Laser radar wind field real-time imaging system and method

Abstract

The invention relates to the technical field of atmospheric wind field observation, and particularly discloses a laser radar wind field real-time imaging system and method. Comprising a laser transmitter, a cassette telescope system, a collimating mirror, a primary polarization modulation light splitting module, a wide-field delay assembly, a middle collimating system, a secondary polarization modulation light splitting module, an imaging mirror and a detector which are sequentially arranged along incident light. The invention aims to solve the technical bottlenecks that the view field is limited, the real-time performance is insufficient and the precision and the coverage range are difficult to consider in the traditional wind field detection, and a set of integrated and high-performance wind field imaging solution is constructed by fusing the active detection advantage of the laser radar and the view field expanding birefringence interference technology. According to the system, the laser radar is used as an active light source, the defects that a passive interference technology depends on atmospheric airglow and the observation time period is limited are overcome, full-time-period and full-height-layer wind field detection can be achieved, and the core requirements of wide view field, high precision and real-time performance are considered by optimizing an optical architecture.

Description

Technical Field

[0001] This invention relates to the field of atmospheric wind field observation technology, and more specifically, to a lidar wind field real-time imaging system and method. Background Technology

[0002] Atmospheric wind fields, as core parameters describing atmospheric dynamics, directly influence the evolution of the global climate system, the development of weather processes, and the generation and propagation of severe weather events due to their spatiotemporal distribution characteristics. They play an irreplaceable role in fields such as meteorological forecasting, aerospace safety assurance, and atmospheric environmental monitoring. With the increasing demands for timeliness, resolution, and coverage in detection, acquiring wide-field-of-view, high-precision, and real-time wind field data has become a core requirement and research hotspot in the field of atmospheric sounding technology.

[0003] Existing wind field detection technologies are mainly divided into two categories: passive interferometric imaging and active lidar. Passive technologies use natural atmospheric airglow as the light source and measure the Doppler frequency shift to retrieve the wind field through an interferometer. Among them, the static birefringent Doppler wind interferometer (BIDWIN) has become a representative of the new generation of technologies due to its advantages of good stability, small size, and low cost. However, it uses a Wollaston prism for angle shearing and beam splitting, which leads to differences in the incident angle and azimuth angle when the beam is incident on the birefringent crystal in the upper and lower fields of view. This causes phase changes in the cross field, which severely limits the effective field of view. In addition, its reliance on airglow signals limits daytime observation and weakens its low-altitude detection capabilities. Although traditional wide-field Michelson interferometers can achieve large-area detection, their complex system structure, large size, and extremely high assembly precision requirements make them difficult to widely apply.

[0004] Active lidar technology acquires wind field information by actively emitting laser beams, offering advantages such as long detection range, high spatiotemporal resolution, and independence from lighting conditions. However, traditional lidar mostly performs single-point scanning, making it difficult to achieve real-time imaging of large-area two-dimensional wind fields. When expanding the field of view, existing imaging lidar is prone to degradation of interference signal quality due to laser beam polarization distortion and optical path deviation, and the increased system complexity reduces the real-time performance of data processing, making it difficult to balance the requirements of field of view, accuracy, and real-time performance.

[0005] In summary, current technologies have not yet achieved synergistic optimization of "wide field of view, high precision, real-time performance, and miniaturization." While passive birefringent interferometers offer significant miniaturization advantages, their field of view is limited and they rely on airglow signals. Active lidar, while possessing active detection capabilities, struggles to balance precision and real-time performance when performing wide-field imaging. Traditional wide-field interferometers suffer from excessive size and cost. Furthermore, the thermal sensitivity of birefringent crystals, the modulation of lidar polarization states, and the extraction of interference signals are all affected by atmospheric turbulence, further limiting the application effectiveness of existing technologies.

[0006] Therefore, developing a real-time wind field imaging scheme that integrates the advantages of active detection by lidar with the miniaturization characteristics of birefringence interferometry, while breaking through the field-of-view limitations, has become a key direction for solving the current technical bottlenecks. Summary of the Invention

