Millimeter wave imaging method and device, security check method and security check system

Abstract

The invention provides a millimeter wave imaging method and device. The millimeter wave imaging method comprises the steps that a row of second millimeter wave receiving antennas located on the two sides of a detected object are configured to be in one-to-one correspondence with a row of first millimeter wave transmitting antennas, and local oscillator signals of the corresponding receiving antennas and carrier wave signals of the transmitting antennas are coherent in phase; enabling a row of second millimeter wave receiving antennas to receive the millimeter waves of the target group frequency transmitted to the inspected object by the row of first millimeter wave transmitting antennas so as to obtain target echo data; demodulating the target echo data by using the local oscillator signal of the receiving antenna and the phase coherent information to obtain target demodulated wave data including amplitude information and phase information; and constructing a transmission holographic image through a transmission holographic imaging algorithm based on the target demodulation wave data. The invention also provides a security check method and a security check system.

Description

Technical Field

[0001] The present invention relates to the field of security inspection technology, and in particular to a millimeter wave imaging method and device, a security inspection method, and a security inspection system. Background Art

[0002] Millimeter-wave security inspection equipment's wide inspection range, fast speed, excellent user experience, and contactless, digital operation make it an ideal choice for various smart security systems. In related technologies, millimeter-wave security inspections primarily use a millimeter-wave transmitting antenna to transmit millimeter waves toward the inspected object (such as the human body), and a millimeter-wave receiving antenna to receive the millimeter-wave signal reflected from the inspected object. Multiple transmitting and receiving antennas are deployed in the scanning area to provide coverage of the inspected object. The millimeter-wave signals from all receiving antennas are analyzed and reconstructed to obtain a millimeter-wave image of the inspected object. Based on this millimeter-wave image, it can be used to determine whether the inspected object contains prohibited items. However, this method can fail to clearly identify whether items are carried in certain areas (such as the sides of the body), which can easily lead to missed inspections. Summary of the Invention

[0003] In view of this, the present invention provides a millimeter wave imaging method and device that can improve the detection accuracy of parts such as the side of the human body, as well as a corresponding security inspection method and security inspection system.

[0004] According to a first aspect of an embodiment of the present invention, a millimeter wave imaging method is provided, the method comprising:

[0005] A row of first millimeter wave transmitting antennas in a first millimeter wave transceiver array are configured to transmit millimeter waves of a target group frequency toward the object to be inspected;

[0006] A row of second millimeter-wave receiving antennas of a second millimeter-wave transceiver array is configured to correspond one-to-one with the row of first millimeter-wave transmitting antennas, and the local oscillator signals of the corresponding receiving antennas and the carrier signals of the transmitting antennas are phase-coherent, so that the row of second millimeter-wave receiving antennas receives millimeter waves of the target group frequency to obtain target echo data; wherein the first millimeter-wave transceiver array and the second millimeter-wave transceiver array are located on both sides of the inspected object;

[0007] Demodulating the target echo data using the local oscillator signal of the row of second millimeter wave receiving antennas and the phase coherence information to obtain target demodulated wave data including amplitude information and phase information; and

[0008] A transmission holographic image of the inspected object is constructed based on the target demodulated wave data, the position information of the row of first millimeter wave transmitting antennas, and the position information of the row of second millimeter wave receiving antennas.

[0009] According to an embodiment of the present invention, configuring the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna to be phase-coherent includes: configuring the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna to be the same signal from the same frequency source.

[0010] According to an embodiment of the present invention, configuring the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna to be phase-coherent includes: configuring the local oscillator signal of the receiving antenna to include multiple signals obtained by subjecting the signal generated by the frequency source of the carrier signal of the corresponding transmitting antenna to multi-stage frequency conversion.

[0011] According to an embodiment of the present invention, configuring the phase coherence of the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna also includes: configuring the frequency conversion parameters of the multi-stage frequency conversion so that the multiple signals are phase coherent with the carrier signal of the corresponding transmitting antenna.

[0012] According to an embodiment of the present invention, the method of demodulating the target echo data using the local oscillator signal of the row of second millimeter-wave receiving antennas and the phase coherence information to obtain target demodulated wave data including amplitude information and phase information includes: obtaining the phase relationship between the multiple signals and the carrier signal of the corresponding transmitting antenna based on the frequency conversion parameters to obtain specific data of phase coherence; and in the process of demodulating the target echo data using the local oscillator signal of the row of second millimeter-wave receiving antennas, using the specific data of phase coherence as a compensation parameter to participate in data processing of the demodulation process.

[0013] According to an embodiment of the present invention, configuring the phase coherence of the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna includes: configuring the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna to be provided by different frequency sources respectively; and calibrating the phase relationship between the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna to obtain calibration data.

[0014] According to an embodiment of the present invention, the method of demodulating the target echo data using the local oscillator signal of the row of second millimeter-wave receiving antennas and the phase-coherent information to obtain target demodulated wave data including amplitude information and phase information includes: in the process of demodulating the target echo data using the local oscillator signal of the row of second millimeter-wave receiving antennas, using the calibration data as a compensation parameter to participate in data processing of the demodulation process.

[0015] According to an embodiment of the present invention, configuring a row of first millimeter-wave transmitting antennas of a first millimeter-wave transceiver array to transmit millimeter waves of a target group frequency toward the inspected object includes: configuring at least some of the transmitting antennas in the row of first millimeter-wave transmitting antennas to transmit millimeter waves of a frequency of the target group frequency toward the inspected object in a time sequence.

[0016] According to an embodiment of the present invention, configuring a row of second millimeter-wave receiving antennas in the second millimeter-wave transceiver array to correspond one-to-one with a row of first millimeter-wave transmitting antennas includes: configuring each receiving antenna in the row of second millimeter-wave receiving antennas to have the same operating frequency as one transmitting antenna in the row of first millimeter-wave transmitting antennas.

[0017] According to an embodiment of the present invention, the method further includes: controlling the row of first millimeter-wave transmitting antennas and the row of second millimeter-wave receiving antennas to move synchronously.

[0018] A second aspect of the embodiments of the present invention provides a security inspection method. The security inspection method includes:

[0019] Constructing a transmission holographic image of the inspected object using the millimeter wave imaging method provided in the first aspect above;

[0020] Configuring a row of first millimeter wave receiving antennas of the first millimeter wave transceiver array to correspond one-to-one with the row of first millimeter wave transmitting antennas to receive millimeter waves of a first group of frequencies transmitted by the row of first millimeter wave transmitting antennas toward the inspected object so as to construct a first reflection holographic image;

[0021] configuring a row of second millimeter wave receiving antennas of the second millimeter wave transceiver array to correspond one-to-one with the row of second millimeter wave transmitting antennas to receive millimeter waves of a second group of frequencies transmitted by the row of second millimeter wave transmitting antennas toward the inspected object so as to construct a second reflection holographic image; and

[0022] Based on the transmission holographic image, the first reflection holographic image, and the second reflection holographic image, it is determined whether the inspected object contains other items.

[0023] According to a third aspect of the embodiments of the present invention, a millimeter wave imaging device is provided, comprising: a first configuration module, a second configuration module, and a transmission holographic imaging module.

