Security check imaging system

Abstract

The invention discloses a security check imaging system. The system comprises an input and output linear array, a plano-convex cylindrical lens, a swing mirror and a processor, the multi-input and multi-output linear array comprises transmitting units which are non-uniformly and sparsely arranged; each transmitting unit transmits a transmitting signal to the plano-convex cylindrical lens; the plano-convex cylindrical lens sends the fan-shaped signal to the oscillating mirror; the swing mirror sends a fan-shaped signal to the security check main body with different heights and different widths through swinging; the multiple-input-output linear array receives reflection signals corresponding to the security inspection main body under different swing amplitudes of the swing mirror; and the processor constructs a holomorphic image corresponding to the security check main body based on the reflection signals corresponding to the different swing amplitudes, and identifies whether the security check main body carries the metal article. Therefore, according to the security check imaging system, through cooperation of the transmitting unit, the plano-convex cylindrical lens, the swing mirror and the processor, the working frequency of the millimeter wave imaging technology in the security check field is improved, and the security check resolution is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of security inspection, more particularly, to a security imaging system. BACKGROUND

[0002] In the field of security inspection, millimeter wave imaging technology has become an important security inspection method due to its non-contact and strong penetration characteristics. Currently, due to problems such as signal attenuation, hardware cost and technical implementation difficulty, millimeter wave imaging systems mostly use two frequency bands of 24GHz and 77GHz.

[0003] However, the lower operating frequency results in insufficient imaging resolution, making it difficult to accurately identify small hazardous materials hidden under clothes, affecting the accuracy and efficiency of security inspection. With the continuous upgrading of security inspection requirements, developing millimeter wave imaging methods suitable for higher frequencies, breaking through the existing technical bottlenecks, and improving the accuracy and reliability of security inspection have become core technical problems that need to be solved in the industry. SUMMARY

[0004] Therefore, the present application provides a security imaging system to solve the problem of low resolution in the existing millimeter wave imaging technology.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following scheme:

[0006] A security imaging system, comprising a multiple-input and multiple-output linear array, a plano-convex cylindrical lens, a wobble mirror and a processor.

[0007] The multiple-input and multiple-output linear array comprises a plurality of transmission units arranged in a non-uniform sparse manner.

[0008] Each transmission unit transmits a transmission signal to the plano-convex cylindrical lens, and the frequency range of the transmission signal is [90GHz, 100GHz].

[0009] The plano-convex cylindrical lens focuses the transmission signal, converts the transmission signal into a fan-shaped signal, and transmits the fan-shaped signal to the wobble mirror.

[0010] The wobble mirror transmits the received fan-shaped signal to different heights and widths of the security subject by wobbling.

[0011] The multiple-input and multiple-output linear array receives the reflection signal corresponding to the security subject under different wobble amplitudes of the wobble mirror through the wobble mirror and the plano-convex cylindrical lens.

[0012] The processor constructs a full image corresponding to the security subject based on the reflection signal corresponding to different wobble amplitudes, and identifies whether the security subject carries a metal object based on the full image.

[0013] Optionally, it further comprises a trigger identification module.

[0014] The trigger identification module generates a swing trigger pulse, a switch control signal and a signal source trigger pulse when determining that the security subject is located at the preset target position.

[0015] The swing trigger pulse is used to control the swing mirror to periodically reciprocate according to the preset swing mode.

[0016] The switch control signal and the signal source trigger pulse are used to control the corresponding target emission unit to send an emission signal to the plano-convex cylindrical lens.

[0017] Optionally, the signal source is further included.

[0018] The signal source generates a frequency signal with a frequency range of [11.25GHz, 12.5GHz] every preset time interval after receiving the signal source trigger pulse.

[0019] Optionally, a multi-throw reflective switch is further included, and the multi-throw reflective switch is connected with each emission unit.

[0020] The multi-throw reflective switch analyzes the switch control signal and determines all target emission units for sending an emission signal every preset time interval.

[0021] Each target emission unit radiates the frequency signal generated by the signal source to form the emission signal.

[0022] Optionally, a driving motor is further included.

[0023] The driving motor drives the swing mirror to periodically reciprocate around the central axis according to the preset swing mode when receiving the swing trigger pulse.

[0024] A medium frequency signal acquisition card is further included.

[0025] The medium frequency signal acquisition card converts the reflected signal collected by the multi-input and output linear array into a digital signal.

[0026] Optionally, the processor includes an image generation module.

[0027] The image generation module pastes the digital signals corresponding to different swing amplitudes in the same swing cycle from large to small to generate a single frame of image, and processes the single frame of image of each swing cycle to generate a full image corresponding to the security subject.

[0028] Optionally, the swing amplitude of each swing cycle ranges from 32.8° to 52°.

[0029] Optionally, the plano-convex cylindrical lens has a focal length of 0.47 m and an aperture of 0.54 m.

[0030] Optionally, the security inspection imaging system according to any one of claims 1-8 is characterized in that the distance between the plano-convex cylindrical lens and the multi-input and output linear array is 0.66m.

