Millimeter-Wave Near-Field Holographic Fast Imaging Method and System Based on Spatial Multiplexing

Abstract

The present invention discloses a method and system for fast millimeter-wave near-field holographic imaging based on spatial multiplexing, including: performing range FFT on a three-dimensional millimeter-wave echo matrix to extract two-dimensional millimeter-wave echo data; dividing an imaging area to obtain a number of imaging sub-areas, selecting the positions of imaging units in a certain imaging sub-area, and obtaining the corresponding positions of imaging units on a symmetric sub-area; dividing a radar array to obtain a number of sub-arrays, selecting the positions of array elements in a certain sub-array, and obtaining the corresponding positions of array elements on a symmetric sub-array; according to the principle of spatial symmetry, obtaining the result of the slant range traversal of the entire array for the echo of the imaging area; processing the obtained result of the slant range traversal of the echo of the imaging area to obtain SAR imaging. The present invention only needs to use the entire antenna array to perform slant range traversal on a quarter of the imaging area, reducing the imaging time required. Since the same echo phase compensation method is adopted, the imaging quality is not lost.

Description

Technical Field

[0001] The present invention belongs to the field of image processing, and relates to a millimeter-wave near-field holographic fast imaging method and system based on spatial multiplexing. Background Art

[0002] With the development of technology and the increase of demands, radar holographic imaging is developing towards the trends of multi-mode, multi-method, and high efficiency. Since millimeter waves have the characteristics of short wavelength, high resolution, and good image clarity, they are widely applied to three-dimensional imaging scenarios. The holographic imaging algorithm is the focus in the millimeter-wave holographic imaging system. Therefore, it is of great significance to study an efficient holographic imaging algorithm.

[0003] The back-projection algorithm BP is a SAR time-domain imaging algorithm derived by McCorkle according to the projection slice theory of CT imaging. Its basic principle is to achieve high-resolution imaging through compensating the phase of the echo signal and coherently superposing in the time domain. The following are the deficiencies of this method:

[0004] Since the BP imaging algorithm needs to compensate the phase of the echo signal caused by the spatial distance between the scattering point and the sampling point point by point, its computational complexity is extremely large. The long calculation time makes it difficult to apply under certain conditions. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems in the prior art, and provide a millimeter-wave near-field holographic fast imaging method and system based on spatial multiplexing, which can significantly reduce the imaging time and enhance the real-time performance of the system on the premise of ensuring the imaging quality unchanged.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] The millimeter-wave near-field holographic fast imaging method based on spatial multiplexing includes:

[0008] Performing range-direction FFT on the three-dimensional millimeter-wave echo matrix to extract two-dimensional millimeter-wave echo data;

[0009] Based on the obtained two-dimensional millimeter-wave echo data, dividing the imaging area to obtain several imaging sub-areas, selecting the position of the imaging unit in a certain imaging sub-area, and obtaining the corresponding imaging unit position on the symmetric sub-area;

[0010] Dividing the radar array to obtain several sub-arrays, selecting the position of the array element in a certain sub-array, and obtaining the corresponding array element position on the symmetric sub-array;

[0011] Perform echo slant range traversal on the positions of the imaging units in the imaging sub-region and the positions of the array elements in the sub-array based on the full array. According to the principle of spatial symmetry, obtain the result of echo slant range traversal of the full array for the imaging region;

[0012] Process the obtained result of echo slant range traversal of the imaging region to obtain SAR imaging.

[0013] A further improvement of the present invention lies in:

[0014] Perform range FFT on the three-dimensional millimeter-wave echo matrix to extract two-dimensional millimeter-wave echo data, specifically:

[0015] For an object at a distance of perform imaging. Let S(X,Y,t) be the three-dimensional echo data cube of the radar, and the expression is as shown in formula (1):

[0016]

[0017] where c is the speed of light, T is the duration of the transmitted signal, rect is the rectangular function, D x and D y are the lengths of the array in the azimuth and elevation directions, X and Y are the positions of the radar array elements, f c is the carrier frequency, (x0,y0,z0) is the target position, and R is the distance from the array element to the target;

[0018] For a volume target composed of scattering points, use (x,y,z) to represent the position of any scattering point in the target region, and σ(x,y,z) is the corresponding scattering coefficient;

[0019]

[0020] Perform range FFT on the three-dimensional echo data cube S(X,Y,t) to stack the target information in the range direction and extract the two-dimensional millimeter-wave echo data S(X,Y) at a distance of ;

[0021] Divide the imaging region to obtain several imaging sub-regions. Select the positions of the imaging units in a certain imaging sub-region and obtain the corresponding positions of the imaging units on the symmetric sub-region, specifically:

[0022] The size of the imaging region is M×N. Divide the imaging region into four equal parts to obtain four imaging sub-regions. Select one imaging sub-region. The position of the imaging unit in this imaging sub-region is P(m,n), then the corresponding positions of the imaging units on its symmetric region are P(M - m + 1,n), P(m,N - n + 1), and P(M - m + 1,N - n + 1).

