Bpsk signal array detector synthetic aperture three-dimensional laser imaging method and system

Abstract

This invention provides a method and system for synthetic aperture three-dimensional laser imaging using a BPSK signal array detector. The method includes: illuminating a moving target with a BPSK laser emission signal to generate a laser echo signal; processing the laser echo signal using a Fourier lens to form a complex laser image signal, which is then acquired by a coherent array detector to generate multiple frames of low-resolution complex laser images; performing synthetic aperture laser imaging and pulse compression processing in the elevation-azimuth and range directions respectively to construct a three-dimensional laser imaging result; and enabling the imaging system to perform multiple repeated observations during target movement, combining spatial sampling signal sparsity reduction, compressed sensing algorithms, and complex dual apodization algorithms to achieve sidelobe suppression of the imaging result. This invention can perform three-dimensional laser imaging on multiple targets passing through the field of view of the imaging system, and has application value in space debris observation and early warning.

Description

Technical Field

[0001] This invention relates to the field of synthetic aperture laser imaging, and more specifically, to a method and system for synthetic aperture three-dimensional laser imaging using a BPSK signal array detector. Background Technology

[0002] To achieve high-resolution laser imaging under the constraint of limited optical aperture size in optical imaging systems, array detector synthetic aperture laser imaging employs a coherent array detector to acquire complex laser images of relatively moving targets. Computer processing enables high-resolution elevation-azimuth imaging. Compared to Synthetic Aperture Laser Radar (SAL) and Inverse Synthetic Aperture Laser Radar (ISAL), this imaging method is less affected by vibration phase errors.

[0003] To simplify laser emission systems, existing array detector synthetic aperture laser imaging uses narrowband laser signals, enabling only high-resolution elevation-azimuth imaging, resulting in the loss of target range information. Furthermore, because this imaging method utilizes the relative motion between the target and the system to increase the spatial sampling signal coverage and construct a high-resolution image, its imaging principle leads to sparse spatial sampling in the imaging results, resulting in high sidelobes in the image.

[0004] The patent document "An Array-type Fiber Optic Ultrasonic Imaging System Based on Multi-channel Delay Parallel Detection" (2025, Patent Application No. CN202511203061.2) describes an invention that uses optical fibers to change the transmission time of the detection optical signals of each channel. Under the condition that the detection optical signals are bundled into a single output, they are distinguished by time division. After photoelectric conversion, the optical signals are used to acquire electrical signals containing multi-channel detection information in parallel, and the signal analysis is performed through an imaging algorithm with an array parallel architecture to achieve image reconstruction. However, the detection optical signals are pulsed and do not involve BPSK waveform laser signals, coherent detection of signals, or pulse compression.

[0005] The patent document "Method and System for Non-destructive Testing of PE Hot Melt Joints Based on Ultrasonic Phased Array" (2025, Patent Application No. CN202511015252.6) uses an ultrasonic phased array probe array to solve or alleviate the problem of insufficient detection accuracy in the non-destructive testing of PE hot melt joints caused by material anisotropy, dynamic density gradient and uneven distribution of elastic modulus. However, it does not involve three-dimensional imaging and synthetic aperture laser imaging of array detectors.

[0006] The patent document "Three-dimensional imaging method of synthetic aperture lidar based on sparse aperture" (patent application number CN201911051582.5, 2019) describes an invention that uses random or pseudo-random sequences as sparse sampling criteria to form sparse apertures. A sparse aperture sampling array is formed in the intersection direction of the SAL and sparse sampling is performed. After interferometric processing, low-pass filtering and principal component analysis, a three-dimensional image is formed after sparse sampling filtering or reconstruction processing. However, it does not involve equipment such as coherent array detectors, and it does not carry out synthetic aperture lidar imaging processing based on array detectors.

[0007] The patent document "A High-Resolution Digital Holographic Diffraction Tomography Imaging" (2018, patent application number CN201810145657.5) describes an invention that uses a two-dimensional electric translation platform to move a charge-coupled device (CCD) to obtain multiple frames of holograms. It then uses intensity registration and sub-pixel micro-displacement of image misalignment to synthesize high-resolution holograms and achieves high-resolution three-dimensional imaging through digital holographic diffraction tomography. However, its system does not involve a coherent array detector and a BPSK laser signal.

[0008] The patent document “Sparse Three-Aperture Optical Synthetic Aperture Coherent Imaging System and Method” (2024, Patent Application No. CN202411062413.2) describes an invention that sets up three small-aperture sub-mirrors and processes the acquired laser composite images by computer to achieve high-resolution optical synthetic aperture imaging. However, it does not involve BPSK laser signals and their pulse compression processing, nor does it involve array detector synthetic aperture laser imaging processing achieved by the relative motion between the imaging system and the target.

[0009] The patent document “Infrared Complex Image Formation of Moving Target and Synthetic Aperture Imaging Method and System with Sub-Mirror Array” (2024, Patent Application No. CN202411580096.3) describes an invention that sets up a multi-sub-mirror imaging system to construct an infrared complex image and complete optical synthetic aperture high-resolution imaging through laser local oscillator orthogonal phase modulation. However, it does not involve BPSK laser signals and their pulse compression processing, or synthetic aperture laser imaging processing based on coherent array detectors. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for synthetic aperture three-dimensional laser imaging using a BPSK signal array detector.