[0031] It can be seen from the above technical solutions that the security imaging system provided by the application can include a multiple input and output linear array, a plano-convex cylindrical lens, a swing mirror and a processor. The multiple input and output linear array contains a plurality of emission units arranged in a non-uniform sparse manner. Each emission unit sends an emission signal to the plano-convex cylindrical lens, and the frequency range of the emission signal is [90GHz, 100GHz]. Based on this, the application can avoid periodic interference, suppress the grating lobe, and optimize the imaging quality by using each emission unit arranged in a non-uniform sparse manner. In the horizontal direction, a certain angle range of the space region is covered, and the horizontal direction information of the security subject is collected to avoid the detection blind area caused by insufficient horizontal direction detection angle. Moreover, the frequency of the emission signal of the application is [90GHz, 100GHz], and the high-frequency emission signal improves the imaging resolution, which helps to find smaller metal objects and other targets, and can be applied to detect small details, such as hidden objects or fine structures in the security process. At the same time, the plano-convex cylindrical lens of the application focuses the emission signal, converts the emission signal into a fan-shaped signal, and sends the fan-shaped signal to the swing mirror. The swing mirror sends the fan-shaped signal to different heights and widths of the security subject by swinging. Since the emission unit has good directional emission characteristics, it can concentrate the signal to a specific direction, and the plano-convex cylindrical lens can focus the emission signal. Therefore, the application can focus the high-frequency emission signal by combining the emission unit and the plano-convex cylindrical lens, enhance the intensity of the generated fan-shaped signal, solve the signal attenuation problem, and improve the accuracy and stability of signal propagation, so that the fan-shaped signal can better penetrate the cover such as clothes, plastic and packaging bags to reach the surface of the security subject, and collect the image of the object carried by the security subject. At the same time, since the fan-shaped signal is generated, it has a certain width, so it can cover a certain angle range of the space region in the vertical direction, collect the horizontal direction information of the security subject, and avoid the detection blind area caused by insufficient vertical direction detection angle. The plano-convex cylindrical lens also transmits the fan-shaped signal to the swing mirror, changes the emission angle of the signal in the vertical direction by swinging of the swing mirror, and emits the signal to different heights of the security subject, so as to obtain detailed information of the security subject at each height in the vertical direction. Moreover, the multiple input and output linear array of the application receives the reflection signal corresponding to the security subject under different swing amplitudes of the swing mirror through the swing mirror and the plano-convex cylindrical lens. The processor constructs a full image corresponding to the security subject based on the reflection signal corresponding to different swing amplitudes, and identifies whether the security subject carries a metal object based on the full image. Based on this, the application can construct the full image of the security subject to present the shape, contour and internal structure of the security subject in an intuitive way, and the security personnel can quickly understand the overall situation of the security subject by observing the image. Based on the full image, the processor further identifies whether the security subject carries a metal object.The reflection characteristics of metal objects, human bodies and other non-metal objects to millimeter waves are different, and the processor uses these differences to analyze the image through a specific algorithm, accurately identifies the presence of metal objects, and timely discovers potential security threats, thereby realizing the core function of human security inspection and ensuring the effectiveness and safety of security inspection. It can be seen that the security imaging system of the present application can improve the working frequency of millimeter wave imaging technology in the security inspection field through the cooperative work of the transmitting unit, the plano-convex cylindrical lens, the swing mirror and the processor, thereby improving the security inspection resolution while performing full-body security inspection on the security inspection subject, effectively improving the accuracy, integrity and safety of security inspection. Therefore, the present application can improve the resolution while collecting a large range of information of the security inspection subject, avoid missing the security inspection range, and realize non-contact inspection of the whole body of the security inspection subject whether it carries metal objects in a non-cooperative mode.

[0032] In addition, the security imaging system of the present application belongs to non-ionizing radiation, which is safer than X-rays and is suitable for long-term monitoring of human bodies or biological tissues, thereby further improving the application universality of the present application.

[0033] Meanwhile, the transmitting signal of the present application belongs to millimeter wave, which is less affected by fog, smoke, weak light, and can be applied to scenes such as fire rescue and night security inspection.

[0034] In addition, the working frequency of the security imaging system of the present application is [90GHz, 100GHz], and the working frequency of civil devices such as WiFi and Bluetooth is irrelevant, so the present application has less conflict with civil devices and has strong stability. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and those skilled in the art can obtain other drawings according to the provided drawings without creative labor.

[0036] Fig. 1 An architecture schematic diagram of a security imaging system provided by an embodiment of the present application;

[0037] Fig. 2 An imaging principle schematic diagram of a security imaging system provided by an embodiment of the present application;

[0038] Fig. 3 An optical path schematic diagram of a security imaging system provided by an embodiment of the present application;

[0039] Figs. 1-3 The correspondence between the component identifiers and the reference signs is as follows:

[0040] Multiple Input Output Linear Array 1, Plano-convex Lenses 2, Galvanometer 3, Processor 4, Transmitting Unit 10, Receiving Unit 11. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0042] Next, the security imaging system of the present application will be described in detail with reference to the drawings. It should be noted that the directions of the structures shown in the drawings of the present application are set for easy understanding of the description, and do not limit the directions of the embodiments of the present application in actual implementation in any way. Moreover, the shapes and sizes of the whole or part of the structures shown in the drawings are also not limited to the actual shapes and sizes.

[0043] Next, the security imaging system of the present application will be described in detail with reference to the drawings. It should be noted that the directions of the structures shown in the drawings of the present application are set for easy understanding of the description, and do not limit the directions of the embodiments of the present application in actual implementation in any way. Moreover, the shapes and sizes of the whole or part of the structures shown in the drawings are also not limited to the actual shapes and sizes. Figs. 1-3 The security imaging system of the present application will be described in detail.

