologies mainly rely on the following two approaches:

[0003] Single-platform lidar detection schemes: Represented by the sodium resonance fluorescence Doppler lidar at Colorado State University in the United States and the ALOMAR (Arctic Lidar Observatory for Middle Atmospheric Research) lidar station in Europe, these schemes mostly use a single-aperture telescope as the receiving system, which can only achieve high-precision detection of specific elements (such as sodium atoms and temperature). They have the problem of poor multi-band detection scalability and cannot simultaneously meet the needs of coordinated detection of atmospheric composition and multiple meteorological elements.

[0004] Multi-device distributed networking scheme: Represented by China's "Meridian Project," this scheme achieves regional near-space observation by deploying independent lidar stations at different latitudes (such as Mohe Station, Beijing Station, and Sanya Station). Although this scheme has a wide coverage area, it lacks a unified optical reference and time synchronization mechanism among the devices, making data fusion difficult. Furthermore, the functions of individual station devices are limited (e.g., some stations can only detect ozone, while others can only detect temperature), making it difficult to form a continuous detection capability covering "all elevations and multiple elements."

[0005] (1) Disadvantages of existing technology: Limitations in detection capabilities: Single-platform solutions can only focus on a single element or a single elevation range, while multi-device network solutions have poor data coordination and neither can achieve integrated detection of "full elevation (20-100km) and multiple elements".

[0006] Low cost and low engineering feasibility: Large-aperture single telescopes are expensive and difficult to manufacture. The grinding and coating processes of 3m-class telescopes are complex, and they require a complex active optical system, making it difficult to implement the project.

[0007] Insufficient data processing efficiency: Existing systems lack a dedicated processing architecture for highly dynamic, multimodal data in the near space, and have weak data storage and real-time analysis capabilities, making it unable to support rapid decision-making and emergency response.

[0008] Poor equipment reliability and scalability: "Laboratory prototype" level equipment has stringent requirements for the operating environment, lacks redundant design, and a single equipment failure will cause the entire detection link to be interrupted; moreover, it mostly adopts a fixed architecture, making it difficult to be compatible with new detection modules. Summary of the Invention

[0009] In view of this, the purpose of the present invention is to provide a multi-element lidar detection platform for near-space full-altitude environment.

[0010] A near-space full-elevation environment multi-element lidar detection platform includes: The common basic support system consists of at least four parabolic receiving telescopes with an effective light transmission aperture ≥1600mm, spliced ​​in a coaxial symmetrical array. Each telescope has multiple fiber optic receiving channels on its focal plane and is equipped with fiber optic couplers and fiber optic routing switching mechanisms. The receiving telescope is used to receive atmospheric echo signals from different altitudes in near space, and the echo signals include at least: The sodium atom resonance fluorescence signal, with a wavelength of 589 nm, was used to invert the sodium atom density profile. The ozone differential absorption signal, including a strong absorption signal at 308 nm and a weak absorption reference signal at 355 nm, is used to retrieve the ozone concentration profile. Elastic scattering signal, wavelength 355nm, used to retrieve atmospheric density and temperature profiles; Rayleigh scattering signal, wavelength 355nm, used to invert atmospheric density profile; Rotating Raman scattering signal, wavelength 355nm, is used to invert stratospheric temperature profile; The atmospheric composition detection system includes: The sodium atom resonance fluorescence lidar uses seed laser injection and sum-frequency technology to generate 589nm pulsed laser, with a detection altitude of 80km-105km, and is equipped with an ultra-narrowband atomic filter to achieve all-weather detection. The ozone differential absorption lidar uses a XeCl excimer laser to generate 308nm strong absorption light and Nd:YAG third harmonic to generate 355nm weak absorption reference light, with a detection altitude of 20km-50km. The near-field meteorological multi-element detection system includes: The meteorological element detection lidar operates at wavelengths of 355nm and 532nm and employs a multi-scattering mechanism for coordinated detection. Specifically: Humidity detection: Vibrational Raman scattering excited by a 532nm laser, with a detection height of ≥6km; Temperature detection: Stratospheric temperature is detected by rotating Raman scattering of a 355nm laser, and mesosphere temperature is detected by Rayleigh scattering of a 355nm laser, with a detection altitude of ≥80km; Density detection: Detection altitude ≥90km via Rayleigh scattering of a 355nm laser; It also features a unified optical reference and time synchronization mechanism. By fixing the position of the fiber optic focal plane of one of the telescopes as an absolute reference, and combining a global timing controller and a time-division transmission strategy, it enables collaborative detection of multiple elements within a full altitude range of 20km-100km.

