Single-frequency pulse laser source multi-dimensional imaging system and method

Abstract

The invention discloses a single-frequency pulse laser source multi-dimensional imaging system and method, and belongs to the technical field of laser radars. The imaging system comprises a single-frequency pulse laser source module, an optical imaging module, a frequency shift and phase modulation module, a time sequence control module and a data processing module, the single-frequency pulse laser source module emits a detection light beam, a first local reference light beam and a second local reference light beam, and the detection light beam irradiates a target to generate a reflection light beam; the time sequence control module controls the three light beams to perform synchronous frequency shift, so that the first local reference light and the reflected light beam are coherent in the optical imaging module to form a holographic image, and the second local reference light beam and the partially reflected light beam generate a beat frequency signal in the frequency shift phase modulation module; the data processing module analyzes the beat frequency signal so as to adjust the initial phase and frequency of outgoing of the detection light beam, and dynamic coherent imaging of the reflected light beam and the first local reference light in the optical imaging module is ensured; and real-time information of the holographic image is analyzed, and a high-quality three-dimensional image is reconstructed.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser radar, and in particular relates to a multi-dimensional imaging system and method of a single-frequency pulse laser source. Background Art

[0002] LiDAR is an active imaging technology that emits a laser beam to illuminate the target and then receives the reflected echo for imaging. LiDAR uses laser beams as detection waves and combines the advantages of lasers such as high brightness, good coherence, and good directionality. Compared with microwave radar, it has better detection accuracy and higher detection efficiency. Laser beams are used to capture target information and are widely used in terrain mapping, autonomous driving, underwater detection, and ecological science.

[0003] Traditional laser imaging methods can usually only collect two-dimensional images of the target, and for small targets at a long distance, the amount of detection information is small and the false alarm rate is high. In the prior art, laser three-dimensional imaging radars usually include flash imaging radar, frequency-modulated continuous wave laser imaging radar, phase-detection laser imaging radar, photon counting laser imaging radar, etc. Each method is different, especially in terms of anti-interference ability and data acquisition and processing. But in general, existing laser three-dimensional imaging systems all require powerful photoelectric detection arrays, and have high requirements for detector hardware. In addition, existing laser three-dimensional imaging systems have problems such as small imaging field of view, short detection distance, and low ranging accuracy. It is difficult to guarantee the imaging quality when detecting and identifying long-distance and small targets. Summary of the invention

[0004] In response to one or more of the above-mentioned defects or improvement needs in the prior art, the present invention provides a single-frequency pulse laser source multi-dimensional imaging system to obtain high-resolution three-dimensional digital image information of small targets in the far field, while realizing Doppler frequency shift compensation for moving targets, providing a new technical approach for improving the detection and recognition capabilities of small targets at a long distance.

[0005] To achieve the above-mentioned purpose, the present invention provides a single-frequency pulse laser source multi-dimensional imaging system, which includes a single-frequency pulse laser source module, an optical imaging module, a frequency shift and phase modulation module, a timing control module and a data processing module; The single-frequency pulse laser source module comprises a laser, a first acousto-optic modulator, a second acousto-optic modulator, a third acousto-optic modulator and a transmitting unit. The laser transmits a single-frequency pulse laser signal which is divided into a detection beam, a first local reference beam and a second local reference beam by a beam splitter. The timing control module controls the timing synchronization of the first AOM, the second AOM and the third AOM, so that the detection beam, the first local reference beam and the second local reference beam can be synchronously shifted in frequency; The detection light beam passes through the first acousto-optic modulator and the transmitting unit in sequence, and then irradiates the target to generate a reflected light beam; The first local reference beam enters the optical imaging module after passing through the second acousto-optic modulator, and the optical imaging module synchronously receives the reflected beam. The reflected beam and the first local reference beam coherently form a holographic image in the optical imaging module and transmit it to the data processing module; The second local reference beam enters the frequency shift and phase modulation module through the third acousto-optic modulator, the frequency shift and phase modulation module synchronously receives part of the reflected beam, and transmits the beat signal formed by the reflected beam and the second local reference beam to the data processing module; The data processing module calculates the radial motion speed of the target by analyzing the beat frequency signal, and issues an adjustment instruction to the timing control module to control the first acousto-optic modulator to adjust the initial phase and frequency of the detection light beam, so as to achieve uniform illumination of the detection light beam uplink and offset compensation for the Doppler frequency shift caused by the target motion, so as to ensure dynamic coherent imaging of the reflected light beam and the first local reference light in the optical imaging module; and obtains the light field data of the target by analyzing the holographic image, so as to correct the aberration caused by the atmosphere and the optical system itself, and reconstruct a high-quality three-dimensional image of the target.