[0044] Referring to Fig. 1 It can be found that the security imaging system of the present application can include a Multiple Input Output Linear Array 1, Plano-convex Lenses 2, Galvanometer 3, and a Processor 4.

[0045] The Multiple Input Output Linear Array 1 can be a millimeter wave radar array such as a MIMO linear array.

[0046] The MIMO linear array is short for Multiple Input Multiple Output.

[0047] The Multiple Input Output Linear Array 1 can include a plurality of transmitting units 10 and a plurality of receiving units 11.

[0048] The output power of each transmitting unit 10 is greater than or equal to 10 dBm; the transmitting power in-band flatness is ±1 dB (fT within any continuous 5 GHz bandwidth); the transmitting excitation frequency is fT / 11.25~12.5 GHz; the input excitation signal (LO) power can be 0±1.5 dBm; the transmitting spurs (in-band) are less than or equal to -50 dBc; and the input / output port VSWR is less than or equal to 1.5.

[0049] The transmitting principle of each transmitting unit 10 is that the frequency signal is amplified by a PA (power amplifier) after multi-stage frequency multiplication and filtering, and is transmitted by a transmitting antenna.

[0050] The receiving gain of each receiving unit 11 has different requirements in different frequency bands. For example, when the frequency band is 200KHz-300KHz, the gain is greater than 0dB, when the frequency band is 300KHz-1MHz, the gain is greater than 8dB, when the frequency band is 1MHz-2MHz, the gain is greater than 35dB, and when the frequency band is 2MHz-10MHz, the gain is 42dB-45dB.

[0051] In order to improve image resolution and enhance the recognition rate of prohibited items during security inspection, the frequency range of the transmission signal sent by each transmitting unit 10 may be [90 GHz, 100 GHz].

[0052] In order to avoid signal attenuation of high-frequency signals, the transmission signal may be sent to the plano-convex cylindrical lens 2 , and the plano-convex cylindrical lens 2 may be used to focus the transmission signal.

[0053] After the plano-convex cylindrical lens 2 focuses the transmitted signal, it converts it into a fan-shaped signal, and uses the narrow side of the fan-shaped signal to perform real beam focused scanning in that direction. The 3dB width of the narrow side of the real beam is the minimum resolution that the security inspection imaging system can achieve in the vertical scanning direction, which is increased to 1.2cm.

[0054] The plano-convex cylindrical lens 2 can send the sector signal to the swing mirror 3, thereby sending the sector signal to different heights and widths of the security inspection subject through the swing mirror 3, such as Fig. 2 shown.

[0055] The broadside of the sector signal is used for fast electronically controlled transmission and reception, and the horizontal resolution is determined by the length of the transceiver aperture of the multi-input and output linear array 1.

[0056] Therefore, each transmitting unit 10 and each receiving unit 11 is arranged non-uniformly and sparsely in the multi-input and output linear array 1. Each transmitting unit 10 and each receiving unit 11 is equivalent to a virtual large aperture, which reduces the cost while improving the horizontal resolution to 0.012m.

[0057] Each transmitting unit 10 may be a pyramid horn.

[0058] The aperture of the horn antenna can be determined based on the thickness, size and output beam waist position of the plano-convex cylindrical lens 2 .

[0059] The oscillating mirror 3 swings to send the focused transmission signal sent by the plano-convex cylindrical lens 2 to different heights of the security inspection subject, such as Fig. 3 shown.

[0060] The security inspection subject may be an object that needs to be inspected.

[0061] Moreover, security inspection subjects also cover different types.

[0062] For example, the security subject can be a bag that needs to be security checked, the security subject can also be a luggage that needs to be security checked, and the security subject can also be a passenger that needs to be security checked.

[0063] The mirror 3 receives the reflected signal returned by the security subject in real time, and sends the received reflected signal to the plano-convex cylindrical lens 2 in real time, and the plano-convex cylindrical lens 2 sends the received reflected signal to the receiving unit 11 of the multi-input-output linear array 1.

[0064] The processor 4 can generate a full shape image corresponding to the security subject according to the reflected signal under different swing amplitudes. The full shape image can contain a full body image of the security subject and can also contain an article image carried by the security subject.

[0065] The processor 4 can determine whether the security subject carries an article according to the full shape image, and determine whether the security subject carries a metal article according to the shape of the article.

[0066] Specifically, the processor 4 can identify whether there is a color mutation area in the full shape image;

[0067] If not, it can be determined that the security subject does not carry an article; if yes, the color mutation area is extracted from the full shape image, and an article image is obtained after extraction; the shape feature of the article image is analyzed, and it is evaluated whether the shape feature of the article image is a regular shape. If it is a regular shape, it can be determined that the security subject carries a metal article, and if it is not a regular shape, it can be determined that the security subject does not carry a metal article.

[0068] Considering that the density of cloth is much lower than that of metal, in the full shape image, the cloth corresponding to the metal article is brighter than the cloth not corresponding to the metal article. Therefore, the region corresponding to the metal article can be identified by analyzing the color change degree of the full shape image.

[0069] Further, the processor 4 can determine the gray value of each pixel point in the full shape image, and identify the color mutation area according to each gray value.

[0070] The regular shape can include a strip shape, a sheet shape, and a ring shape, etc.

