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CN-121978709-A - Laser radar wind field real-time imaging system and method

CN121978709ACN 121978709 ACN121978709 ACN 121978709ACN-121978709-A

Abstract

The invention relates to the technical field of atmospheric wind field observation, in particular to a laser radar wind field real-time imaging system and a laser radar wind field real-time imaging method, the device comprises a laser transmitter, a card type telescopic system, a collimating mirror, a primary polarization modulation light splitting module, a wide-field delay component, an intermediate 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 traditional wind field detection has limited view field, insufficient instantaneity and difficult precision and coverage range, and constructs an integrated and high-performance wind field imaging solution by integrating the laser radar active detection advantage and the field-expanding birefringence interference technology. The system takes the laser radar as an active light source, breaks through the defects that the passive interference technology depends on atmospheric glow and the observation period is limited, can realize wind field detection of all-period and all-height layers, and meets the core requirements of wide view field, high precision and real-time performance by optimizing an optical architecture.

Inventors

  • YIN YE
  • WANG HANTAO
  • ZHANG HUI
  • CHEN CUIHUA
  • ZHAO NANSHAN

Assignees

  • 三峡金沙江川云水电开发有限公司

Dates

Publication Date
20260505
Application Date
20260309

Claims (10)

  1. 1. A lidar wind field real-time imaging system, comprising: The laser transmitter (1) receives and processes incident light rays with the main optical axis direction being the Z-axis direction, irradiates the target atmosphere area in a directional way, interacts with atmosphere particles to generate scattering echoes, and constructs an XYZ coordinate system meeting the right hand rule by combining the X-axis direction and the Z-axis direction which is the inward direction perpendicular to the main optical axis; A card type telescopic system (2) for collecting scattered echoes; the light modulation component modulates the polarization state of light to form four light beams; an imaging mirror (8) for receiving the four light beams processed by the light modulation component; The detector (9) receives the light beam processed by the imaging mirror (8) to form four phase stepping interference images; the light modulation component comprises a collimating mirror (3), a primary polarization modulation light-splitting module (4), a wide-field delay component (5), a middle collimating system (6) and a secondary polarization modulation light-splitting module (7) which are sequentially arranged along an optical channel.
  2. 2. The laser radar wind field real-time imaging system according to claim 1, wherein the primary polarization modulation beam splitter module (4) comprises a first wedge beam splitter prism (44), an upper polarizer (41) and a lower polarizer (43) which are adhered to the surface of the first wedge beam splitter prism (44), and an upper quarter wave plate (42), wherein the upper quarter wave plate (42) is adhered between the upper polarizer (41) and the first wedge beam splitter prism (44); the projection of the vibration transmission direction of the upper polaroid (41) in the XY plane is along the X-axis direction and is in the horizontal direction; the projection of the vibration transmission direction of the lower polaroid (43) in the XY plane is along the Y-axis direction and is in the vertical direction; the projection of the optical axis direction of the upper quarter wave plate (42) in the XY plane forms a 45-degree positive angle with the X axis.
  3. 3. A lidar wind field real-time imaging system according to claim 2, characterized in that the wide field retardation assembly (5) comprises a first birefringent crystal plate (51), an intermediate half-wave plate (52) and a second birefringent crystal plate (53); the optical axis direction of the first birefringent crystal plate (51) is in an XY plane, and the positive included angle between the first birefringent crystal plate and the X axis is 45 degrees; the optical axis direction of the intermediate half-wave plate (52) is in the XY plane and the same as the positive direction of the Y axis; The optical axis direction of the second birefringent crystal plate (53) is in the XY plane and has a forward angle of 135 DEG with the X axis.
  4. 4. A lidar wind field real-time imaging system according to claim 3, wherein the secondary polarization modulation beam splitter module (7) comprises a second wedge beam splitter prism (73), a left polarizer (71) and a right polarizer (72) which are adhered to the surface of the second wedge beam splitter prism (73); The projection of the vibration transmission direction of the left polaroid (71) in the XY plane is along the Y-axis direction and is in the vertical direction; the projection of the vibration transmission direction of the right polarizer (72) in the XY plane is along the X-axis direction and is in the horizontal direction.