[0006] As a further improvement of the present invention, an amplifier is provided between the laser and the transmitting unit to amplify the detection light beam.

[0007] As a further improvement of the present invention, the optical imaging module includes an imaging unit and a first photodetector, the imaging unit is used to receive the reflected light beam and the first local reference light beam, and the first photodetector is used to form a holographic image.

[0008] As a further improvement of the present invention, the optical imaging module adopts a single-aperture transceiver optical imaging system or a multi-aperture transceiver optical imaging system.

[0009] As a further improvement of the present invention, the timing control module controls the timing synchronization of the first photodetector with the first acousto-optic modulator, the second acousto-optic modulator and the third acousto-optic modulator.

[0010] As a further improvement of the present invention, the timing control module synchronously controls the trigger timing of the first acousto-optic modulator, the second acousto-optic modulator, the third acousto-optic modulator, and the first photodetector according to the frequency-shifted voltage pulse and the voltage rising edge signal output by the data processing module corresponding to the movement speed of the target.

[0011] As a further improvement of the present invention, the frequency shift phase modulation module includes a frequency shift phase modulation unit and a second photoelectric detector, the frequency shift phase modulation unit is used to receive part of the reflected light beam and the second local reference beam, and the second photoelectric detector is used to collect light signals within a period to obtain the beat frequency signal.

[0012] As a further improvement of the present invention, the processing of the holographic image by the data processing module includes complex field extraction, aberration correction, three-dimensional image reconstruction, real-time distortion correction of the light beam wavefront caused by atmospheric turbulence, and micro-Doppler feature extraction.

[0013] As a further improvement of the present invention, the data processing module is provided with a hardware platform, and the hardware platform is a server, a VPX processing platform or an FPGA processing platform.

[0014] Another aspect of the present invention further provides a single-frequency pulse laser source multi-dimensional imaging method, which is implemented by applying the above-mentioned single-frequency pulse laser source multi-dimensional imaging system, comprising: S100: the data control module outputs a synchronization trigger signal to the timing control module to control the first acousto-optic modulator, the second acousto-optic modulator and the third acousto-optic modulator to trigger timing synchronization; S200: The laser emits a pulsed laser signal which is divided into a detection beam, a first local reference beam and a second local reference beam by a beam splitter. The detection beam passes through the first acousto-optic modulator and the transmitting unit and then irradiates the target to generate a reflected beam. S300: The optical imaging module synchronously receives the reflected light beam and the first local reference light beam passing through the second acousto-optic modulator, and forms a holographic image to be transmitted to the data processing module; the frequency shifting and phase modulation module synchronously receives part of the reflected light beam and the second local reference light beam passing through the third acousto-optic modulator, and forms a beat frequency signal to be transmitted to the data processing module; S400: The data processing module calculates the radial motion speed of the target by analyzing the beat frequency signal, and issues an adjustment instruction to the timing control module to adjust the first acousto-optic modulator to adjust the initial phase and frequency of the detection light beam, so as to achieve uniform illumination of the detection light beam uplink and offset compensation for the Doppler frequency shift caused by the target motion, so as to ensure dynamic coherent imaging of the reflected light beam and the first local reference light in the optical imaging module; by analyzing the holographic image, the light field data of the target is obtained to correct the aberration caused by the atmosphere and the optical system itself, and reconstruct a high-quality three-dimensional image of the target.