[0071] It can be seen from the above technical solutions that the security imaging system provided by the application can include a multi-input and output linear array 1, a plano-convex cylindrical lens 2, a swing mirror 3 and a processor 4. The multi-input and output linear array 1 contains a plurality of emission units 10 arranged in a non-uniform sparse manner. Each emission unit 10 sends an emission signal to the plano-convex cylindrical lens 2, and the frequency range of the emission signal is [90GHz, 100GHz]. Based on this, the application can avoid periodic interference, suppress the grating lobe, and optimize the imaging quality by using each emission unit 10 arranged in a non-uniform sparse manner. It covers a certain angle range of the space region in the horizontal direction, collects the horizontal direction information of the security subject, and avoids the detection blind area caused by insufficient horizontal direction detection angle. Moreover, the frequency of the emission signal of the application is [90GHz, 100GHz], and the high-frequency emission signal improves the imaging resolution, which helps to find smaller metal objects and other targets, and can be applied to detect small details, such as hidden objects or fine structures in the security process. At the same time, the plano-convex cylindrical lens 2 of the application focuses the emission signal, converts it into a fan-shaped signal, and sends it to the swing mirror 3. The swing mirror 3 sends the fan-shaped signal to different heights and widths of the security subject by swinging. Since the emission unit 10 has good directional emission characteristics, it can concentrate the signal to a specific direction, and the plano-convex cylindrical lens 2 can focus the emission signal. Therefore, the application can focus the high-frequency emission signal by combining the emission unit 10 and the plano-convex cylindrical lens 2, enhance the intensity of the fan-shaped signal, solve the signal attenuation problem, and improve the accuracy and stability of signal propagation, so that the fan-shaped signal can better penetrate the cover such as clothes, plastic and packaging bags to reach the surface of the security subject, and collect the image of the object carried by the security subject. At the same time, since the fan-shaped signal is generated, it has a certain width, so it can cover a certain angle range of the space region in the vertical direction, collect the horizontal direction information of the security subject, and avoid the detection blind area caused by insufficient vertical direction detection angle. The plano-convex cylindrical lens 2 also transmits the fan-shaped signal to the swing mirror 3, changes the emission angle of the signal in the vertical direction by swinging the swing mirror 3, and emits the signal to different heights of the security subject, so as to obtain the detailed information of the security subject at each height in the vertical direction. The multi-input and output linear array 1 of the application receives the reflection signal corresponding to the security subject under different swing amplitudes of the swing mirror 3 through the swing mirror 3 and the plano-convex cylindrical lens 2. The processor 4 constructs a full image corresponding to the security subject based on the reflection signal corresponding to different swing amplitudes, and identifies whether the security subject carries metal objects based on the full image. Based on this, the application can construct the full image of the security subject to present the shape, contour and internal structure of the security subject in an intuitive way, and the security personnel can quickly understand the overall situation of the security subject by observing the image.Based on the full shape image, the processor 4 further identifies whether the security subject carries a metal article. The reflection characteristics of the metal article, the human body and other non-metal articles to the millimeter wave are different, and the processor 4 uses these differences to analyze the image through a specific algorithm, accurately identifies the existence of the metal article, discovers potential security threats in time, realizes the core function of human security, and ensures the effectiveness and safety of the security work. It can be seen that the present application can improve the working frequency of the millimeter wave imaging technology in the security field through the cooperative work of the security imaging system, the transmitting unit 10, the plano-convex cylindrical lens 2, the swing mirror 3 and the processor 4, so as to improve the security resolution while performing full-body security on the security subject, and effectively improve the accuracy, integrity and safety of the security. Therefore, the present application can collect a large range of information of the security subject while improving the resolution, avoid missing the security range, and realize non-contact inspection of whether the security subject carries a metal article in a non-cooperative mode of the security subject.

[0072] In addition, the security imaging system of the present application belongs to non-ionizing radiation, which is safer than X-rays and is suitable for long-term monitoring of human bodies or biological tissues, further improving the application universality of the present application.

[0073] Meanwhile, the transmitting signal of the present application belongs to millimeter wave, which is less affected by fog, smoke, weak light, and can be applied to scenes such as fire rescue and night security.

[0074] In addition, the working frequency of the security imaging system of the present application is [90GHz, 100GHz], and the working frequency of the civil equipment such as WiFi and Bluetooth is irrelevant, so the present application has less conflict with civil equipment and has strong stability.

[0075] In some embodiments of the present application, the security imaging system can further comprise a trigger identification module.

[0076] The trigger identification module can generate a swing trigger pulse, a switch control signal and a signal source trigger pulse when it is determined that the security subject is located at a preset target position.

[0077] Specifically, the trigger identification module can be a field programmable gate array (FPGA).

[0078] The target position refers to a position that can generate a full shape image with the highest resolution after verification, and the target position can be located within the imaging range.

[0079] The target position can be represented as a horizontal distance from the security imaging system or as a three-dimensional coordinate.

[0080] The swing trigger pulse can be used to control the swing mirror 3 to periodically reciprocate according to a preset swing mode.

[0081] The swing mode can include a swing amplitude range and a swing speed of each swing cycle.

[0082] The switch control signal and the signal source trigger pulse can be coordinated to control the corresponding target transmitting unit to send a transmitting signal to the plano-convex cylindrical lens 2.

