Rayleigh laser radar system based on stratosphere floating platform

Abstract

The invention discloses a Rayleigh laser radar system based on a stratosphere floating platform, which is used for realizing all-weather and all-time observation of middle atmosphere and comprises the stratosphere floating platform and a Rayleigh laser radar system, and the stratosphere floating platform comprises a mounting interface, a power supply module and a communication data transmission module. The Rayleigh laser radar system comprises a laser emission subsystem, an optical receiving subsystem, a signal detection subsystem, a temperature control subsystem, a power supply subsystem, an automatic control subsystem and an electrical cabinet mechanical subsystem. Compared with the ground-based laser radar under the observation conditions that the night is clear and the visibility is good, the influence of severe weather can be avoided based on the Rayleigh laser radar system, and all-weather observation of the middle-layer atmosphere is realized; background noise caused by low-altitude strong background scattering can be avoided, and all-day observation of the middle-layer atmosphere is achieved; the distance to a detection target area can be shortened, the detection height can be increased, or observation of the middle atmosphere can be realized by adopting a simpler and low-cost laser radar system.

Description

Technical Field

[0001] The present invention relates to the technical field of atmospheric laser radar, and in particular to a Rayleigh laser radar system for middle atmosphere observation. Background Art

[0002] The middle atmosphere is showing more and more important value in basic science, climate environment, national defense and military fields. At present, the main means of detecting the middle atmosphere can be divided into four categories: sounding rockets, microwave radars, artificial satellites and laser radars. Laser radars have the advantages of high precision, high temporal and spatial resolution and uninterrupted detection. Laser radars measure the environmental parameters of the middle atmosphere by collecting the backscattered signals of atmospheric molecules or components.

[0003] According to the different detection principles, it can be divided into Raman scattering, resonance fluorescence, Rayleigh scattering and other laser radars. Raman laser radar can cover the ground to 30km, resonance fluorescence radar can cover 80~110km, and Rayleigh laser radar can detect atmospheric environmental parameters up to 110km. Rayleigh laser radar has the advantages of simple principle, strong echo signal, and no dependence on gas composition. It can achieve high-precision and long-term continuous observation of the atmospheric environment in the full altitude range of near-space, which is crucial for studying the atmospheric dynamics process in near-space. Using the atmospheric density and temperature data obtained by Rayleigh laser radar inversion, gravity waves, tidal changes, stratospheric warming, planetary waves, mesosphere inversion layer, seasonal changes, noctilucent clouds, etc. can be further studied.

[0004] Rayleigh LiDAR is the most commonly used method for detecting the middle atmosphere environment. Improving the detection range is the core goal of the Rayleigh LiDAR platform construction. At present, Rayleigh LiDAR is mainly ground-based. After decades of development, it can obtain echo signals within 110km and has become an important force for the detection of the middle atmosphere. Since the ground-based LiDAR detects the middle atmosphere at a long distance, the cost of improving the detection range is extremely high. At the same time, it is still impossible to avoid problems such as bad weather and strong scattering background noise caused by sunlight during the day. These problems are also the key factors that restrict LiDAR from realizing all-weather and all-day detection of the middle atmosphere. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a Rayleigh lidar system based on a stratospheric floating platform, which solves the problems that the existing ground-based lidar cannot avoid bad weather and strong background scattering noise at low altitudes, and can realize all-weather and all-day observation of the middle atmosphere.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A Rayleigh laser radar system based on a stratospheric floating platform, used for realizing all-weather and all-day observation of the middle atmosphere, comprises: a stratospheric floating platform and a Rayleigh laser radar system; the stratospheric floating platform comprises a mounting interface, a power supply module and a communication data transmission module; the Rayleigh laser radar system comprises a laser emission subsystem, an optical receiving subsystem, a signal detection subsystem, a temperature control subsystem, a power supply subsystem, an automatic control subsystem and an electrical box mechanical subsystem;

[0008] The laser emission subsystem comprises a laser, a beam expander, a deflection mirror and an optical window arranged in sequence;

[0009] The optical receiving subsystem includes a telescope and an optical fiber receiving unit;

[0010] The signal detection subsystem includes a multimode optical fiber, an optical fiber collimator, a narrow-band filter, a beam splitter, a first converging mirror, a first single-photon detector, a reflecting mirror, a second converging mirror, a second single-photon detector and a photon counter;