[0015] The above-mentioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0016] In general, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects: (1) The single-frequency pulse laser source multi-dimensional imaging system of the present invention comprises a single-frequency pulse laser source module, an optical imaging module, a frequency shifting and phase modulation module, a timing control module and a data processing module. The single-frequency pulse laser source module emits a detection beam, a first local reference beam and a second local reference beam. The detection beam is irradiated on a target to generate a reflected beam. The timing control module controls the detection beam, the first local reference beam and the second local reference beam to synchronously shift the frequency, so that the first local reference light and the reflected beam are coherently formed into a holographic image in the optical imaging module, and the real-time information of the holographic image is analyzed through the data processing module to reconstruct a high-quality three-dimensional image. The frequency shifting and phase modulation module synchronously receives the second local reference beam and a part of the reflected beam to obtain the beat frequency signal of the two and transmits it to the data processing module to calculate the radial motion speed of the target, and then adjusts the initial phase and frequency of the detection beam to ensure that the reflected beam and the first local reference light are dynamically coherently imaged in the optical imaging module. In the single-frequency pulse laser source multi-dimensional imaging system of the present invention, the transmitting unit can transmit the detection light beam to a distant target, and coherent imaging can perform long-distance detection. At the same time, the data processing module corrects the errors caused by the optical system and the atmospheric environment, and also performs offset compensation for the Doppler frequency shift caused by the target movement, and finally reconstructs a three-dimensional image with high angular resolution and good quality, so that the single-frequency pulse laser source multi-dimensional imaging system of the present invention can obtain high-resolution three-dimensional digital image information of small targets in the far field.

[0017] (2) In the single-frequency pulse laser source multi-dimensional imaging system of the present invention, the timing control module synchronously controls the trigger timing of the first acousto-optic modulator, the second acousto-optic modulator, the third acousto-optic modulator, and the first photoelectric detector according to the frequency-shifted voltage pulse and voltage rising edge signal corresponding to the target's movement speed output by the data processing module, thereby ensuring that the laser radar active detection operates continuously and stably in a predetermined time sequence.

[0018] (3) The single-frequency pulse laser source multi-dimensional imaging method of the present invention is realized by the above-mentioned single-frequency pulse laser source multi-dimensional imaging system, by controlling the trigger timing synchronization of the first acousto-optic modulator, the second acousto-optic modulator and the third acousto-optic modulator, synchronously shifting the frequency of the detection beam, the first local reference beam and the second local reference beam, so that the first local reference light and the reflected light beam coherently form a holographic image in the optical imaging module, and the second local reference light beam and part of the reflected light beam generate a beat signal in the frequency shifting and phase modulation module. The data processing module analyzes the beat signal and then adjusts the initial phase and frequency of the detection beam emission to ensure that the reflected light beam and the first local reference light are dynamically coherently imaged in the optical imaging module; analyze the real-time information of the holographic image and reconstruct a high-quality three-dimensional image. Compared with other laser imaging methods, the single-frequency pulse laser source multi-dimensional imaging method of the present invention has a large amount of detection information and lower requirements on the detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 is a schematic diagram of a multi-dimensional imaging system with a single-frequency pulsed laser source according to an embodiment of the present invention; In all the drawings, the same reference numerals represent the same technical features, specifically: 100, single-frequency pulse laser source module; 101, laser; 102, first acousto-optic modulator; 103, amplifier; 104, transmitting unit; 105, second acousto-optic modulator; 106, third acousto-optic modulator; 200, optical imaging module; 201, imaging unit; 202, first photodetector; 300, frequency shift and phase modulation module; 301, frequency shift and phase modulation unit; 302, second photodetector; 400, timing control module; 500, data processing module. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0023] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0024] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0026] Example: See also Figure 1 The single-frequency pulse laser source multi-dimensional imaging system in the preferred embodiment of the present invention includes a single-frequency pulse laser source module 100, an optical imaging module 200, a frequency shift and phase modulation module 300, a timing control module 400 and a data processing module 500.