[0007] The technical problem this invention aims to solve is to provide a real-time wind field imaging system and method using lidar, which addresses the technical bottlenecks of traditional wind field detection, such as limited field of view, insufficient real-time performance, and the difficulty in balancing accuracy and coverage. By integrating the advantages of active lidar detection with extended field-of-view birefringence interferometry, an integrated, high-performance wind field imaging solution is constructed. This system uses lidar as the active light source, overcoming the limitations of passive interferometry, which relies on atmospheric airglow and is subject to time-limited observation periods. It enables wind field detection at all times and altitudes, and by optimizing the optical architecture, it balances the core requirements of wide field of view, high accuracy, and real-time performance. The solution adopted by this invention to solve the technical problem is: on the one hand: This invention provides a real-time lidar wind field imaging system, comprising: The laser emitter receives and processes incident light rays with the principal optical axis in the Z-axis direction, directs them to the target atmospheric region, and generates scattered echoes by interacting with atmospheric particles; the direction perpendicular to the principal optical axis and inward is the X-axis direction, which, combined with the Z-axis direction, constructs an XYZ coordinate system that satisfies the right-hand rule; The Cassette telescope system collects the scattered echoes; The light modulation component modulates the polarization state of light to form four beams; The imaging mirror receives the four beams of light processed by the light modulation component; The detector receives the beam of light processed by the imaging mirror and forms four phase-stepped interferometric images; The light modulation assembly includes a collimating lens, a primary polarization modulation beam splitter, a wide-field delay assembly, an intermediate collimation system, and a secondary polarization modulation beam splitter arranged sequentially along the optical channel.

[0008] In some possible implementations, the primary polarization modulation beam splitting module includes a first wedge-shaped beam splitter, an upper polarizer and a lower polarizer attached to the surface of the first wedge-shaped beam splitter, and an upper quarter-wave plate; the upper quarter-wave plate is attached between the upper polarizer and the first wedge-shaped beam splitter. The projection of the transmission direction of the upper polarizer in the XY plane is along the X-axis direction, which is horizontal. The projection of the transmission direction of the lower polarizer onto the XY plane is along the Y-axis and is vertical. The projection of the upper quarter-wave plate's optical axis onto the XY plane forms a 45° angle with the positive X-axis, thus allowing the light beam to pass through the upper polarizer first, and then through the upper quarter-wave plate.

[0009] In some possible implementations, the wide-field delay assembly includes a first birefringent crystal plate, an intermediate half-wave plate, and a second birefringent crystal plate. The optical axis of the first birefringent crystal plate lies in the XY plane and forms an angle of 45° with the positive X-axis. The optical axis of the intermediate half-wave plate is in the XY plane and is the same as the positive Y-axis direction. The optical axis of the second birefringent crystal plate lies in the XY plane and forms an angle of 135° with the positive X-axis.

[0010] In some possible implementations, the secondary polarization modulation beam splitting module includes a second wedge-shaped beam splitting prism, a left polarizer and a right polarizer attached to the surface of the second wedge-shaped beam splitting prism; The projection of the transmission direction of the left polarizer onto the XY plane is along the Y-axis and is vertical. The projection of the transmission direction of the right polarizer onto the XY plane is along the X-axis and is horizontal.

[0011] In some possible implementations, the detector has a pixel resolution of not less than 256×256 and a frame rate of not less than 10fps.

[0012] on the other hand: This invention also provides a real-time imaging method for lidar wind fields, based on the lidar real-time imaging system for wind fields described above, specifically including the following steps: Step S1: The laser emitter receives the incident light and outputs a linearly polarized laser with a wavelength adapted to the atmospheric scattering characteristics. After power amplification, collimation and beam expansion, the linearly polarized laser forms a parallel beam, which is directed to irradiate the target atmospheric region, forming a backscattered echo carrying wind field Doppler frequency shift information. Step S2: The scattered echo is incident on the Casio telescope system and the scattered echo is collected; Step S3: The collected scattered echoes pass through the collimating lens to form a converged collimated beam, which is then incident on the primary polarization modulation beam splitter module to split the beam into two mutually orthogonal polarized beams A. In this process, the upper polarized beam in polarized beam A is converted into circularly polarized light by a first polarization modulation beam splitter, while the lower polarized beam in polarized beam A remains vertically polarized. The two beams after being processed by the first polarization modulation beam splitter are sheared by the first wedge beam splitter to form an angle. Step S4: The beam processed by the first wedge beam splitter enters the wide-field delay component for processing, eliminating cross-field phase changes and achieving a significant expansion of the field of view; Step S5: The beam processed by the wide-field delay component is collimated by the intermediate collimation system to form a collimated beam, and the pupil image is conjugated on the secondary polarization modulation beam splitting module to split the upper polarization beam and the lower polarization beam into two mutually orthogonal polarization beams B, forming four beams. Step S6: The four beams pass through the imaging mirror and form four 90° phase-stepped interference images on the detector, which are spatially distributed in four zones.