[0024] The first configuration module is used to configure a row of first millimeter-wave transmitting antennas of the first millimeter-wave transceiver array to transmit millimeter waves of a target group frequency toward the object to be inspected.

[0025] The second configuration module is used to configure a row of second millimeter-wave receiving antennas of the second millimeter-wave transceiver array to correspond one-to-one with the row of first millimeter-wave transmitting antennas, and the local oscillator signals of the corresponding receiving antennas and the carrier signals of the transmitting antennas are phase-coherent, so that the row of second millimeter-wave receiving antennas receives the millimeter waves of the target group frequency to obtain target echo data; wherein, the first millimeter-wave transceiver array and the second millimeter-wave transceiver array are located on both sides of the inspected object.

[0026] The transmission holographic imaging module is used to: demodulate the target echo data using the local oscillator signal of the row of second millimeter-wave receiving antennas and the phase coherence information to obtain target demodulated wave data including amplitude information and phase information; and construct a transmission holographic image of the inspected object based on the target demodulated wave data, the position information of the row of first millimeter-wave transmitting antennas, and the position information of the row of second millimeter-wave receiving antennas.

[0027] A fourth aspect of the present invention provides a security inspection system, comprising: one or more processors; and a memory for storing one or more computer programs. The one or more processors execute the one or more computer programs to implement the steps of the method provided in the first or second aspect.

[0028] According to a fifth aspect of an embodiment of the present invention, a computer-readable storage medium is provided, on which a computer program or instruction is stored. When the computer program or instruction is executed by a processor, the steps of the method provided in the first or second aspect are implemented.

[0029] According to a sixth aspect of an embodiment of the present invention, a computer program product is provided, comprising a computer program or instructions, which implement the steps of the method provided in the first or second aspect when executed by a processor.

[0030] One or more of the above embodiments have the following advantages or beneficial effects:

[0031] In some embodiments, by configuring the arrays on both sides of the inspected object, a row of transmitting antennas in the array on one side corresponds to a row of receiving antennas in the array on the other side, and the carrier signals of the transmitting antennas and the local oscillator signals of the receiving antennas are phase-coherent, so that not only the amplitude signal but also the phase information can be accurately demodulated from the target echo data received by the receiving antennas. This provides more detailed information for constructing a transmission holographic image of the inspected object. This technology is combined with the processing of the transmission holographic imaging algorithm, making the constructed transmission holographic image clearer than the image constructed by the transmission amplitude imaging algorithm, thereby more accurately detecting suspicious items on the side of the human body and improving the accuracy of security inspections.

[0032] In some embodiments, the reflected holographic image and the transmitted holographic image of the inspected object can also be combined to determine whether the inspected object contains other items. In this way, the inspected object (such as the human body) can be inspected in all directions, and suspicious items on the human body that are difficult to inspect because they absorb millimeter waves can be detected at the same time, providing convenient, fast and accurate inspection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0034] Figure 1 The schematic diagram of the millimeter wave reflection holographic imaging principle is shown;

[0035] Figure 2 A schematic diagram of distinguishing suspicious objects according to an embodiment of the present invention is shown;

[0036] Figure 3 A schematic diagram showing a millimeter wave imaging device to which the method according to an embodiment of the present invention can be applied;

[0037] Figure 4 A schematic diagram of the principle architecture of millimeter wave transmission holographic imaging according to an embodiment of the present invention is shown;

[0038] Figure 5 A flow chart of a millimeter wave imaging method according to an embodiment of the present invention is shown;

[0039] Figure 6 The present invention illustrates an operation flow for configuring the phase coherence of the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna in the millimeter wave imaging method according to an embodiment of the present invention;

[0040] Figure 7 The present invention shows an operation flow of configuring the phase coherence of the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna in the millimeter wave imaging method according to another embodiment of the present invention;

[0041] Figure 8 The present invention shows an operation flow of configuring the phase coherence of the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna in the millimeter wave imaging method according to another embodiment of the present invention;

[0042] Figure 9 A flow chart of a security inspection method according to an embodiment of the present invention is shown;

[0043] Figure 10 A schematic diagram of the working timing of a millimeter wave imaging device in a security inspection method according to an embodiment of the present invention is shown, which includes four groups of frequencies;

[0044] Figure 11 A schematic diagram of the working timing of a millimeter wave imaging device in a security inspection method according to another embodiment of the present invention is shown, which includes three groups of frequencies;

[0045] Figure 12 A block diagram of a millimeter wave imaging device according to an embodiment of the present invention is shown; and

[0046] Figure 13 A block diagram of a security inspection system according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0047] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concept of the present invention.

[0048] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0049] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having meanings consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner. The terms "first" and "second" are used herein solely for the purpose of terminology distinction and do not have a limiting meaning.

[0050] Millimeter waves have strong penetration capabilities through common clothing but have difficulty penetrating human skin, making low-power millimeter wave signals harmless. Human skin's reflectivity for millimeter waves is close to that of metal, resulting in a relatively high signal-to-noise ratio for millimeter wave signals reflected from the human surface. Furthermore, against a brightly lit human background, the outlines of low-brightness powdery and other suspicious objects stand out.

[0051] Millimeter-wave imaging can be categorized as active and passive. Passive millimeter-wave imaging does not transmit millimeter waves, but instead uses a receiving antenna to receive millimeter waves emitted by the object being examined, such as the human body. This offers the advantages of completely eliminating the need for millimeter waves and providing fast imaging speeds, but is relatively susceptible to environmental influences. Active millimeter-wave imaging uses a transmitting antenna to emit millimeter waves to illuminate an object, such as the human body, and a receiving antenna to receive the returned millimeter waves. This approach is relatively costly and requires a relatively long acquisition time, but is less susceptible to environmental influences and offers superior image quality. Active millimeter-wave imaging can achieve holographic imaging. "Holographic" refers to the complete information required to reconstruct an object's image, including amplitude and phase information. Millimeter-wave holographic imaging systems typically utilize arrays without lens-based focusing mechanisms, instead achieving focused imaging through signal processing algorithms. Millimeter-wave holographic imaging relies on heterodyne mixing technology, which measures complex signals containing both amplitude and phase information, rather than millimeter-wave intensity.

[0052] In the related technology, the active millimeter wave imaging solution mainly uses the antenna array on the same side to transmit millimeter waves and receive echo signals. Its principle architecture can be referred to Figure 1 For example, millimeter-wave transceiver antennas can be placed adjacent to each other and roughly considered to be in the same location. A pair of transceiver antennas is called a channel. For an array, the transceiver array includes a group of transceiver antenna pairs, for example, n pairs of transceiver antennas, that is, n channels. During the inspection, the first pair of transceiver antennas starts transmitting and receiving signals, for example, for a few milliseconds. Then, the second pair of transceiver antennas starts transmitting and receiving signals, for a few milliseconds. The n pairs of transceiver antennas work in sequence, completing a scan of the transceiver antenna array, where the transmitted signal is at a fixed frequency (so-called fixed-frequency scan). The transceiver antenna array can perform a second scan, similar to the first scan, but with the transmitted signal at another fixed frequency. The transceiver antenna array can perform multiple scans of a set of frequencies. The transmitting antenna emits millimeter waves that illuminate the imaging object. Each point on the object scatters the millimeter wave signal, and the scattered signal received by the receiving antenna will be the superposition of the scattered signals at various locations on the object's surface. By scanning the entire planar aperture, a holographic image of the object being measured can be obtained.