[0011] Preferably, in the common basic support system, the received atmospheric echo signal further includes: The nitrogen vibration Raman signal, with a wavelength of 386 nm, provides an independent atmospheric parameter depth correction mechanism for the system. By collecting measured data from this channel and inputting it into the atmospheric extinction coefficient correction model, the interference caused by complex aerosol nonlinear scattering above 30 km in the stratosphere on ozone differential absorption inversion is eliminated.

[0012] Water vapor vibration Raman signal, wavelength 407nm; the ratio of the 407nm water vapor Raman signal to the 386nm nitrogen vibration Raman signal is calculated, and after canceling aerosol extinction interference, high-precision water vapor mixing ratio profile data is obtained by inversion.

[0013] Preferably, each telescope has three optical fibers on its focal plane, with a receiving range of Φ7.5mm, corresponding to a 3mrad field of view, a fiber core diameter of Φ1.5mm, and an incident end equipped with a Φ2.2mm steel sleeve and a bending protection device.

[0014] Preferably, the four telescopes in the common basic support system achieve the following three operating modes through focal plane optical fiber, optical fiber combiner, optical fiber distribution frame and signal detection unit: Coaxial receiving mode: The optical fibers of the focal plane of the four telescopes are respectively output to a fiber bundle combiner. The combiner tightly arranges the cores of the four optical fibers and connects them to the same signal detection unit, so that the equivalent light transmission aperture of the four telescopes reaches 3m. Independent operating mode: The optical fibers of the four telescopes are connected to four independent signal detection subsystems via fiber optic distribution frames. Each channel is physically isolated in space, specifically allocated as follows: The optical fiber at the focal plane of the first telescope is connected to a 589nm sodium atom detection unit for detecting sodium atom layers in the 80km-105km range. The second telescope's focal plane fiber is connected to the 308nm ozone detection unit for ozone concentration detection in the 20km-50km range. The third telescope's focal plane fiber is connected to a 355nm meteorological element detection unit for atmospheric density, temperature, and humidity detection at a range of 30km-80km. The fourth telescope's focal plane fiber is connected to the polarization detection unit or used as a backup channel; Combined detection mode: According to the specific observation task requirements, the fiber optic routes are switched through the fiber optic distribution frame to simultaneously connect the fibers of at least two telescopes to the same signal detection unit to improve the signal-to-noise ratio and time resolution of the detection element; the fibers of the remaining telescopes remain in independent working mode to synchronously acquire auxiliary reference data.

[0015] Preferably, the unified optical reference and time synchronization mechanism includes: The three optical fibers of the designated northeast corner telescope are fixed to the focal plane as the optical reference anchor points for the entire platform; At least two optical fibers in the remaining telescopes are finely adjusted in the XY direction via an electric two-dimensional adjustment mount, with an adjustment range of 0.5 mm towards the center and 2 mm outward, and a resolution of 5 μm. The focusing tube has a Z-axis manual focusing function with an adjustment range of ±6mm and an accuracy of ≤0.05mm; The adjustable fiber optic mount has a circumferential rotation adjustment function with an adjustment range of ±3°.

[0016] Preferably, the time synchronization mechanism includes: Each lidar unit is equipped with a GPS or BeiDou timing module, with a time synchronization accuracy of ≤1μs; The central timing controller uses a time-division multiplexing strategy to stagger the transmission time windows of each device, with the transmission interval between adjacent devices being ≥3ms; The data acquisition terminal is equipped with a timestamp filtering mechanism to collect only the echo signal corresponding to the transmission period of this device.

[0017] Furthermore, it also includes a triple signal isolation mechanism: Spatial isolation: achieved by controlling the divergence angle of the emitted beam and the receiving field of view, and by installing a light shield; Temporal isolation: achieved through time-division multiplexing and timestamp filtering; Spectrum isolation: The three sets of lidar operate at wavelengths ≥30nm apart, and the receiver is equipped with a narrowband filter with center wavelength matching and bandwidth ≤0.6nm.

[0018] Preferably, the telescope used to receive the echo signal from the ozone detection lidar employs a two-stage beam splitting architecture: the first stage separates the 308nm and 355nm signals using a dichroic mirror; the second stage is equipped with narrowband interference filters, namely: 308nm filter: center wavelength 308±0.1nm, bandwidth ≤0.3nm, OD≥6; 355nm filter: center wavelength 355±0.1nm, bandwidth ≤0.5nm, OD≥6, to suppress solar background light and stray light.