[0013] In some possible implementations, according to the Jones matrix notation, the Jones matrix of the upper polarizer in the primary polarization modulation beam splitter is: The Jones matrix of the lower polarizer is The Jones matrix of the upper quarter-wave plate is , is represented as; ; ; .

[0014] In some possible implementations, according to the Jones matrix notation, the Jones matrix of the first and second birefringent crystal plates of the wide-field delay assembly is represented as follows: : ; in: ; ; ; in, The angle of incidence of the light ray; It is the angle from the incident surface along the counterclockwise direction to the positive direction of the optical axis of the first and second birefringent crystal plates; The refractive indices of the first and second birefringent crystal plates for ordinary light are... difference; The refractive indices of the first and second birefringent crystal plates for unusual light are... difference; The Jones matrix of the intermediate half-wave plate is represented as follows: : .

[0015] The left and right polarizers in the secondary polarization modulation beam splitter module are equivalent to two orthogonal analyzers. The Jones matrix of the left polarizer is represented as follows: The Jones matrix of the right-hand polarizer is represented as follows: : ; .

[0016] In some possible implementations, the emitted electric fields of the four zones in step S6 are represented as follows: ; ; ; ; The equations for obtaining the interference intensity values ​​of the four partitions are as follows:

[0017] in: This represents the interference intensity values ​​of the four zones; This represents the relative intensity coefficient between the two partitions within each combination; Indicates the intensity of the light source; Indicates the instrument adjustment level; Represented as spectral line modulation; Indicates the reference phase; Indicates the step phase.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention achieves a comprehensive breakthrough in addressing the many shortcomings of traditional atmospheric wind field detection technology, demonstrating outstanding technical advantages and application value. This invention achieves differentiated polarization modulation of the scattered echo polarization segmentation and modulation module through a primary polarization modulation beam splitting module and a secondary polarization modulation beam splitting module; and combines the first birefringent crystal plate, the second birefringent crystal plate and the middle half-wave plate arranged orthogonally to fundamentally eliminate the cross-field phase change problem of traditional birefringent interferometers, expands the effective detection field of view to more than 8°, and has no obvious error blind zone within the field of view, and can realize large field of view full-domain wind field imaging, solving the pain point of the sharp increase in inversion error in the edge region of traditional instruments.

[0019] This invention features no moving parts. The wide-field delay component employs a birefringence delay component, which is compact and lightweight, can be assembled using conventional tools, and combines low cost with easy maintenance. It is suitable for both ground-based observation and spaceborne platform payload constraints. It overcomes the time-limited limitations of passive airglow detection, enabling day and night observation. Furthermore, the algorithm has extremely short single-pixel computation time, allowing it to be matched with high-frame-rate detectors to achieve real-time wind field imaging. This provides a high-quality technical solution for atmospheric dynamics research and severe weather early warning. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the system structure in this invention; Figure 2 This is a top view of the system of the present invention; Figure 3 This is a schematic diagram of the single polarization modulation beam splitting structure in this invention; Figure 4 This is a schematic diagram of the secondary polarization modulation beam splitting structure in this invention; Figure 5 This is a schematic diagram of the wide-field delay component structure of the present invention; Figure 6 This is a simulation result diagram of the system detection of the present invention; Wherein: 1-Laser emitter, 2-Cassette telescope system, 3-Collimating lens, 4-Single polarization modulation beam splitter module, 5-Wide field delay component, 6-Intermediate collimating system, 7-Secondary polarization modulation beam splitter module, 8-Imaging mirror, 9-Detector, 41-Upper polarizer, 42-Upper quarter-wave plate, 43-Lower polarizer, 44-First wedge beam splitter prism, 51-First birefringent crystal plate, 52-Intermediate half-wave plate, 53-Second birefringent crystal plate, 71-Left polarizer, 72-Right polarizer, 73-Second wedge beam splitter prism. Detailed Implementation

[0021] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. The terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "one," etc., do not indicate a quantity limitation, but rather indicate the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more. For example, multiple positioning posts refer to two or more positioning posts. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] The present invention will now be described in detail.