[0011] The temperature control subsystem includes a passive temperature control unit, an air cooling unit, a liquid cooling unit and a heating unit;

[0012] The automatic control subsystem includes a load control unit, a floating platform communication unit and a ground control unit;

[0013] The electrical box mechanical subsystem includes a pod, a wire shock absorber, an electrical box upper cover and an electrical box body;

[0014] The mounting interface is used to connect the stratospheric floating platform and the pod, and the pod and the Rayleigh laser radar system are connected through a steel wire shock absorber; the power supply module is used to output a wide-range voltage, and the wide-range voltage is converted by the power supply subsystem into the voltage required by each component of the Rayleigh laser radar system; the communication data transmission module provides a transmission channel for control instructions and data between the load control unit and the ground control unit; the temperature control subsystem provides the temperature conditions required for the Rayleigh laser radar system to work normally in the low-temperature environment of the stratosphere; the electrical box mechanical subsystem is used to provide the air pressure conditions required for the Rayleigh laser radar system to work normally in the low-pressure environment of the stratosphere;

[0015] The ground control unit issues an operation control instruction, which is transmitted to the load control unit via the communication data transmission module to control the operation of the laser. The liquid cooling unit dissipates heat for the laser. The laser pulse emitted by the laser passes through the beam expander and then enters the deflection mirror, and enters the atmosphere through the optical window to interact with atmospheric molecules to generate a backward Rayleigh scattering echo signal; the backward Rayleigh scattering echo signal is collected by the telescope and then transmitted through the optical fiber receiving unit and enters the interior of the mechanical subsystem of the electrical box through the optical interface of the electrical box cover; then, the backward Rayleigh scattering echo signal is transmitted to the optical fiber collimator through the multimode optical fiber, enters the spectroscope through the narrow-band filter and becomes two beams of echo signals, one beam of echo signal reflected from the spectroscope passes through the first converging mirror and reaches the first single-photon detector, and the other beam of echo signal transmitted from the spectroscope passes through the reflector and enters the second converging mirror and reaches the second single-photon detector, and the number of photons recorded by the first single-photon detector and the second single-photon detector are respectively connected to two different channels of the photon counter to realize the recording and storage of the echo photon number profile, and the echo photon number is transmitted to the ground control unit via the communication data transmission module.

[0016] Furthermore, the stratospheric floating platform is a floating platform with dynamic characteristics, including but not limited to stratospheric balloons, tethered balloons and stratospheric airships.

[0017] Furthermore, the mounting interface is located at the front end of the stratospheric floating platform, ensuring that the Rayleigh laser radar system is mounted at an oblique upward angle.

[0018] Furthermore, the beam expander is used to compress the divergence angle of the laser pulse of the laser, the deflection mirror is used to correct the tilt error in the optical path of the laser emitting subsystem, and realize the coaxiality calibration of the divergence angle of the laser pulse after beam expansion and the field of view angle of the optical receiving subsystem, and the optical window is used to transmit the emitted laser pulse while ensuring the airtightness and constant temperature of the mechanical subsystem of the electrical box.

[0019] Furthermore, the passive temperature control unit is used to realize the passive insulation function of the Rayleigh lidar system; the air cooling unit realizes heat exchange between the inside of the electrical box mechanical subsystem and the external environment, so that the inside of the electrical box mechanical subsystem is in a normal temperature environment; the heating unit realizes temperature control inside the telescope, the receiving optical fiber unit and the electrical box mechanical subsystem.

[0020] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0021] 1. All-weather observation capability: The Rayleigh LiDAR system based on the stratospheric floating platform can effectively prevent the ground observation system from being affected by bad weather and ensure stable observation of the middle atmosphere. Compared with the traditional ground-based LiDAR system, it greatly improves the stability and continuity of atmospheric detection.

[0022] 2. All-day observation capability: Since the system is placed in the stratosphere, away from the interference of strong background scattering noise in the low altitude, it avoids the problem of strong scattering background noise caused by daytime sunlight, realizes all-day uninterrupted monitoring of the middle atmosphere, and significantly improves the time resolution of detection.

[0023] 3. Improved detection accuracy and efficiency: The system shortens the distance to the detection target area through the floating platform, thereby reducing the signal attenuation of the lidar and enhancing the strength of the echo signal. Without significantly increasing the complexity and cost of the system, a simpler lidar configuration can be used to achieve high-precision mid-atmosphere observations.