[0019] Preferably, in a telescope used to receive the echo signal from a lidar system for detecting meteorological elements, the received optical signal enters an optical fiber, is collimated, and then splits by a multi-stage dichroic mirror. First-stage spectral separation: The 308nm signal is separated, passes through a narrow-band filter, and enters the PMT detector for ozone concentration profile inversion. Second-stage spectral separation: Separates the elastic scattering signal of the 355nm laser for the detection of atmospheric density and temperature at 30km-80km. Third-stage spectroscopy: Separates the 386nm nitrogen vibration Raman signal and the 407nm water vapor vibration Raman signal.

[0020] Preferably, the primary mirror material of the telescope is low-expansion quartz glass, coated with an enhanced aluminum film and a SiO2 protective film, with a reflectivity ≥97% at wavelengths of 532nm and 1064nm, a surface accuracy RMS better than λ / 10, λ=632.8nm, and a single-unit field of view of 2ω=3mrad.

[0021] The present invention has the following beneficial effects: This invention provides a near-space full-altitude environment multi-element lidar detection platform, constructing a three-in-one framework of "common basic support + atmospheric composition detection + meteorological multi-element detection". Through a unified optical benchmark and time synchronization mechanism, it solves the problem of multi-device data fusion and improves the spatiotemporal consistency of detection data; it achieves high-precision collaborative detection of "full altitude, multi-element", overcoming the limitations of single-platform and distributed networking schemes; it constructs an efficient multi-source heterogeneous data processing architecture to meet the real-time storage, analysis, and visualization needs of massive data; it improves the reliability and scalability of the equipment, enabling all-weather unattended operation and supporting flexible expansion of subsequent functional modules. Attached Figure Description

[0022] Figure 1 For the overall architecture; Figure 2 Diagram of the telescope array; Figure 3 For sodium atom detection lidar; Figure 4 For ozone detection lidar; Figure 5 Lidar for detecting meteorological elements. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] This invention constructs a three-in-one detection system consisting of a "common basic support platform + near-air atmospheric composition detection platform + near-air meteorological multi-element detection platform," integrating core technologies such as array telescopes, single-photon detection, and intelligent data processing to overcome the shortcomings of existing technologies. The specific solution is as follows: 1. Overall Architecture When multiple lidar systems are deployed close together, the biggest risk is laser beam crossing and echo signal crosstalk, which can lead to data distortion. A triple protection mechanism of "spatial isolation + temporal isolation + spectrum isolation" is implemented. 1) Spatial isolation: isolation of emitted beam divergence angle and received field of view. Spatial isolation is the physical basis for avoiding signal interference between three lidar systems. The core of this is achieved by controlling the independent layout of the emitted beam divergence angle and the receiving field of view, thus preventing signal overlap along the propagation path. At the transmitting end, a reasonable laser emission direction needs to be planned based on the laser divergence angle parameters of each device (typically 0.1-0.5 mrad for atmospheric sounding lidar). At the receiving end, the receiving field of view angle of each device needs to be calibrated (typically 0.2-1 mrad). Simultaneously, a two-dimensional adjustable base is installed at the focal plane of the receiving telescope. By adjusting the XY position of the focal plane telescope's receiving field of view, atmospheric echo signals from different locations in space can be received, achieving spatial isolation. Furthermore, a customized light shield can be added to the front of the receiving telescope to limit the field of view and reduce the entry of other laser beams into the receiving system through sidelobes. Combined with optical path collimation calibration (such as using a red light indicator to confirm the beam propagation direction), the spatial matching between transmission and reception is ensured, physically blocking signal crosstalk.

[0025] 2) Timing isolation: Unified timing, three lasers emit in a time-division manner. Timing isolation, through precise time synchronization and time-division transmission mechanisms, allows the three LiDAR systems to emit lasers in different time windows, avoiding overlap of echo signals in the time dimension. A unified timing synchronization system can be built, equipping each device with a GPS / BeiDou timing module to ensure time synchronization accuracy ≤1μs. The control units of the three devices are connected to the central timing controller via a local area network to achieve unified scheduling of trigger signals. Based on the pulse repetition frequency (PRF, typically 20-100Hz) of the LiDAR, the time-division transmission cycle is planned: if the PRF of a single device is 100Hz, the transmission time window can be divided into three independent time periods, with each device occupying 1 / 3 of the cycle sequentially (e.g., device 1 transmits from 0-3.3ms, device 2 from 3.4-6.6ms, and device 3 from 6.7-10ms), ensuring that the transmission interval between adjacent devices is ≥3ms (3ms corresponds to a detection altitude of approximately 450km), reserving sufficient time for echo signal reception and processing. Meanwhile, a timestamp filtering mechanism is set up at the data acquisition end, so that each device only collects the echo signal corresponding to its own transmission period. Trigger commands are issued in real time through the timing controller to avoid overlapping time windows caused by device delays. This ensures the stability of time-division transmission and completely separates the signals of the three devices from the time dimension.

