Device for rapidly detecting atmospheric temperature and wind speed profile

Abstract

A device for rapidly detecting atmospheric temperature and wind speed profiles comprises a laser, a VIPA etalon, an imaging lens and a CCD camera, the imaging lens is connected with the VIPA etalon and the CCD camera, one end, far away from the imaging lens, of the VIPA etalon is connected with a cylindrical lens, a receiving lens is arranged between the cylindrical lens and the laser, and the receiving lens is connected with the CCD camera. The laser outputs high-energy narrow-linewidth single-longitudinal-mode continuous laser beams to interact with gas, then Rayleigh-Brillouin scattering signals are generated at all positions of the laser beams, scattering light beams are collected through the receiving lens and compressed and focused in the direction perpendicular to the light beams through the cylindrical lens, the light beams enter the VIPA etalon for spectral analysis, and the spectral analysis result is obtained. Rayleigh-Brillouin scattering spectrums are converged to the CCD camera through the imaging lens to be collected. According to the device, temperature inversion is carried out on Rayleigh-Brillouin scattering spectrums of different detection distances through a theoretical model, so that atmospheric temperature profile detection is rapidly and accurately realized, and measurement of a wind speed profile is realized by calculating Doppler frequency shift of the Rayleigh-Brillouin scattering spectrums.

Description

Technical Field

[0001] The present invention relates to the technical field of light scattering and spectroscopy, and particularly to a device for rapidly detecting the atmospheric temperature and wind speed profiles. Background Art

[0002] Gas environmental parameters, especially the temperature and wind speed of the gas, are of crucial significance in aspects such as meteorological forecasting and disaster warning, environmental protection, and energy utilization. With the increasingly serious global climate change problem, the importance of monitoring the atmospheric temperature distribution and wind speed has become even more prominent. Obtaining accurate temperature data not only helps to understand the mechanisms of atmospheric processes and climate change but also provides key support for multiple fields such as disaster prevention and agricultural production. Precise knowledge of wind speed information helps meteorologists gain a deeper understanding of the atmospheric circulation, improve the accuracy and timeliness of weather forecasting, and also provides a rapid warning for the occurrence of extreme weather. As one of the most powerful active remote sensing technologies, lidar has the advantages of high spatio-temporal resolution and has been widely used in atmospheric monitoring.

[0003] The temperature measurement system based on lidar earliest used the Rayleigh / Mie scattering echo energy to measure the atmospheric temperature profile. However, since the received echo energy simultaneously contains the Mie scattering spectrum and the Rayleigh-Brillouin scattering spectrum, and the two cannot be distinguished, it is difficult to accurately measure the temperature by this method. With the advent of narrow linewidth lasers, the high spectral resolution lidar based on Rayleigh-Brillouin scattering has been developed. There has emerged a spectral detection lidar system based on Rayleigh-Brillouin scattering to obtain the vertical profile of atmospheric temperature. Existing technologies mostly use Fabry-Perot etalons or Fizeau interferometers for spectral profile detection. To meet the precise requirements of spectral resolution and extinction ratio for obtaining the spectrum, a relatively long acquisition time is required, which may range from several minutes to several hours depending on the insertion loss, affecting the real-time continuous high-density atmospheric vertical detection. The wind measurement system based on lidar mainly analyzes the Doppler shift of the Mie scattering signal of atmospheric aerosol particles at different altitudes to invert the wind speed, but it cannot be applied to the upper atmosphere without aerosols. Existing atmospheric lidar systems usually can only measure one gas parameter of atmospheric temperature or wind speed with one set of systems, and the acquisition method is mostly point scanning, lacking certain research means for obtaining a complete temperature profile and wind speed measurement at one time. Summary of the Invention

[0004] In view of the above technical problems, the present invention proposes a device for rapidly detecting the atmospheric temperature profile and wind speed.