[0027] The single-frequency pulse laser source module 100 includes a laser 101, a first acousto-optic modulator 102, a second acousto-optic modulator 105, a third acousto-optic modulator 106 and a transmitting unit 104. The laser 101 transmits a single-frequency pulse laser signal which is divided into a detection beam, a first local reference beam and a second local reference beam by a beam splitter. The timing control module 400 controls the timing synchronization of the first AOM 102, the second AOM 105 and the third AOM 106, so that the detection beam, the first local reference beam and the second local reference beam can be synchronously shifted in frequency; The detection beam passes through the first acousto-optic modulator 102 and the transmitting unit 104 in sequence, and then irradiates the target and generates a reflected beam; the first local reference beam passes through the second acousto-optic modulator 105 and enters the optical imaging module 200, and the optical imaging module 200 synchronously receives the reflected beam. The reflected beam and the first local reference light coherently form a holographic image in the optical imaging module 200 and transmit it to the data processing module 500; the second local reference beam passes through the third acousto-optic modulator 106 and enters the frequency shift phase modulation module 300, and the frequency shift phase modulation module 300 synchronously receives part of the reflected beam, and transmits the beat signal formed by the reflected beam and the second local reference beam to the data processing module 500; The data processing module 500 calculates the radial motion speed of the target by analyzing the beat frequency signal, and issues an adjustment instruction to the timing control module 400 to control the first acousto-optic modulator 102 to adjust the initial phase and frequency of the detection beam emission, so as to achieve uniform illumination of the detection beam uplink and offset compensation for the Doppler frequency shift caused by the target motion, so as to ensure dynamic coherent imaging of the reflected light beam and the first local reference light in the optical imaging module 200; and obtains the light field data of the target by analyzing the holographic image, so as to correct the aberration caused by the atmosphere and the optical system itself, and reconstruct a high-quality three-dimensional image of the target.

[0028] In this preferred embodiment, on the one hand, the first local reference light and the reflected light beam of the same frequency coherently form a two-dimensional image in the optical imaging module 200, and the timing control module 400 controls the first acousto-optic modulator 102, the second acousto-optic modulator 105 and the third acousto-optic modulator 106 to shift the frequency of the detection beam, the first local reference beam and the second local reference beam respectively, so that the first local reference light and the reflected light beam of different frequencies coherently form different two-dimensional images in the optical imaging module 200, and the optical imaging module 200 fuses multiple two-dimensional images to form a holographic image and transmits the holographic image to the data processing module 500. The data processing module 500 obtains the light field data of the target by analyzing the real-time information of the holographic image, and can reconstruct it to form a high-quality three-dimensional image to correct the error caused by the detection beam passing through the atmosphere and the aberration caused by the optical system itself. On the other hand, the detection target may be stationary or moving. Since the Doppler phenomenon will occur between the target movement and the imaging system, affecting the formation and quality of the holographic image, the frequency shifting and phase modulation module 300 synchronously receives the second local reference beam and the partially reflected beam to obtain the beat frequency signal of the two and transmits it to the data processing module 500, so that the data processing module 500 can calculate the radial movement speed of the target according to the beat frequency signal, and then adjust the initial phase and frequency of the detection beam emission, so that the detection beam can achieve uniform illumination of the uplink, and at the same time, the Doppler frequency shift caused by the target movement can be offset compensated to ensure dynamic coherent imaging of the reflected beam and the first local reference light in the optical imaging module 200.

[0029] In this preferred embodiment, the transmitting unit 104 can transmit the detection light beam to a distant target, and coherent imaging can be used for long-distance detection. At the same time, the data processing module 500 corrects the errors caused by the optical system and the atmospheric environment, and also compensates for the Doppler frequency shift caused by the target movement, and finally reconstructs a three-dimensional image with high angular resolution and good quality, so that the single-frequency pulse laser source multi-dimensional imaging system of the present invention can realize the detection and identification of long-distance and small targets.

[0030] Preferably, the timing control module 400 can frequency-shift modulate the single-frequency pulse laser emitted by the laser 100 into dual-wavelength dual pulses, and the data processing module 500 can calculate the 3D information of the target according to the relevant formula of dual-wavelength coherence.

[0031] Preferably, an amplifier 103 is provided between the laser 101 and the transmitting unit 104 to amplify the detection light beam.

