Direct wind measurement laser radar system

Abstract

The utility model belongs to the field of laser radars, and particularly relates to a direct wind measurement laser radar system. The laser radar system comprises a laser, a telescope, a subsequent optical element and a processing unit. A first beam splitter is arranged at the output end of the laser and divides laser emitted by the laser into first laser and second laser, the first laser is emitted to the atmosphere, and the second laser is guided into a subsequent optical element to be processed and then converted into the processing unit. The frequency of the emergent laser is located at a dual-channel frequency spectrum intersection point of the F-P etalon in the subsequent optical element; the telescope is connected with a subsequent optical element and is used for receiving an atmosphere back scattering signal generated after the first laser acts with the atmosphere and transmitting the atmosphere back scattering signal to the F-P etalon; and the processing unit is used for calculating the Doppler frequency shift according to the frequency difference between the second laser and the atmosphere back scattering signal passing through the F-P etalon to obtain the radial wind speed, so that the debugging difficulty of subsequent optical elements can be effectively reduced.

Description

Technical Field

[0001] This utility model belongs to the field of lidar, and specifically relates to a direct wind measurement lidar system. Background Technology

[0002] Atmospheric wind fields are among the most important parameters in numerical weather prediction and climate research. Closely related to human life, atmospheric wind fields play a vital role in many fields such as environmental monitoring, atmospheric transport, atmospheric thermodynamics, and global climate change.

[0003] Direct wind lidar works on the principle of laser Doppler. It uses a laser as a light source to emit laser pulses into the atmosphere. Atmospheric molecules or aerosol particles move accordingly under the influence of the atmospheric wind field. A large-aperture telescope is used to receive the Doppler frequency shift information carried by the backscattered signals of atmospheric aerosol particles and atmospheric molecules. By analyzing the backscattered signals of atmospheric aerosol particles and atmospheric molecules and the Doppler frequency shift of the emitted laser, atmospheric wind speed can be inverted.

[0004] The application of direct wind lidar systems is still in its early stages, and there is still much room for development before they become commercial products. Measurements are mainly performed using three-channel FP etalons, but tunable three-channel FP etalons have drawbacks such as large aperture, high cost, and numerous subsequent optical components. Utility Model Content

[0005] To address the aforementioned problems, this utility model discloses a direct wind measurement lidar system, which includes a laser, a telescope, subsequent optical elements, and a processing unit.

[0006] The output end of the laser is provided with a first beam splitter, which splits the laser output into a first laser and a second laser. The first laser is directed toward the atmosphere, and the second laser passes through a subsequent optical element and is then converted into the processing unit. The frequency of the output laser is located at the crossover point of the dual-channel spectrum of the FP etalon in the subsequent optical element.

[0007] The telescope is connected to a subsequent optical element to receive the atmospheric backscattering signal generated after the first laser interacts with the atmosphere, and transmit it to the FP etalon.

[0008] The processing unit is used to calculate the Doppler frequency shift based on the frequency difference between the second laser and the atmospheric backscattered signal after passing through the FP etalon, and to derive the radial wind speed based on the Doppler frequency shift.

[0009] Furthermore, a first beam expander and a first coupler are disposed behind the first beam splitter;

[0010] The first beam expander is used to expand the first laser beam and direct it into the atmosphere;

[0011] The first coupler is used to couple the second laser into the optical fiber for transmission to subsequent optical elements, and then convert it into the processing unit.

[0012] Furthermore, the FP etalon is a fixed dual-channel FP etalon.

[0013] Furthermore, the telescope is a Cassegrain telescope, and an optical fiber adapter and an optical switch are sequentially arranged after the Cassegrain telescope;

[0014] The atmospheric backscattered signal received by the Cassegrain telescope enters the optical fiber through the optical fiber adapter and is transmitted to subsequent optical elements.

[0015] Furthermore, the subsequent optical elements include a collimator, a second beam splitter, a third beam splitter, and an FP etalon;

[0016] The collimator is used to collimate the backscattered signal received by the telescope. The second beam splitter is used to split the collimated beam. Part of the split beam enters the energy channel of the FP etalon, and the other part of the beam enters the two interference channels of the FP etalon after being split by the third beam splitter.

[0017] Furthermore, the ratio of light entering the energy channel and the interference channel through the second beam splitter is 1:9.

[0018] The advantages of this utility model are as follows:

[0019] 1) This utility model effectively reduces the number of subsequent optical components and detectors. By actively adjusting the frequency of the laser, it ensures that the frequency of the emitted laser is stable at the crossover point of the dual-channel spectrum of the FP standard etalon, thus reducing the difficulty of debugging subsequent optical components.

