CN109633776B - Millimeter wave/terahertz wave imaging device and human body or article detection method - Google Patents
Millimeter wave/terahertz wave imaging device and human body or article detection method Download PDFInfo
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- CN109633776B CN109633776B CN201811654172.5A CN201811654172A CN109633776B CN 109633776 B CN109633776 B CN 109633776B CN 201811654172 A CN201811654172 A CN 201811654172A CN 109633776 B CN109633776 B CN 109633776B
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- 238000003384 imaging method Methods 0.000 title claims abstract description 51
- 238000001514 detection method Methods 0.000 title abstract description 11
- 230000007246 mechanism Effects 0.000 claims abstract description 64
- 230000005855 radiation Effects 0.000 claims abstract description 15
- 230000002269 spontaneous effect Effects 0.000 claims abstract description 14
- 238000000034 method Methods 0.000 claims description 15
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- 230000010355 oscillation Effects 0.000 claims description 7
- 238000002360 preparation method Methods 0.000 claims description 7
- 238000006073 displacement reaction Methods 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
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- 238000005070 sampling Methods 0.000 abstract description 10
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V8/00—Prospecting or detecting by optical means
- G01V8/10—Detecting, e.g. by using light barriers
- G01V8/20—Detecting, e.g. by using light barriers using multiple transmitters or receivers
- G01V8/22—Detecting, e.g. by using light barriers using multiple transmitters or receivers using reflectors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V8/00—Prospecting or detecting by optical means
- G01V8/005—Prospecting or detecting by optical means operating with millimetre waves, e.g. measuring the black losey radiation
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Abstract
The present disclosure provides a millimeter wave/terahertz wave imaging apparatus and a human body or article detection method, including a quasi-optical assembly, a detector array, and a reflective plate adjusting device, where the quasi-optical assembly is used for reflecting and converging beams spontaneously radiated or reflected by an object to be detected to the detector array, and includes a plurality of reflective plates adapted to receive and reflect beams from the object to be detected, angles between the plurality of reflective plates and a normal direction of a field of view where the object to be detected is located are different, and angles between the plurality of reflective plates and a horizontal plane are different; the detector array is used for receiving the beam from the quasi-optical component; the reflecting plate adjusting device comprises a rotating mechanism and is used for driving the reflecting plates to rotate in the horizontal direction, so that the reflecting plates sequentially reflect partial spontaneous radiation or reflected beams of the detected object, which are positioned at different vertical positions of the view field, so that the view field is comprehensively reflected, sampling dense points are concentrated in the middle of the view field, and the sampling points are uniformly distributed in most areas of the view field and are convenient to interpolate.
Description
Technical Field
The disclosure relates to the technical field of security inspection, in particular to millimeter wave/terahertz wave imaging equipment and a method for detecting a human body or an article by using the millimeter wave/terahertz wave imaging equipment.
Background
In the increasingly severe situation of the current domestic and foreign anti-terrorist situation, terrorists carry dangerous articles such as cutters, guns, explosives and the like with themselves in a hidden mode to form a serious threat to public safety. The human body security inspection technology based on passive millimeter wave/terahertz wave has the unique advantages that imaging is achieved through millimeter wave/terahertz wave radiation of a detection target, active radiation is not needed, security inspection is conducted on a human body, and detection of hidden dangerous objects is achieved through penetrating capacity of millimeter wave/terahertz wave. Passive millimeter wave and terahertz wave imaging techniques can be classified into focal plane imaging systems and imaging systems based on mechanical scanning, depending on the imaging system.
Millimeter-wave terahertz cameras based on focal plane imaging technology use complex technology and require special devices, the basic principle of which is to simultaneously image different positions of a target through numerous unit antennas distributed on a focal plane and appropriate mirrors and lenses. Real-time imaging can be achieved using focal plane array antennas, such as the NGC system from Northrop Grumman, usa, but the system is complex, e.g., the NGC system requires 1040 detectors at an angular resolution of 0.5 ° for a field of view of 15 ° horizontally and 10 ° vertically. To reduce system cost and complexity, the current mainstream solution is to scan the entire field of view in a one-dimensional linear detector array plus mechanical scanning.
When a typical detector array is linearly distributed and the detector cone scans, the linear arrangement of the detectors results in an image with a much lower sampling density in the middle part of the field of view than at the edges, while the edge areas are less of a concern than the central areas. Furthermore, for such an arrangement, rotating the image (not rotating the entire camera) may result in some loss of potential information.
Disclosure of Invention
The purpose of the present disclosure is to provide a millimeter wave/terahertz wave imaging apparatus so that the sampling density of an image in a field of view is relatively uniform.