  5. 5. The lidar wind field real-time imaging system of claim 1, wherein the detector has a pixel resolution of not less than 256 x 256 and a frame rate of not less than 10fps.
  6. 6. A method for real-time imaging of a lidar wind field based on the system for real-time imaging of a lidar wind field according to any one of claims 1 to 6, comprising the following steps: S1, a laser transmitter (1) receives incident light and outputs linear polarized laser with wavelength adaptive to atmospheric scattering characteristics, the linear polarized laser forms parallel beams after power amplification, collimation and beam expansion, and the parallel beams directionally irradiate an atmospheric region of a target to form a backward scattering echo carrying Doppler frequency shift information of a wind field; S2, scattering echoes are incident to a card type telescopic system (2), and the scattering echoes are collected; S3, forming a concentrated collimated light beam by the collected scattered echoes through a collimating mirror (3), and entering a primary polarization modulation light splitting module (4), and splitting the light beam into an upper polarized light beam A and a lower polarized light beam A which are mutually orthogonal; The upper polarized light beam in the polarized light beam A is converted into circularly polarized light by the primary polarization modulation light splitting module, the lower polarized light beam in the polarized light beam A keeps vertical linear polarization, and the two light beams processed by the primary polarization modulation light splitting module are sheared by the first wedge-shaped light splitting prism (44) to form an included angle; S4, the light beam processed by the first wedge-shaped beam splitting prism (44) enters the wide-field delay assembly (5) for processing, so that the phase change of the crossed field is eliminated, and the wide expansion of the field of view is realized; s5, forming a collimated beam by a beam processed by the wide-field delay assembly (5) through an intermediate collimation system (6), conjugating a pupil image on a secondary polarization modulation light-splitting module (7), and respectively splitting an upper polarized beam and a lower polarized beam into a left polarized beam and a right polarized beam which are mutually orthogonal to form four beams; And S6, forming four 90-degree phase stepping interference images which are spatially distributed in four subareas on the detector (9) by the four light beams through the imaging mirror (8).
  7. 7. The method for real-time imaging of a lidar wind field according to claim 6, wherein the jones matrix of the upper polarizer (41) in the primary polarization modulation spectroscopic module (4) is according to jones matrix representation The Jones matrix of the lower polarizer (43) is The Jones matrix of the upper quarter wave plate (42) is Denoted as; ; ; 。
  8. 8. A lidar wind field real-time imaging method according to claim 7, wherein the jones matrix representation of the first (51) and second (53) birefringent crystal plates of the wide field delay component (5) is given by : ; Wherein: ; ; ; Wherein, the Is the incident angle of the light; is an angle from the incident surface in the counterclockwise direction to the positive direction of the optical axes of the first birefringent crystal plate (51) and the second birefringent crystal plate (53); refractive index of the first birefringent crystal plate (51) and the second birefringent crystal plate (53) to ordinary light A difference between; refractive index for extraordinary rays for the first birefringent crystal plate (51) and the second birefringent crystal plate (53) A difference between; the Jones matrix of the intermediate half-wave plate (52) is expressed as : 。
  9. 9. The method for real-time imaging of a lidar wind field according to claim 8, wherein the left polarizer (71) and the right polarizer (72) in the secondary polarization modulation spectroscopic module are equivalent to two orthogonal analyzers, and the jones matrix of the left polarizer (71) is expressed as The Jones matrix of the right polarizer (72) is expressed as : ; 。
  10. 10. The method for real-time imaging of a lidar wind field according to claim 9, wherein the emergent electric fields of the four partitions in step S6 are expressed as: ; ; ; ; The interference intensity values of the four partitions are obtained by the following equation: ; Wherein: representing interference intensity values of the four partitions; representing the relative intensity coefficients of the two partitions within each combination; Representing the intensity of the light source; Indicating the modulation degree of the instrument; Expressed as the degree of spectral line modulation; Representing a reference phase; representing the step phase.