[0083] From the above technical solution, it can be seen that the embodiment provides an optional composition of the security imaging system. Through the above-mentioned manner, the present application can actively start security inspection when the security subject reaches the optimal position, and generate a full shape image, thereby ensuring the resolution and timeliness of the generated full shape image, improving the reliability and accuracy of the full shape image, and improving the accuracy and efficiency of identifying metal objects.

[0084] In some embodiments of the present application, the security imaging system can further include a signal source.

[0085] The signal source can generate a frequency signal with a frequency range of [11.25GHz, 12.5GHz] every preset time interval after receiving the signal source trigger pulse.

[0086] Specifically, the signal source can be an FMCW signal source (Frequency Modulated Continuous Wave), which can be used to generate a frequency-modulated continuous wave, and the frequency modulation bandwidth can be 1.25GHz, and the output power is greater than or equal to 15dBm.

[0087] The interval time of generating the frequency signal can be set according to the sampling frequency of each receiving unit 11. By adjusting the bandwidth of the signal source, the resolution in the depth direction can be adjusted.

[0088] The related information of the power flatness of the signal source: the typical value is ±1.0dB, the maximum value is ±1.5dB; the scanning period is 100μs; the frequency resolution is better than 1.0Hz; the linearity is better than 0.05% and supports pre-distortion correction; the phase noise is better than -115dBc / Hz@10kHz; the spurious suppression is better than -60dBc for non-harmonics and better than -50dBc for harmonics, and the size is ≤30cm×25cm×5cm.

[0089] The interface of the signal source needs to support: 1 route 3.3V LVTTL rising edge trigger pulse input (SMA interface), 1 route 100MHz clock output (>10dBm, 50Ω, SMA interface, phase noise <-155dBc / Hz@10kHz), and +12V power supply (current <3A).

[0090] The number of transmitting units 10 included in the multi-input-output linear array 1 can be determined according to the frequency range generated by the signal source.

[0091] For example, when the signal source generates a frequency signal with a frequency range of [11.25GHz, 12.5GHz], in order to ensure that the frequency range of the transmitted signal is [90GHz, 100GHz], the number of the transmitting units 10 included in the multi-input and output linear array 1 can be 8.

[0092] Each transmitting unit 10 can multiply the frequency signal generated by the signal source to [90GHz, 100GHz] and then output through the standard waveguide port.

[0093] Each receiving unit 11 receives the reflected signal with a frequency of [90GHz, 100GHz].

[0094] The aperture size in each of the two main planes of each transmitting unit 10 is greater than one wavelength, and the lobe pattern in one plane is substantially independent of the aperture of the other plane. The E (or H) plane sector horn has the same E (or H) plane lobe pattern as the pyramidal horn with the same E (or H) profile.

[0095] The 3dB width of the E plane and the 3dB width of the H plane of the transmitting unit 10 can be set according to the frequency range of the transmitted signal.

[0096] For example, when the frequency of the transmitted signal is 90GHz, the 3dB width of the E plane is about 21.81 degrees and the 3dB width of the H plane is about 12.7001 degrees; when the frequency of the transmitted signal is 95GHz, the 3dB width of the E plane is about 20.9706 degrees and the 3dB width of the H plane is about 12.5044 degrees; when the frequency of the transmitted signal is 100GHz, the 3dB width of the E plane is about 20.0866 degrees and the 3dB width of the H plane is about 12.2947 degrees.

[0097] The size of the transmitting unit 10 can be an opening width (E plane) of 1.96 mm, an opening height (H plane) of 0.77 mm, and a horn axial length of 3.55 mm.

[0098] The incident beam waist of the transmitted signal radiated by the transmitting unit 10 at 95GHz is 0.0028m, and the incident distance is 0.56m.

[0099] The plano-convex cylindrical lens 2 focuses the H plane of the transmitting unit 10, and thus the incident Gaussian beam waist radius of the plano-convex cylindrical lens 2 can be calculated based on the H plane direction of the transmitting unit 10.

[0100] As can be seen from the above technical solutions, the present embodiment provides an optional composition of a security imaging system. The present embodiment can generate stable frequency signals with the aid of a signal source, and enable the transmitting unit 10 to efficiently generate transmitted signals, thereby significantly enhancing the transmission performance and radiation effect of the transmitted signals.

[0101] In some embodiments of the present application, the security imaging system can further comprise a multi-throw reflective switch, and the multi-throw reflective switch is connected with each transmitting unit 10.

[0102] The multi-throw reflective switch can analyze the switch control signal generated by the trigger identification module, and determine all target transmitting units for transmitting the transmitting signal every preset time interval.

[0103] Each target transmitting unit can radiate the frequency signal transmitted by the signal source, and the signals radiated by each target transmitting unit form a transmitting signal with a frequency range of [90GHz, 100GHz].

[0104] The interval time of the multi-throw reflective switch for determining the target transmitting unit can match the interval time for generating the frequency signal.

[0105] Specifically, the type of the multi-throw reflective switch can match the number of the transmitting units 10.

[0106] For example, when the number of the transmitting units 10 is 8, the type of the multi-throw reflective switch can be an eight-throw reflective switch.

[0107] The switch control signal can be used to set the radiation strategy of the transmitting units.

[0108] For example, the switch control signal can control the multi-throw reflective switch to sequentially open each transmitting unit 10.

[0109] For another example, the switch control signal can also control the multi-throw reflective switch to open the transmitting units 10 in pairs.

[0110] The switch control signal can be a three-bit control signal, and by changing the value of each bit of the three-bit control signal, the radiation strategy of the transmitting units can be adjusted.