The invention also aims to provide a method for detecting the human body or the object by utilizing the millimeter wave/terahertz wave imaging device, and the detection result of the method is more accurate, and the method is particularly suitable for various applications for carrying out safety detection on the human body or the object.
According to an embodiment of one aspect of the present disclosure, there is provided a millimeter wave/terahertz wave imaging apparatus including: a quasi-optical component, a millimeter wave/terahertz wave detector array and a reflecting plate adjusting device,
the quasi-optical component is suitable for reflecting and converging millimeter wave/terahertz wave spontaneously radiated or reflected by a detected object to the millimeter wave/terahertz wave detector array, and comprises a plurality of reflecting plates which are suitable for receiving and reflecting beams from the detected object, wherein angles between the reflecting plates and a normal of a field of view where the detected object is positioned are different, and angles between the reflecting plates and a horizontal plane are different;
the millimeter wave/terahertz wave detector array is adapted to receive a beam from the quasi-optical assembly; and
the reflecting plate adjusting device comprises a rotating mechanism, and the rotating mechanism is suitable for driving a plurality of reflecting plates to rotate in the horizontal direction, so that the reflecting plates sequentially reflect partial spontaneous radiation or reflected beams of the detected object, which are positioned at different vertical positions of the field of view.
In some embodiments, an angle between at least one of the plurality of reflective plates and a horizontal plane is adjustable.
In some embodiments, the rotation mechanism comprises:
a base; and
the turntable is rotationally connected with the base, and the reflecting plates are arranged on the turntable so as to rotate in the horizontal direction under the drive of the turntable;
and the turntable driving device is connected with the turntable and is suitable for driving the turntable to rotate.
In some embodiments, the turntable comprises
The turntable body is suitable for being connected with the base in a rotating mode; and
the rotary table comprises an inverted L-shaped bracket, wherein one end part of the L-shaped bracket is connected with the rotary table body, and the other end part of the L-shaped bracket is connected with the reflecting plate.
In some embodiments, a tilt mechanism adapted to adjust an angle between the reflective plate and the horizontal plane is also included.
In some embodiments, the pitch swing mechanism comprises:
the crank of the crank connecting rod mechanism is connected with the reflecting plate and is rotationally connected with the L-shaped bracket, and a connecting rod of the crank connecting rod mechanism is slidably connected with the L-shaped bracket so as to drive the crank to rotate through the sliding of the connecting rod relative to the L-shaped bracket and further drive the reflecting plate to swing in a pitching way;
and the pitching swinging driving device is suitable for driving the sliding motion of the connecting rod relative to the L-shaped bracket.
In some embodiments, the crank employs a semicircular plate, and a diameter portion of the semicircular plate is connected to the reflecting plate.
In some embodiments, a guide is provided on the L-shaped bracket, and a link of the crank link mechanism is slidably sleeved in the guide.
In some embodiments, the turntable is provided with an angular displacement measuring mechanism for measuring the angular displacement of the turntable.
In some embodiments, the base is an L-shaped structure and includes a horizontal portion and a vertical portion connected to the horizontal portion.
In some embodiments, the millimeter wave/terahertz wave imaging apparatus further comprises a detector platform adapted to mount the millimeter wave/terahertz wave detector array, the detector platform being fixed on a vertical portion of the L-shaped structure.
In some embodiments, the quasi-optical assembly further comprises a focusing lens adapted to converge a beam from the reflecting plate, the focusing lens being located between the reflecting plate and the millimeter wave/terahertz wave detector array along the path of the beam.
In some embodiments, a lens holder adapted to mount the focusing lens is also included, the lens holder being disposed on a vertical portion of the L-shaped structure.
In some embodiments, the quasi-optical assembly further comprises a focusing lens adapted to converge a beam from the inspected object, the focusing lens being located between the reflective plate and the inspected object.
In some embodiments, the plurality of millimeter wave/terahertz wave detectors in the millimeter wave/terahertz wave detector array are in linear distribution or double-row staggered distribution.
In some embodiments, the plurality of reflection plates are equally spaced on an imaginary circle centered on the rotation axis of the rotation mechanism.
In some embodiments, the reflective plate is planar.
In some embodiments, the reflector plate employs a smooth metal surface or a metal grid.
In some embodiments, the reflective plate is a fresnel mirror or a parabolic mirror.
In some embodiments, further comprising:
a data processing device connected with the millimeter wave/terahertz wave detector array to receive scan data for a detected object from the millimeter wave/terahertz wave detector array and generate a millimeter wave/terahertz wave image; and
and the display device is connected with the data processing device and is used for receiving and displaying millimeter wave/terahertz wave images from the data processing device.