Description

Laser radar wind field real-time imaging system and method Technical Field The invention relates to the technical field of atmospheric wind field observation, in particular to a laser radar wind field real-time imaging system and method. Background The atmospheric wind field is used as a core parameter for describing the aerodynamic characteristics, the time-space distribution characteristic directly dominates the global climate system evolution, the weather process development and the generation and propagation of disastrous weather, and the atmospheric wind field has irreplaceable functions in the fields of weather forecast, aerospace safety guarantee, atmospheric environment monitoring and the like. With the continuous improvement of the requirements of detection timeliness, resolution and coverage, obtaining wind field data with wide field of view, high precision and real-time performance has become a core requirement and research hotspot in the technical field of atmospheric detection. The existing wind field detection technology is mainly divided into two major types, namely a passive interference imaging technology and an active laser radar technology. The passive technology takes atmospheric natural airglow as a light source, and the Doppler frequency shift inversion wind field is measured through an interferometer, wherein the static birefringence Doppler wind measuring interferometer (BIDWIN) becomes a new generation technology representative by virtue of the advantages of good stability, small volume and low cost, but the angle shearing and the light splitting are carried out by adopting a Wollaston prism, so that the difference of an incident angle and an azimuth angle exists when an upper view field and a lower view field of a light beam are incident on a birefringent crystal, the phase change of a crossed field is caused, the effective view field is strictly limited, and the daytime observation is limited and the low-altitude detection capability is weak due to the dependence on an airglow signal. Although the traditional Michelson interferometer with wide field of view can realize large-scale detection, the system has complex structure, huge volume and extremely high assembly precision requirement, and is difficult to popularize and apply. The active laser radar technology obtains wind field information by actively emitting laser beams, has the advantages of long detection distance, high space-time resolution and no limitation of illumination conditions, however, the traditional laser radar is mostly single-point scanning, and the large-range two-dimensional wind field real-time imaging is difficult to realize. When the field of view is expanded, the existing imaging laser radar is easy to cause interference signal quality reduction due to laser beam polarization state distortion and light path deviation, and the real-time performance of data processing is reduced due to the increase of system complexity, so that the requirements of the field of view, precision and real-time performance are difficult to balance. In a combined view, the prior art has not realized cooperative optimization of 'wide field of view, high precision, real-time performance and miniaturization'. Although the passive birefringence interferometer has obvious miniaturization advantages, the field of view is limited and depends on an airglow signal, and the active laser radar has active detection capability, but the accuracy and the instantaneity in the field-expanding imaging process are difficult to be compatible. The traditional wide-field interferometer has the problem of overhigh volume and cost. In addition, the heat sensitivity of the birefringent crystal, the polarization state modulation of the laser radar and the extraction of interference signals are interfered by atmospheric turbulence and the like, so that the application effect of the prior art is further limited. Therefore, the wind field real-time imaging scheme which combines the active detection advantage of the laser radar with the miniaturization characteristic of the birefringent interference technology and breaks through the limitation of the field of view becomes a key direction for solving the bottleneck of the current technology. Disclosure of Invention The invention aims to solve the technical problems of limited field of view, insufficient instantaneity, difficult precision and coverage in the traditional wind field detection, and provides a laser radar wind field real-time imaging system and method, and a set of integrated and high-performance wind field imaging solution is constructed by integrating the active detection advantage of a laser radar and the field-expanding birefringence interference technology. The system takes the laser radar as an active light source, breaks through the defects that the passive interference technology depends on atmospheric glow and the observation period is limited, can realize wind field detection of all time