[0023] Partition the radar array to obtain a number of sub-arrays, select the positions of the array elements in a certain sub-array, and obtain the corresponding positions of the array elements on the symmetric sub-array. Specifically:

[0024] The size of the radar array is X×Y. Divide the radar array into four equal parts to obtain four sub-arrays. Select one sub-array. If the position of the array element in this sub-array is T(x,y), then the corresponding positions of the array elements on its symmetric sub-array are T(X-x+1,y), T(x,Y-y+1), and T(X-x+1,Y-y+1).

[0025] Perform echo slant range traversal based on the positions of the imaging units in the imaging sub-region and the positions of the array elements in the sub-array on the entire array. According to the principle of spatial symmetry, obtain the result of echo slant range traversal of the entire imaging region by the entire array. Specifically:

[0026] Based on the positions of the imaging unit and the array element, calculate the distance L(P(m,n),T(x,y)) between P(m,n) and T(x,y). According to the principle of spatial symmetry, L(P(m,n),T(x,y)) = L(P(M-m+1,n),T(X-x+1,y)) = L(P(m,N-n+1),T(x,Y-y+1)) = L(P(M-m+1,N-n+1),T(X-x+1,Y-y+1)). That is, use the entire array to perform echo slant range traversal on an imaging sub-region. According to the principle of spatial symmetry, obtain the slant range traversal result of the entire imaging region by the entire array.

[0027] Process the obtained result of echo slant range traversal of the imaging region to obtain SAR imaging. Specifically:

[0028] Based on the obtained slant range traversal result of the entire imaging region by the entire array, obtain the two-way phase between the imaging unit and the antenna array element, Φ(P(m,n),T(x,y)), Φ(P(M-m+1,n),T(X-x+1,y)), Φ(P(m,N-n+1),T(x,Y-y+1)), Φ(P(M-m+1,N-n+1),T(X-x+1,Y-y+1)). After compensating the echo vector signal with the obtained two-way phase and performing coherent superposition, obtain SAR imaging. The expression is as shown in formula (3):

[0029]

[0030] A millimeter-wave near-field holographic fast imaging system based on spatial multiplexing, including: =

[0031] A first acquisition module, which performs range-direction FFT on the three-dimensional millimeter-wave echo matrix to extract two-dimensional millimeter-wave echo data;

[0032] A first division module, which divides an imaging area based on the acquired two-dimensional millimeter-wave echo data, obtains a plurality of imaging sub-areas, selects the positions of imaging units in a certain imaging sub-area, and obtains the corresponding positions of imaging units on the symmetric sub-area;

[0033] A second division module, which divides a radar array to obtain a plurality of sub-arrays, selects the positions of array elements in a certain sub-array, and obtains the corresponding positions of array elements on the symmetric sub-array;

[0034] An echo slant range traversal module, which traverses the echo slant range based on the full array for the positions of imaging units in the imaging sub-area and the positions of array elements in the sub-array, and obtains the result of the echo slant range traversal of the full array for the imaging area according to the principle of spatial symmetry;

[0035] A second acquisition module, which processes the obtained result of the echo slant range traversal of the imaging area to obtain SAR imaging.

[0036] A terminal device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the above method are implemented. =

[0037] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] By dividing the imaging area and the radar array, the present invention only needs to use the entire antenna array to traverse the slant range of a quarter of the imaging area, greatly reducing the imaging time. And because the same echo phase compensation method is adopted, the imaging quality of the present invention is exactly the same as that of the prior art. The present invention adopts the method of spatial symmetry multiplexing, significantly reducing the imaging time, and can also be used for imaging of a larger area. When there are requirements for imaging time, the method adopted by the present invention has low requirements for the array radar system, is easier to implement, and saves costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0041] Figure 1 Flow chart of the millimeter-wave near-field holographic fast imaging method based on spatial multiplexing of the present invention;

[0042] Figure 2 Another flow chart of the millimeter-wave near-field holographic fast imaging method based on spatial multiplexing of the present invention;

[0043] Figure 3 Schematic diagram of the relationship between the array and the imaging area of the present invention;

[0044] Figure 4 Schematic diagram of the block division of the array and the imaging area of the present invention;

[0045] Figure 5 Structure diagram of the millimeter-wave near-field holographic fast imaging system based on spatial multiplexing of the present invention. Detailed implementation manners

[0046] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0047] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

[0048] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0049] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention. In addition, terms such as "first", "second", etc. are only used for descriptive distinction and cannot be construed as indicating or implying relative importance.