According to an embodiment of another aspect of the present disclosure, there is provided a method of detecting a human body or an article using a millimeter wave/terahertz wave imaging apparatus, including the steps of:
step S1: the rotating mechanism drives the plurality of reflecting plates to rotate in the horizontal direction, so that the plurality of reflecting plates sequentially reflect part of spontaneous radiation or reflected beam millimeter waves/terahertz waves of the detected object, which are positioned at different vertical positions of the field of view;
step S2: transmitting the scanning data of the detected object obtained by the millimeter wave/terahertz wave detector array to a data processing device; and
step S3: reconstructing the scan data with a data processing device to generate a millimeter wave/terahertz wave image of the object under examination.
In some embodiments, in step S1, the rotation mechanism drives the plurality of reflection plates to rotate a certain angle in the horizontal direction, and the pitching mechanism drives at least one of the plurality of reflection plates to oscillate a predetermined angle N in the vertical direction v Secondary to reflect the spontaneous radiation or reflected beam of the detected object in the corresponding vertical range of the field of view, and the rotating mechanism drives the reflecting plate to rotate in the horizontal direction by N h And secondly, the beam reflected by or spontaneous radiation of the part of the detected object in the horizontal range of the field of view is reflected.
In some embodiments, each of the reflective plates performs a number N of oscillations required for reflection of the inspected object within a corresponding predetermined vertical range of the field of view v Calculated by the following formula:
wherein [ (formula) represents an upward rounding);
l is the distance from the center of the field of view to the center of the reflecting plate;
H 0 a static field of view arranged for millimeter wave/terahertz wave detectors;
θ pre-preparation A vertical range H of a preset visual field corresponding to each reflecting plate Pre-preparation The corresponding angle of the field of view.
In some embodiments, the number of rotations N required to complete reflection of the horizontal range of the field of view in which the inspected object is located h Calculated by the following formula:
wherein [ (formula) represents an upward rounding);
v is the horizontal range of the field of view;
d is the center-to-center distance between two adjacent millimeter wave/terahertz wave detectors;
L 1 is the object distance;
L 2 is the image distance.
In some embodiments, step S4 is further included: after the millimeter wave/terahertz wave image of the object to be detected is generated, whether the object to be detected has suspicious objects and the positions of the suspicious objects are identified, and the result is output.
According to the millimeter wave/terahertz wave imaging apparatus of the various embodiments of the present disclosure, the rotation mechanism drives the plurality of reflection plates to rotate simultaneously, so that the plurality of reflection plates sequentially reflect the millimeter wave/terahertz waves reflected back or spontaneously radiated by the part of the object to be detected, which is located at different vertical positions of the field of view, so as to comprehensively reflect the field of view, the sampling concentration points are concentrated in the middle of the whole field of view, and in most of the area of the field of view, the sampling points are uniformly distributed, and the interpolation is convenient.
Drawings
Fig. 1 is a schematic structural view of a millimeter wave/terahertz wave imaging apparatus according to an embodiment of the present disclosure;
fig. 2 is a schematic structural view of the millimeter wave/terahertz wave imaging apparatus shown in fig. 1 with only one reflection plate provided thereon;
fig. 3 is a schematic diagram of a millimeter wave/terahertz wave imaging apparatus according to the present disclosure;
fig. 4 is a schematic diagram of a millimeter wave/terahertz wave imaging apparatus according to another embodiment of the present disclosure;
FIG. 5 is a schematic illustration of reflector pitching and vertical extent of the field of view, according to one embodiment of the present disclosure;
FIG. 6 is a schematic diagram of lens imaging;
fig. 7 is a schematic view of a structure in which a focus lens is located between a subject and a reflection plate according to still another embodiment of the present disclosure;
fig. 8 is a schematic diagram of the operation of a millimeter wave/terahertz wave imaging apparatus according to one embodiment of the disclosure;
fig. 9 is a schematic operation diagram of a millimeter wave/terahertz wave imaging apparatus according to another embodiment of the disclosure;
fig. 10 is a schematic operation diagram of a millimeter wave/terahertz wave imaging apparatus according to still another embodiment of the present disclosure; and
fig. 11 is a flowchart of a method of detecting a human body or an article using a millimeter wave/terahertz wave imaging apparatus according to the present disclosure.
Detailed Description
While the present disclosure will be fully described with reference to the accompanying drawings, which contain preferred embodiments of the present disclosure, it is to be understood before this description that one of ordinary skill in the art can modify the disclosure described herein while achieving the technical effects of the present disclosure. Accordingly, it is to be understood that the foregoing description is a broad disclosure by those having ordinary skill in the art, and is not intended to limit the exemplary embodiments described in the present disclosure.
Furthermore, in the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in the drawings in order to simplify the drawings.