[0053] Since the human body has a strong reflectivity to millimeter waves, the human body as a whole appears bright in the image, while the space outside the human body (background) appears black. Items that the human body may carry will appear in different grayscales and shapes in the image, depending on their reflectivity and placement angles. These items can be distinguished by image recognition personnel or software against the bright background of the human body. However, some items have a strong absorption capacity for millimeter waves but a weak reflectivity. The grayscale of these items in the image is very close to that of the background. If these items are imaged in an area with the human body as the background, they can be distinguished. However, if these items are imaged outside the human body imaging area and within the background area, they cannot be distinguished (e.g. Figure 2 (As shown in the figure on the left in the middle.) In millimeter-wave imaging solutions where the antenna array transmits millimeter waves and receives echo signals on the same side, such background areas exist (different arrangements / scanning methods may result in different specific background area locations), such as the waist and shoulders. If such special objects are placed in these areas, they will not be distinguishable in the millimeter-wave image, resulting in missed detections.

[0054] The millimeter wave imaging method of the embodiment of the present invention can work through the cooperation of two-sided arrays. In addition to performing millimeter wave reflection imaging on the array on the same side, the characteristic that millimeter waves can penetrate clothing but not the human body can be utilized. The array on the opposite side receives the millimeter wave signal emitted by the other side. The complex signal containing amplitude and phase information collected on the opposite side is reconstructed using a transmission holographic imaging algorithm to obtain a transmission holographic image of the side of the human body. The transmission holographic image can clearly distinguish the contours of the body surface, such as Figure 2 As shown in the figure on the right, it is possible to determine whether there are any special items hidden on the side of the body. On this basis, combined with traditional millimeter wave reflection imaging, the recognition rate of suspects can be significantly improved.

[0055] The millimeter wave imaging device according to the embodiment of the present invention can have a variety of different transmission antenna / reception antenna arrangement scanning methods: one is to arrange multiple transmission antennas and reception antennas on a horizontal linear array, and then scan the entire array in the vertical direction to form coverage of the object to be inspected and then form an image (such as Figure 3 As shown in the figure); the second is to arrange multiple transmitting / receiving antennas in a vertical linear array, then rotate the entire array horizontally around the object being inspected to image the object; the third is to directly spread more transmitting / receiving antennas across an entire plane to form a planar array, eliminating the need for mechanical scanning and electronically scanning the object. Of course, there are many other millimeter-wave transmitting / receiving antenna arrangements and array scanning methods, such as arranging them in a vertical linear array for horizontal scanning, arranging them in a horizontal arc array (or zigzag array) for vertical scanning, and so on.

[0056] by Figure 3 For example, the millimeter wave imaging device according to an embodiment of the present invention may include two millimeter wave transceiver arrays, such as a first millimeter wave transceiver array 100 and a second millimeter wave transceiver array 200. The first millimeter wave transceiver array 100 and the second millimeter wave transceiver array 200 are arranged substantially opposite to each other and are located on both sides of the inspected object (e.g., a human body). For example, the area between the first millimeter wave transceiver array 100 and the second millimeter wave transceiver array 200 may be an inspection channel for the inspected object to pass through. In other embodiments, the millimeter wave imaging device may include more than two millimeter wave transceiver arrays. It is understood that Figure 3 The first millimeter wave transceiver array 100 is located on the back of the human body, while the second millimeter wave transceiver array 200 is located on the front side of the human body is only an example.

[0057] In some embodiments of the present invention, the first millimeter wave transceiver array 100 may include a row of first millimeter wave transmitting antennas 100T. The second millimeter wave transceiver array 200 may include a row of second millimeter wave receiving antennas 200R. The millimeter wave imaging device may be configured such that the second millimeter wave receiving antennas 200R receive millimeter waves transmitted by the first millimeter wave transmitting antennas 100T to construct a transmission holographic image of the object under inspection.

[0058] Specifically, the first millimeter wave transmitting antenna 100T transmits millimeter waves of a certain frequency, which are reflected by the human body or other inspected objects when passing through the inspection channel. If there are other objects, such as suspected objects, that absorb the millimeter waves, the second millimeter wave receiving antenna 200R will not receive the millimeter waves reflected by the human body or other inspected objects and the millimeter waves absorbed by the suspected objects. In this way, the outlines of the human body and the suspected objects will appear in the transmission holographic image, as shown in FIG. Figure 2 As shown in the figure, the millimeter wave signal cannot be detected in the projection area blocked by the human body, other inspected objects, or suspected objects. The millimeter wave signal can only be detected in areas outside the edges of the human body or object. For example, if a suspected object is located next to the human body, the suspected object will absorb or reflect the millimeter wave to a certain extent, causing the edge of the human body outline in the transmission holographic image to appear raised, allowing the suspected object located next to the human body to be quickly identified.

[0059] The first millimeter wave transceiver array 100 further includes a row of first millimeter wave receiving antennas 100R, and the second millimeter wave transceiver array 200 further includes a row of second millimeter wave transmitting antennas 200T. Accordingly, in some embodiments, similar to the manner in which a row of first millimeter wave transmitting antennas 100T transmit millimeter waves, which are then received by the second millimeter wave receiving antennas 200R after being transmitted through the inspection channel, the millimeter wave imaging device can also be configured such that the first millimeter wave receiving antennas 100R receive the millimeter waves transmitted by the second millimeter wave transmitting antennas 200T to construct another transmission holographic image of the inspected object. In this way, the millimeter wave imaging device can construct transmission holographic images from both sides.

[0060] According to an embodiment of the present invention, the millimeter wave signal transmitted through the inspection channel by the first millimeter wave transmitting antenna 100T is received by the second millimeter wave receiving antenna 200R, or the millimeter wave signal transmitted through the inspection channel by the second millimeter wave transmitting antenna 200T is received by the first millimeter wave receiving antenna 100R. Amplitude and phase information are extracted from the received millimeter wave signal, and a transmission holographic image of the inspected object is constructed according to a transmission holographic imaging algorithm. Because the resulting projection hologram utilizes not only the amplitude information of the detection signal but also the phase information, the image is clearer, clearly displaying the outline of suspected objects at the edges of the inspected object (e.g., located to the side of a person's body) after being obscured. This effectively avoids the inability to detect suspected objects located to the side of a person's body, as is often the case with related technologies, and reduces the rate of missed detections.

[0061] In other embodiments of the present invention, the first millimeter wave transceiver array 100 can also be configured so that each receiving antenna in a row of first millimeter wave receiving antennas 100R corresponds one-to-one with a transmitting antenna in a row of first millimeter wave transmitting antennas 100T, so as to respectively receive the millimeter waves transmitted by the row of first millimeter wave transmitting antennas 100T to construct a first reflected holographic image. Similarly, the second millimeter wave transceiver array 200 can also be configured so that each receiving antenna in a row of second millimeter wave receiving antennas 200R corresponds one-to-one with a transmitting antenna in a row of second millimeter wave transmitting antennas 200T, so as to respectively receive the millimeter waves transmitted by the row of second millimeter wave transmitting antennas 200T to construct a second reflected holographic image. In an embodiment of the present invention, the first millimeter wave transceiver array 100 is configured to transmit millimeter waves toward an inspected object on an inspection channel and receive reflected millimeter waves to construct a first holographic image of the inspected object, and the second millimeter wave transceiver array 200 is configured to transmit millimeter waves of different frequencies toward an inspected object on an inspection channel and receive reflected millimeter waves to construct a second holographic image of the inspected object.