[0023] like Figures 1-6 As shown: A real-time wind field imaging method using lidar includes a laser emitter 1, a cassette telescope system 2, a collimating lens 3, a primary polarization modulation beam splitter module 4, a wide-field delay component 5, an intermediate collimating system 6, a secondary polarization modulation beam splitter module 7, an imaging mirror 8, and a detector 9 arranged sequentially along the incident light ray; wherein the incident direction of the incident light ray is the Z-axis direction; the direction perpendicular to the principal optical axis and inward is the X-axis direction, and combined with the Z-axis direction, an XYZ coordinate system satisfying the right-hand rule is constructed; A polarization detection laser with wavelength adapted to atmospheric scattering characteristics is output from a laser emitter and directed to illuminate the target atmospheric region. It undergoes elastic scattering with atmospheric molecules and aerosol particles, forming a scattered echo carrying dynamic information about the wind field. The scattered echoes are then collected by the cassette telescope system 2 and collimated by the collimating lens 3. The collimated beam is then incident on the primary polarization modulation beam splitter 4, splitting the beam into two mutually orthogonal polarized beams A, thereby achieving differential polarization modulation.

[0024] The primary polarization modulation beam splitting module 4 includes a first wedge beam splitting prism 44, an upper polarizer 41, an upper quarter-wave plate 42, and a lower polarizer 43 attached to the surface of the first wedge beam splitting prism 44. The projection of the transmission direction of the upper polarizer 41 onto the XY plane is along the X-axis and is horizontal; the projection of the transmission direction of the lower polarizer 43 onto the XY plane is along the Y-axis and is vertical. The projection of the upper quarter-wave plate 42 onto the XY plane forms a 45° angle with the positive X-axis. The upper quarter-wave plate 42 is attached between the upper polarizer 41 and the first wedge-shaped beam splitter 44, meaning the beam first passes through the upper polarizer 41 and then through the upper quarter-wave plate 42. The upper polarized beam in polarized beam A is converted into circularly polarized light by the first polarization modulation beam splitter module 4, while the lower polarized beam in polarized beam A remains vertically polarized. The two beams are sheared by the wedge-shaped prism A, forming an angle between them.

[0025] According to the Jones matrix notation, the Jones matrix of the upper polarizer 41 of the primary polarization modulation beam splitter 4 is as follows: The Jones matrix of the lower polarizer 43 is The Jones matrix of the upper quarter-wave plate 42 is The matrix representation is as follows: ; ; ; The light beam is then incident on the wide-field delay component 5, which includes a first birefringent crystal plate 51, an intermediate half-wave plate 52, and a second birefringent crystal plate 53. The optical axis of the first birefringent crystal plate 51 is in the XY plane and forms an angle of 45° with the positive X-axis; the optical axis of the intermediate half-wave plate 52 is in the XY plane and is the same as the positive Y-axis; the optical axis of the second birefringent crystal plate 53 is in the XY plane and forms an angle of 135° with the positive X-axis.

[0026] The crystal birefringence effect formed by the first birefringent crystal plate 51 and the second birefringent crystal plate 53 generates a stable and fixed optical path difference. At the same time, with the help of the polarization state rotation effect of the intermediate half-wave plate 52, the phase change of the cross field is eliminated, and the field of view is greatly expanded, with an effective field of view angle of 8°×8° or more.

[0027] The wide-field delay component 5 is based on the Jones matrix notation, and the Jones matrix of the first birefringent crystal plate 51 and the second birefringent crystal plate 53 is... Represented as: ; in, ; ; ; in, The angle of incidence of the light ray; The angle is the angle from the incident surface along the counterclockwise direction to the positive direction of the optical axis of the first birefringent crystal plate 51 and the second birefringent crystal plate 53; The refractive indices of the first birefringent crystal plate 51 and the second birefringent crystal plate 53 for ordinary light. difference; The refractive indices of the first birefringent crystal plate 51 and the second birefringent crystal plate 53 for unusual light. difference.

[0028] Jones matrix of intermediate half-wave plate 52 Represented as: ; Subsequently, the two orthogonal polarized beams A are collimated again by the intermediate collimation system 6, and the pupil image is conjugated on the secondary polarization modulation beam splitting module 7, which splits the polarized beam A into two orthogonal linearly polarized beams, namely the two orthogonal polarized beams B, thus obtaining four sets of beams.

[0029] The secondary polarization modulation beam splitting module 7 includes a second wedge beam splitting prism 73, a left polarizer 71 and a right polarizer 72 attached to the surface of the second wedge beam splitting prism 73; The projection of the transmission direction of the left polarizer 71 onto the XY plane is along the Y-axis and is vertical. The projection of the transmission direction of the right polarizer 72 onto the XY plane is along the X-axis and is horizontal.