[0011] The synthetic aperture three-dimensional laser imaging method for BPSK signal array detectors provided by the present invention includes:

[0012] Step 1: In the preset imaging system, a binary phase-shift keying laser emission signal is used to illuminate the moving target. The emission signal is reflected by the target to form a laser echo signal. Step 2: The laser echo signal is processed by a Fourier lens to form a laser complex image signal, which is then acquired by a coherent array detector to form multiple frames of low-resolution laser complex images; Step 3: Estimate the target's motion direction and distance parameters based on the multi-frame low-resolution laser complex image, and construct a high-resolution laser complex image using an array detector synthetic aperture laser imaging algorithm; Step 4: Based on the multi-frame laser complex image, construct an elevation-azimuth-time three-dimensional matrix, and perform pulse compression processing on the time dimension data corresponding to each pixel in the coherent array detector to achieve range imaging of the target within the field of view corresponding to each pixel; Step 5: Combine the high-resolution laser composite image with the range imaging result to construct a three-dimensional laser imaging result; Step 6: The imaging system performs multiple repeated observations during the target's motion to construct multi-frame laser complex images. By combining spatial sampling signal sparsity reduction, compressed sensing algorithm, and complex dual apodization algorithm, sidelobe suppression of the imaging results is achieved.

[0013] Preferably, at the target distance When the far-field condition is met, the resolution of the low-resolution laser complex image is... The pixel size of the coherent array detector of the imaging system ,focal length Distance to target Decide:

[0014]

[0015] in, The aperture of the Fourier lens. is the laser wavelength.

[0016] Preferably, the high-resolution elevation-azimuth laser complex image generated by the synthetic aperture laser imaging processing of the array detector is combined with the range pulse compression result to form a three-dimensional laser imaging result, including: Let the multi-frame laser complex image acquired by the coherent array detector be the elevation-azimuth-time three-dimensional matrix formed by the acquisition of multiple frames. ,in, , and Let these represent the elevation, azimuth, and time coordinates, respectively, and satisfy the following conditions:

[0017]

[0018] in, and These represent the number of pixels in the elevation and azimuth directions of the array detector, respectively. The results of synthetic aperture laser imaging of the array detector are as follows: The coordinates in the coherent array detector are The pixel-corresponding distance pulse compression result is ; Based on the synthetic aperture laser imaging results of the array detector Construct a three-dimensional matrix with the same time dimension as the image. ; The distance corresponding to each pixel is compressed into the pulse result. By splicing in the pitch and azimuth directions, a To satisfy:

[0019]

[0020]

[0021] The constructed three-dimensional matrix and Element-wise multiplication is used to construct the three-dimensional laser imaging result:

[0022] in, These are the spatial coordinates corresponding to the stitched parts. This indicates that the elements in the matrix are multiplied together.

[0023] Preferably, the compressed sensing algorithm and the complex dual apodization algorithm are combined to achieve pitch-azimuth sidelobe suppression of the imaging results, including: For the initial synthetic aperture laser imaging results, first use a sparsity of The compressed sensing algorithm processes each row of image data and then uses a sparsity of 1. The compressed sensing algorithm processes each column of image data. For the initial synthetic aperture laser imaging results, first use a sparsity of The compressed sensing algorithm processes each column of image data and then uses a sparsity of 1. The compressed sensing algorithm processes each row of image data. The output image is processed by the complex double apodization algorithm to form a low sidelobe imaging result; The expression for the compressed sensing algorithm to measure one-dimensional sparse signals is as follows:

[0024] in, For the observation matrix, For the observation results, The original signal, It is a sparse matrix. It is a sensing matrix. It is the original signal In the sparse representation of the signal in the transform domain, and the signal has only Each coefficient is non-zero; in the setting Under the condition of using a standard orthogonal basis dictionary, the original signal Represented as:

[0025] In the formula, Let N be an orthonormal basis, where N is the signal length and n is the index of the signal length. It is the nth orthonormal basis vector. For signal exist Decomposition coefficients; through orthogonal matching pursuit algorithm:

[0026]

[0027] The original signal can be reconstructed. The algorithm constructs a matrix based on the corresponding columns of the support set. Through iterative processing, the estimated value is obtained. Caused residuals minimize; Let the outputs of the two compressed sensing processes be respectively and The result of the complex double azotization algorithm is: ,include: according to and Build The real part: if and If the signs of the real parts are the same, then The real part takes the minimum of the two; if and If the signs of the real parts are different, then The real part is set to 0:

[0028] in, To obtain the real part, To obtain the minimum value; according to and Build The method for imaginary parts is the same as that for real parts, that is:

[0029] in, To extract the imaginary part; To build and Combined to form the sidelobe suppression treatment result .

[0030] Preferably, the time interval between the acquisition of the multi-frame laser complex image by the coherent array detector is less than the subcode width of the binary phase shift keying signal.