[0062] In other embodiments of the present invention, the first millimeter wave transceiver array 100 or the second millimeter wave transceiver array 200 may include more than one row of millimeter wave transmitting antennas and more than one row of first millimeter wave receiving antennas.

[0063] Accordingly, in embodiments of the present invention, the first holographic image, the second holographic image, and at least one transmission holographic image of the inspected object can be combined to determine whether the inspected object contains other items. This allows for a comprehensive inspection of an inspected object, such as a human body, and can also detect suspected items on the human body that are difficult to detect due to their millimeter wave absorption, providing convenient, fast, and accurate inspection results.

[0064] According to an embodiment of the present invention, the receiving antennas of a row of millimeter-wave receiving antennas T correspond one-to-one with the transmitting antennas of a row of millimeter-wave transmitting antennas R to respectively receive the millimeter waves transmitted by the millimeter-wave transmitting antennas. For example, each millimeter-wave transmitting antenna of a row of millimeter-wave transmitting antennas is paired with the closest millimeter-wave receiving antenna, and the paired transmitting antenna and receiving antenna start working at the same time, thereby ensuring that the receiving antenna receives the millimeter-wave signal transmitted by the paired transmitting antenna, rather than the millimeter-wave signal transmitted by other transmitting antennas.

[0065] Next, refer to Figure 1 and Figure 4 To illustrate the principles of millimeter wave reflection holography and millimeter wave transmission holography. It should be noted that the derivation of the following principles is based on the processing of a single antenna unit. Figure 1 and Figure 4 The antenna units forming a planar array in the example are only for illustration purposes. The same principle also applies to antenna units forming a planar array. Figure 3 The situation of the array shown.

[0066] refer to Figure 1 , assuming the antenna array is On the plane, the position of a single antenna unit is ( ), the position of any point to be detected in the target area is , then the distance between the antenna unit and the point to be detected is:

[0067] (1)

[0068] use Indicates the point to be detected in the target area The millimeter wave scattering rate, for continuous targets, the scattered echo signal collected by the antenna unit (receiving antenna) is the integral sum of the echo signals of all scattering points within the illumination range. If the operating frequency of the transmitted broadband millimeter wave signal is , assuming that the amplitude of the transmitted signal is unity and the initial phase is zero, the scattered signal received by the receiving antenna is as follows:

[0069] (2)

[0070] After processing, it can be expressed as follows (3) and (4):

[0071] (3)

[0072] (4)

[0073] in, is the reconstructed 3D holographic data, The middle edge of the reconstructed 3D holographic data Direction of a certain layer data, are echo signals sampled at different positions, is the horizontal sampling position, is the vertical sampling position, is the frequency of electromagnetic waves. middle, is a natural constant, is the imaginary unit, is the wave number, and Wave number exist and The components in two directions, is the distance from the antenna array to the imaging center. is the three-dimensional inverse Fourier transform, is the two-dimensional Fourier transform, is the interpolation operator, The speed of light.

[0074] refer to Figure 4 Let's introduce the principle of transmission holographic imaging. Transmission holographic imaging involves the position parameters of the transmitting antenna ( ), receiving antenna position parameters ( ), here we use It represents the scattering rate of the object in the detection interval obtained by the transmission holographic imaging algorithm. The resulting image is the object scattering rate image as shown in formula (5):

[0075] (5)

[0076] in, is the target echo data, It is a transmission holographic algorithm. It should be noted that the object scattering rate during transmission imaging is Object scattering rate during reflection imaging is the value of the object scattering rate at different angles. Therefore, in this paper, for the transmission imaging process, To represent the object scattering rate.

[0077] The transmission imaging in the embodiment of the present invention uses a transmission holographic imaging algorithm. Compared with the transmission amplitude imaging algorithm in related technologies, the resulting image is clearer. Specifically, when constructing an image of the inspected object using the transmission amplitude imaging algorithm, only the amplitude information in the echo data is extracted, and phase information is not involved. There is no need to inversely solve the object scattering coefficient. , imaging is performed only by the amplitude of the received signal.

[0078] For example, the signal received by the receiving antenna during transmission amplitude imaging The relationship with the object scattering rate is shown in formula (6):

[0079] (6)

[0080] in, , only the amplitude signal is taken during imaging, no phase information is involved, and no inverse is required Imaging can be performed only by the amplitude of the received signal. The imaging result is shown in formula (7):

[0081] (7)

[0082] By comparison, transmission holographic imaging requires not only the amplitude information of the detection signal but also its phase information. Furthermore, the scattering rate of the object in the detection interval must be inversely calculated during imaging to obtain transmission holographic imaging. This shows that transmission holographic imaging can utilize more information from the signal collected by the antenna unit and construct an image through more detailed processing. The resulting transmission holographic image is clearer than that created by the transmission amplitude imaging algorithm, enabling more accurate detection of suspicious objects on the side of the human body and improving security inspection accuracy.

[0083] Figure 5 A flow chart of a millimeter wave imaging method according to an embodiment of the present invention is shown.

[0084] like Figure 5 As shown, the millimeter wave imaging method according to the embodiment of the present invention may include operations S501 to S504. The method may be applied to Figure 3 The millimeter wave imaging device shown in the figure can construct a transmission holographic image of the object under inspection by this method. Figure 3 The instructions are as follows,

[0085] In operation S501 , a row of first millimeter wave transmitting antennas 100T of the first millimeter wave transceiver array 100 is configured to transmit millimeter waves of a target group frequency toward an object under inspection.

[0086] In operation S502, a row of second millimeter-wave receiving antennas 200R of the second millimeter-wave transceiver array 200 is configured to correspond one-to-one with a row of first millimeter-wave transmitting antennas 100T, and the local oscillator signals of the row of second millimeter-wave receiving antennas 200R and the carrier signals of the row of first millimeter-wave transmitting antennas 100T are phase-coherent, so that the row of second millimeter-wave receiving antennas 200R receives the millimeter waves of the target group frequency transmitted by the row of first millimeter-wave transmitting antennas 100T to the inspected object to obtain target echo data; wherein, the first millimeter-wave transceiver array 100 and the second millimeter-wave transceiver array 200 are located on both sides of the inspected object.

[0087] According to an embodiment of the present invention, applying a transmission holographic imaging algorithm to acquire a transmission holographic image of an inspected object requires adding linked operations to the integrated front-ends of the arrays on both sides of the millimeter-wave imaging device, synchronizing the electronic scanning and mechanical scanning (mechanical scanning is not required if the millimeter-wave imaging device is a planar array) of the antenna arrays on both sides. Furthermore, a portion of time is added to the frequency sweep process to ensure that the antenna arrays on both sides operate at the same frequency. During the scanning process, at least some of the transmitting antennas in a row of first millimeter-wave transmitting antennas 100T sequentially transmit millimeter waves at a frequency of a target group toward the inspected object. Simultaneously, corresponding receiving antennas in a row of second millimeter-wave receiving antennas 200R receive the millimeter waves transmitted through the inspection channel to obtain target echo data.