Fig. 1 and 2 schematically illustrate a millimeter wave/terahertz wave imaging apparatus according to an embodiment of the present disclosure. The imaging apparatus includes a quasi-optical assembly adapted to reflect and converge a beam spontaneously radiated by an object 31 to be inspected to the millimeter wave/terahertz wave detector array 2, a reflecting plate adjusting device, and a millimeter wave/terahertz wave detector array 2, and includes three reflecting plates 1A, 1B, 1C adapted to receive and reflect a beam from the object 31 to be inspected, and a focusing lens 4 adapted to converge a beam from each of the reflecting plates 1A, 1B, 1C, wherein angles between the three reflecting plates 1A, 1B, 1C and a normal to a field of view in which the object 31 to be inspected is located are different, and angles between the plurality of reflecting plates 1A, 1B, 1C and a horizontal plane are also different. Here, the field normal (as indicated by the open arrow in fig. 1 and 2) refers to the direction of a horizontal line from the center of the reflection plate 1 to the longitudinal center line of the field of view 3. The millimeter wave/terahertz wave detector array 2 is adapted to receive the beams reflected and converged by the quasi-optical assembly. The reflecting plate adjusting device includes a rotating mechanism 6, the rotating mechanism 6 is suitable for driving the reflecting plate 1 to rotate in the horizontal direction, and since angles between the three reflecting plates 1A, 1B, 1C and the normal of the field of view where the object to be inspected is located are different, the reflecting plates 1A, 1B, 1C can be driven by the rotating mechanism 6 to reflect the beam spontaneously radiated from the object to be inspected 31 in turn, and furthermore, since angles between the three reflecting plates 1A, 1B, 1C and the horizontal plane are also different, the three reflecting plates 1A, 1B, 1C can be made to reflect the beam spontaneously radiated from the object to be inspected 31 located at different vertical positions of the field of view 3.
According to the embodiment of the present disclosure, the millimeter wave/terahertz wave imaging apparatus receives and reflects the beam spontaneously radiated by the object under test 31 through the reflection plate 1 and receives by the millimeter wave/terahertz wave detector array 2 after the converging action of the focusing lens 4 (as shown in fig. 3). Since the angles between the three reflection plates 1A, 1B, 1C and the normal of the field of view where the object 31 is located are different, the reflection plates 1A, 1B, 1C can sequentially reflect the beam spontaneously radiated from the object 31 under the drive of the rotation mechanism 6, and furthermore, since the angles between the three reflection plates 1A, 1B, 1C and the horizontal plane are also different, the reflection plates 1A, 1B, 1C can reflect the beam spontaneously radiated from the object 31 located at different vertical positions of the field of view 3, so that the reflection plate 1 totally reflects the field of view 3, and the sampling dense point is concentrated in the middle of the whole field of view 3.
It should be noted that, although in this embodiment, the beam reflected by the reflection plates 1A, 1B, 1C is a millimeter wave or terahertz wave spontaneously radiated by the object 31 to be inspected, it should be understood by those skilled in the art that the beam may be a millimeter wave/terahertz wave irradiated to the object 31 and reflected back through the object 31 to be inspected.
As shown in fig. 1 and 2, in one exemplary embodiment, the angle between at least one of the three reflection plates 1A, 1B, 1C and the horizontal plane is adjustable. In order to facilitate adjustment of the angle between the reflection plates 1A, 1B, 1C and the horizontal plane, it is preferable that the millimeter wave/terahertz wave imaging apparatus further include a pitching mechanism 7A, 7B, 7C for adjusting the angle between each reflection plate 1A, 1B, 1C and the horizontal plane. When the reflection plates 1A, 1B, 1C are driven by the rotation mechanism 6 to rotate for a certain angle, the pitching and swinging mechanisms 7A, 7B, 7C drive the reflection plates 1A, 1B, 1C connected with the same to perform pitching and swinging in the vertical direction so as to enlarge the vertical range of the field of view 3 corresponding to the reflection plates, so that the millimeter wave/terahertz wave imaging device can meet the field of view 3 of a larger vertical range without increasing the number of millimeter wave/terahertz wave detectors.
It should be noted that, in other embodiments of the present disclosure, the angles between the reflective plates 1A, 1B, 1C and the horizontal plane may be fixed (as shown in fig. 4). When the view field angle corresponding to the vertical range of the whole view field is θm, the deviation angles of the three reflection plates 1A, 1B, 1C and the horizontal plane are respectively
Where α is an angle between the reflective plate 1B and the horizontal plane, and preferably α is 45 °, it should be understood that, in other embodiments of the present invention, α may be other values, for example, α is in the range of 30 ° to 60 °, and so on.
If the static field of view of the millimeter wave/terahertz wave detector array is H 0 Then the total field of view height is about 3H 0 . Static field of view H 0 The size of (2) depends on the number of millimeter wave/terahertz wave detectors and the center-to-center spacing.