[0111] Each transmitting unit 10 that is opened can be used as a target transmitting unit.

[0112] At the current time, the signals radiated by each target transmitting unit together form the transmitting signal at this moment.

[0113] The target transmitting units at different times can be different.

[0114] The multi-throw reflective switch can switch the target transmitting units within 50ns.

[0115] As can be seen from the above technical solutions, the present embodiment provides another optional composition of a security imaging system. By using the above combination, the trigger identification module and the multi-throw reflective switch can cooperate with each other to realize intelligent control of the transmitting units 10, and significantly enhance the flexibility and reliability of the operation of the security imaging system.

[0116] In some embodiments of the present application, the security imaging system can further comprise a driving motor.

[0117] The driving motor can drive the swing mirror 3 to periodically reciprocate around the central axis as the rotation axis according to the preset swing mode upon receiving the swing trigger pulse.

[0118] Specifically, the driving motor can drive the swing mirror 3 to rotate around the central axis upon receiving the swing trigger pulse sent by the trigger identification module.

[0119] During the rotation of the swing mirror 3, the received emission signal can be sent to different heights of the security subject.

[0120] Referring to Fig. 3 It can be found that the swing mirror 3 rotates around the central axis, and during the continuous change of the rotation angle, the emission signal can reach each height position of the security subject.

[0121] The horizontal line where the center point of the swing mirror 3 is located can be the central axis.

[0122] The driving motor can control the rotation angle, rotation speed, rotation acceleration and / or rotation deceleration of the swing mirror 3.

[0123] For example, the driving motor can control the swing mirror 3 to start from the maximum swing amplitude and sequentially decrease to the minimum swing amplitude with a fixed angle gradient according to the preset driving strategy, so as to realize the periodic reciprocation of the swing mirror 3 around the central axis as the rotation axis according to the preset swing mode. During this process, the reflection signal of the swing mirror 3 at different swing amplitudes can be captured in real time.

[0124] As can be seen from the above technical solution, the present embodiment provides another optional composition of the security imaging system. Through the above-mentioned manner, the present application can control the swing mirror 3 to swing to the corresponding amplitude by the driving motor, so as to acquire the reflection signal under multiple swing amplitudes, thereby obtaining the reflection signal that can be used to construct the full image.

[0125] In some embodiments of the present application, the security imaging system can comprise an intermediate frequency signal acquisition card.

[0126] The intermediate frequency signal acquisition card converts the reflection signal acquired by the multiple input and output linear arrays 1 into a digital signal.

[0127] Specifically, the intermediate frequency signal acquisition card can filter and amplify the reflection signal and convert it into a digital signal.

[0128] The passband of the intermediate frequency signal acquisition card is 11-13GHz high frequency signal, the output bandwidth is 200KHz-10MHz, and the intermediate frequency signal acquisition card has the characteristics of low loss (≤3dB), low in-band fluctuation (≤1dB), low passband standing wave (≤1.7), high out-of-band suppression (≥55dBc) and compact size (62×18×10mm).

[0129] The type of the intermediate frequency signal acquisition card can be matched with the receiving unit 11.

[0130] The number of channels of the receiving unit 11 can be proportional to the number of the transmitting units 10.

[0131] For example, when the number of the transmitting units 10 is 8, the number of channels of the receiving unit 11 can be twice the number of the transmitting units 10, that is, the number of channels of the receiving unit 11 can be 16.

[0132] The number of channels of the intermediate frequency signal acquisition card can be consistent with the number of channels of the receiving unit 11.

[0133] For example, when the number of channels of the receiving unit 11 is 16, the number of channels of the intermediate frequency signal acquisition card is also 16.

[0134] In order to facilitate the reception of the transmitted signal and increase the size of the long side of the transmitted signal, each receiving unit 11 can be arranged at the middle of the multi-input-output linear array 1, and each transmitting unit 10 can be arranged on both sides of each receiving unit 11.

[0135] The distance between two adjacent transmitting units 10 is less than the distance between two adjacent receiving units 11.

[0136] For example, the distance between two adjacent transmitting units 10 can be 1.2cm, and the distance between two adjacent receiving units 11 can be 4.78cm.

[0137] The size of the transmitting unit 10 and the receiving unit 11 can be the same, which is 1.96cm in length and 0.77cm in width. The channels of the intermediate frequency signal acquisition card can be matched with the channels of the receiving unit 11 one by one.

[0138] The digital signal collected by the intermediate frequency signal acquisition card can contain characteristic information of the security subject at different amplitudes.

[0139] As can be seen from the above technical solutions, the embodiment provides another optional composition of the security imaging system. Through the above-mentioned manner, the intermediate frequency signal acquisition card can convert the reflection signals corresponding to different swing amplitudes collected by the receiving unit 11 into digital signals, which is convenient for subsequent processing by the processor 4.

[0140] In some embodiments of the present application, the processor 4 can include an image generation module.

[0141] The image generation module combines the digital signals corresponding to different swing amplitudes in the same swing period in descending order of swing amplitude, generates a single-frame image, and processes the single-frame images of each swing period to generate a full image of the security subject.

[0142] Specifically, all digital signals corresponding to the same swing amplitude in the same swing period can be determined.

[0143] The digital signals corresponding to different swing angles in the same swing period can be integrated, calibrated and fused based on the spatial position relationship to construct a single-frame image reflecting the overall appearance of the security subject in descending order of swing amplitude.