[0020] 2) A high-precision fixed dual-channel FP etalon is used as a frequency discriminator. Before each wind speed measurement, the transmittance curve of the dual-channel FP etalon is remeasured. Based on the transmittance curve of the dual-channel FP etalon, the frequency of the laser emitted by the laser is actively adjusted to stabilize the frequency of the emitted laser at the crossover point of the dual-channel spectrum of the FP etalon. This avoids the disadvantages of using a tunable three-channel FP etalon, such as large aperture, high cost, and many subsequent optical components in the system.

[0021] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained by means of the structures pointed out in the description, claims, and drawings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A schematic diagram of the optical path of a direct wind-measuring lidar system according to an embodiment of the present invention is shown.

[0024] In the diagram: 1. Laser; 2. First beam splitter; 3. First beam expander; 4. Telescope; 5. Fiber optic adapter; 6. Optical switch; 7. Collimator; 8. Second beam splitter; 9. Third beam splitter; 10. First reflector; 11. FP etalon; 12. Detector; 13. Acquisition unit; 14. Processing unit; 15. First coupler. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0026] This utility model discloses a direct wind measurement lidar system, which includes a laser 1, a telescope 4, subsequent optical elements, and a processing unit 14.

[0027] The output end of the laser 1 is provided with a first beam splitter 2, which splits the laser emitted by the laser 1 into a first laser and a second laser. The first laser is directed toward the atmosphere, and the second laser is guided into the subsequent optical element and then converted into the processing unit 14. The frequency of the emitted laser is located at the crossover point of the dual-channel spectrum of the FP etalon 11 in the subsequent optical element.

[0028] The telescope 4 is connected to a subsequent optical element to receive the atmospheric backscattering signal generated after the first laser interacts with the atmosphere, and transmit it to the FP etalon 11;

[0029] The processing unit 14 is used to calculate the magnitude of the Doppler frequency shift based on the frequency difference between the second laser and the atmospheric backscattered signal after passing through the FP etalon 11, and to derive the magnitude of the radial wind speed based on the Doppler frequency shift.

[0030] Specifically, the laser emitted by laser 1 passes through the first beam splitter 2, which splits the emitted laser from laser 1 into a first laser and a second laser. The first laser is directed into the atmosphere, interacts with atmospheric aerosol particles and molecules, and is then received by telescope 4. The second laser passes through subsequent optical elements and is converted into processing unit 14, where it is used as a reference light for frequency detection. By comparing the frequency of the second laser, the frequency of the emitted laser is ensured to be stable at the intersection of the dual-channel spectrum of the FP etalon 11. The receiving telescope 4 receives the atmospheric backscattering signal generated after the first laser interacts with the atmosphere and transmits the signal to the FP etalon 11. The processing unit 14 calculates the Doppler frequency shift by combining the frequency difference between the second laser and the atmospheric backscattering signal after passing through the FP etalon 11, and then determines the radial wind speed. This embodiment effectively reduces the number of subsequent optical elements and detectors, and by actively adjusting the frequency of laser 1, ensures that the emitted laser frequency is stable at the intersection of the dual-channel spectrum of the FP etalon, thus reducing the difficulty of debugging subsequent optical elements.

[0031] Preferably, the FP etalon 11 is a fixed dual-channel FP etalon.

[0032] A high-precision fixed dual-channel FP etalon is used as a frequency discriminator. Before each wind speed measurement, the transmittance curve of the dual-channel FP etalon is remeasured. Based on the transmittance curve of the dual-channel FP etalon, the frequency of the laser emitted by laser 1 is actively adjusted to stabilize the frequency of the emitted laser at the crossover point of the dual-channel spectrum of the FP etalon. This avoids the disadvantages of using a tunable three-channel FP etalon, such as large aperture, high cost, and many subsequent optical components in the system.

[0033] Furthermore, the laser 1 is a tunable laser. By employing a tunable laser, the frequency of laser 1 is actively adjusted to stabilize the emitted laser frequency at the crossover point of the dual-channel FP etalon spectrum. Before each wind speed measurement, the transmittance curve of the dual-channel FP etalon is remeasured. Based on the transmittance curve, the frequency of the emitted laser 1 is actively adjusted to stabilize it at the crossover point of the dual-channel FP etalon spectrum, avoiding the disadvantages of using a tunable three-channel FP etalon, such as large aperture, high cost, and numerous subsequent optical components.

[0034] Furthermore, a first reflector 10 and a first coupler 15 are disposed behind the first beam splitter 2;

[0035] The first beam expander 3 is used to expand the first laser beam and direct it into the atmosphere;

[0036] The first coupler 15 is used to couple the second laser into the optical fiber for transmission to subsequent optical elements, and then convert it into the processing unit 14.

[0037] Specifically, the first beam splitter 2 splits the emitted laser from the laser 1 into a first laser and a second laser. The first laser enters the first beam expander 3, and after being expanded by the first beam expander 3, the divergence angle of the first laser is compressed, and it is finally emitted into the atmosphere. The second laser enters the first coupler 15, and is coupled into the optical fiber through the first coupler 15. After being transmitted to subsequent optical elements, it is converted and sent to the processing unit 14.