[0030] In the secondary polarization modulation beam splitter module 7, the left polarizer 71 and the right polarizer 72 are equivalent to two orthogonal analyzers. The Jones matrix of the left polarizer 71 is represented as follows: The Jones matrix of the right polarizer 72 is represented as follows: : ; ; Ultimately, four beams are formed, which pass through imaging mirror 8 and form four 90° phase-step interference images on detector 9, spatially distributed in four zones. Preferably, the detector has a 9-pixel resolution of not less than 256×256 and a frame rate of not less than 10fps to ensure synchronous signal acquisition; The emitted electric fields of the four zones are represented as follows: ; ; ; ; Finally, the equations for obtaining the interference intensity values ​​of the four partitions are as follows: ; in: This represents the interference intensity values ​​of the four zones; This represents the relative intensity coefficient between the two partitions within each combination; Indicates the intensity of the light source; Indicates the instrument adjustment level; Represented as spectral line modulation; Indicates the reference phase; This indicates the step phase; each combination refers to a pairwise combination of the four partitions.

[0031] Four beams form four interference images in the four quadrants of the high-frame-rate scientific-grade CCD / CMOS detector 9, corresponding to four fixed phase steps, which are ideally 0°, 90°, 180°, and 270°.

[0032] In actual wind field measurement, the four-intensity algorithm is used, combined with the intensity of the interferometric image obtained during the calibration process, to directly solve the interference phase of each pixel from four images in a single frame; based on the linear relationship between the solved phase and the line-of-sight wind speed, the corrected phase change is converted into wind speed, and the two-dimensional wind field distribution is reconstructed in real time.

[0033] That is: using the four-intensity method, according to Extracting phase information from the corrected intensity ; in, These represent the four interference intensity values ​​for each corresponding point in the four partitions; Then according to Obtain the line-of-sight wind speed along the line of sight. The same method is used to calculate each corresponding point in the four partitions, and the real-time two-dimensional wind field can be obtained after splicing.

[0034] Experiments have verified that this data processing flow, working in conjunction with the aforementioned optical path design, can achieve real-time wind field inversion at a detector frame rate of 910fps. Under a signal-to-noise ratio of 700, the system's single-point wind speed measurement accuracy (standard deviation) can reach approximately 5 m / s, and the error in most areas of the two-dimensional wind field image can be controlled within 2 m / s, meeting the application requirements for high spatiotemporal resolution and high-precision detection of wind fields in the middle and upper atmosphere.

[0035] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A real-time lidar wind field imaging system, characterized in that, include: The laser emitter (1) receives and processes incident light rays with the main optical axis in the Z-axis direction, directs them to the target atmospheric region, and generates scattered echoes by interacting with atmospheric particles; The direction perpendicular to and inward from the principal optical axis is the X-axis direction. Combined with the Z-axis direction, an XYZ coordinate system that satisfies the right-hand rule is constructed. The cassette telescope system (2) collects the scattered echoes; The light modulation component modulates the polarization state of light to form four beams; Imaging mirror (8) receives four beams of light processed by the light modulation component; The detector (9) receives the beam processed by the imaging mirror (8) and forms four phase-stepped interference images; The light modulation assembly includes a collimating lens (3), a primary polarization modulation beam splitter (4), a wide-field delay assembly (5), an intermediate collimation system (6), and a secondary polarization modulation beam splitter (7) arranged sequentially along the optical channel.

2. The real-time imaging system for wind fields using lidar according to claim 1, characterized in that, The primary polarization modulation beam splitting module (4) includes a first wedge beam splitter (44), an upper polarizer (41) and a lower polarizer (43) attached to the surface of the first wedge beam splitter (44), and an upper quarter-wave plate (42); the upper quarter-wave plate (42) is attached between the upper polarizer (41) and the first wedge beam splitter (44); The projection of the transmission direction of the upper polarizer (41) in the XY plane is along the X-axis direction, which is horizontal. The projection of the transmission direction of the lower polarizer (43) in the XY plane is along the Y-axis direction, which is the vertical direction; The projection of the upper quarter-wave plate (42) onto the XY plane is at an angle of 45° with the positive direction of the X-axis.

3. The real-time imaging system for a lidar wind field according to claim 2, characterized in that, The wide-field delay component (5) includes a first birefringent crystal plate (51), an intermediate half-wave plate (52), and a second birefringent crystal plate (53). The optical axis of the first birefringent crystal plate (51) is in the XY plane and the angle between it and the positive direction of the X axis is 45°. The optical axis of the intermediate half-wave plate (52) is in the XY plane and is the same as the positive Y-axis direction. The optical axis of the second birefringent crystal plate (53) is in the XY plane and the angle between it and the positive direction of the X axis is 135°.