[0005] To achieve the above object, the present invention adopts the following technical solutions: The present invention provides a device for rapidly detecting atmospheric temperature and wind speed profiles, comprising a laser, a VIPA etalon, an imaging lens, and a CCD camera. The imaging lens is connected to the VIPA etalon and the CCD camera. One end of the VIPA etalon away from the imaging lens is connected with a cylindrical lens, and a receiving lens is arranged between the cylindrical lens and the laser. The laser outputs a high-energy narrow-linewidth single-longitudinal-mode continuous laser beam to interact with gas, and then Rayleigh-Brillouin scattering signals are generated at various positions of the laser beam. The Rayleigh-Brillouin scattering beam is collected by the receiving lens, compressed and focused in the direction perpendicular to the beam direction by the cylindrical lens, enters the VIPA etalon for spectral analysis. The Rayleigh-Brillouin scattering beam after spectral analysis by the VIPA etalon is converged to the CCD camera through the imaging lens for acquisition, and finally saved and analyzed by a computer connected to the CCD camera.

[0006] Further, each column of pixels of the CCD camera constitutes a Rayleigh-Brillouin scattering spectrum, and the horizontal pixel sequence of the CCD camera constitutes the Rayleigh-Brillouin scattering spectrum distribution at various positions of the imaging beam.

[0007] Further, the horizontal distribution of the spectral signal collected on the CCD camera is consistent with the horizontal distribution of the scattered beam collected by the receiving lens.

[0008] Further, the computer fits the Rayleigh-Brillouin scattering spectrum through a theoretical model, seeks the best fitting value with temperature as the only variable to invert the temperature, and corresponds to the detection distance of the laser beam to obtain the atmospheric temperature profile.

[0009] Further, the computer calculates the wind speed by calculating the Doppler shift of the Rayleigh-Brillouin scattering spectrum, and corresponds to the detection distance of the laser beam to obtain the atmospheric wind speed profile.

[0010] The device for rapidly detecting atmospheric temperature and wind speed profiles of the present invention obtains the scattered beam of the atmospheric Rayleigh-Brillouin scattering signal from near distance to far distance through the principle of geometric optics, and converts the obtained scattered beam from an energy signal distributed in space into a spectral signal distributed in space through the cylindrical lens and the VIPA etalon. The Rayleigh-Brillouin scattering spectra at different detection distances are used to invert the temperature through a theoretical model and calculate the wind speed by Doppler shift, so as to rapidly and accurately detect the atmospheric temperature and wind speed profiles. Description of the Drawings

[0011] Figure 1 It is a schematic structural diagram of the device for rapidly detecting the atmospheric temperature profile of the present invention; Figure 2Schematic diagram of pixels for collecting Rayleigh-Brillouin scattering spectral signals by a CCD camera; Figure 3 Schematic diagram of Rayleigh-Brillouin scattering spectra at altitudes of 1 - 14 km; Figure 4 Atmospheric temperature profile at altitudes of 1 - 14 km; In the figure: 1 - Laser, 2 - Laser beam, 3 - Receiving lens, 4 - Cylindrical lens, 5 - VIPA etalon, 6 - Imaging lens, 7 - CCD camera, 8 - Computer. Specific implementation manner

[0012] Please refer to Figures 1-4 , the present invention provides a device for rapidly detecting atmospheric temperature and wind speed profiles, including a laser 1, a VIPA etalon 5, an imaging lens 6, and a CCD camera 7. The imaging lens 6 is connected to the VIPA etalon 5 and the CCD camera 7. One end of the VIPA etalon 5 away from the imaging lens 6 is connected to the cylindrical lens 4. A receiving lens 3 is provided between the cylindrical lens 4 and the laser 1. The laser 1 outputs a high-energy narrow-linewidth single-longitudinal-mode continuous laser beam 2 to interact with the gas, and then Rayleigh-Brillouin scattering signals are generated at various positions of the laser beam 2. The scattered light beam is collected by the receiving lens 3, compressed and focused in the direction perpendicular to the beam direction by the cylindrical lens 4, and enters the VIPA etalon 5 for spectral analysis. The Rayleigh-Brillouin scattering spectrum is converged to the CCD camera 7 by the imaging lens 6 for collection, and finally saved and analyzed by a computer 8 connected to the CCD camera 7.