[0038] Furthermore, the telescope 4 is a Cassegrain telescope 4, and an optical fiber adapter 5 and an optical switch 6 are sequentially arranged after the Cassegrain telescope 4;

[0039] The atmospheric backscattered signal received by the Cassegrain telescope 4 enters the optical fiber through the optical fiber adapter 5 and is transmitted to the subsequent optical elements.

[0040] Specifically, the first laser is emitted into the atmosphere through multiple reflectors 10 and a beam expander 3, and the atmospheric backscattered signal is then received by the Cassegrain telescope 4. The atmospheric backscattered signal enters the optical fiber through an optical fiber adapter 5 and is then transmitted to the subsequent optical element. An optical switch 6 is also provided at the other end of the optical fiber, which controls the time-division multiplexing of the atmospheric backscattered signal and the reference light second laser into the subsequent optical element.

[0041] Furthermore, the subsequent optical elements include a collimator 7, a second beam splitter 8, a third beam splitter 9, and an FP etalon 11;

[0042] The collimator 7 is used to collimate the backscattered signal received by the telescope 4. The second beam splitter 8 is used to split the collimated beam. Part of the split beam enters the energy channel of the FP etalon 11, and the other part of the beam enters the two interference channels of the FP etalon 11 after being split by the third beam splitter 9.

[0043] Specifically, the optical fiber guides the backscattered signal into collimator 7, which collimates the light output from the optical fiber into a parallel beam for transmission in free space. A second beam splitter 8 splits the backscattered signal into a first collimated beam and a second collimated beam. The first collimated beam is directed into the energy channel of the dual-channel FP etalon 11, and the second collimated beam, after being evenly split by a third beam splitter 9, enters the two channels of the FP etalon 11 respectively. A detector 12 detects multiple optical signals and performs photoelectric conversion, converting the optical signals into electrical signals. After being acquired by a data acquisition card, the electrical signals are transmitted to the processing unit 14 for calculating the Doppler frequency shift. Preferably, the ratio of light split into the energy channel and the interference channel by the second beam splitter 8 is 1:9. Specifically, the energy ratio of the first collimated beam and the second collimated beam is 1:9.

[0044] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A direct wind measurement lidar system, characterized in that, The lidar system includes a laser (1), a telescope (4), subsequent optical elements and a processing unit (14). The output end of the laser (1) is provided with a first beam splitter (2). The first beam splitter (2) splits the laser emitted by the laser (1) into a first laser and a second laser. The first laser is directed toward the atmosphere, and the second laser is fed into the subsequent optical element for processing and then converted into the processing unit (14). The frequency of the emitted laser is located at the crossover point of the dual-channel spectrum of the FP etalon (11) in the subsequent optical element. The telescope (4) is connected to a subsequent optical element to receive the atmospheric backscattering signal generated after the first laser interacts with the atmosphere and transmit it to the FP etalon (11). The processing unit (14) is used to calculate the Doppler frequency shift based on the frequency difference between the second laser and the atmospheric backscattered signal after passing through the FP etalon (11), and to determine the radial wind speed based on the Doppler frequency shift.

2. The direct wind measurement lidar system according to claim 1, characterized in that, A first beam expander (3) and a first coupler (15) are disposed behind the first beam splitter (2); The first beam expander (3) is used to expand the first laser beam and direct it into the atmosphere; The first coupler (15) is used to couple the second laser into the optical fiber for transmission to the subsequent optical element and then convert it into the processing unit (14).

3. The direct wind measurement lidar system according to claim 1, characterized in that, The FP etalon (11) is a fixed dual-channel FP etalon.

4. The direct wind measurement lidar system according to claim 1, characterized in that, The telescope (4) is a Cassegrain telescope, and an optical fiber adapter (5) and an optical switch (6) are sequentially installed behind the Cassegrain telescope. The atmospheric backscattered signal received by the Cassegrain telescope enters the optical fiber through the optical fiber adapter (5) and is transmitted to the subsequent optical element through the optical fiber.

5. A direct wind-measuring lidar system according to claim 1, characterized in that, The subsequent optical elements include a collimator (7), a second beam splitter (8), a third beam splitter (9), and an FP etalon (11). The collimator (7) is used to collimate the backscattered signal received by the telescope (4). The second beam splitter (8) is used to split the collimated beam. Part of the split beam enters the energy channel of the FP etalon (11), and the other part of the beam enters the two interference channels of the FP etalon (11) after being split by the third beam splitter (9).

6. A direct wind-measuring lidar system according to claim 5, characterized in that, The ratio of light entering the energy channel and the interference channel by the second beam splitter (8) is 1:9.

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