[0144] In order to ensure the reliability of the generated full image, the image features of each single-frame image can be compared, and the single-frame images can be fused to generate a full image.

[0145] From the above technical solution, it can be seen that the embodiment provides an optional composition of the processor 4. Through the above method, the reflection signals of different swing amplitudes can be integrated to form a full image that can reflect whether the security subject carries metal articles.

[0146] In some embodiments of the present application, the swing angle range of the swing mirror 3 can be [32.8°, 52°].

[0147] Specifically, the swing mirror 3 can be periodically swung multiple times, and the swing angle range of the swing mirror 3 in each swing period is [32.8°, 52°].

[0148] After the transmitted fan-shaped signal is focused at the focusing position, it diverges, and when the security subject is too far from the focusing position, the fan-shaped signal diverges from the narrow side, and the resolution is reduced. In order to ensure the resolution in actual application, the imaging range can be set according to the focusing position of the fan-shaped signal.

[0149] And the imaging range is affected by the swing angle of the swing mirror 3.

[0150] Therefore, the swing angle range of the swing mirror 3 can be set according to the imaging range.

[0151] For example, the focusing position of the fan-shaped signal is 2.9m, and the imaging range can be set to 2.4m to 3.4m.

[0152] At this time, the swing angle range of the swing mirror 3 can be [32.8°, 52°].

[0153] In the swing angle range, the swing mirror 3 can send the focused each transmission signal to different heights of the target position, and the detectable height range of the security subject is [0, 2m], and the detectable width range is [0, 1.5m].

[0154] From the above technical solution, it can be seen that the embodiment provides a swing range of the swing mirror 3, and the swing process of the swing mirror 3 can be better controlled through the swing range, so that the construction of the full image is better completed.

[0155] In some embodiments of the present application, the focal length of the plano-convex cylindrical lens 2 is 0.47m and the aperture is 0.54m.

[0156] In order to better focus the transmission signal, the focal length and aperture of the plano-convex cylindrical lens 2 can be determined according to multiple dimensions such as the target position, the transmission signal, and the swing mirror 3.

[0157] Since the size of the plano-convex cylindrical lens 2 can affect the reachable height range of the fan-shaped signal sent by the swing mirror 3;

[0158] Therefore, the length of the plano-convex cylindrical lens 2 can be set according to the imaging range and the pre-set height range.

[0159] The height range can be set according to the average height of the object to be security checked.

[0160] From the above technical solution, it can be seen that the embodiment provides a selectable combination number of the focal length and aperture of the plano-convex cylindrical lens 2, and through the above-mentioned manner, the transmission signal can be better focused, the data amount contained in the reflected signal is improved, and the resolution of the full image is ensured, so that the security reliability of the present application is improved.

[0161] In some embodiments of the present application, the distance between the plano-convex cylindrical lens 2 and the multi-input-output linear array 1 is 0.66m.

[0162] Specifically, the distance between the plano-convex cylindrical lens 2 and the multi-input-output linear array 1 can be set according to the signal attenuation degree of the transmission signal.

[0163] From the above technical solution, it can be seen that the embodiment provides a selectable range of the distance between the plano-convex cylindrical lens 2 and the multi-input-output linear array 1, and through the above-mentioned manner, the plano-convex cylindrical lens 2 can better focus the transmission signal when the transmission signal is not attenuated, so that the transmission signal with a higher working frequency is applied to the security imaging field.

[0164] Next, the security imaging system of the present application will be described in detail through a specific example.

[0165] The entire security imaging system can have a size of 1m*1m*1.5m.

[0166] In the security imaging system, from bottom to top in the vertical direction, there are a MIMO linear array, a plano-convex cylindrical lens and a swing mirror.

[0167] The MIMO linear array can include 8 transmitting units and 16 receiving units.

[0168] The plano-convex cylindrical lens has a focal length of 0.47m and an aperture of 0.54m.

[0169] The swing mirror is connected with a driving motor.

[0170] The center points of the MIMO linear array, the plano-convex cylindrical lens and the swing mirror are located on the same vertical line.

[0171] The distance between the center point of the MIMO linear array and the center point of the plano-convex cylindrical lens is 0.66m.

[0172] The distance between the center point of the plano-convex cylindrical lens and the center point of the swing mirror is 0.84m.

[0173] The 16 receiving units of the MIMO linear array are connected with 16-channel intermediate frequency acquisition cards.

[0174] The 8 transmitting units in the MIMO linear array in a fan-shaped distribution are connected with a single-pole eight-throw reflective switch SHX8S60.

[0175] The 8 transmitting units are connected with an FMCW signal source.

[0176] The single-pole eight-throw reflective switch, the driving motor and the FMCW signal source are connected with a trigger identification module.

[0177] When the target object needing security check is 3.5m away from the security imaging system, the trigger identification module generates a swing trigger pulse, a switch control signal and a signal source trigger pulse, and sends the swing trigger pulse to the driving motor, the switch control signal to the single-pole eight-throw reflective switch and the signal source trigger pulse to the FMCW signal source.

[0178] After receiving the signal source trigger pulse, the FMCW signal source generates a frequency signal with a frequency range of [11.25GHz, 12.5GHz] every 250us.