[0026] 3) Spectrum isolation: Differentiation of three laser wavelengths Spectrum isolation is the core method for distinguishing the three sets of equipment based on their signal characteristics. By selecting laser sources of different wavelengths and combining them with narrowband filtering technology, the receiving system responds only to the echo signal of its own wavelength, exhibiting high suppression capability against light outside its response wavelength. The three lidar systems need to be configured with differentiated detection wavelengths, prioritizing bands with stable atmospheric transmission characteristics and no spectral overlap. The three wavelengths should be spaced at least 30nm apart to avoid filtering failure caused by spectral proximity. At the receiving end, each set of equipment is equipped with a narrowband filter (bandwidth ≤ 0.6nm) precisely matched to the emitted wavelength. The center wavelength error of the filter is controlled within ±0.1nm, effectively filtering laser signals of other wavelengths and interference from solar background light. Simultaneously, the wavelength stability of the laser is optimized by using frequency stabilization devices (such as saturated absorption spectral stabilization) to control wavelength fluctuations within ±0.1nm, ensuring long-term stability of the matching degree between the emitted wavelength and the filter. In addition, a spectrum selection module can be added to the front end of the preamplifier to further enhance the response sensitivity to the target wavelength, suppress the amplification of non-target wavelength signals, and achieve complete isolation of the signals of the three sets of equipment at the spectrum level, ensuring the independence and accuracy of data acquisition.

[0027] 2. Optical foundation support system for airborne detection radar Composition: It consists of four parabolic receiving telescopes with an effective light transmission aperture of 1600mm (including optical primary mirror, primary mirror tube electromechanical structure), splicing base and outer frame, and adopts coaxial symmetrical array splicing method.

[0028] The optical primary mirror is made of low-expansion quartz glass, coated with an enhanced aluminum film and a SiO2 protective film. It has a reflectivity of ≥97% at laser wavelengths such as 532nm and 1064nm, and a surface accuracy RMS better than λ / 10 (λ=632.8nm). The single-unit field of view is 2ω=3mrad, which can capture more scattered photons to improve the signal-to-noise ratio.

[0029] Electromechanical structure of the main lens barrel: It adopts a multi-point floating bottom support + center positioning structure. Through finite element optimization design, the deformation of the main lens support is ≤1 / 83λ (vertical optical axis); it is equipped with an electric focusing mechanism (adjustment range ±5mm, fine adjustment accuracy 0.25mm / revolution) and a double-opening electric main lens cover (opening time ≤10s) to ensure the relative position stability of the main lens and the main focal plane.

[0030] Splicing base and outer frame: The footprint is 5m×5m, the load-bearing capacity is ≥6 tons, the natural frequency is ≥15Hz, and an independent foundation is adopted (the telescope base and the outer frame foundation are separated) to isolate the effects of vibration and settlement; the frame has reserved debugging channels, and the outer frame can be covered with a panel to block stray light from the environment.

[0031] Working principle: The four telescopes can achieve three working modes: ① Coaxial receiving mode: The four primary mirrors have an equivalent aperture of 3m, enabling the reception of signals in the same wavelength band to enhance light collection capabilities. The focal planes of the four telescopes (1, 2, 3, 4) are coupled to output four optical fibers. The output ends of these four optical fibers are connected to the same fiber bundle combiner. The output end of the combiner tightly arranges the cores of the four optical fibers and connects them to the same signal detection unit (e.g., a sodium atomic fluorescence detection box).

[0032] ② Independent Operating Mode: The optical fibers of the four telescopes are connected to four independent signal detection subsystems via fiber optic distribution frames. Telescope 1 is connected to the 589nm sodium atom detection unit for detecting metallic layers at 80-105km; Telescope 2 is connected to the 308nm ozone detection unit for detecting ozone concentration at 20-50km; Telescope 3 is connected to the 355nm Rayleigh / Raman detection unit for detecting atmospheric density / temperature and water vapor at 30-80km; Telescope 4 serves as a backup channel or is connected to the polarization detection unit. Each channel is physically isolated in space, completely avoiding crosstalk between strong signals (such as 355nm low-altitude echoes) and weak signal channels (such as 589nm). In this mode, the platform can simultaneously acquire data on all elements across the entire altitude range, including wind field, temperature, density, ozone, and water vapor, with each element strictly aligned in time and space, facilitating research on the coupling mechanism of multiple atmospheric spheres.