[0013] Further, each column of pixels of the CCD camera 7 constitutes a Rayleigh-Brillouin scattering spectrum, and the horizontal pixel sequence constitutes the Rayleigh-Brillouin scattering spectrum distribution at various positions of the imaging light beam.

[0014] Further, the horizontal distribution of the spectral signals collected on the CCD camera 7 is consistent with the horizontal distribution of the scattered light beam collected by the receiving lens 3.

[0015] Further, the computer 8 fits the Rayleigh-Brillouin scattering spectrum through a theoretical model, seeks the best fitting value to invert the temperature with temperature as the only variable, and corresponds to the detection distance of the laser beam 2 to obtain the atmospheric temperature profile.

[0016] Further, the computer 8 obtains the wind speed by calculating the Doppler shift of the Rayleigh-Brillouin scattering spectrum, and corresponds to the detection distance of the laser beam to obtain the atmospheric wind speed profile.

[0017] Specifically, the present invention provides a device for rapidly detecting the atmospheric temperature and wind speed profiles. A high-energy single-longitudinal-mode continuous laser beam 2 with a wavelength of 532 nm and a linewidth less than 5 MHz output by a laser 1 enters the atmosphere. The laser beam 2 interacts with the gas to generate Rayleigh-Brillouin scattering signals at various positions. The scattered light beams are collected by a receiving lens 3, and then compressed and focused in the direction perpendicular to the beam direction by a cylindrical lens 4 and enter a VIPA etalon 5 for spectral analysis. The Rayleigh-Brillouin scattering spectrum is converged to a CCD camera 7 by an imaging lens 6 for acquisition, and finally saved and analyzed by a computer 8.

[0018] Among them, each column of pixels of the CCD camera 7 constitutes a Rayleigh-Brillouin scattering spectrum, and the horizontal pixel sequence constitutes the Rayleigh-Brillouin scattering spectrum distribution at various positions of the scattered light beam.

[0019] The imaging lens 6 converges the Rayleigh-Brillouin scattering spectrum after spectral analysis by the VIPA etalon 5 in the horizontal direction (perpendicular to the paper surface) to the CCD camera 7 for acquisition.

[0020] The VIPA etalon 5 and the imaging lens 6 do not change the horizontal distribution (x-direction) of the collected scattered light beam on the image plane. The horizontal distribution of the spectral signal collected by the CCD camera 7 is consistent with the collected scattered light beam. According to the geometric optics principle, the actual detection distance corresponding to the horizontal pixel sequence (x-direction) of the CCD camera 7 can be obtained, which can be expressed as: (1); In the formula, z is the detection distance, L I is the distance from the reference pixel I to the extension of the detection plane of the CCD camera 7 to the laser beam, L i is the distance from pixel i to the reference pixel I, φ is the angle between the scattered light beam and the laser beam, θ i is the angle between the line connecting pixel i and the center of the receiving lens and the scattered light beam; Among them, the wind speed retrieved by Doppler shift can be expressed as: (2); In the formula, V is the wind speed, ν i is the central frequency of the Rayleigh-Brillouin scattering spectrum carrying the wind speed information, ν 0 is the central frequency of the Rayleigh-Brillouin scattering spectrum without wind speed, c is the speed of light, θ i is the angle between the line connecting pixel i and the center of the receiving lens and the scattered light beam.

[0021] Please refer to Figures 2-4, the computer 8 stores and analyzes by fitting the Rayleigh-Brillouin scattering spectrum composed of a row of pixels (in the direction perpendicular to the paper surface) collected by the CCD camera 7 through the Tenti S6 theoretical model, and seeking the best fitting value with temperature as the only variable to invert the temperature. The temperature is inverted for the Rayleigh-Brillouin scattering spectra at every 1 km interval of the detection distances from 1 to 14 km corresponding to a longitudinal pixel sequence collected by the CCD camera 7, and the Doppler frequency shift of the Rayleigh-Brillouin scattering spectrum is calculated to invert the wind speed, and then the temperature and the detection distance are corresponded to obtain the temperature profile and the wind speed profile of the atmosphere from 1 to 14 km.