It should be noted that, although three reflection plates are shown here, it should be understood by those skilled in the art that the number of reflection plates may be other values, for example, 2, 4, 5, 6, etc., and preferably 4, 5, or 6. In some embodiments, the plurality of reflecting plates are equally spaced on an imaginary circle centered on the rotation axis of the rotation mechanism 6
As shown in fig. 1 and 2, in one exemplary embodiment, the rotation mechanism 6 comprises a base 61 and a turntable, wherein the turntable comprises a turntable body 62 and two inverted L-shaped brackets 63, wherein the rotating body 62 is adapted for rotational connection with the base 61; the two L-shaped brackets 63 are symmetrically arranged on two sides of the pitching swinging mechanism 7, one end part of each L-shaped bracket 63 is connected with the turntable body 62, and the other end part of each L-shaped bracket 63 is connected with the pitching swinging mechanism 7, so that the pitching swinging mechanism 7 can be driven to rotate in the horizontal direction through rotation of the turntable, and then the reflecting plate 1 connected with the pitching swinging mechanism 7 is driven to rotate in the horizontal direction.
As shown in fig. 1 and 2, in one exemplary embodiment, the turntable includes a turntable body 62 and an inverted L-shaped bracket 63, wherein a rotating body 621 is adapted for rotational connection with the base 61; the two L-shaped brackets 63 are symmetrically arranged on two sides of the pitching swinging mechanism 7, one end part of each L-shaped bracket 63 is connected with the turntable body 62, and the other end part of each L-shaped bracket 63 is connected with the pitching swinging mechanism 7, so that the pitching swinging mechanism 7 can be driven to rotate in the horizontal direction through rotation of the turntable, and then the reflecting plate 1 connected with the pitching swinging mechanism 7 is driven to rotate in the horizontal direction.
As shown in fig. 1 and 2, in one exemplary embodiment, the pitching oscillation mechanism 7 includes: the crank of the crank connecting rod mechanism adopts a semicircular plate 71, the diameter part of the semicircular plate 71 is connected with the reflecting plate 1, and the circle center of the semicircular plate 71 is respectively and rotatably connected with the two L-shaped brackets 63 through a rotating shaft 73; the connecting rod 72 of the crank-connecting rod mechanism is in sliding connection with the L-shaped support 63, so that the semicircular plate 71 is driven to rotate through the sliding of the connecting rod 72 relative to the L-shaped support 63, and then the pitching swing of the reflecting plate 1 is driven, so that the angle between the reflecting plate 1 and the vertical direction is adjusted, the reflection of partial spontaneous radiation beams of the detected object 31 at different vertical positions of the field of view 3 is realized, and the data acquisition of the field of view 3 in the vertical direction is completed. The pitching mechanism 7 further comprises a pitching drive means 74, e.g. a linear actuator, adapted to drive the sliding movement of the link 72 and the L-shaped bracket 63.
As shown in fig. 1 and 2, in an exemplary embodiment, a cylindrical guide is provided on the L-shaped bracket 63, and a link 72 of a crank link mechanism is slidably fitted in the guide, so that sliding of the link 72 with respect to the L-shaped bracket 63 can be ensured.
Furthermore, the turret is provided with an angular displacement measuring mechanism (not shown) adapted to measure the angular displacement of the turret, so as to control the rotation amplitude of the turret to operate only in the horizontal range of the field of view 3.
As shown in fig. 1 and 2, in one exemplary embodiment, the base 61 has an L-shaped structure including a horizontal portion and a vertical portion disposed substantially perpendicular to the horizontal portion, wherein the turntable is rotatably mounted on the horizontal portion of the base 61.
As shown in fig. 1 and 2, in one exemplary embodiment, the imaging apparatus further includes a millimeter wave/terahertz wave detector platform 8 adapted to mount the millimeter wave/terahertz wave detector array 2, the millimeter wave/terahertz wave detector platform 8 being mounted on a vertical portion of the L-shaped structure so that the millimeter wave/terahertz wave detector array 2 receives the beam from the quasi-optical component.
As shown in fig. 1 to 3, in one exemplary embodiment, a focusing lens 4 is located between the reflection plate 1 and the millimeter wave/terahertz wave detector array 2 along the path of the beam. It should be noted that, in other embodiments of the present disclosure, the focusing lens 4 may be disposed between the reflecting plate 1 and the object 31, that is, the beam spontaneously radiated by the object 31 passes through the focusing lens 4 and is then reflected by the reflecting plate 1 to the millimeter wave/terahertz wave detector array 2 and received by the millimeter wave/terahertz wave detector array 2, as shown in fig. 7.
As shown in fig. 1 and 2, in one exemplary embodiment, the imaging apparatus further includes a lens holder 5 adapted to mount the focusing lens 4, the lens holder 5 being fixed on the vertical portion of the L-shaped structure and located between the millimeter wave/terahertz wave detector platform 8 and the reflection plate 1.