[0050] In addition, when the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0051] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, when the terms "arranged", "installed", "connected", and "coupled" appear, they 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 directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0052] The present invention will be further described in detail below with reference to the accompanying drawings:

[0053] See Figure 1 and Figure 2 , the present invention discloses a millimeter-wave near-field holographic fast imaging method based on spatial multiplexing, including:

[0054] S101, performing range-direction FFT on the three-dimensional millimeter-wave echo matrix to extract two-dimensional millimeter-wave echo data.

[0055] For imaging an object at a distance of , let S(X, Y, t) be the three-dimensional echo data cube of the radar, and the expression is as shown in formula (1):

[0056]

[0057] where c is the speed of light, T is the duration of the transmitted signal, rect is the rectangular function, D x , D y are the lengths of the array in the azimuth direction and the height direction, X, Y are the positions of the radar array elements, f c is the carrier frequency, (x0, y0, z0) is the target position, and R is the distance from the array element to the target;

[0058] (x0, y0, z0) is the target position, σ(x0, y0, z0) is the corresponding scattering coefficient, R is the distance from the array element to the target, and the relationship between the array and the imaging area is as Figure 3 shown;

[0059] The three-dimensional volume target is composed of scattering points. Let (x, y, z) represent the position of any scattering point in the target area, and σ(x, y, z) is the corresponding scattering coefficient;

[0060]

[0061] Perform range FFT on the three-dimensional echo data cube S(X, Y, t) so that the target information is stacked in the range direction, and extract the two-dimensional millimeter-wave echo data S(X, Y) located at the range.

[0062] S102, based on the acquired two-dimensional millimeter-wave echo data, divide the imaging area to obtain several imaging sub-areas, select the position of the imaging unit in a certain imaging sub-area, and obtain the corresponding imaging unit position on the symmetric sub-area.

[0063] The size of the imaging area is M×N. Divide the imaging area into four equal parts to obtain four imaging sub-areas. Select an imaging sub-area. The position of the imaging unit in this imaging sub-area is P(m, n). Then the corresponding imaging unit positions on its symmetric areas are P(M - m + 1, n), P(m, N - n + 1), and P(M - m + 1, N - n + 1), as Figure 4 shown.

[0064] S103, divide the radar array to obtain several sub-arrays, select the position of the array element in a certain sub-array, and obtain the corresponding array element position on the symmetric sub-array.

[0065] The size of the radar array is X×Y. Divide the radar array into four equal parts to obtain four sub-arrays. Select a sub-array. The position of the array element in this sub-array is T1(x, y). Then the corresponding array element positions on its symmetric sub-arrays are T(X - x + 1, y), T(x, Y - y + 1), and T(X - x + 1, Y - y + 1).

[0066] S104, based on the full array, perform echo slant range traversal on the position of the imaging unit in the imaging sub-area and the position of the array element in the sub-array. According to the principle of spatial symmetry, obtain the result of echo slant range traversal of the full array for the imaging area.

[0067] Based on the position of the imaging unit and the position of the array element, calculate the distance L(P(m, n), T(x, y)) between P(m, n) and T(x, y). According to the principle of spatial symmetry, L(P(m, n), T(x, y)) = L(P(M - m + 1, n), T(X - x + 1, y)) = L(P(m, N - n + 1), T(x, Y - y + 1)) = L(P(M - m + 1, N - n + 1), T(X - x + 1, Y - y + 1)), that is, use the full array to perform echo slant range traversal on an imaging sub-area. According to the principle of spatial symmetry, obtain the slant range traversal result of the full array for the entire imaging area.

[0068] S105, process the obtained result of echo slant range traversal of the imaging area to obtain SAR imaging.