[0031] The BPSK signal array detector synthetic aperture three-dimensional laser imaging system provided by the present invention includes: Module M1: In the preset imaging system, a binary phase-shift keying laser emission signal is used to illuminate the moving target, and the emission signal is reflected by the target to form a laser echo signal; Module M2: Processes the laser echo signal through a Fourier lens to form a laser complex image signal, which is then acquired by a coherent array detector to form multiple frames of low-resolution laser complex images; Module M3: Estimates the target's motion direction and distance parameters based on the multi-frame low-resolution laser complex image, and constructs a high-resolution laser complex image through an array detector synthetic aperture laser imaging algorithm; Module M4: Based on the multi-frame laser complex image, a three-dimensional matrix of elevation-azimuth-time is constructed. Pulse compression processing is performed on the time dimension data corresponding to each pixel in the coherent array detector to realize range imaging of the target in the field of view corresponding to each pixel. Module M5: Combines the high-resolution laser complex image with the range imaging result to construct a three-dimensional laser imaging result; Module M6: Enables the imaging system to perform multiple repeated observations during the target's motion, constructing multi-frame laser complex images. It combines spatial sampling signal sparsity reduction, compressed sensing algorithm, and complex dual apodization algorithm to achieve sidelobe suppression of the imaging results.

[0032] Preferably, at the target distance When the far-field condition is met, the resolution of the low-resolution laser complex image is... The pixel size of the coherent array detector of the imaging system ,focal length Distance to target Decide:

[0033]

[0034] in, The aperture of the Fourier lens. is the laser wavelength.

[0035] Preferably, the high-resolution elevation-azimuth laser complex image generated by the synthetic aperture laser imaging processing of the array detector is combined with the range pulse compression result to form a three-dimensional laser imaging result, including: Let the multi-frame laser complex image acquired by the coherent array detector be the elevation-azimuth-time three-dimensional matrix formed by the acquisition of multiple frames. ,in, , and Let these represent the elevation, azimuth, and time coordinates, respectively, and satisfy the following conditions:

[0036]

[0037] in, and These represent the number of pixels in the elevation and azimuth directions of the array detector, respectively. The results of synthetic aperture laser imaging of the array detector are as follows: The coordinates in the coherent array detector are The pixel-corresponding distance pulse compression result is ; Based on the synthetic aperture laser imaging results of the array detector Construct a three-dimensional matrix with the same time dimension as the image. ; The distance corresponding to each pixel is compressed into the pulse result. By splicing in the pitch and azimuth directions, a To satisfy:

[0038]

[0039]

[0040] The constructed three-dimensional matrix and Element-wise multiplication is used to construct the three-dimensional laser imaging result:

[0041] in, These are the spatial coordinates corresponding to the stitched parts. This indicates that the elements in the matrix are multiplied together.

[0042] Preferably, the compressed sensing algorithm and the complex dual apodization algorithm are combined to achieve pitch-azimuth sidelobe suppression of the imaging results, including: For the initial synthetic aperture laser imaging results, first use a sparsity of The compressed sensing algorithm processes each row of image data and then uses a sparsity of 1. The compressed sensing algorithm processes each column of image data. For the initial synthetic aperture laser imaging results, first use a sparsity of The compressed sensing algorithm processes each column of image data and then uses a sparsity of 1. The compressed sensing algorithm processes each row of image data. The output image is processed by the complex double apodization algorithm to form a low sidelobe imaging result; The expression for the compressed sensing algorithm to measure one-dimensional sparse signals is as follows:

[0043] in, For the observation matrix, For the observation results, The original signal, It is a sparse matrix. It is a sensing matrix. It is the original signal In the sparse representation of the signal in the transform domain, and the signal has only Each coefficient is non-zero; in the setting Under the condition of using a standard orthogonal basis dictionary, the original signal Represented as:

[0044] In the formula, Let N be an orthonormal basis, where N is the signal length and n is the index of the signal length. It is the nth orthonormal basis vector. For signal exist Decomposition coefficients; through orthogonal matching pursuit algorithm:

[0045]

[0046] The original signal can be reconstructed. The algorithm constructs a matrix based on the corresponding columns of the support set. Through iterative processing, the estimated value is obtained. Caused residuals minimize; Let the outputs of the two compressed sensing processes be respectively and The result of the complex double azotization algorithm is: ,include: according to and Build The real part: if and If the signs of the real parts are the same, then The real part takes the minimum of the two; if and If the signs of the real parts are different, then The real part is set to 0:

[0047] in, To obtain the real part, To obtain the minimum value; according to and Build The method for imaginary parts is the same as that for real parts, that is:

[0048] in, To extract the imaginary part; To build and Combined to form the sidelobe suppression treatment result .

[0049] Preferably, the time interval between the acquisition of the multi-frame laser complex image by the coherent array detector is less than the subcode width of the binary phase shift keying signal.

[0050] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention combines BPSK laser emission signals with the synthetic aperture laser imaging method of array detectors. While constructing high-resolution imaging results in the pitch and azimuth directions, it obtains the distance information of the target in the field of view corresponding to each pixel of the coherent array detector by pulse compression processing of the BPSK signal, thereby realizing three-dimensional laser imaging of moving targets. (2) The method of the present invention sets up an imaging system to repeatedly observe the target and splices the spatial sampling signals corresponding to the composite aperture laser imaging results of multiple array detectors. By reducing the sparsity of spatial sampling, sidelobe suppression of pitch-azimuth imaging results is achieved. (3) The method of the present invention combines CS, CDA and PGA algorithms to realize sidelobe suppression and focusing processing of the synthetic aperture laser imaging results of array detectors, effectively improving image quality. Attached Figure Description