[0024] 4. Optimization of high-altitude working environment: By using temperature control and air pressure control subsystems, the present invention ensures the normal operation of the Rayleigh lidar system in the low temperature and low pressure environment of the stratosphere, providing reliable guarantee for long-term operation.

[0025] 5. Potential for expanded applications: This system can not only be used for environmental monitoring in the middle atmosphere, but can also provide design and application references for other optical equipment operating in the stratosphere, and has great value for expanded applications.

[0026] In summary, the advantages of the present invention in all-weather and all-day observation and improving detection accuracy and efficiency are mentioned, and its potential expanded application value is also mentioned. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of a Rayleigh laser radar system provided by the present invention mounted on a stratospheric floating platform;

[0028] Figure 2 A system block diagram of a Rayleigh laser radar system provided by the present invention;

[0029] Figure 3 An optical block diagram of a Rayleigh laser radar system provided by the present invention;

[0030] Figure 4 A block diagram of an automatic control subsystem in a Rayleigh laser radar system provided by the present invention;

[0031] Figure 5 A block diagram of a temperature control subsystem in a Rayleigh laser radar system provided by the present invention.

[0032] Figure numerals: 1-laser emission subsystem, 2-optical receiving subsystem, 3-signal detection subsystem, 4-temperature control subsystem, 5-power supply subsystem, 6-automatic control subsystem, 7-electrical box mechanical subsystem, 11-laser, 12-beam expander, 13-deflection mirror, 14-optical window, 21-telescope, 22-optical fiber receiving unit, 30-photon counter, 31-multimode optical fiber, 32-optical fiber collimator, 33-narrow band filter, 34-beam splitter, 35-first converging mirror, 36-first single photon detector, 37-reflector, 38-second converging mirror, 39-second single photon detector, 41-passive temperature control unit, 42-air cooling unit, 43-liquid cooling unit, 44-heating unit, 61-load control unit, 62-floating platform communication unit, 63-ground control unit, 71-optical interface. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] It should be noted that, in this embodiment, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0035] When ground-based laser radar detects the middle atmosphere, there are problems such as high cost of increasing the detection range and the inability to avoid bad weather and strong scattered background noise caused by sunlight during the day. In view of this, an embodiment of the present invention provides a Rayleigh laser radar system for achieving all-weather and all-day observation of the middle atmosphere.

[0036] like Figure 1 As shown, it is a schematic diagram of a Rayleigh LiDAR system provided in this embodiment mounted on a stratospheric floating platform. The Rayleigh LiDAR system is mounted on the front end of the stratospheric floating platform at an upward mounting angle of 45°.

[0037] like Figure 2 As shown, it is a system block diagram of a Rayleigh laser radar system embodiment provided by this embodiment, including: a laser emission subsystem 1, an optical receiving subsystem 2, a signal detection subsystem 3, a temperature control subsystem 4, a power supply subsystem 5, an automatic control subsystem 6 and an electrical box mechanical subsystem 7;

[0038] The laser emission subsystem 1 is used to generate 532nm laser pulses and emit the laser pulses into the air, interacting with atmospheric molecules to generate backscattered Rayleigh echo signals; the backscattered Rayleigh echo signals are collected by the optical receiving subsystem 2 and enter the signal detection subsystem 3 to realize the statistics of the collected backscattered Rayleigh echo signals and convert them into echo photon number data; the temperature control subsystem 4 controls the temperature of the Rayleigh laser radar system to meet the working temperature requirements, the power supply subsystem 5 provides the required power supply voltage for the Rayleigh laser radar system to ensure normal operation, and the automatic control subsystem 6 performs information monitoring and work control on the Rayleigh laser radar system; the electrical box mechanical subsystem 7 is used to provide a normal temperature and pressure working environment for the laser emission subsystem 1, the signal detection subsystem 2, the temperature control subsystem 4, the power supply subsystem 5 and the automatic control subsystem 6.

[0039] like Figure 3 As shown, an optical block diagram of an embodiment of a Rayleigh lidar system provided by the present invention includes: a laser 11, a beam expander 12, a deflection mirror 13, an optical window 14, a telescope 21, an optical fiber receiving unit 22, a photon counter 30, a multimode optical fiber 31, a fiber collimator 32, a narrow-band filter 33, a beam splitter 34, a first converging mirror 35, a first single-photon detector 36, a reflector 37, a second converging mirror 38, a second single-photon detector 39, and an optical interface 71.