[0069] Based on obtaining the slant-range traversal results of the entire imaging area for the full array, the round-trip phase between the imaging unit and the antenna element, Φ(P(m,n),T(x,y)), Φ(P(M - m + 1,n),T(X - x + 1,y)), Φ(P(m,N - n + 1),T(x,Y - y + 1)), Φ(P(M - m + 1,N - n + 1),T(X - x + 1,Y - y + 1)) is obtained. After compensating the echo vector signal with the obtained round-trip phase and performing coherent superposition, SAR imaging is obtained; the expression is as shown in formula (3):

[0070]

[0071] See Figure 5 , the present invention discloses a millimeter-wave near-field holographic fast imaging system based on spatial multiplexing, including: =

[0072] The first acquisition module, the first extraction module performs range-direction FFT on the three-dimensional millimeter-wave echo matrix to extract two-dimensional millimeter-wave echo data;

[0073] The first division module, based on the obtained two-dimensional millimeter-wave echo data, divides the imaging area to obtain several imaging sub-areas, selects the position of the imaging unit in a certain imaging sub-area, and obtains the corresponding imaging unit position on the symmetric sub-area;

[0074] The second division module is used to divide the radar array to obtain several sub-arrays, select the position of the array element in a certain sub-array, and obtain the corresponding array element position on the symmetric sub-array;

[0075] The echo slant-range traversal module, based on the full array, performs echo slant-range traversal on the position of the imaging unit in the imaging sub-area and the position of the array element in the sub-array, and according to the spatial symmetry principle, obtains the result of the echo slant-range traversal of the full array for the imaging area;

[0076] The second acquisition module is used to process the obtained result of the echo slant-range traversal of the imaging area to obtain SAR imaging.

[0077] The following further illustrates the technical effects of the present invention through actual measurement data processing:

[0078] 1. Parameter conditions

[0079] Use the radar to receive the echo of the metal plate. On the computer, use MATLAB = R2020a software for imaging testing. The parameters of the millimeter-wave holographic imaging system are shown in Table 1:

[0080] Table 1 == Millimeter-wave holographic imaging system parameters

[0081] Target distance 0.28m Carrier frequency 7.7e10Hz Number of sampling points on the X-axis 407 Frequency modulation rate 6.3343e13 Number of sampling points on the Y-axis 101 Sampling frequency 9.121e7

[0082] 2. Experimental Content

[0083] Experiment 1: Under the parameters of the millimeter-wave holographic imaging system in Table 1, use the BP imaging algorithm to image the echo data.

[0084] Experiment 2: Under the parameters of the millimeter-wave holographic imaging system in Table 1, use the method of the present invention to image the echo data.

[0085] 3. Analysis of Simulation Results

[0086] Comparing the two experiments, it can be seen that the imaging effects of the background technology and the method of the present invention are exactly the same. The imaging time used by the background technology is 389 s, while the imaging time used by the present invention is only 129 s. This shows that the present invention not only ensures the same imaging quality without loss compared with the existing BP imaging algorithm, but also is very efficient, saving a large amount of time and solving the problem of huge time consumption in the background technology.

[0087] The terminal device provided by an embodiment of the present invention. The terminal device of this embodiment includes: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the above-mentioned various method embodiments are implemented. Alternatively, when the processor executes the computer program, the functions of each module / unit in the above-mentioned various device embodiments are implemented.

[0088] The computer program can be divided into one or more modules / units, and the one or more modules / units are stored in the memory and executed by the processor to complete the present invention.

[0089] The terminal device can be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The terminal device may include, but is not limited to, a processor and a memory.

[0090] The processor may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0091] The memory can be used to store the computer program and / or module. By running or executing the computer program and / or module stored in the memory, and by invoking the data stored in the memory, the processor implements various functions of the terminal device.

[0092] If the modules / units integrated in the terminal device are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, to implement all or part of the processes in the above-described embodiment methods of the present invention, it can also be completed by instructing relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps of the above various method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0093] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A millimeter-wave near-field holographic fast imaging method based on spatial multiplexing, characterized in that including: Performing range-direction FFT on the three-dimensional millimeter-wave echo matrix to extract two-dimensional millimeter-wave echo data; Based on the obtained two-dimensional millimeter-wave echo data, dividing the imaging region to obtain several imaging sub-regions, selecting the positions of imaging units in a certain imaging sub-region, and obtaining the corresponding positions of imaging units on the symmetric sub-region; Dividing the radar array to obtain several sub-arrays, selecting the positions of array elements in a certain sub-array, and obtaining the corresponding positions of array elements on the symmetric sub-array; Based on the full array, performing echo slant-range traversal on the positions of imaging units in the imaging sub-region and the positions of array elements in the sub-array, and according to the principle of spatial symmetry, obtaining the result of echo slant-range traversal of the full array for the imaging region; processing the obtained result of echo slant-range traversal of the imaging region to obtain SAR imaging.