[0051] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic flowchart of the method of the present invention; Figure 2 This is a schematic diagram of the synthetic aperture three-dimensional laser imaging system using a BPSK signal array detector according to the method of the present invention; Figure 3 This is a schematic diagram of the image sidelobe suppression processing flow of the BPSK signal array detector synthetic aperture three-dimensional laser imaging system combined with the CS algorithm and CDA algorithm according to the present invention. Figures 4a-4d This is an example of image sidelobe suppression processing combining the CS algorithm and the CDA algorithm of the present invention; Figure 4a This is an amplitude diagram of the elevation-azimuth imaging results of the satellite and the 3×3 dot matrix target before the image sidelobe suppression processing of the present invention; Figure 4b This is an amplitude diagram of the elevation-azimuth imaging results of satellites and 3×3 dot matrix targets after image sidelobe suppression processing according to the method of the present invention; Figure 4c This is an X-axis slice of the 3×3 dot matrix target imaging results before and after the image sidelobe suppression processing of the method of the present invention; Figure 4d This is a Y-direction slice of the 3×3 dot matrix target imaging results before and after the image sidelobe suppression processing of the method of the present invention; Figures 5a-5c This is an example of the sidelobe suppression processing of synthetic aperture laser imaging results based on repeated observations of array detectors according to the method of the present invention; Figure 5a The method of this invention is based on the imaging results of satellite targets and 3×3 dot matrix targets from a single observation and their corresponding spatial sampling signals; Figure 5b The method of this invention is based on the imaging results of satellite targets and 3×3 dot matrix targets from 25 repeated observations and their corresponding spatial sampling signals; Figure 5c for Figure 5b The imaging results of satellite targets and 3×3 dot matrix targets after further processing of image sidelobes are obtained by combining the CS algorithm and CDA algorithm, as well as the slices of dot matrix targets in the X and Y directions. Detailed Implementation

[0052] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0053] Example 1 This invention provides a synthetic aperture 3D laser imaging method for array detectors based on binary phase shift keying (BPSK) signals. The imaging system uses BPSK signals as the laser emission signal. Distance information of the target in the field of view corresponding to each pixel of the coherent array detector is obtained through pulse compression, and a 3D laser imaging result of the target is constructed. Furthermore, by repeatedly observing the target and combining compressed sensing (CS) and complex dual apodization (CDA) algorithms, image sidelobes are effectively suppressed, improving the system's imaging quality.

[0054] See Figure 1 , Figure 1 This embodiment provides a flowchart of a BPSK signal array detector synthetic aperture three-dimensional laser imaging method. The method steps are as follows: Step S100: Illuminate the moving target with a BPSK laser emission signal, and the emission signal is reflected by the target to form a laser echo signal; Step S200: The laser echo signal is processed by a Fourier lens to form a laser complex image signal, which is then acquired by a coherent array detector to form multiple frames of low-resolution laser complex images; Step S300: Estimate the target's motion direction and distance parameters based on the multi-frame low-resolution laser complex image, and construct a high-resolution laser complex image using an array detector synthetic aperture laser imaging algorithm; Step S400: The multi-frame laser complex image constitutes a three-dimensional matrix of elevation-azimuth-time. Pulse compression processing is performed on the time dimension data corresponding to each pixel in the coherent array detector to realize range imaging of the target in the field of view corresponding to each pixel. Step S500: Combine the high-resolution laser composite image with the range imaging result to construct a three-dimensional laser imaging result; Step S600: The imaging system performs multiple repeated observations during the target's motion. Repeat steps S100 to M500 to construct multiple laser complex images. Combine the reduction of spatial sampling signal sparsity, the CS algorithm, and the CDA algorithm to achieve sidelobe suppression of the imaging results.

[0055] Furthermore, the BPSK signal array detector synthetic aperture three-dimensional laser imaging system of the present invention comprises a Fourier lens, a coherent array detector, a laser seed source, a timer, a phase modulator, an acousto-optic modulator (AOM), a laser collimator, and a beam expander. A schematic diagram of the BPSK signal array detector synthetic aperture three-dimensional laser imaging system of the invention is shown below. Figure 2 .

[0056] Further, in step S100, the signal generated by the laser seed source of the present invention, after being modulated by BPSK phase modulation by the phase modulator and frequency-converted by AOM, has specific waveform and phase information. After being emitted by the laser collimator and processed by the beam expander, a laser emission signal is formed, and its light spot covers the moving target during the sampling process of the imaging system.

[0057] Further, in step S200, the coherent array detector of the present invention is composed of a BPD and an intermediate frequency sampling ADC, etc., and forms the multi-frame low-resolution laser complex image by sampling the laser complex image signal.

[0058] Furthermore, at the target distance When the far-field condition is met, the resolution of the low-resolution laser complex image of the present invention is determined by the pixel size of the coherent array detector of the imaging system. ,focal length Distance to target Decide:

[0059]

[0060] in, The aperture of the Fourier lens. is the laser wavelength.

[0061] Further, in step S500, the present invention combines the high-resolution elevation-azimuth laser complex image formed by the array detector's synthetic aperture laser imaging processing with the range pulse compression result to form a three-dimensional laser imaging result. Its main steps include: Step S501: The elevation-azimuth-time three-dimensional matrix formed by the coherent array detector acquiring multiple frames of laser complex images is denoted as . ,in, , and Let these represent the elevation, azimuth, and time coordinates, respectively, and satisfy the following conditions:

[0062]

[0063] in, and Let represent the number of pixels in the elevation and azimuth directions of the array detector, respectively; and let the synthetic aperture laser imaging result of the array detector be denoted as . The coordinates in the coherent array detector are The pixel-corresponding distance pulse compression result is ; Step S502: Based on the synthetic aperture laser imaging results of the array detector Construct a three-dimensional matrix with the same time dimension as the image. ; Step S503: Compress the distance corresponding to each pixel into the pulse compression result. By splicing in the pitch and azimuth directions, a To satisfy:

[0064]

[0065]

[0066] Step S504: The three-dimensional matrix constructed in steps 5.2 and 5.3 and Element-wise multiplication is used to construct the three-dimensional laser imaging result:

[0067] in, This indicates that the elements in the matrix are multiplied together.