In an exemplary embodiment, the millimeter wave/terahertz wave detector arrays 2 are in a double-row staggered distribution (as shown in fig. 8), and the distribution direction of each row is parallel to the normal direction of the field of view. Here, the field normal refers to a direction of a horizontal line from the center of the reflection plate 1 to the longitudinal center line of the field 3. The number of millimeter wave/terahertz wave detectors in the millimeter wave/terahertz wave detector array 2 is determined according to the required field size and the required resolution, and the millimeter wave/terahertz wave detector size is determined according to the wavelength, the processing technology, the required sampling density and the like. It should be noted that, in other embodiments of the present disclosure, the millimeter wave/terahertz wave detector array 2 may also be linearly distributed, and the distribution direction is also parallel to the normal of the field of view, as will be understood by those skilled in the art.
Furthermore, it should be noted that those skilled in the art will appreciate that in some embodiments of the present disclosure, the reflector plate 1 may be planar, such as a smooth metal surface or a metal grid mesh, and in other embodiments of the present disclosure, the reflector plate 1 may also be non-planar, such as a fresnel mirror or a parabolic mirror.
In one embodiment of the present disclosure, the imaging apparatus may further include a data processing device (not shown). The data processing apparatus is connected wirelessly or by wire to the millimeter wave/terahertz wave detector array 2 to receive scan data for the object 3 to be inspected from the millimeter wave/terahertz wave detector array 2 and generate a millimeter wave/terahertz wave image. The imaging apparatus may further include a display device connected to the data processing device for receiving and displaying the millimeter wave/terahertz wave image from the data processing device.
In an exemplary embodiment, the data processing device may be configured to generate and send control signals to the turntable drive and the pitch drive to drive the turntable in rotation and/or the pitch mechanism 7 in oscillation. In another exemplary embodiment, the image forming apparatus may also include a control device independent from the data processing device.
The present disclosure also provides a method for detecting a human body or an article using a passive millimeter wave/terahertz wave imaging apparatus, as shown in fig. 11, including the steps of:
step S1: the rotation mechanism 6 drives the three reflection plates 1A, 1B, 1C to rotate in the horizontal direction, so that the three reflection plates 1A, 1B, 1C sequentially reflect the millimeter wave/terahertz wave spontaneously radiated from the portion of the object 31 to be inspected located at different vertical positions of the field of view 3;
step S2: transmitting the scanning data for the detected object obtained by the millimeter wave/terahertz wave detector array 2 to a data processing device; and
step S3: the scan data is reconstructed with a data processing device to generate a millimeter wave/terahertz wave image of the object to be inspected.
The method can accurately image and detect the detected object 31 in all directions, wherein the detected object 31 can be a human body or an article.
Preferably, in step S1, the rotation mechanism 6 drives three reflection plates 1A, 1B, 1C to rotate every certain angle in the horizontal direction, and the pitching mechanism 7A, 7B, 7C simultaneously drives the reflection plates 1A, 1B, 1C connected thereto to oscillate by a predetermined angle N in the vertical direction v The rotation mechanism 6 drives the three reflection plates 1A, 1B, 1C to rotate N in the horizontal direction to complete the reflection of the beam of the partial spontaneous radiation of the inspected object located in the corresponding preset vertical range of the field of view 3 h And again to complete the reflection of the beam of spontaneous radiation of the portion of the object 31 to be examined lying in the horizontal range of the field of view 3. Here, the pitching mechanisms 7A, 7B, and 7C may be synchronized or unsynchronized by driving the reflection plates 1A, 1B, and 1C connected thereto to oscillate.
Fig. 5 shows a schematic view of the pitching and vertical extent of the field of view of the reflection plate 1. As shown in fig. 5, the static field of view of the millimeter wave/terahertz wave detector array 2 is H 0 The horizontal distance from the center of the field of view 3 to the center of the reflecting plate 1 is L, the vertical field of view range is H, and the field angle corresponding to the vertical field of view range H is θ m . The reflecting plate 1 swings theta, and the corresponding view field angle changes by 2 theta, so the view field angle corresponding to the vertical view field range H is theta m The swing angle of the corresponding reflection plate 1 is theta m /2. When three reflection plates 1A, 1B, 1C are employed, each of the reflection plates completes a corresponding preset vertical range H of the inspected object 31 in the field of view 3 Pre-preparation Number of required wobbles N by reflection of (a) v Calculated by the following formula:
wherein [ (formula) represents an upward rounding);
l is the distance from the center of the field of view to the center of the reflecting plate;
H 0 a static field of view for millimeter wave/terahertz wave detector arrangement 2;
θ pre-preparation A vertical range H of a preset visual field corresponding to each reflecting plate Pre-preparation The corresponding angle of the field of view.