[0088] Transmission holographic imaging requires that the detection millimeter wave signals of the front-end of the array integration on both sides be phase-coherent. There are two methods for phase coherence. One is the carrier signal f of the transmitting antenna. t and the local oscillator signal f of the receiving antenna L Provided by the same frequency source as below Figure 6 or Figure 7 As shown; One is that the antennas on both sides are provided by different frequency sources, but each time the frequency is re-established, both sides must be calibrated, and the calibration data is used as compensation parameters and brought into the data processing, as shown below Figure 8 shown.

[0089] In operation S503, the target echo data is demodulated using the local oscillation signal of the row of second millimeter wave receiving antennas 200R and the phase coherence information to obtain target demodulated wave data including amplitude information and phase information.

[0090] In operation S504, a transmission holographic image of the inspected object is constructed by a transmission holographic imaging algorithm based on the target demodulated wave data, position information of a row of first millimeter wave transmitting antennas 100T, and position information of a row of second millimeter wave receiving antennas.

[0091] For example, the first millimeter wave transmitting antenna 100T transmits millimeter waves f t When the object under inspection is illuminated and carrying a suspected item, the signal is scattered to the opposite side and received by the second millimeter wave receiving antenna 200R as a millimeter wave signal fr. Millimeter waves can penetrate clothing but not the human body. The local oscillator signal f of the second millimeter wave receiving antenna 200R is used. L Demodulate the received signal f r , a complex signal containing phase information and amplitude information is obtained. The transmission holographic image of the object under inspection is constructed by the transmission holographic imaging algorithm shown in formula (5). Among them, obtaining the transmission holographic image of the object under inspection requires the local oscillator signal f of the receiving antenna to be received. L The carrier signal f tIt must be coherent so that the phase information of the detection interval can be obtained.

[0092] Figure 6 The present invention shows an operation flow of configuring one-to-one correspondence between the local oscillator signal of the receiving antenna and the phase coherence of the carrier signal of the transmitting antenna in the millimeter wave imaging method according to an embodiment of the present invention.

[0093] like Figure 6 As shown, according to this embodiment, operation S502 may specifically include operation S512.

[0094] Specifically, in operation S512, the local oscillator signals of the second millimeter wave receiving antenna 200R in a row and the carrier signals of the first millimeter wave transmitting antenna 100T in a row are configured to be the same signal from the same frequency source. In this embodiment, the local oscillator signals f of the corresponding receiving antennas in the two arrays are the same signal from the same frequency source. L The carrier signal f t Provided by the same frequency source, wherein the signal generated by the same frequency source is simultaneously provided to the corresponding transmitting antenna and receiving antenna in the arrays on both sides, so that the signals of the corresponding transmitting antenna and receiving antenna can be guaranteed to be correlated in real time.

[0095] Figure 7 The diagram shows an operation flow of configuring phase coherence of a local oscillator signal of a receiving antenna and a carrier signal of a transmitting antenna in a one-to-one correspondence in a millimeter wave imaging method according to another embodiment of the present invention.

[0096] like Figure 7 As shown, according to this embodiment, operation S502 includes operations S5221 to S5222.

[0097] In operation S5221, local oscillation signals of receiving antennas of a row of second millimeter wave receiving antennas 200R include multiple signals obtained by performing multi-stage frequency conversion on signals generated by frequency sources of carrier signals of corresponding transmitting antennas.

[0098] In one embodiment, the frequency conversion parameters may be configured so that the multiple signals obtained by the frequency conversion are phase-coherent with the carrier signal of the transmitting antenna corresponding to the receiving antenna.

[0099] Specifically, according to this embodiment, the local oscillator signals f of the corresponding receiving antennas in the two side arrays are L The carrier signal f t From the same frequency source, but the local oscillator signal to the receiving antenna can be combined with the carrier signal f t The same signal can be divided into f after two frequency conversions. L1 and f L2Two levels, in which the frequency conversion parameters must be set to ensure that the information after frequency conversion is consistent with the carrier signal f t Phase coherence. This ensures that the signals from the corresponding transmitting antenna and receiving antenna are coherent.

[0100] In operation S5222, the phase relationship between a plurality of local oscillator signals of the receiving antennas of a row of second millimeter wave receiving antennas 200R and the carrier signals of the corresponding transmitting antennas is obtained to obtain specific data of phase coherence.

[0101] In this way, in the process of demodulating the target echo data using the local oscillator signal of a row of second millimeter wave receiving antennas 200R in operation S504, the specific data of the phase coherence can be used as a compensation parameter to participate in the data processing of the demodulation process, so that the phase information can be demodulated.

[0102] Figure 8 The present invention shows an operation flow of configuring phase coherence of a local oscillator signal of a receiving antenna and a carrier signal of a transmitting antenna in a millimeter wave imaging method according to another embodiment of the present invention;

[0103] like Figure 8 As shown, according to this embodiment, operation S502 may include operations S5321 to S5322.

[0104] In operation S5321, local oscillation signals for a row of second millimeter wave receiving antennas 200R and carrier signals for a row of first millimeter wave transmitting antennas 100T are provided by different frequency sources.

[0105] In operation S5322, the phase relationship between the local oscillator signal of the receiving antenna in the row of the second millimeter wave receiving antenna 200R and the carrier signal of the transmitting antenna corresponding to the receiving antenna in the row of the first millimeter wave transmitting antenna 100T is calibrated to obtain calibration data.

[0106] Specifically, when the signals from the corresponding receiving antennas and transmitting antennas in the two arrays are provided by different frequency sources, calibration must be performed on both sides at each re-established frequency, with the calibration data used as compensation parameters. Thus, in operation S504, when the target echo data is demodulated using the local oscillator signal from the second row of millimeter-wave receiving antennas 200R, the calibration data is used as compensation parameters in the data processing of the demodulation process, thereby enabling demodulation to obtain phase information.

[0107] Figure 9 A flow chart of a security inspection method according to an embodiment of the present invention is shown.

[0108] like Figure 9 As shown, the security inspection method 900 according to the embodiment of the present invention may include operations S901 to S904.

[0109] In operation S901 , a transmission holographic image of an inspected object is constructed using the millimeter wave imaging method described above.

[0110] In operation S902, a row of first millimeter wave receiving antennas 100R of the first millimeter wave transceiver array 100 is configured to correspond one-to-one with a row of first millimeter wave transmitting antennas 100T to receive millimeter waves of a first group of frequencies transmitted by the row of first millimeter wave transmitting antennas 100T toward the inspected object to construct a first reflection holographic image.

[0111] In operation S903, a row of second millimeter wave receiving antennas 200R of the second millimeter wave transceiver array 200 is configured to correspond one-to-one with a row of second millimeter wave transmitting antennas 200T to receive millimeter waves of a second set of frequencies transmitted by the row of second millimeter wave transmitting antennas 200T toward the inspected object to construct a second reflection holographic image.

[0112] In operation S904, it is determined whether the inspected object contains other items based on the transmission holographic image, the first reflection holographic image, and the second reflection holographic image.