[0068] Further, in step S600, the present invention combines the CS algorithm and the CDA algorithm to achieve pitch-azimuth sidelobe suppression of the imaging results. Its main steps include: Step S610: For the initial synthetic aperture laser imaging results, first use a sparsity of... The CS algorithm processes each row of image data, and then uses a sparsity of 1 / 2. The CS algorithm processes each column of image data. Step S620: For the initial synthetic aperture laser imaging results, first use a sparsity of... The CS algorithm processes each column of image data, and then uses a sparsity of 1 / 2. The CS algorithm processes each row of image data. Step S630: The output images from steps S610 and S620 are processed using the CDA algorithm to form a low sidelobe imaging result.

[0069] The schematic diagram of the image sidelobe suppression processing flow of the BPSK signal array detector synthetic aperture three-dimensional laser imaging system combined with the CS algorithm and CDA algorithm is shown below. Figure 3 ; Furthermore, the expression for measuring one-dimensional sparse signals using the CS algorithm described in this invention is as follows:

[0070] in, For the observation matrix, For the observation results, The original signal, It is a sparse matrix. It is the original signal In the sparse representation of the signal in the transform domain, and the signal has only Each coefficient is non-zero. In the settings... Under the condition of using a standard orthogonal basis dictionary, the original signal It can be represented as:

[0071] In the formula, As a set of orthonormal bases, For signal exist The decomposition coefficients are obtained using the Orthogonal Matching Pursuit (OMP) algorithm.

[0072]

[0073] The original signal can be reconstructed. The algorithm constructs a matrix based on the corresponding columns of the support set. Through iterative processing, the estimated value is obtained. Caused residuals minimize.

[0074] When using CS to process the initial synthetic aperture laser imaging results in both row and column directions, the sparsity... , and , These are one-dimensional matrices, with lengths equal to the number of columns and rows of the image, respectively. Their values ​​are based on the normalized amplitude map of the initial synthetic aperture laser imaging results. , , and The threshold setting can be calculated. The threshold setting range is (0,1), aiming to minimize the image entropy and maximize the contrast of the sidelobe suppression processing result. The threshold and sparsity values ​​can be obtained through optimization algorithm.

[0075] Furthermore, the CS results output in steps S610 and S620 of this invention are respectively and The CDA algorithm processing result is Its main steps include: Step S631: According to and Build The real part: if and If the signs of the real parts are the same, then The real part takes the minimum of the two; if and If the signs of the real parts are different, then The real part is set to 0:

[0076] in, To obtain the real part, To obtain the minimum value; Step S632: According to and Build The method for imaginary part is the same as step 631, that is:

[0077] in, To extract the imaginary part; Step S633: The components constructed in steps S631 and S632 and Combined to form the sidelobe suppression treatment result .

[0078] For an example of image sidelobe suppression processing combining the CS and CDA algorithms of this invention, see [link to example]. Figures 4a-4d ,in, Figure 4a This is an amplitude diagram of the elevation-azimuth imaging results of the satellite and the 3×3 dot matrix target before the image sidelobe suppression processing of the present invention; Figure 4b This is an amplitude diagram of the elevation-azimuth imaging results of satellites and 3×3 dot matrix targets after image sidelobe suppression processing according to the method of the present invention; Figure 4c This is an X-axis slice of the 3×3 dot matrix target imaging results before and after the image sidelobe suppression processing of the method of the present invention; Figure 4d This is a Y-direction slice of the 3×3 dot matrix target imaging results before and after the sidelobe suppression processing of the method of the present invention. (At the threshold) , , and Under the conditions of setting the values ​​to 0.25, 0.3, 0.25, and 0.4 respectively, by Figure 4c and Figure 4d It can be seen that the combined CS and CDA algorithms effectively suppressed sidelobes and reduced the image entropy of the imaging result from 10.30 to 8.97, while increasing the contrast from 2.80 to 8.29.

[0079] Further, in step S600, under the condition that the target is in relative motion with the imaging system, the present invention performs repeated observations and synthetic aperture laser imaging processing on the target, and stitches together the spatial sampling signal corresponding to the imaging result according to the relative position of the target. This further expands the range of the spatial sampling signal while reducing its sparsity, achieving sidelobe suppression of the pitch-azimuth imaging result. For an example of sidelobe suppression processing of synthetic aperture laser imaging results based on repeated observations of an array detector, see [link to example]. Figures 5a-5c ,in, Figure 5a The method of this invention is based on the imaging results of satellite targets and 3×3 dot matrix targets from a single observation and their corresponding spatial sampling signals; Figure 5b The method of this invention is based on the imaging results of satellite targets and 3×3 dot matrix targets from 25 repeated observations and their corresponding spatial sampling signals; Figure 5c for Figure 5b Imaging results of satellite targets and 3×3 dot matrix targets after further processing of image sidelobes using the CS and CDA algorithms, as well as slices of the dot matrix targets in the X and Y directions. Comparison. Figure 5a Under the condition of overlapping spatial sampling signals, 25 repeated observations reduced the entropy of the imaging results from 10.58 to 10.04, improved the contrast from 2.67 to 3.95, and effectively reduced the influence of grating lobes in the imaging results. Based on this, the CS algorithm and CDA algorithm were used to further refine the imaging results. Figure 5b After processing, the effects of side lobes and grating lobes can be largely removed. At this point, the entropy of the imaging result is 9.51 and the contrast is 7.54.