Whether the reflection plate needs to perform pitching oscillation and the number of pitching oscillation are determined by the static field of view of the millimeter wave/terahertz wave detector array and the number of reflection plates. As the number of reflection plates increases, the possibility that the reflection plates do not need to do pitching motion increases.
Assuming that the number of millimeter wave/terahertz wave detectors is N, when the center distance d between two adjacent millimeter wave/terahertz wave detectors is the maximum offset feed distance y of the millimeter wave/terahertz wave detectors m Then
Thus, the static view field of the millimeter wave/terahertz wave detector array can be calculated to be H 0 . As shown in fig. 6, the static field of view H of the millimeter wave/terahertz wave detector array 0 Distance from object L 1 Image distance L 2 It is required to satisfy the following relation
Number of rotations N required to reflect the beam of the partial spontaneous emission of the object 31 lying in the horizontal range of the field of view h Calculated by the following formula:
wherein [ (formula) represents an upward rounding);
v is the horizontal field of view range;
d is the center-to-center distance between two adjacent millimeter wave/terahertz wave detectors;
L 1 is the object distance;
L 2 is the image distance.
The angle at which the rotation mechanism 6 drives the three reflection plates 1A, 1B, 1C to rotate each time in the horizontal direction should be determined in accordance with the static field of view of the millimeter wave/terahertz wave detector array in the horizontal direction. Likewise, the angle at which the pitching oscillation mechanism 7 oscillates should be determined from the static field of view of the millimeter wave/terahertz wave detector array in the vertical direction.
As an exemplary embodiment, the method may further include:
step S4: after the millimeter wave/terahertz wave image of the human body or the object is generated, whether the human body or the object carries a suspicious object or not and the position of the suspicious object are identified, and the result is output.
In the above step S4, the identification of the suspicious object 32 and the position thereof may be performed by a method of automatic identification or manual identification or a combination of both. The output of the result may be achieved by, for example, displaying a conclusion marked with a direct display of whether or not the suspicious object 32 is present on the display device, or the detection result may be printed or transmitted directly.
The security check personnel performing the detection can confirm whether the human body or the article has the suspicious object 32 or not and the position of the suspicious object 32 according to the detection result given in the step S4, and can check by manual detection.
As shown in fig. 8, in an exemplary embodiment, the number N of millimeter wave/terahertz wave detectors is 20 and is distributed in a row, the center-to-center distance d between two adjacent millimeter wave/terahertz wave detectors is 7mm, and the maximum offset feed distance y m 7cm. Object distance L 1 3.5m, image distance L 2 At 0.7m, the static field of view H can be calculated according to equation (3) 0 =70 cm. Three different angles (theta) A 、θ B 、θ C ) The reflection plates 1A, 1B and 1C can reflect the vertical range of the visual field of 2m without pitching and swinging, and the number of times N of rotation is needed for the horizontal range of the visual field of 1m h At least 29, ultimately resulting in a field of view distribution as shown in fig. 8.
As shown in fig. 9, in an exemplary embodiment, the number N of millimeter wave/terahertz wave detectors is 40, and the millimeter wave/terahertz wave detectors are distributed in a double row staggered manner, the center-to-center distance d between two adjacent millimeter wave/terahertz wave detectors in each row is 14mm, and the maximum offset feed distance y m =7cm. Object distance L 1 3.5m, image distance L 2 At 0.7m, the static field of view H can be calculated according to equation (3) 0 =70 cm. To achieve a reflection of the vertical range of the field of view of 2m, three different angles (θ A 、θ B 、θ C ) The three reflecting plates 1A, 1B and 1C can be stationary at corresponding angles, and can be completed without pitching movement, and the number of times N of rotation is required when the horizontal range of the view field is 1m h At least 15, ultimately resulting in a field of view distribution as shown in fig. 9.
As shown in fig. 10, in an exemplary embodiment, the number N of millimeter wave/terahertz wave detectors is 10, the millimeter wave/terahertz wave detectors are linearly distributed, the center-to-center distance d between two adjacent millimeter wave/terahertz wave detectors is 7mm, and the maximum offset feed distance y m 7cm. Object distance L 1 3.5m, image distance L 2 At 0.7m, the static field of view H can be calculated according to equation (3) 0 =70 cm. In order to realize the reflection of the field of view with the vertical range of 2m, three angle-adjustable reflecting plates 1A, 1B and 1C are adopted, and the required swinging times of each reflecting plate are 2 and are respectively' pitching upper angle theta On A Sum pitch angle θ Under A "(corresponding vertical extent of field of view is H On A And H Under A ) Upper pitch angle theta On B Sum pitch angle θ Under B "(corresponding vertical extent of field of view is H On B And H Under B ) Upper pitch angle theta On C Sum pitch angle θ Under C "(corresponding vertical extent of field of view is H On C And H Under C ). The number of times N of rotation required for a horizontal range of field of view of 1m h At least 15, ultimately resulting in a field of view distribution as shown in fig. 10.