[0032] Preferably, the first AOM 102, the second AOM 105, and the third AOM 106 transmit the detection beam, the first local reference beam, and the second local reference beam respectively through an optical fiber structure.

[0033] Further preferably, the optical imaging module 200 comprises an imaging unit 201 and a first photodetector 202, the imaging unit 201 is used to receive the reflected light beam and the first local reference light beam, and the first photodetector 202 is used to form a holographic image.

[0034] Specifically preferably, the imaging unit 201 is provided with an imaging optical path consisting of a Schirmer telescope, a reflector, a relay lens group, etc.; preferably, the first photodetector 202 is a CCD.

[0035] Preferably, the optical imaging module 200 adopts a single-aperture transceiver optical imaging system or a multi-aperture transceiver optical imaging system.

[0036] Preferably, the timing control module 400 controls the timing synchronization between the first photodetector 202 and the first AOM 102 , the second AOM 105 , and the third AOM 106 .

[0037] Preferably, the timing control module 400 synchronously controls the trigger timing of the first acousto-optic modulator 102, the second acousto-optic modulator 105, the third acousto-optic modulator 106, and the first photodetector 202 according to the frequency-shifted voltage pulse and the voltage rising edge signal corresponding to the movement speed of the target output by the data processing module 500.

[0038] Specifically, the data processing module 500 calculates the distance of the detection light beam to the specified target and the corresponding time of the shutter start of the first photodetector 202, and outputs the frequency-shifted voltage pulse and voltage rising edge signal corresponding to the target movement speed to the first acousto-optic modulator 102, the second acousto-optic modulator 105, the third acousto-optic modulator 106, and the first photodetector 202, respectively, to ensure that the active detection of the laser radar continues to work stably in a predetermined time sequence.

[0039] Preferably, the frequency shift phase modulation module 300 includes a frequency shift phase modulation unit 301 and a second photodetector 302, wherein the frequency shift phase modulation unit 301 is used to receive part of the reflected light beam and the second local reference beam, and the second photodetector 302 is used to collect optical signals within a period to obtain the beat frequency signal.

[0040] Specifically and preferably, the frequency-shifting and phase-modulating unit 301 is provided with a frequency-shifting and phase-modulating optical path composed of a Schirmer telescope, a reflecting mirror, a relay lens group, etc.; preferably, the second photodetector 201 is an APD.

[0041] Preferably, the processing of the holographic image by the data processing module 500 includes complex field extraction, aberration correction, three-dimensional image reconstruction, real-time distortion correction of the beam wavefront caused by atmospheric turbulence, and micro-Doppler feature extraction. Among them, the aberration correction optimization algorithm adopts a deep learning algorithm to perform Zernike aberration estimation; the dual-wavelength phase unwrapping algorithm obtains the target three-dimensional information through dual-wavelength holographic reconstruction; the speckle denoising algorithm combines deep learning and probability model algorithms to achieve target image speckle noise suppression and improve image quality; the micro-Doppler feature extraction algorithm adopts the empirical mode decomposition method.

[0042] Preferably, the data processing module 500 is provided with a hardware platform, and the hardware platform is a server, a VPX processing platform or a FPGA processing platform.

[0043] Furthermore, the present invention also provides a single-frequency pulse laser source multi-dimensional imaging method, which is implemented by applying the above-mentioned single-frequency pulse laser source multi-dimensional imaging system, including: S100: the data control module outputs a synchronization trigger signal to the timing control module to control the first acousto-optic modulator, the second acousto-optic modulator and the third acousto-optic modulator to trigger timing synchronization; S200: The laser emits a pulsed laser signal which is divided into a detection beam, a first local reference beam and a second local reference beam by a beam splitter. The detection beam passes through the first acousto-optic modulator and the transmitting unit and then irradiates the target to generate a reflected beam. S300: The optical imaging module synchronously receives the reflected light beam and the first local reference light beam passing through the second acousto-optic modulator, and forms a holographic image to be transmitted to the data processing module; the frequency shifting and phase modulation module synchronously receives part of the reflected light beam and the second local reference light beam passing through the third acousto-optic modulator, and forms a beat frequency signal to be transmitted to the data processing module; S400: The data processing module calculates the radial motion speed of the target by analyzing the beat frequency signal, and issues an adjustment instruction to the timing control module to adjust the first acousto-optic modulator to adjust the initial phase and frequency of the detection light beam, so as to achieve uniform illumination of the detection light beam uplink and offset compensation for the Doppler frequency shift caused by the target motion, so as to ensure dynamic coherent imaging of the reflected light beam and the first local reference light in the optical imaging module; by analyzing the holographic image, the light field data of the target is obtained to correct the aberration caused by the atmosphere and the optical system itself, and reconstruct a high-quality three-dimensional image of the target.