[0113] In this embodiment, by combining the transmission holographic image, the first reflection holographic image and the second reflection holographic image, it is possible to more accurately detect whether the inspected object (such as a human body) contains other items, effectively reducing missed detections. Specifically, the transmitting antenna and the receiving antenna of the first holographic image and the second holographic image are on the same side, detecting the signal returned by the inspected object, and the imaging effect is clear for the parts of the human body that are parallel to or at a small angle to the antenna array. The imaging effect is poor for the parts of the human body that are on the side or at a large angle, or it is completely impossible to image, such as the shoulders and side waist of the human body. The transmitting antenna and the receiving antenna of the transmission holographic image are respectively on the front and back sides of the human body, which can well detect the parts that pass through the unreflected area of ​​the human body. The two complement each other to obtain a more complete detection effect (such as Figure 2 (as shown in the middle right image).

[0114] Below Figure 10 and Figure 11 A specific scanning operation of the millimeter wave imaging device according to an embodiment of the present invention is described in the example.

[0115] by Figure 3 Taking the millimeter wave imaging device shown as an example, a first millimeter wave transceiver array 100 and a second millimeter wave transceiver array 200 are arranged opposite each other. The first and second millimeter wave transceiver arrays 100 and 200 move simultaneously and perform scanning synchronously. The following description assumes that the first millimeter wave transceiver array 100 is the master and the second millimeter wave transceiver array 200 is the slave.

[0116] In one embodiment, the transmit frequency and the receive frequency may be as follows: Figure 10As shown, four groups of frequency millimeter waves are emitted.

[0117] During the time period t0 to t1, the first millimeter wave transmitting antenna 100T transmits millimeter waves of the first frequency group, wherein during the time period T 1-1 , the first millimeter wave transmitting antenna 100T transmits a millimeter wave of the first frequency of the first group of frequencies; at T 1-2 , the second first millimeter wave transmitting antenna 100T transmits a millimeter wave of a second frequency of the first frequency group; ... at T 1-m , the mth first millimeter wave transmitting antenna 100T transmits the millimeter wave of the mth frequency of the first group of frequencies. At the same time, the first millimeter wave receiving antenna 100R receives the millimeter wave of the first group of frequencies, wherein at T 1-1 , the first first millimeter wave receiving antenna 100R receives the millimeter wave of the first frequency of the first group of frequencies; at T 1-2 , the second first millimeter wave receiving antenna 100R receives the millimeter wave of the second frequency of the first frequency group; ... at T 1-m , the mth first millimeter wave receiving antenna 100R receives the millimeter wave of the mth frequency of the first frequency group. The first holographic image is constructed through the above operations.

[0118] At the same time, in the time period t0 to t1, the second millimeter wave transmitting antenna 200T transmits millimeter waves of the second frequency group, wherein at T 2-1 , the first second millimeter wave transmitting antenna 200T transmits the millimeter wave of the first frequency of the second group of frequencies; at T 2-2 , the second millimeter wave transmitting antenna 200T transmits a millimeter wave of a second frequency of a second group of frequencies; ... at T 2-m , the mth second millimeter wave transmitting antenna 200T transmits the millimeter wave of the mth frequency of the second group of frequencies. At the same time, the second millimeter wave receiving antenna 200R receives the millimeter wave of the second group of frequencies, wherein at T 2-1 , the first second millimeter wave receiving antenna 200R receives the millimeter wave of the first frequency of the second group of frequencies; at T 2-2 , the second second millimeter wave receiving antenna 200R receives the millimeter wave of the second frequency of the second group of frequencies; ... at T 2-m The m-th second millimeter wave receiving antenna 200R receives the millimeter wave of the m-th frequency of the second frequency group. The second holographic image is constructed through the above operations.

[0119] During the time period t1 to t2, the first millimeter wave transmitting antenna 100T transmits millimeter waves of the third frequency group, wherein during the time period T 3-1, the first (for a row of millimeter wave transceiver arrays, it can also be the m+1th, at this time a row scan completes the transmission of the first group of frequencies and the third group of frequencies in sequence) first millimeter wave transmitting antenna 100T transmits the first frequency of the third group of frequencies; at T 3-2 , the second first millimeter wave transmitting antenna 100T transmits a millimeter wave of a second frequency of the third frequency group; ... at T 3-n , the nth first millimeter wave transmitting antenna 100T transmits the millimeter wave of the nth frequency of the third group of frequencies. At the same time, the second millimeter wave receiving antenna 200R can be operated to receive the millimeter wave of the third group of frequencies, wherein R 3-1 , the first second millimeter wave receiving antenna 200R receives the millimeter wave of the first frequency of the third group of frequencies; 3-2 , the second second millimeter wave receiving antenna 200R receives the millimeter wave of the second frequency of the third frequency group; ... at R 3-m , the mth second millimeter wave receiving antenna 200R receives the millimeter wave of the mth frequency of the third frequency group. Through the above operation, the first transmission holographic image is obtained.

[0120] In such Figure 10 In the embodiment shown, during the time period t1 to t2, the second millimeter wave transmitting antenna 200T transmits millimeter waves of the fourth frequency group, wherein during the time period T 4-1 , the first second millimeter wave transmitting antenna 200T transmits the millimeter wave of the first frequency of the fourth group of frequencies; at T 4-2 , the second second millimeter wave transmitting antenna 200T transmits the millimeter wave of the second frequency of the fourth frequency group; ... at T 4-n , the nth second millimeter wave transmitting antenna 200T transmits the millimeter wave of the nth frequency of the fourth group of frequencies. At the same time, the first millimeter wave receiving antenna 100R can be operated to receive the millimeter wave of the fourth group of frequencies, wherein R 4-1 , the first first millimeter wave receiving antenna 100R receives the millimeter wave of the first frequency of the fourth group of frequencies; 4-2 , the second first millimeter wave receiving antenna 100R receives the millimeter wave of the second frequency of the fourth frequency group; ... at R 4-m , the mth first millimeter wave receiving antenna 100R receives the millimeter wave of the mth frequency of the fourth frequency group. Through the above operation, a second transmission holographic image is obtained.

[0121] In another embodiment of the present invention, during the time period t0 to t1, the first millimeter wave transmitting antenna 100T transmits a millimeter wave of one frequency in the first group of frequencies, and a row of the first millimeter wave transmitting antennas 100T at T 1-1 、T 1-2 ,…T 1-mThe millimeter wave of the frequency is transmitted in sequence, and the echo signal is received in sequence through the receiving antenna; in the time period t1~t2, the first millimeter wave transmitting antenna 100T transmits a millimeter wave of a frequency in the third group of frequencies, and a row of the first millimeter wave transmitting antennas 100T are at T 3-1 、T 3-2 ,…T 3-m Millimeter waves of this frequency are sequentially transmitted. Correspondingly, the second millimeter-wave receiving antenna 200R receives the millimeter waves transmitted through the inspection channel, generating a transmission holographic image. Similarly, the second millimeter-wave transmitting antenna 200T performs a similar scan, with the 1-m transmitting antennas transmitting millimeter waves of the same (fixed) frequency, but at a different frequency than the millimeter waves transmitted by the first millimeter-wave transmitting antenna 100T.

[0122] In such Figure 11 In the embodiment shown, other parts are Figure 10 The same as the embodiment shown, in the time period t1 to t2, the second millimeter wave transmitting antenna 200T and the first millimeter wave receiving antenna 100R are turned off. At this time, no second transmission holographic image is obtained.