[0022] Based on the geometric optical principle, the present invention sets up a receiving lens at a specific position to achieve long beam collection, and based on the virtual imaging phase array (VIPA) to achieve rapid detection of the spontaneous Rayleigh-Brillouin scattering spectrum, and completes the distance resolution measurement of the Rayleigh-Brillouin scattering spectrum of the long-distance atmosphere. VIPA is a special type of Fabry-Perot etalon, which can obtain the information within the required spectral range within a few seconds or even shorter time, and achieve rapid spectral frequency analysis. To solve some limitations in the existing field of scattered signal detection and achieve rapid detection of the atmospheric temperature and wind speed profiles.

[0023] The device for rapidly detecting the atmospheric temperature and wind speed profiles of the present invention obtains the scattered light beam of the atmospheric Rayleigh-Brillouin scattering signal from near to far through the geometric optical principle, and converts the obtained scattered light beam from the energy signal distributed in space into the spectral signal distributed in space through the cylindrical lens and the VIPA etalon. The Rayleigh-Brillouin scattering spectra at different detection distances are used to invert the temperature through the theoretical model and invert the wind speed through the Doppler frequency shift, so as to rapidly and accurately achieve the measurement of the atmospheric temperature and wind speed profiles.

[0024] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not limited to the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An apparatus for rapidly detecting the atmospheric temperature and wind speed profiles, characterized in that, It includes a laser (1), a VIPA etalon (5), an imaging lens (6) and a CCD camera (7). The imaging lens (6) connects the VIPA etalon (5) and the CCD camera (7). One end of the VIPA etalon (5) far from the imaging lens (6) is connected with a cylindrical lens (4). A receiving lens (3) is arranged between the cylindrical lens (4) and the laser (1). The laser (1) outputs a high-energy narrow-linewidth single-longitudinal-mode continuous laser beam (2) to interact with a gas, and then Rayleigh-Brillouin scattering signals are generated at various positions of the laser beam (2). The Rayleigh-Brillouin scattering beam is collected by the receiving lens (3), compressed and focused in the direction perpendicular to the beam direction by the cylindrical lens (4), enters the VIPA etalon (5) for spectral analysis. The Rayleigh-Brillouin scattering beam after spectral analysis by the VIPA etalon (5) is converged to the CCD camera (7) for acquisition by the imaging lens (6), and finally is saved and analyzed by a computer (8) connected to the CCD camera (7).

2. The device for rapidly detecting the atmospheric temperature and wind speed profiles according to claim 1, characterized in that, Each column of pixels of the CCD camera (7) constitutes a Rayleigh-Brillouin scattering spectrum, and the horizontal pixel sequence of the CCD camera (7) constitutes the Rayleigh-Brillouin scattering spectrum distribution at various positions of the imaging beam.

3. The device for rapidly detecting the atmospheric temperature and wind speed profiles according to claim 2, characterized in that, The horizontal distribution of the spectral signal acquired on the CCD camera (7) is consistent with the horizontal distribution of the scattered beam collected by the receiving lens (3).

4. The device for rapidly detecting the atmospheric temperature and wind speed profiles according to claim 1, characterized in that, The computer (8) fits the Rayleigh-Brillouin scattering spectrum through a theoretical model, seeks the best fitting value with temperature as the only variable to invert the temperature, and corresponds to the detection distance of the laser beam (2) to obtain the atmospheric temperature profile.

5. The device for rapidly detecting the atmospheric temperature and wind speed profiles according to claim 1, wherein The computer (8) compares the Rayleigh-Brillouin scattering spectrum with the reference position of the Rayleigh-Brillouin scattering spectrum under no wind speed, calculates the Doppler frequency shift of the Rayleigh-Brillouin scattering spectrum to invert the wind speed, and corresponds to the detection distance of the laser beam (2) to obtain the atmospheric wind speed profile.

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