[0044] The single-frequency pulse laser source multi-dimensional imaging system of the present invention comprises a single-frequency pulse laser source module 100, an optical imaging module 200, a frequency shifting and phase modulation module 300, a timing control module 400 and a data processing module 500. The single-frequency pulse laser source module 100 emits a detection beam, a first local reference beam and a second local reference beam. The detection beam is irradiated on a target to generate a reflected beam. The timing control module 400 controls the first acousto-optic modulator 102, the second acousto-optic modulator 105 and the third acousto-optic modulator 106 to shift the frequency of the detection beam, the first local reference beam and the second local reference beam respectively. The first local reference light of different frequencies and the reflected beam coherently form different two-dimensional images in the optical imaging module 200. The optical imaging module 200 fuses multiple two-dimensional images to form a holographic image and transmits the holographic image to the target. The data processing module 500 obtains the light field data of the target by analyzing the real-time information of the holographic image, and can be reconstructed to form a high-quality three-dimensional image to correct the error caused by the detection beam passing through the atmosphere and the aberration caused by the optical system itself; on the other hand, the frequency shifting and phase modulation module 300 synchronously receives the second local reference beam and the partially reflected beam to obtain the beat signal of the two and transmits it to the data processing module 500, so that the data processing module 500 can calculate the radial motion speed of the target according to the beat signal, and then adjust the initial phase and frequency of the detection beam emission, so that the detection beam can achieve uniform illumination of the uplink, and at the same time, the Doppler frequency shift caused by the target movement can be offset compensated to ensure the dynamic coherent imaging of the reflected beam and the first local reference light in the optical imaging module 200. The single-frequency pulse laser source multi-dimensional imaging system of the present invention can obtain high-resolution three-dimensional digital image information of small targets in the far field, and realize the detection and recognition of small targets at a long distance.

[0045] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A single-frequency pulse laser source multi-dimensional imaging system, characterized in that: It includes a single-frequency pulse laser source module, an optical imaging module, a frequency shift and phase modulation module, a timing control module and a data processing module; The single-frequency pulse laser source module comprises a laser, a first acousto-optic modulator, a second acousto-optic modulator, a third acousto-optic modulator and a transmitting unit. The laser transmits a single-frequency pulse laser signal which is divided into a detection beam, a first local reference beam and a second local reference beam by a beam splitter. The timing control module controls the timing synchronization of the first AOM, the second AOM and the third AOM, so that the detection beam, the first local reference beam and the second local reference beam can be synchronously shifted in frequency; The detection light beam passes through the first acousto-optic modulator and the transmitting unit in sequence, and then irradiates the target to generate a reflected light beam; The first local reference beam enters the optical imaging module after passing through the second acousto-optic modulator, and the optical imaging module synchronously receives the reflected beam. The reflected beam and the first local reference beam coherently form a holographic image in the optical imaging module and transmit it to the data processing module; The second local reference beam enters the frequency shift and phase modulation module after passing through the third acousto-optic modulator, and the frequency shift and phase modulation module synchronously receives part of the reflected beam, and transmits the beat signal formed by the reflected beam and the second local reference beam to the data processing module; The data processing module calculates the radial motion speed of the target by analyzing the beat frequency signal, and issues an adjustment instruction to the timing control module to control the first acousto-optic modulator to adjust the initial phase and frequency of the detection light beam, so as to achieve uniform illumination of the detection light beam uplink and offset compensation for the Doppler frequency shift caused by the target motion, so as to ensure dynamic coherent imaging of the reflected light beam and the first local reference light in the optical imaging module; and obtains the light field data of the target by analyzing the holographic image, so as to correct the aberration caused by the atmosphere and the optical system itself, and reconstruct a high-quality three-dimensional image of the target.