[0123] After the scan is complete, obtain Figure 10 The four groups of valid echo data shown, or Figure 11 Three sets of valid echo data are shown.

[0124] by Figure 10 Taking the embodiment shown in the figure as an example, the four sets of valid echo data obtained are respectively denoted as S 1 (first group of frequencies), S 2 (second frequency group), S 3 (third frequency group), S 4 (the fourth frequency group). Among them, the scattered wave S is transmitted and received on the same side. 1 and S 2 Use traditional calibration methods to calibrate, such as using a standard object as a reference to calibrate the transmit and receive channels. 3 and S 4 , using synchronous real-time self-calibration, such as calibrating the transmit and receive channels based on the position of the transmit and receive arrays, to ensure the amplitude and phase consistency of each transmit and receive channel.

[0125] Targeting S 1 and S 2 , through the millimeter wave reflection holographic imaging algorithm, the first holographic image and the second holographic image are constructed using formula (3) or formula (4).

[0126] Targeting S 3 and S 4,Through the millimeter wave transmission holographic imaging algorithm, the first transmission holographic image and the second transmission holographic image are constructed using formula (5).

[0127] Figure 12 FIG. 1 is a block diagram of a millimeter wave imaging device 1200 according to an embodiment of the present invention. The millimeter wave imaging device 1200 may be arranged in a Figure 3 In the millimeter wave imaging device shown.

[0128] like Figure 12 As shown, the millimeter wave imaging device 1200 may include a first configuration module 1210 , a second configuration module 1220 and a transmission holographic imaging module 1230 .

[0129] The first configuration module 1210 is used to configure a row of first millimeter wave transmitting antennas 100T of the first millimeter wave transceiver array 100 to transmit millimeter waves of a target group frequency toward the inspected object. In one embodiment, the first configuration module 1210 may perform the operation S501 described above.

[0130] The second configuration module 1220 is configured to configure a one-to-one correspondence between a row of second millimeter-wave receiving antennas 200R of the second millimeter-wave transceiver array 200 and a row of first millimeter-wave transmitting antennas 100T, with the local oscillator signals of the row of second millimeter-wave receiving antennas 200R and the carrier signals of the row of first millimeter-wave transmitting antennas 100T being phase-coherent, so that the row of second millimeter-wave receiving antennas 200R receives millimeter waves of the target group frequency transmitted by the row of first millimeter-wave transmitting antennas 100T toward the inspected object to obtain target echo data. In one embodiment, the second configuration module 1220 may perform operation S502 described above.

[0131] The transmission holographic imaging module 1230 is configured to: demodulate the target echo data using the local oscillator signals from the row of second millimeter-wave receiving antennas 200R and the phase coherence information to obtain target demodulated wave data including amplitude and phase information; and construct a transmission holographic image of the inspected object using a transmission holographic imaging algorithm based on the target demodulated wave data, the position information of the row of first millimeter-wave transmitting antennas 100T, and the position information of the row of second millimeter-wave receiving antennas 200R. In one embodiment, the transmission holographic imaging module 1230 may perform operations S503 and S504 described above.

[0132] According to other embodiments of the present invention, the millimeter wave imaging device 1200 may further include a security inspection module. The security inspection module is configured to: configure a row of first millimeter wave receiving antennas 100R of the first millimeter wave transceiver array 100 in one-to-one correspondence with a row of first millimeter wave transmitting antennas 100T to receive millimeter waves of a first set of frequencies transmitted by the row of first millimeter wave transmitting antennas 100T toward the inspected object to construct a first reflection holographic image; configure a row of second millimeter wave receiving antennas 200R of the second millimeter wave transceiver array 200 in one-to-one correspondence with a row of second millimeter wave transmitting antennas 200T to receive millimeter waves of a second set of frequencies transmitted by the row of second millimeter wave transmitting antennas 200T toward the inspected object to construct a second reflection holographic image; and determine whether the inspected object contains other items based on the first reflection holographic image, the second reflection holographic image, and the transmission holographic image.

[0133] The millimeter wave imaging device 1200 can perform reference Figure 5 or Figure 9 The methods introduced here can be found in the previous article and will not be described in detail here.

[0134] According to embodiments of the present invention, any multiple modules among the first configuration module 1210, the second configuration module 1220, the transmission holographic imaging module 1230, and the security inspection module can be combined into a single module, or any one of these modules can be split into multiple modules. Alternatively, at least part of the functionality of one or more of these modules can be combined with at least part of the functionality of other modules and implemented in a single module. According to embodiments of the present invention, at least one of the first configuration module 1210, the second configuration module 1220, the transmission holographic imaging module 1230, and the security inspection module can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application-specific integrated circuit (ASIC), or can be implemented in hardware or firmware through any other reasonable means of circuit integration or packaging, or can be implemented in any one of software, hardware, and firmware, or any appropriate combination of these. Alternatively, at least one of the first configuration module 1210, the second configuration module 1220, the transmission holographic imaging module 1230 and the security inspection module can be at least partially implemented as a computer program module, and when the computer program module is executed, the corresponding function can be performed.

[0135] Figure 13 A block diagram of a security inspection system 1300 according to an embodiment of the present invention is shown. Figure 13 The security inspection system shown is only an example and should not limit the functions and scope of use of the embodiments of the present invention.

[0136] like Figure 13 As shown, the security inspection system 1300 includes a processor 1310, a computer readable storage medium 1320, and a millimeter wave imaging device 1330. The millimeter wave imaging device 1330 may be Figure 3 The millimeter wave imaging device shown in FIG. 1300 can execute the method according to the embodiment of the present invention.

[0137] Specifically, the processor 1310 may include, for example, a general-purpose microprocessor, an instruction set processor and / or a related chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 1310 may also include onboard memory for cache purposes. The processor 1310 may be a single processing unit or multiple processing units for executing different actions of the method flow according to an embodiment of the present invention.

[0138] The computer-readable storage medium 1320 may be, for example, a non-volatile computer-readable storage medium, specific examples of which include but are not limited to: a magnetic storage device, such as a magnetic tape or a hard disk (HDD); an optical storage device, such as a compact disc (CD-ROM); a memory, such as a random access memory (RAM) or a flash memory; and the like.

[0139] The computer-readable storage medium 1320 may include a computer program 1321 , which may include code / computer-executable instructions that, when executed by the processor 1310 , cause the processor 1310 to perform a method according to an embodiment of the present invention or any variation thereof.

[0140] Computer program 1321 may be configured to include computer program code, for example, including computer program modules. For example, in an exemplary embodiment, the code in computer program 1321 may include one or more program modules, such as 1321A, module 1321B, etc. It should be noted that the division method and number of modules are not fixed, and those skilled in the art may use appropriate program modules or combinations of program modules according to actual circumstances. When these program module combinations are executed by processor 1310, processor 1310 may perform the method according to an embodiment of the present invention or any variation thereof.

[0141] According to an embodiment of the present invention, the processor 1310 may interact with the millimeter wave imaging device 1330 to execute a method according to an embodiment of the present invention or any variation thereof.