[0080] Furthermore, given the complex relative motion of the target and the defocusing problem in the synthetic aperture laser imaging results of the array detector, this invention performs PGA processing on the elevation-azimuth imaging results.

[0081] Furthermore, the time interval between the acquisition of the multi-frame laser complex image by the coherent array detector of the present invention is less than the subcode width of the BPSK signal.

[0082] Example 2 The present invention also provides a BPSK signal array detector synthetic aperture three-dimensional laser imaging system, comprising: Module M1: In the preset imaging system, a binary phase-shift keying laser emission signal is used to illuminate the moving target, and the emission signal is reflected by the target to form a laser echo signal; Module M2: Processes the laser echo signal through a Fourier lens to form a laser complex image signal, which is then acquired by a coherent array detector to form multiple frames of low-resolution laser complex images; Module M3: Estimates the target's motion direction and distance parameters based on the multi-frame low-resolution laser complex image, and constructs a high-resolution laser complex image through an array detector synthetic aperture laser imaging algorithm; Module M4: Based on the multi-frame laser complex image, a three-dimensional matrix of elevation-azimuth-time is constructed. Pulse compression processing is performed on the time dimension data corresponding to each pixel in the coherent array detector to realize range imaging of the target in the field of view corresponding to each pixel. Module M5: Combines the high-resolution laser complex image with the range imaging result to construct a three-dimensional laser imaging result; Module M6: Enables the imaging system to perform multiple repeated observations during the target's motion, constructing multi-frame laser complex images. It combines spatial sampling signal sparsity reduction, compressed sensing algorithm, and complex dual apodization algorithm to achieve sidelobe suppression of the imaging results.

[0083] Preferably, at the target distance When the far-field condition is met, the resolution of the low-resolution laser complex image is... The pixel size of the coherent array detector of the imaging system ,focal length Distance to target Decide:

[0084]

[0085] in, The aperture of the Fourier lens. is the laser wavelength.

[0086] Preferably, the high-resolution elevation-azimuth laser complex image generated by the synthetic aperture laser imaging processing of the array detector is combined with the range pulse compression result to form a three-dimensional laser imaging result, including: Let the multi-frame laser complex image acquired by the coherent array detector be the elevation-azimuth-time three-dimensional matrix formed by the acquisition of multiple frames. ,in, , and Let these represent the elevation, azimuth, and time coordinates, respectively, and satisfy the following conditions:

[0087]

[0088] in, and These represent the number of pixels in the elevation and azimuth directions of the array detector, respectively. The results of synthetic aperture laser imaging of the array detector are as follows: The coordinates in the coherent array detector are The pixel-corresponding distance pulse compression result is ; Based on the synthetic aperture laser imaging results of the array detector Construct a three-dimensional matrix with the same time dimension as the image. ; The distance corresponding to each pixel is compressed into the pulse result. By splicing in the pitch and azimuth directions, a To satisfy:

[0089]

[0090]

[0091] The constructed three-dimensional matrix and Element-wise multiplication is used to construct the three-dimensional laser imaging result:

[0092] in, These are the spatial coordinates corresponding to the stitched parts. This indicates that the elements in the matrix are multiplied together.

[0093] Preferably, the compressed sensing algorithm and the complex dual apodization algorithm are combined to achieve pitch-azimuth sidelobe suppression of the imaging results, including: For the initial synthetic aperture laser imaging results, first use a sparsity of The compressed sensing algorithm processes each row of image data and then uses a sparsity of 1. The compressed sensing algorithm processes each column of image data. For the initial synthetic aperture laser imaging results, first use a sparsity of The compressed sensing algorithm processes each column of image data and then uses a sparsity of 1. The compressed sensing algorithm processes each row of image data. The output image is processed by the complex double apodization algorithm to form a low sidelobe imaging result; The expression for the compressed sensing algorithm to measure one-dimensional sparse signals is as follows:

[0094] in, For the observation matrix, For the observation results, The original signal, It is a sparse matrix. It is a sensing matrix. It is the original signal In the sparse representation of the signal in the transform domain, and the signal has only Each coefficient is non-zero; in the setting Under the condition of using a standard orthogonal basis dictionary, the original signal Represented as:

[0095] In the formula, Let N be an orthonormal basis, where N is the signal length and n is the index of the signal length. It is the nth orthonormal basis vector. For signal exist Decomposition coefficients; through orthogonal matching pursuit algorithm:

[0096]

[0097] The original signal can be reconstructed. The algorithm constructs a matrix based on the corresponding columns of the support set. Through iterative processing, the estimated value is obtained. Caused residuals minimize; Let the outputs of the two compressed sensing processes be respectively and The result of the complex double azotization algorithm is: ,include: according to and Build The real part: if and If the signs of the real parts are the same, then The real part takes the minimum of the two; if and If the signs of the real parts are different, then The real part is set to 0:

[0098] in, To obtain the real part, To obtain the minimum value; according to and Build The method for imaginary parts is the same as that for real parts, that is:

[0099] in, To extract the imaginary part; To build and Combined to form the sidelobe suppression treatment result .