[0040] The laser pulse emitted by the laser 11 passes through the beam expander 12 and then enters the deflection mirror 13, and then enters the atmosphere through the optical window 14 to interact with the atmospheric molecules to generate a backward Rayleigh scattered echo signal; the backward Rayleigh scattered echo signal is collected by the telescope 21 and then transmitted through the optical fiber receiving unit 22 and enters the inside of the electrical box mechanical subsystem 7 through the optical interface 71; then, the backward Rayleigh scattered echo signal is transmitted to the optical fiber collimator 32 through the multimode optical fiber 31, and then enters the beam splitter 34 through the narrowband filter 33 with a bandwidth of 0.25nm to become two beams of echo signals, one beam of echo signal reflected from the beam splitter 34 passes through the first converging mirror 35 and then reaches the first single photon detector 36, and the other beam of echo signal transmitted from the beam splitter passes through the reflector 37 and then enters the second converging mirror 38 and then reaches the second single photon detector 39, and the number of photons recorded by the first single photon detector and the second single photon detector are respectively connected to two different channels of the photon counter 30 to realize the echo photon number profile recording.

[0041] In the embodiment of the present invention, the beam expander 12 is used to compress the divergence angle of the laser pulse emitted by the laser 11, the beam expansion ratio is 15X, and the spot diameter after beam expansion is 40mm. The deflection mirror 13 is used to correct the tilt error in the emission optical path and realize the coaxial calibration of the divergence angle of the laser pulse after beam expansion and the optical field angle, and meet the requirements of the Rayleigh laser radar system receiving and transmitting field matching echo signals are all collected. The optical window 14 is used to transmit the laser pulse while ensuring the airtightness and constant temperature of the electrical box mechanical subsystem. The diameter of the telescope 21 is 350mm, the focal length is 1200mm, and it also includes a gap with a diameter of 50mm to provide an emission channel for the laser pulse passing through the optical window. The first / second single photon detector is an avalanche diode / photomultiplier tube respectively. The optical interface 71 transmits the echo signal to the inside of the electrical box mechanical subsystem while ensuring the airtightness and constant temperature of the electrical box mechanical subsystem. The intensity of the two beams of echo signals transmitted and reflected by the spectroscope is 90% and 10%. The laser 11 is connected to the photon counter 30, and the electrical pulse signal output by the laser is connected to the trigger input channel of the counter to control the acquisition timing of the Rayleigh laser radar system, thereby realizing automatic recording and storage of the echo signal data.

[0042] like Figure 4 , which is a block diagram of the automatic control subsystem 6 in this embodiment, including: a load control unit 61 , a floating platform communication unit 62 and a ground control unit 63 .

[0043] like Figure 5 , which is a block diagram of the temperature control subsystem 4 in this embodiment, includes: a passive temperature control unit 41 , an air cooling unit 42 , a liquid cooling unit 43 and a heating unit 44 .

[0044] The passive temperature control unit 41 realizes the passive insulation function of the electrical box mechanical subsystem 7 and the telescope 21. The air cooling unit 42 realizes the heat exchange between the inside of the electrical box mechanical subsystem and the external environment, so that the inside of the electrical box mechanical subsystem is in a normal temperature environment. The liquid cooling unit 43 realizes temperature control to ensure the normal operation of the laser 11. The heating unit 44 realizes temperature control inside the telescope 21, the optical fiber receiving unit 22 and the electrical box mechanical subsystem 7.

[0045] The above are only preferred specific implementations of the present invention, but the protection scope of the invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present invention should be covered within the protection scope of the present invention.