[0142] According to an embodiment of the present invention, at least one of the first configuration module 1210, the second configuration module 1220, the transmission holographic imaging module 1230 and the security inspection module can be implemented as a reference module. Figure 13 The computer program modules described above, when executed by the processor 1310, can implement the corresponding operations described above.

[0143] The present invention also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments, or may exist independently and not incorporated into the device / apparatus / system. The computer-readable storage medium carries one or more programs, which, when executed, implement the method according to the embodiments of the present invention.

[0144] According to an embodiment of the present invention, a computer-readable storage medium may be a non-volatile computer-readable storage medium, such as, but not limited to, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0145] Those skilled in the art will appreciate that the features described in the various embodiments and / or claims of the present invention may be combined and / or coupled in various ways, as long as they do not conflict, even if such combinations and / or couplings are not explicitly described in the present invention. In particular, the features described in the various embodiments and / or claims of the present invention may be combined and / or coupled in various ways, without departing from the spirit and teachings of the present invention. All such combinations and / or couplings fall within the scope of the present invention.

[0146] Although the present invention has been shown and described with reference to specific exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made to the present invention without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined not only by the appended claims but also by the equivalents of the appended claims.

Claims

1. A millimeter wave imaging method, wherein: The method comprises: A row of first millimeter wave transmitting antennas in a first millimeter wave transceiver array are configured to transmit millimeter waves of a target group frequency toward the object to be inspected; A row of second millimeter-wave receiving antennas of a second millimeter-wave transceiver array is configured to correspond one-to-one with the row of first millimeter-wave transmitting antennas, and the local oscillator signals of the corresponding receiving antennas and the carrier signals of the transmitting antennas are phase-coherent, so that the row of second millimeter-wave receiving antennas receives millimeter waves of the target group frequency to obtain target echo data; wherein the first millimeter-wave transceiver array and the second millimeter-wave transceiver array are located on both sides of the inspected object; Demodulating the target echo data using the local oscillator signal of the row of second millimeter wave receiving antennas and the phase coherence information to obtain target demodulated wave data including amplitude information and phase information; and A transmission holographic image of the inspected object is constructed based on the target demodulated wave data, the position information of the row of first millimeter wave transmitting antennas, and the position information of the row of second millimeter wave receiving antennas.

2. The millimeter wave imaging method according to claim 1, wherein: Configuring the phase coherence of the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna includes: The local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna are configured to be the same signal from the same frequency source.

3. The method according to claim 1, wherein Configuring the phase coherence of the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna includes: The local oscillator signal configured for the receiving antenna includes multiple signals obtained by performing multi-stage frequency conversion on the signal generated by the frequency source of the carrier signal of the corresponding transmitting antenna.

4. The method according to claim 3, wherein: Configuring the phase coherence of the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna also includes: The frequency conversion parameters of the multi-stage frequency conversion are configured so that the multiple signals are phase-coherent with the carrier signals of the corresponding transmitting antennas.

5. The method according to claim 4, wherein The demodulating the target echo data using the local oscillator signal of the row of second millimeter wave receiving antennas and the phase coherent information to obtain target demodulated wave data including amplitude information and phase information includes: Obtaining a phase relationship between the multiple signals and a carrier signal of a corresponding transmitting antenna based on the frequency conversion parameter to obtain specific data of phase coherence; and In the process of demodulating the target echo data using the local oscillator signal of the row of second millimeter wave receiving antennas, the specific data of the phase coherence is used as a compensation parameter to participate in the data processing of the demodulation process.

6. The method according to claim 1, wherein Configuring the phase coherence of the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna includes: Configuring the corresponding receiving antenna's local oscillator signal and transmitting antenna's carrier signal to be provided by different frequency sources; and The phase relationship between the local oscillator signal of the corresponding receiving antenna and the carrier signal of the transmitting antenna is calibrated to obtain calibration data.

7. The method according to claim 6, wherein: The demodulating the target echo data using the local oscillator signal of the row of second millimeter wave receiving antennas and the phase coherent information to obtain target demodulated wave data including amplitude information and phase information includes: In the process of demodulating the target echo data using the local oscillator signal of the row of second millimeter wave receiving antennas, the calibration data is used as a compensation parameter to participate in data processing of the demodulation process.

8. The method according to claim 1, wherein The configuring of a row of first millimeter wave transmitting antennas of a first millimeter wave transceiver array to transmit millimeter waves of a target group frequency toward the inspected object includes: At least part of the transmitting antennas in the row of first millimeter-wave transmitting antennas are configured to transmit millimeter waves of a frequency of the target group of frequencies toward the inspected object in a time sequence.

9. The method according to claim 1, wherein Configuring a one-to-one correspondence between a row of second millimeter wave receiving antennas and a row of first millimeter wave transmitting antennas in the second millimeter wave transceiver array includes: Each receiving antenna in the row of second millimeter wave receiving antennas is configured to operate at the same frequency as one transmitting antenna in the row of first millimeter wave transmitting antennas.

10. The method according to claim 1, wherein The method further comprises: The row of first millimeter-wave transmitting antennas and the row of second millimeter-wave receiving antennas are controlled to move synchronously.

11. A security inspection method, comprising: constructing a transmission holographic image of the inspected object using the millimeter wave imaging method according to any one of claims 1 to 10; Configuring a row of first millimeter wave receiving antennas of the first millimeter wave transceiver array to correspond one-to-one with the row of first millimeter wave transmitting antennas to receive millimeter waves of a first group of frequencies transmitted by the row of first millimeter wave transmitting antennas toward the inspected object so as to construct a first reflection holographic image; Configuring a row of second millimeter wave receiving antennas of the second millimeter wave transceiver array to correspond one-to-one with the row of second millimeter wave transmitting antennas to receive millimeter waves of a second group of frequencies transmitted by the row of second millimeter wave transmitting antennas toward the inspected object so as to construct a second reflection holographic image; as well as Based on the transmission holographic image, the first reflection holographic image, and the second reflection holographic image, it is determined whether the inspected object contains other items.

12. A millimeter wave imaging device, wherein: The device comprises: A first configuration module is configured to configure a row of first millimeter-wave transmitting antennas of a first millimeter-wave transceiver array to transmit millimeter waves of a target group frequency toward an object to be inspected; a second configuration module, configured to configure a row of second millimeter-wave receiving antennas of a second millimeter-wave transceiver array to correspond one-to-one with the row of first millimeter-wave transmitting antennas, and to configure local oscillator signals of the corresponding receiving antennas to be phase-coherent with carrier signals of the transmitting antennas, so that the row of second millimeter-wave receiving antennas receives millimeter waves of the target group frequency to obtain target echo data; wherein the first millimeter-wave transceiver array and the second millimeter-wave transceiver array are located on both sides of the inspected object; Transmission holographic imaging module for: Demodulating the target echo data using the local oscillator signal of the row of second millimeter wave receiving antennas and the phase coherence information to obtain target demodulated wave data including amplitude information and phase information; and A transmission holographic image of the inspected object is constructed based on the target demodulated wave data, the position information of the row of first millimeter wave transmitting antennas, and the position information of the row of second millimeter wave receiving antennas.

13. A security inspection system comprising: one or more processors; as well as a memory for storing one or more computer programs, The one or more processors execute the one or more computer programs to implement the steps of the method according to any one of claims 1 to 11.

Images