[0100] Preferably, the time interval between the acquisition of the multi-frame laser complex image by the coherent array detector is less than the subcode width of the binary phase shift keying signal.

[0101] Those skilled in the art will understand that, in addition to implementing the system, apparatus, and their modules provided by this invention in purely computer-readable program code, the same program can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system, apparatus, and their modules provided by this invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; alternatively, modules for implementing various functions can be considered both software programs implementing the method and structures within the hardware component.

[0102] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for synthetic aperture three-dimensional laser imaging using a BPSK signal array detector, characterized in that, include: Step 1: In the preset imaging system, a binary phase-shift keying laser emission signal is used to illuminate the moving target. The emission signal is reflected by the target to form a laser echo signal. Step 2: The laser echo signal is processed by a Fourier lens to form a laser complex image signal, which is then acquired by a coherent array detector to form multiple frames of low-resolution laser complex images; Step 3: Estimate the target's motion direction and distance parameters based on the multi-frame low-resolution laser complex image, and construct a high-resolution laser complex image using an array detector synthetic aperture laser imaging algorithm; Step 4: Based on the multi-frame laser complex image, construct an elevation-azimuth-time three-dimensional matrix, and perform pulse compression processing on the time dimension data corresponding to each pixel in the coherent array detector to achieve range imaging of the target within the field of view corresponding to each pixel; Step 5: Combine the high-resolution laser composite image with the range imaging result to construct a three-dimensional laser imaging result; Step 6: The imaging system performs multiple repeated observations during the target's motion to construct multi-frame laser complex images. By combining spatial sampling signal sparsity reduction, compressed sensing algorithm, and complex dual apodization algorithm, sidelobe suppression of the imaging results is achieved.

2. The BPSK signal array detector synthetic aperture three-dimensional laser imaging method according to claim 1, characterized in that, At target distance When the far-field condition is met, the resolution of the low-resolution laser complex image is... The pixel size of the coherent array detector of the imaging system ,focal length Distance to target Decide: in, The aperture of the Fourier lens. is the laser wavelength.

3. The BPSK signal array detector synthetic aperture three-dimensional laser imaging method according to claim 2, characterized in that, The elevation-azimuth high-resolution laser complex image generated by the synthetic aperture laser imaging processing of the array detector is combined with the range pulse compression result to form a three-dimensional laser imaging result, including: Let the multi-frame laser complex image acquired by the coherent array detector be the elevation-azimuth-time three-dimensional matrix. ,in, , and Let these represent the elevation, azimuth, and time coordinates, respectively, and satisfy the following conditions: in, and These represent the number of pixels in the elevation and azimuth directions of the array detector, respectively. The results of synthetic aperture laser imaging of the array detector are as follows: The coordinates in the coherent array detector are The pixel-corresponding distance pulse compression result is ; Based on the synthetic aperture laser imaging results of the array detector Construct a three-dimensional matrix with the same time dimension as the image. ; The distance corresponding to each pixel is compressed into the pulse result. By splicing in the pitch and azimuth directions, a To satisfy: The constructed three-dimensional matrix and Element-wise multiplication is used to construct the three-dimensional laser imaging result: in, These are the spatial coordinates corresponding to the stitched parts. This indicates that the elements in the matrix are multiplied together.

4. The BPSK signal array detector synthetic aperture three-dimensional laser imaging method according to claim 1, characterized in that, Combining compressed sensing algorithms and complex dual apodization algorithms, elevation-azimuth sidelobe suppression of imaging results is achieved, including: For the initial synthetic aperture laser imaging results, first use a sparsity of The compressed sensing algorithm processes each row of image data and then uses a sparsity of 1. The compressed sensing algorithm processes each column of image data. For the initial synthetic aperture laser imaging results, first use a sparsity of The compressed sensing algorithm processes each column of image data and then uses a sparsity of 1. The compressed sensing algorithm processes each row of image data. The output image is processed by the complex double apodization algorithm to form a low sidelobe imaging result; The expression for the compressed sensing algorithm to measure one-dimensional sparse signals is as follows: in, For the observation matrix, For the observation results, The original signal, It is a sparse matrix. It is a sensing matrix. It is the original signal In the sparse representation in the transform domain, and the signal has only Each coefficient is non-zero; in the setting Under the condition of using a standard orthogonal basis dictionary, the original signal Represented as: In the formula, Let N be an orthonormal basis, where N is the signal length and n is the index of the signal length. It is the nth orthonormal basis vector. For signal exist Decomposition coefficients; through orthogonal matching pursuit algorithm: The original signal can be reconstructed. The algorithm constructs a matrix based on the corresponding columns of the support set. Through iterative processing, the estimated value is obtained. Caused residuals minimize; Let the outputs of the two compressed sensing processes be respectively and The result of the complex double azotization algorithm is: ,include: according to and Build The real part: if and If the signs of the real parts are the same, then The real part takes the minimum of the two; if and If the signs of the real parts are different, then The real part is set to 0: in, To obtain the real part, To obtain the minimum value; according to and Build The method for imaginary parts is the same as that for real parts, that is: in, To extract the imaginary part; To build and Combined to form the sidelobe suppression treatment result .