4. The real-time imaging system for a lidar wind field according to claim 3, characterized in that, The secondary polarization modulation beam splitting module (7) includes a second wedge beam splitting prism (73), a left polarizer (71) and a right polarizer (72) attached to the surface of the second wedge beam splitting prism (73). The projection of the transmission direction of the left polarizer (71) onto the XY plane is along the Y-axis and is vertical. The projection of the transmission direction of the right polarizer (72) onto the XY plane is along the X-axis direction and is horizontal.

5. A real-time lidar wind field imaging system according to claim 1, characterized in that, The detector's pixel resolution is no less than 256×256 and its frame rate is no less than 10fps.

6. A real-time imaging method for a lidar wind field, based on the lidar real-time imaging system for a wind field according to any one of claims 1-6, characterized in that, Specifically, the following steps are included: Step S1: The laser emitter (1) receives the incident light and outputs a linearly polarized laser with a wavelength adapted to the atmospheric scattering characteristics. After power amplification, collimation and beam expansion, the linearly polarized laser forms a parallel beam, which is directed to irradiate the target atmospheric region, forming a backscattered echo carrying wind field Doppler frequency shift information. Step S2: The scattered echo is incident on the Casio telescope system (2) and the scattered echo is collected; Step S3: The collected scattered echoes pass through the collimating mirror (3) to form a converged collimated beam, which is then incident on the first polarization modulation beam splitting module (4) to split the beam into two mutually orthogonal polarized beams A. Among them, the upper polarized beam in polarized beam A is converted into circularly polarized light by a first polarization modulation beam splitting module, and the lower polarized beam in polarized beam A remains vertically polarized. The two beams after being processed by the first polarization modulation beam splitting module are sheared by the first wedge beam splitting prism (44) to form an angle. Step S4: The beam processed by the first wedge beam splitter (44) enters the wide field delay component (5) for processing to eliminate cross-field phase changes and achieve a significant expansion of the field of view. Step S5: The beam processed by the wide-field delay component (5) is collimated by the intermediate collimation system (6) and the pupil image is conjugated on the secondary polarization modulation beam splitting module (7) to split the upper polarization beam and the lower polarization beam into two mutually orthogonal polarization beams B, forming four beams; Step S6: The four beams pass through the imaging mirror (8) and form four 90° phase-stepped interference images on the detector (9), which are spatially distributed in four partitions.

7. A real-time imaging method for a lidar wind field according to claim 6, characterized in that, According to the Jones matrix notation, the Jones matrix of the upper polarizer (41) in the primary polarization modulation beam splitter module (4) is: The Jones matrix of the lower polarizer (43) is The Jones matrix of the upper quarter-wave plate (42) is , is represented as; ； ； 。 8. A real-time imaging method for a lidar wind field according to claim 7, characterized in that, According to the Jones matrix notation, the Jones matrix of the first birefringent crystal plate (51) and the second birefringent crystal plate (53) of the wide-field delay component (5) is represented as follows: : ； in: ； ； ； in, The angle of incidence of the light ray; The angle is the angle from the incident surface along the counterclockwise direction to the positive direction of the optical axis of the first birefringent crystal plate (51) and the second birefringent crystal plate (53); The refractive index of the first birefringent crystal plate (51) and the second birefringent crystal plate (53) for ordinary light. difference; The refractive indices of the first birefringent crystal plate (51) and the second birefringent crystal plate (53) for unusual light. difference; The Jones matrix of the intermediate half-wave plate (52) is represented as follows: : 。 9. A real-time imaging method for a lidar wind field according to claim 8, characterized in that, The left polarizer (71) and right polarizer (72) in the secondary polarization modulation beam splitter module are equivalent to two orthogonal analyzers. The Jones matrix of the left polarizer (71) is expressed as follows: The Jones matrix of the right polarizer (72) is represented as follows: : ； 。 10. A real-time imaging method for a lidar wind field according to claim 9, characterized in that, The emitted electric fields of the four zones in step S6 are represented as follows: ； ； ； ； The equations for obtaining the interference intensity values ​​of the four partitions are as follows: ； in: This represents the interference intensity values ​​of the four zones; This represents the relative intensity coefficient between the two partitions within each combination; Indicates the intensity of the light source; Indicates the instrument adjustment level; Represented as spectral line modulation; Indicates the reference phase; Indicates the step phase.

Images