[0033] ③ Combined Detection Mode: Based on the specific observation task requirements, the optical fiber routes can be combined. In a sudden ozone observation task, the optical fibers of three telescopes (Telescope 1, Telescope 2, and Telescope 3) can be simultaneously connected to the 308nm ozone detection unit. This utilizes a 3 times larger receiving area to significantly improve the signal-to-noise ratio of the ozone signal and shorten the integration time of a single profile (e.g., from 30 minutes to 10 minutes), thereby capturing the rapid changes in ozone concentration. Telescope 4 is used alone to acquire atmospheric temperature reference data.

[0034] The main focal plane receiving mechanism is mounted on the central cylinder of the main focal plane cage and is equipped with an optical fiber coupler; the main focal plane has three optical fibers, and the receiving range of the main focal plane optical fiber is Φ7.5mm (3mrad field of view); the receiving optical fiber of the main focal plane is designed with a core diameter of Φ1.5mm and an incident end with a steel sleeve of Φ2.2mm, and is equipped with an optical fiber bending protection device; The calibration method for the four telescopes includes the following steps: Step 1: Complete the basic physical installation of the main focal plane receiving mechanism and optical fiber. First, the main focal plane receiving mechanism is installed on the central cylinder of the main focal plane cage and equipped with an optical fiber coupler. The system's main focal plane is designed with three optical fiber channels, and the overall optical fiber receiving range is set at Φ7.5mm, corresponding to a receiving field of view of 3mrad. For the optical fiber specifications, the receiving fiber uses a core diameter of Φ1.5mm, and its incident end is reinforced with a Φ2.2mm steel sleeve. Furthermore, to prevent physical damage during operation, all optical fibers are equipped with fiber bending protection devices.

[0035] Step 2: Establish the absolute optical calibration reference for the northeastern telescope Of the four telescopes in the array, the one located in the northeast corner was specifically designated for calibration work. All three of its assigned optical fibers were securely fixed to the focal plane without any dynamic adjustments. The fixed position of this telescope and its fibers will serve as the absolute reference "anchor point" for the entire optical reference plane of the detection platform; the fiber optic field of view of all subsequent telescopes must be aligned with this reference.

[0036] Step 3: Install the optical fibers for the remaining three telescopes and introduce a dynamic adjustment mechanism. When configuring the other three telescopes, the primary principle was to ensure that the position and arrangement of the three optical fibers on their focal planes were absolutely consistent with the calibration telescope in the northeast corner. In terms of specific mechanical connections, these three telescopes adopted a "one fixed, two moving" strategy: one optical fiber was fixed separately to the focal plane (similar to the calibration telescope), while the other two optical fibers were fixed to the central focusing cylinder via an electrically operated two-dimensional adjustment mount. This design provided the mechanical basis for subsequent fine-tuning to mitigate assembly errors in the system.

[0037] Step 4: Perform precise XY-axis (focal plane two-dimensional space) motorized alignment via computer interface. Using a computer interface, the electric two-dimensional adjustment mount on the central focusing cylinder is operated to precisely adjust the two movable optical fibers in the X and Y directions. This adjustment mount is designed to allow the fiber to move 0.5 mm towards the center and 2 mm outward, with a resolution of 5 μm. By observing the signal, the operator fine-tunes the fiber's coordinates in the two-dimensional space of the focal plane at the micrometer level, ensuring its receiving field of view perfectly matches the calibration reference in the northeast corner.

[0038] Step 5: Perform the final overall calibration of Z-axis (optical axis) focusing and circumferential rotation. After completing the two-dimensional alignment in the XY plane, manual focusing of the focusing tube in the Z-axis (i.e., along the optical axis) is required. The Z-axis adjustment range is controlled within ±6mm, with an adjustment accuracy of ≤0.05mm to ensure absolute focus. Finally, the three adjustable fiber optic mounts are rotated circumferentially, correcting minor rotational deviations within a ±3° adjustment range. Through these multi-dimensional spatial fine-tuning, installation tolerances between the various equipment sets can be completely eliminated, completing the overall calibration of the multi-element detection platform.