2. The single-frequency pulse laser source multi-dimensional imaging system according to claim 1, characterized in that: An amplifier is provided between the laser and the transmitting unit to amplify the detection light beam.

3. The single-frequency pulse laser source multi-dimensional imaging system according to claim 1, characterized in that: The optical imaging module includes an imaging unit and a first photodetector, wherein the imaging unit is used to receive the reflected light beam and the first local reference light beam, and the first photodetector is used to form a holographic image.

4. The single-frequency pulse laser source multi-dimensional imaging system according to claim 3, characterized in that: The optical imaging module adopts a single-aperture transceiver optical imaging system or a multi-aperture transceiver optical imaging system.

5. The single-frequency pulse laser source multi-dimensional imaging system according to claim 3 or 4, characterized in that: The timing control module controls the first photodetector to be in timing synchronization with the first AOM, the second AOM and the third AOM.

6. The single-frequency pulse laser source multi-dimensional imaging system according to claim 5, characterized in that: The timing control module synchronously controls the trigger timing of the first acousto-optic modulator, the second acousto-optic modulator, the third acousto-optic modulator, and the first photodetector according to the frequency-shifted voltage pulse and the voltage rising edge signal output by the data processing module corresponding to the movement speed of the target.

7. The single-frequency pulse laser source multi-dimensional imaging system according to claim 1, characterized in that: The frequency shift phase modulation module includes a frequency shift phase modulation unit and a second photoelectric detector, wherein the frequency shift phase modulation unit is used to receive part of the reflected light beam and the second local reference light beam, and the second photoelectric detector is used to collect light signals within a period to obtain the beat frequency signal.

8. The single-frequency pulse laser source multi-dimensional imaging system according to claim 1, characterized in that: The processing of the holographic image by the data processing module includes complex field extraction, aberration correction, three-dimensional image reconstruction, real-time distortion correction of the light beam wavefront caused by atmospheric turbulence, and micro-Doppler feature extraction.

9. The single-frequency pulse laser source multi-dimensional imaging system according to claim 1, characterized in that: The data processing module is provided with a hardware platform, and the hardware platform is a server, a VPX processing platform or a FPGA processing platform.

10. A single-frequency pulse laser source multi-dimensional imaging method, characterized in that: The method is implemented by using a single-frequency pulse laser source multi-dimensional imaging system as claimed in any one of claims 1 to 9, comprising: S100: the data control module outputs a synchronization trigger signal to the timing control module to control the first acousto-optic modulator, the second acousto-optic modulator and the third acousto-optic modulator to trigger timing synchronization; S200: The laser emits a pulsed laser signal which is divided into a detection beam, a first local reference beam and a second local reference beam by a beam splitter. The detection beam passes through the first acousto-optic modulator and the transmitting unit and then irradiates the target to generate a reflected beam. S300: The optical imaging module synchronously receives the reflected light beam and the first local reference light beam passing through the second acousto-optic modulator, and forms a holographic image to be transmitted to the data processing module; the frequency shifting and phase modulation module synchronously receives part of the reflected light beam and the second local reference light beam passing through the third acousto-optic modulator, and forms a beat frequency signal to be transmitted to the data processing module; S400: The data processing module calculates the radial motion speed of the target by analyzing the beat frequency signal, and issues an adjustment instruction to the timing control module to adjust the first acousto-optic modulator to adjust the initial phase and frequency of the detection light beam, so as to achieve uniform illumination of the detection light beam uplink and offset compensation for the Doppler frequency shift caused by the target motion, so as to ensure dynamic coherent imaging of the reflected light beam and the first local reference light in the optical imaging module; by analyzing the holographic image, the light field data of the target is obtained to correct the aberration caused by the atmosphere and the optical system itself, and reconstruct a high-quality three-dimensional image of the target.

Images