5. The BPSK signal array detector synthetic aperture three-dimensional laser imaging method according to claim 1, characterized in that, The time interval between the acquisition of the multi-frame laser complex image by the coherent array detector is less than the subcode width of the binary phase shift keying signal.

6. A BPSK signal array detector synthetic aperture three-dimensional laser imaging system, characterized in that, include: Module M1: In the preset imaging system, a binary phase-shift keying laser emission signal is used to illuminate the moving target, and the emission signal is reflected by the target to form a laser echo signal; Module M2: Processes the laser echo signal through a Fourier lens to form a laser complex image signal, which is then acquired by a coherent array detector to form multiple frames of low-resolution laser complex images; Module M3: Estimates the target's motion direction and distance parameters based on the multi-frame low-resolution laser complex image, and constructs a high-resolution laser complex image through an array detector synthetic aperture laser imaging algorithm; Module M4: Based on the multi-frame laser complex image, a three-dimensional matrix of elevation-azimuth-time is constructed. Pulse compression processing is performed on the time dimension data corresponding to each pixel in the coherent array detector to realize range imaging of the target in the field of view corresponding to each pixel. Module M5: Combines the high-resolution laser complex image with the range imaging result to construct a three-dimensional laser imaging result; Module M6: Enables the imaging system to perform multiple repeated observations during the target's motion, constructing multi-frame laser complex images. It combines spatial sampling signal sparsity reduction, compressed sensing algorithm, and complex dual apodization algorithm to achieve sidelobe suppression of the imaging results.

7. The BPSK signal array detector synthetic aperture three-dimensional laser imaging system according to claim 6, characterized in that, At target distance When the far-field condition is met, the resolution of the low-resolution laser complex image is... The pixel size of the coherent array detector of the imaging system ,focal length Distance to target Decide: in, The aperture of the Fourier lens. is the laser wavelength.

8. The BPSK signal array detector synthetic aperture three-dimensional laser imaging system according to claim 7, characterized in that, The elevation-azimuth high-resolution laser complex image generated by the synthetic aperture laser imaging processing of the array detector is combined with the range pulse compression result to form a three-dimensional laser imaging result, including: Let the multi-frame laser complex image acquired by the coherent array detector be the elevation-azimuth-time three-dimensional matrix. ,in, , and Let these represent the elevation, azimuth, and time coordinates, respectively, and satisfy the following conditions: in, and These represent the number of pixels in the elevation and azimuth directions of the array detector, respectively. The results of synthetic aperture laser imaging of the array detector are as follows: The coordinates in the coherent array detector are The pixel-corresponding distance pulse compression result is ; Based on the synthetic aperture laser imaging results of the array detector Construct a three-dimensional matrix with the same time dimension as the image. ; The distance corresponding to each pixel is compressed into the pulse result. By splicing in the pitch and azimuth directions, a To satisfy: The constructed three-dimensional matrix and Element-wise multiplication is used to construct the three-dimensional laser imaging result: in, These are the spatial coordinates corresponding to the stitched parts. This indicates that the elements in the matrix are multiplied together.

9. The BPSK signal array detector synthetic aperture three-dimensional laser imaging system according to claim 6, characterized in that, Combining compressed sensing algorithms and complex dual apodization algorithms, elevation-azimuth sidelobe suppression of imaging results is achieved, including: For the initial synthetic aperture laser imaging results, first use a sparsity of The compressed sensing algorithm processes each row of image data and then uses a sparsity of 1. The compressed sensing algorithm processes each column of image data. For the initial synthetic aperture laser imaging results, first use a sparsity of The compressed sensing algorithm processes each column of image data and then uses a sparsity of 1. The compressed sensing algorithm processes each row of image data. The output image is processed by the complex double apodization algorithm to form a low sidelobe imaging result; The expression for the compressed sensing algorithm to measure one-dimensional sparse signals is as follows: in, For the observation matrix, For the observation results, The original signal, It is a sparse matrix. It is a sensing matrix. It is the original signal In the sparse representation in the transform domain, and the signal has only Each coefficient is non-zero; in the setting Under the condition of using a standard orthogonal basis dictionary, the original signal Represented as: In the formula, Let N be an orthonormal basis, where N is the signal length and n is the index of the signal length. It is the nth orthonormal basis vector. For signal exist Decomposition coefficients; through orthogonal matching pursuit algorithm: The original signal can be reconstructed. The algorithm constructs a matrix based on the corresponding columns of the support set. Through iterative processing, the estimated value is obtained. Caused residuals minimize; Let the outputs of the two compressed sensing processes be respectively and The result of the complex double azotization algorithm is: ,include: according to and Build The real part: if and If the signs of the real parts are the same, then The real part takes the minimum of the two; if and If the signs of the real parts are different, then The real part is set to 0: in, To obtain the real part, To obtain the minimum value; according to and Build The method for imaginary parts is the same as that for real parts, that is: in, To extract the imaginary part; To build and Combined to form the sidelobe suppression treatment result .

10. The BPSK signal array detector synthetic aperture three-dimensional laser imaging system according to claim 6, characterized in that, The time interval between the acquisition of the multi-frame laser complex image by the coherent array detector is less than the subcode width of the binary phase shift keying signal.

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