[0039] 3. Atmospheric composition detection platform This platform focuses on the detection of near-space chemical elements and includes the following core systems: (1) Airborne sodium atom detection system Sodium atom detection lidar: laser wavelength 589nm (sodium atom resonance line), power ≥10W, capable of detecting sodium atom density at heights of 80-105km, spatial resolution 1000m, temporal resolution 30min, detection accuracy 2%@90km; employs "seed laser injection + sum-frequency technology" to generate 589nm pulsed laser (sum-frequency of 1319nm and 1064nm lasers), equipped with an ultra-narrowband atomic filter to suppress background light noise during the day, achieving all-day detection.

[0040] 1064nm laser: A 10mW single-frequency continuous seed light is chopped into a 60-80ns pulse by an acousto-optic modulator (AOM), pre-amplified by an optical fiber amplifier, and then injected into a two-stage side-pumped Nd:YAG rod amplifier, with an output energy of 120mJ.

[0041] 1319nm optical path: The Ramp-Hold-Fire seed injection electro-optic Q-switching technology is adopted, and the output energy is 50mJ after two-stage amplification by end pump and side pump.

[0042] Two beams of light are combined and frequency-controlled in an LBO nonlinear crystal, resulting in an output wavelength of 589.158 nm (locked to the sodium atom D2 line), a single pulse energy of >50 mJ, a repetition frequency of 100 Hz, and a linewidth narrowed to the GHz level.

[0043] Working principle: The sodium atom detection lidar emits a 589nm laser to excite sodium atoms in the high atmosphere to produce resonant fluorescence. The echo signal is received by the array telescope and the sodium atom density profile is obtained by inversion.

[0044] (2) Airborne ozone detection system Ozone detection lidar: It uses an XeCl excimer laser to generate 308nm (strong absorption light) and Nd:YAG third harmonic laser to generate 355nm (weak absorption reference light), with a power ≥20W. It can detect ozone density at 20-50km, with a spatial resolution of 1000m and a detection accuracy of <5%@30km. The ozone concentration profile is retrieved through differential absorption equation.

[0045] A two-stage beam splitting architecture is adopted: the first stage separates the 308nm and 355nm signals through a dichroic mirror (DM1) (308nm transmittance ≥95%, 355nm reflectance ≥95%); the second stage is equipped with narrowband interference filters (308nm filter: center wavelength 308±0.1nm, bandwidth ≤0.3nm, OD≥6; 355nm filter: center wavelength 355±0.1nm, bandwidth ≤0.5nm, OD≥6) to suppress solar background light and stray light.

[0046] Working principle: The 308nm laser is absorbed by ozone molecules, while the 355nm laser is used as a reference (not absorbed by ozone). The ozone density is calculated by differentially analyzing the two channels.

[0047] 4. Near-Air Meteorological Multi-Element Detection Platform This platform enables the detection of near-space physical elements (temperature, humidity, density), including the following core systems: Meteorological element detection lidar: Composition: Laser wavelength 355nm / 532nm, power ≥20W, employing a multi-scattering mechanism for coordinated detection.

[0048] Humidity detection: via vibrational Raman scattering (532nm laser), detection height ≥6km, accuracy ≤10%@5km; Temperature detection: Stratospheric temperature is detected by rotating Raman scattering (355nm laser), and mesosphere temperature is detected by Rayleigh scattering. The detection altitude is ≥80km and the accuracy is ≤3K@30km. Density detection: Detection height ≥90km with accuracy ≤2%@30km via Rayleigh scattering (355nm laser).

[0049] Working principle: After the laser is emitted, the echo signals generated by different scattering mechanisms are received by the array telescope and respectively introduced into the corresponding signal detection channels (such as Raman channel and Rayleigh channel). The temperature, humidity and density profiles are calculated by the data inversion algorithm.

[0050] In a telescope system, the received optical signal enters an optical fiber, is collimated, and then splits by a multi-stage dichroic mirror. First-stage spectral separation: The 308nm signal is separated, passes through a narrow-band filter, and enters the PMT detector for inverting the ozone concentration profile.

[0051] Second-stage spectral separation: Separates the elastic scattering signal of the 355nm laser for the detection of atmospheric density and temperature in the 30km-80km range.

[0052] The third-stage spectrophotometer separates the 386nm (nitrogen N2 vibration Raman signal) and the 407nm (water vapor H2O vibration Raman signal).