[0046] The present invention is not limited to the embodiments described above. The above description of the specific embodiments is intended to describe and illustrate the technical solution of the present invention. The above specific embodiments are merely illustrative and not restrictive. Without departing from the scope of the present invention and the scope of protection of the claims, a person of ordinary skill in the art can also make many forms of specific changes under the guidance of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A Rayleigh LiDAR system based on a stratospheric floating platform for all-weather and all-day observation of the middle atmosphere, characterized in that: include: Stratospheric floating platform and Rayleigh laser radar system; the stratospheric floating platform includes a mounting interface, a power supply module and a communication data transmission module; the Rayleigh laser radar system includes a laser emission subsystem, an optical receiving subsystem, a signal detection subsystem, a temperature control subsystem, a power supply subsystem, an automatic control subsystem and an electrical box mechanical subsystem; The laser emission subsystem comprises a laser, a beam expander, a deflection mirror and an optical window arranged in sequence; The optical receiving subsystem includes a telescope and an optical fiber receiving unit; The signal detection subsystem includes a multimode optical fiber, an optical fiber collimator, a narrow-band filter, a beam splitter, a first converging mirror, a first single-photon detector, a reflecting mirror, a second converging mirror, a second single-photon detector and a photon counter; The temperature control subsystem includes a passive temperature control unit, an air cooling unit, a liquid cooling unit and a heating unit; The automatic control subsystem includes a load control unit, a floating platform communication unit and a ground control unit; The electrical box mechanical subsystem includes a pod, a wire shock absorber, an electrical box upper cover and an electrical box body; The mounting interface is used to connect the stratospheric floating platform and the pod, and the pod and the Rayleigh laser radar system are connected through a steel wire shock absorber; the power supply module is used to output a wide-range voltage, and the wide-range voltage is converted by the power supply subsystem into the voltage required by each component of the Rayleigh laser radar system; the communication data transmission module provides a transmission channel for control instructions and data between the load control unit and the ground control unit; the temperature control subsystem provides the temperature conditions required for the Rayleigh laser radar system to work normally in the low-temperature environment of the stratosphere; the electrical box mechanical subsystem is used to provide the air pressure conditions required for the Rayleigh laser radar system to work normally in the low-pressure environment of the stratosphere; The ground control unit issues an operation control instruction, which is transmitted to the load control unit via the communication data transmission module to control the operation of the laser. The liquid cooling unit dissipates heat for the laser. The laser pulse emitted by the laser passes through the beam expander and then enters the deflection mirror, and enters the atmosphere through the optical window to interact with atmospheric molecules to generate a backward Rayleigh scattering echo signal. After being collected by the telescope, the backward Rayleigh scattered echo signal is transmitted through the optical fiber receiving unit and enters the mechanical subsystem of the electrical box through the optical interface on the upper cover of the electrical box; then, the backward Rayleigh scattered echo signal is transmitted to the optical fiber collimator through the multimode optical fiber, enters the spectroscope through the narrow-band filter and becomes two beams of echo signals, one beam of echo signal reflected from the spectroscope passes through the first converging mirror and reaches the first single-photon detector, and the other beam of echo signal transmitted from the spectroscope passes through the reflecting mirror and enters the second converging mirror and reaches the second single-photon detector, the number of photons recorded by the first single-photon detector and the second single-photon detector are respectively connected to two different channels of the photon counter to realize the recording and storage of the echo photon number profile, and the echo photon number is transmitted to the ground control unit through the communication data transmission module.

2. The Rayleigh laser radar system based on the stratospheric floating platform according to claim 1, characterized in that: The stratospheric floating platform is a floating platform with dynamic characteristics, including but not limited to stratospheric balloons, tethered balloons and stratospheric airships.

3. The Rayleigh laser radar system based on the stratospheric floating platform according to claim 1, characterized in that: The mounting interface is located at the front end of the stratospheric floating platform, ensuring that the Rayleigh laser radar system is mounted at an oblique upward angle.

4. The Rayleigh laser radar system based on the stratospheric floating platform according to claim 1, characterized in that: The beam expander is used to compress the divergence angle of the laser pulse of the laser, the deflection mirror is used to correct the tilt error in the optical path of the laser emission subsystem, and realize the coaxial calibration of the divergence angle of the laser pulse after beam expansion and the field of view angle of the optical receiving subsystem, and the optical window is used to transmit the emitted laser pulse while ensuring the airtightness and constant temperature of the mechanical subsystem of the electrical box.

5. The Rayleigh laser radar system based on the stratospheric floating platform according to claim 1, characterized in that: The passive temperature control unit is used to realize the passive insulation function of the Rayleigh laser radar system; the air cooling unit realizes heat exchange between the inside of the electrical box mechanical subsystem and the external environment, so that the inside of the electrical box mechanical subsystem is in a normal temperature environment; the heating unit realizes temperature control of the telescope, the receiving optical fiber unit and the inside of the electrical box mechanical subsystem.

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