2. The method for fast millimeter-wave near-field holographic imaging based on spatial multiplexing according to claim 1, wherein The performing range-direction FFT on the three-dimensional millimeter-wave echo matrix to extract two-dimensional millimeter-wave echo data is specifically as follows: Imaging is performed on an object at a distance of Let S(X, Y, t) be the three-dimensional echo data cube of the radar, and its expression is shown in formula (1): where c is the speed of light, T is the duration of the transmitted signal, rect is the rectangular function, D x , D y and D c are the lengths of the array in the azimuth and elevation directions, X, Y are the positions of the radar array elements, f is the carrier frequency, (x0, y0, z0) is the target position, and R is the distance from the array element to the target; For a volume target composed of scattering points, the position of any scattering point in the target region is represented by (x, y, z), and σ(x, y, z) is the corresponding scattering coefficient; Perform range FFT on the three-dimensional echo data cube S(X, Y, t) to stack the target information in the range dimension, and extract the two-dimensional millimeter-wave echo data S(X, Y) located at the range.

3. The method for fast millimeter-wave near-field holographic imaging based on spatial multiplexing according to claim 1, wherein The dividing the imaging region to obtain several imaging sub-regions, selecting the positions of imaging units in a certain imaging sub-region, and obtaining the corresponding positions of imaging units on the symmetric sub-region is specifically as follows: The size of the imaging region is M×N. Divide the imaging region into four equal parts to obtain four imaging sub-regions. Select one imaging sub-region. The position of the imaging unit in this imaging sub-region is P(m, n). Then the corresponding positions of the imaging units on its symmetric region are P(M - m + 1, n), P(m, N - n + 1), and P(M - m + 1, N - n + 1); The dividing the radar array to obtain several sub-arrays, selecting the positions of array elements in a certain sub-array, and obtaining the corresponding positions of array elements on the symmetric sub-array is specifically as follows: The size of the radar array is X×Y. Divide the radar array into four equal parts to obtain four sub-arrays. Select one sub-array. The position of the array element in this sub-array is T(x, y). Then the corresponding positions of the array elements on its symmetric sub-array are T(X - x + 1, y), T(x, Y - y + 1), and T(X - x + 1, Y - y + 1).

4. The method for fast millimeter-wave near-field holographic imaging based on spatial multiplexing according to claim 3, wherein The performing echo slant-range traversal on the positions of imaging units in the imaging sub-region and the positions of array elements in the sub-array based on the full array, and according to the principle of spatial symmetry, obtaining the result of echo slant-range traversal of the full array for the imaging region is specifically as follows: Based on the positions of the imaging unit and the array element, calculate the distance L(P(m, n), T(x, y)) between P(m, n) and T(x, y). According to the principle of spatial symmetry, L(P(m, n), T(x, y)) = L(P(M - m + 1, n), T(X - x + 1, y)) = L(P(m, N - n + 1), T(x, Y - y + 1)) = L(P(M - m + 1, N - n + 1), T(X - x + 1, Y - y + 1)), that is, using the full array to perform echo slant-range traversal on an imaging sub-region, and according to the principle of spatial symmetry, obtaining the slant-range traversal result of the full array for the entire imaging region.

5. The method for millimeter-wave near-field holographic rapid imaging based on spatial multiplexing according to claim 4, wherein Processing the obtained result of the slant-range traversal of the echo of the imaging area to obtain SAR imaging, specifically: Based on the obtained slant-range traversal result of the entire imaging area by the full array, obtain the round-trip phases between the imaging unit and the antenna elements, Φ(P(m,n),T(x,y)), Φ(P(M-m+1,n),T(X-x+1,y)), Φ(P(m,N-n+1),T(x,Y-y+1)), Φ(P(M-m+1,N-n+1),T(X-x+1,Y-y+1)). After compensating the echo vector signal with the obtained round-trip phases and performing coherent superposition, obtain SAR imaging; the expression is as shown in formula (3):

6. A millimeter-wave near-field holographic fast imaging system based on spatial multiplexing, characterized in that, Including: A first acquisition module, which performs range-direction FFT on the three-dimensional millimeter-wave echo matrix to extract two-dimensional millimeter-wave echo data; A first division module, which divides the imaging area based on the obtained two-dimensional millimeter-wave echo data to obtain a number of imaging sub-areas, selects the position of the imaging unit in a certain imaging sub-area, and obtains the corresponding imaging unit position in the symmetric sub-area; A second division module, which is used to divide the radar array to obtain a number of sub-arrays, selects the position of the element in a certain sub-array, and obtains the corresponding element position in the symmetric sub-array; An echo slant-range traversal module, which performs echo slant-range traversal based on the full array on the position of the imaging unit in the imaging sub-area and the position of the element in the sub-array, and obtains the result of the echo slant-range traversal of the full array on the imaging area according to the principle of spatial symmetry; A second acquisition module, which is used to process the obtained result of the echo slant-range traversal of the imaging area to obtain SAR imaging.

7. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1-5.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the method according to any one of claims 1-5.

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