[0053] Among them, the 386nm channel provides an independent atmospheric parameter depth correction mechanism for the system. By collecting the measured data of this channel and inputting it into the atmospheric extinction coefficient correction model, the interference caused by the nonlinear scattering of complex aerosols above 30km in the stratosphere on the differential absorption inversion of ozone is completely eliminated from the algorithm level, thereby greatly improving the inversion accuracy of upper-level ozone concentration.

[0054] The 407nm detection channel directly uses the 355nm laser emitted by the system as the excitation source to excite atmospheric water vapor molecules to produce inelastic vibration Raman scattering, emitting a 407nm Raman echo signal. This signal is purified by a narrowband interference filter with a center wavelength of 407.5nm and then enters the PMT for photoelectric conversion. The data processing unit calculates the ratio between the 407nm water vapor Raman signal and the 386nm nitrogen Raman signal. After canceling aerosol extinction interference, high-precision water vapor mixing ratio profile data is obtained through inversion, thus providing multi-parameter collaborative observation data for atmospheric chemical dynamics research in the troposphere to the lower stratosphere.

[0055] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A near-space full-elevation environment multi-element lidar detection platform, characterized in that, include: The common basic support system consists of at least four parabolic receiving telescopes with an effective light transmission aperture ≥1600mm, spliced ​​in a coaxial symmetrical array. Each telescope has multiple fiber optic receiving channels on its focal plane and is equipped with fiber optic couplers and fiber optic routing switching mechanisms. The receiving telescope is used to receive atmospheric echo signals from different altitudes in near space, and the echo signals include at least: The sodium atom resonance fluorescence signal, with a wavelength of 589 nm, was used to invert the sodium atom density profile. The ozone differential absorption signal, including a strong absorption signal at 308 nm and a weak absorption reference signal at 355 nm, is used to retrieve the ozone concentration profile. Elastic scattering signal, wavelength 355nm, used to retrieve atmospheric density and temperature profiles; Rayleigh scattering signal, wavelength 355nm, used to invert atmospheric density profile; Rotating Raman scattering signal, wavelength 355nm, is used to invert stratospheric temperature profile; The atmospheric composition detection system includes: The sodium atom resonance fluorescence lidar uses seed laser injection and sum-frequency technology to generate 589nm pulsed laser, with a detection altitude of 80km-105km, and is equipped with an ultra-narrowband atomic filter to achieve all-weather detection. The ozone differential absorption lidar uses a XeCl excimer laser to generate 308nm strong absorption light and Nd:YAG third harmonic to generate 355nm weak absorption reference light, with a detection altitude of 20km-50km. The near-field meteorological multi-element detection system includes: The meteorological element detection lidar operates at wavelengths of 355nm and 532nm and employs a multi-scattering mechanism for coordinated detection. Specifically: Humidity detection: Vibrational Raman scattering excited by a 532nm laser, with a detection height of ≥6km; Temperature detection: Stratospheric temperature is detected by rotating Raman scattering of a 355nm laser, and mesosphere temperature is detected by Rayleigh scattering of a 355nm laser, with a detection altitude of ≥80km; Density detection: Detection altitude ≥90km via Rayleigh scattering of a 355nm laser; It also features a unified optical reference and time synchronization mechanism. By fixing the position of the fiber optic focal plane of one of the telescopes as an absolute reference, and combining a global timing controller and a time-division transmission strategy, it enables collaborative detection of multiple elements within a full altitude range of 20km-100km.

2. The detection platform according to claim 1, characterized in that, The received atmospheric echo signals in the aforementioned common basic support system also include: The nitrogen vibration Raman signal, with a wavelength of 386 nm, provides an independent atmospheric parameter depth correction mechanism for the system. By collecting measured data from this channel and inputting it into the atmospheric extinction coefficient correction model, the interference caused by complex aerosol nonlinear scattering above 30 km in the stratosphere on ozone differential absorption inversion is eliminated. Water vapor vibration Raman signal, wavelength 407nm; the ratio of the 407nm water vapor Raman signal to the 386nm nitrogen vibration Raman signal is calculated, and after canceling aerosol extinction interference, high-precision water vapor mixing ratio profile data is obtained by inversion.

3. The detection platform according to claim 1, characterized in that, Each telescope has three optical fibers on its focal plane. The optical fiber receiving range is Φ7.5mm, corresponding to a 3mrad field of view. The fiber core diameter is Φ1.5mm, and the incident end is equipped with a Φ2.2mm steel sleeve and a bending protection device.