[0179] When receiving the switch control signal, the single-pole eight-throw reflective switch compares the switch control signal with a truth table every 250us to determine the transmitting unit needing to be radiated, wherein the truth table records the correspondence between different three-bit control signals and the radiation strategy of each transmitting unit.

[0180] Each open transmitting unit radiates the frequency signal to generate a transmitting signal.

[0181] The transmitting signal is focused to the swing mirror via the plano-convex cylindrical lens.

[0182] The driving motor controls the swing mirror to swing periodically when receiving the swing trigger pulse, and the swing angle range of the swing mirror in each swing period is [32.8°, 52°], so as to send the focused transmitting signal to different heights and widths of the target object at 3.5 m through the swing mirror, wherein the time length of each swing period can be the same, and can be 0.4 s.

[0183] The swing mirror transmits the reflection signals corresponding to the target object at different swing angles to the 16 receiving units via the plano-convex cylindrical lens.

[0184] The 16 receiving units collect the reflection signals every 2 ms, and the time length of each reflection signal collection is 200 us, and the received reflection signals are transmitted to the 16-channel intermediate frequency acquisition card, wherein the time domain data collected by each receiving unit is 2000 points.

[0185] The 16-channel intermediate frequency acquisition card extracts the intermediate frequency information of the reflection signals at different swing angles to form a digital signal.

[0186] The processor combines the digital signals corresponding to different swing amplitudes in the same swing period from large to small to generate a single frame image, and processes the single frame images of each swing period to generate a full image with a resolution of 1.2, so as to detect whether the concealed article carried by the target object belongs to a metal article through the full image.

[0187] Finally, it should be noted that in this text, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "including a…" does not exclude the presence of other identical elements in the process, method, article or equipment including the element.

[0188] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same or similar parts between each embodiment can be referred to each other.

[0189] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and, while certain embodiments according to the principles of the application are shown as described and / or illustrated herein, it is understood that the same are not limited thereto and that all changes and modifications that come within the spirit and / or scope of the basic underlying principles of the application can be made. The various embodiments of the application can be combined in order to create additional embodiments of the application. Therefore, the application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A security inspection imaging system, characterized in that: It includes a multi-input and output linear array, a plano-convex cylindrical lens, an oscillating mirror and a processor; The multiple input and output linear array includes a plurality of transmitting units that are non-uniformly and sparsely arranged; Each transmitting unit sends a transmitting signal to the plano-convex cylindrical lens, and the frequency range of the transmitting signal is [90 GHz, 100 GHz]; The plano-convex cylindrical lens focuses the transmission signal, converts the transmission signal into a fan-shaped signal, and sends the fan-shaped signal to the oscillating mirror; The oscillating mirror transmits the received fan-shaped signal to different heights and widths of the security inspection subject by swinging; The multi-input and output linear array receives the reflection signals corresponding to the security inspection subject at different swing amplitudes of the swing mirror through the swing mirror and the plano-convex cylindrical lens; The processor constructs a full-shape image corresponding to the security inspection subject based on the reflection signals corresponding to different swing amplitudes, and identifies whether the security inspection subject carries a metal object based on the full-shape image.

2. The security inspection imaging system according to claim 1, characterized in that: Also included is a trigger recognition module; The trigger recognition module generates a swing trigger pulse, a switch control signal and a signal source trigger pulse when determining that the security inspection subject is located at a preset target position; Wherein, the swing trigger pulse is used to control the swing mirror to swing back and forth periodically according to a preset swing pattern; The switch control signal and the signal source trigger pulse are used to control the corresponding target transmitting unit to send a transmitting signal to the plano-convex cylindrical lens.

3. The security inspection imaging system according to claim 2, characterized in that: Also includes signal sources; The signal source generates a frequency signal in the frequency range of [11.25 GHz, 12.5 GHz] at preset time intervals after receiving the signal source trigger pulse.

4. The security inspection imaging system according to claim 3, characterized in that: Also included is a multi-throw reflective switch, and the multi-throw reflective switch is connected to each transmitting unit; The multi-throw reflective switch analyzes the switch control signal and determines all target transmitting units for sending the transmission signal at predetermined intervals; Each target transmitting unit radiates the frequency signal generated by the signal source to form the transmitting signal.

5. The security inspection imaging system according to claim 2, characterized in that: Also includes a drive motor; The driving motor drives the oscillating mirror to oscillate periodically back and forth with the central axis as the rotation axis according to a preset oscillation mode when receiving the oscillation trigger pulse.

6. The security inspection imaging system according to claim 2, characterized in that: Also includes an intermediate frequency signal acquisition card; The intermediate frequency signal acquisition card converts the reflected signal collected by the multi-input and output linear array into a digital signal.

7. The security inspection imaging system according to claim 6, characterized in that: The processor includes an image generation module; The image generation module combines the digital signals corresponding to different swing amplitudes in the same swing cycle according to the swing amplitude from large to small to generate a single-frame image; and processes the single-frame images of each swing cycle to generate a full-shape image corresponding to the security inspection subject.

8. The security inspection imaging system according to claim 7, characterized in that: The swing amplitude range of each swing cycle is [32.8°, 52°].

9. The security inspection imaging system according to any one of claims 1 to 8, characterized in that: The plano-convex cylindrical lens has a focal length of 0.47 m and an aperture of 0.54 m.

10. The security inspection imaging system according to any one of claims 1 to 8, characterized in that: The distance between the plano-convex cylindrical lens and the multi-input and output linear array is 0.66 m.

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