4. The detection platform according to claim 1, characterized in that, The four telescopes in the common basic support system achieve the following three operating modes through focal plane optical fibers, optical fiber combiners, optical fiber distribution frames, and signal detection units: Coaxial receiving mode: The optical fibers of the focal plane of the four telescopes are respectively output to a fiber bundle combiner. The combiner tightly arranges the cores of the four optical fibers and connects them to the same signal detection unit, so that the equivalent light transmission aperture of the four telescopes reaches 3m. Independent operating mode: The optical fibers of the four telescopes are connected to four independent signal detection subsystems via fiber optic distribution frames. Each channel is physically isolated in space, specifically allocated as follows: The optical fiber at the focal plane of the first telescope is connected to a 589nm sodium atom detection unit for detecting sodium atom layers in the 80km-105km range. The second telescope's focal plane fiber is connected to the 308nm ozone detection unit for ozone concentration detection in the 20km-50km range. The third telescope's focal plane fiber is connected to a 355nm meteorological element detection unit for atmospheric density, temperature, and humidity detection at a range of 30km-80km. The fourth telescope's focal plane fiber is connected to the polarization detection unit or used as a backup channel; Combined detection mode: According to the specific observation task requirements, the fiber optic routes are switched through the fiber optic distribution frame to simultaneously connect the fibers of at least two telescopes to the same signal detection unit to improve the signal-to-noise ratio and time resolution of the detection element; the fibers of the remaining telescopes remain in independent working mode to synchronously acquire auxiliary reference data.

5. The detection platform according to claim 1, characterized in that, The unified optical reference and time synchronization mechanism includes: The three optical fibers of the designated northeast corner telescope are fixed to the focal plane as the optical reference anchor points for the entire platform; At least two optical fibers in the remaining telescopes are finely adjusted in the XY direction via an electric two-dimensional adjustment mount, with an adjustment range of 0.5 mm towards the center and 2 mm outward, and a resolution of 5 μm. The focusing tube has a Z-axis manual focusing function with an adjustment range of ±6mm and an accuracy of ≤0.05mm; The adjustable fiber optic mount has a circumferential rotation adjustment function with an adjustment range of ±3°.

6. The detection platform according to claim 1, characterized in that, The time synchronization mechanism includes: Each lidar unit is equipped with a GPS or BeiDou timing module, with a time synchronization accuracy of ≤1μs; The central timing controller uses a time-division multiplexing strategy to stagger the transmission time windows of each device, with the transmission interval between adjacent devices being ≥3ms; The data acquisition terminal is equipped with a timestamp filtering mechanism to collect only the echo signal corresponding to the transmission period of this device.

7. The detection platform according to claim 1, characterized in that, It also includes a triple signal isolation mechanism: Spatial isolation: achieved by controlling the divergence angle of the emitted beam and the receiving field of view, and by installing a light shield; Temporal isolation: achieved through time-division multiplexing and timestamp filtering; Spectrum isolation: The three sets of lidar operate at wavelengths ≥30nm apart, and the receiver is equipped with a narrowband filter with center wavelength matching and bandwidth ≤0.6nm.

8. The detection platform according to claim 2, characterized in that, The telescope used to receive the echo signal from the ozone detection lidar employs a two-stage beam splitting architecture: the first stage separates the 308nm and 355nm signals using a dichroic mirror; the second stage is equipped with narrowband interference filters, specifically: the 308nm filter has a center wavelength of 308±0.1nm, bandwidth ≤0.3nm, and OD≥6; the 355nm filter has a center wavelength of 355±0.1nm, bandwidth ≤0.5nm, and OD≥6, to suppress solar background light and stray light.

9. The detection platform according to claim 1, characterized in that, In the telescope used to receive the echo signal from the lidar for meteorological element detection, the received light signal enters the optical fiber, is collimated, and then splits by a multi-stage dichroic mirror. First-stage spectral separation: The 308nm signal is separated, passes through a narrow-band filter, and enters the PMT detector for ozone concentration profile inversion. Second-stage spectral separation: Separates the elastic scattering signal of the 355nm laser for the detection of atmospheric density and temperature at 30km-80km. Third-stage spectroscopy: Separates the 386nm nitrogen vibration Raman signal and the 407nm water vapor vibration Raman signal.

10. The detection platform according to claim 1, characterized in that, The telescope's primary mirror is made of low-expansion quartz glass, coated with an enhanced aluminum film and a SiO2 protective film. It has a reflectivity of ≥97% at wavelengths of 532nm and 1064nm, a surface accuracy RMS better than λ / 10, λ=632.8nm, and a single-unit field of view of 2ω=3mrad.

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