According to the millimeter wave/terahertz wave imaging apparatus of the various embodiments of the disclosure, the rotation mechanism 6 drives the plurality of reflection plates 1 to rotate simultaneously, so that the plurality of reflection plates sequentially reflect partial spontaneous radiation or reflected beams of the inspected object located at different vertical positions of the field of view, so as to comprehensively reflect the field of view, the sampling concentration points are concentrated in the middle of the whole field of view, and in most areas of the field of view, the sampling points are uniformly distributed, and the interpolation is convenient.
Those skilled in the art will appreciate that the embodiments described above are exemplary and that modifications may be made by those skilled in the art, and that the structures described in the various embodiments may be freely combined without conflict in terms of structure or principle.
Having described the preferred embodiments of the present disclosure in detail, those skilled in the art will readily appreciate that various changes and modifications may be made without departing from the scope and spirit of the following claims, and that the present disclosure is not limited to the implementations of the exemplary embodiments set forth in the specification.
Claims (25)
1. A millimeter wave/terahertz wave imaging apparatus, characterized by comprising: a quasi-optical component, a millimeter wave/terahertz wave detector array and a reflecting plate adjusting device,
the quasi-optical component is suitable for reflecting and converging millimeter wave/terahertz wave spontaneously radiated or reflected by a detected object to the millimeter wave/terahertz wave detector array, and comprises a plurality of reflecting plates which are suitable for receiving and reflecting beams from the detected object, wherein angles between the reflecting plates and a normal of a field of view where the detected object is positioned are different, and angles between the reflecting plates and a horizontal plane are also different;
the millimeter wave/terahertz wave detector array is adapted to receive a beam from the quasi-optical assembly; and
the reflecting plate adjusting device comprises a rotating mechanism, the plurality of reflecting plates are arranged at intervals around the rotating axis of the rotating mechanism, and the rotating mechanism is suitable for driving the plurality of reflecting plates to rotate in the horizontal direction, so that the plurality of reflecting plates sequentially reflect partial spontaneous radiation or reflected beams of the detected object, which are positioned at different vertical positions of the visual field.
2. The imaging apparatus of claim 1, wherein an angle between at least one of the plurality of reflective plates and a horizontal plane is adjustable.
3. The image forming apparatus according to claim 1, wherein the rotation mechanism includes:
a base; and
the turntable is rotationally connected with the base, and the reflecting plates are arranged on the turntable so as to rotate in the horizontal direction under the drive of the turntable;
and the turntable driving device is connected with the turntable and is suitable for driving the turntable to rotate.
4. An image forming apparatus according to claim 3, wherein said turntable includes
The turntable body is suitable for being connected with the base in a rotating mode; and
the rotary table comprises an inverted L-shaped bracket, wherein one end part of the L-shaped bracket is connected with the rotary table body, and the other end part of the L-shaped bracket is connected with the reflecting plate.
5. The imaging apparatus of claim 4, further comprising a tilt mechanism adapted to adjust an angle between the reflective plate and the horizontal plane.
6. The imaging apparatus according to claim 5, wherein the pitching swinging mechanism comprises:
the crank of the crank connecting rod mechanism is connected with the reflecting plate and is rotationally connected with the L-shaped bracket, and a connecting rod of the crank connecting rod mechanism is slidably connected with the L-shaped bracket so as to drive the crank to rotate through the sliding of the connecting rod relative to the L-shaped bracket and further drive the reflecting plate to swing in a pitching way;
and the pitching swinging driving device is suitable for driving the sliding motion of the connecting rod relative to the L-shaped bracket.
7. The image forming apparatus according to claim 6, wherein the crank employs a semicircular plate, and a diameter portion of the semicircular plate is connected to the reflecting plate.
8. The image forming apparatus according to claim 6, wherein a guide is provided on the L-shaped bracket, and a link of the crank link mechanism is slidably fitted in the guide.
9. An image forming apparatus according to claim 3, wherein said turntable is provided with an angular displacement measuring mechanism for measuring an angular displacement of said turntable.
10. An image forming apparatus according to claim 3, wherein said base has an L-shaped structure and includes a horizontal portion and a vertical portion connected to said horizontal portion.
11. The imaging apparatus of claim 10, further comprising a detector platform adapted to mount the millimeter wave/terahertz wave detector array, the detector platform being secured to a vertical portion of the L-shaped structure.
12. The imaging device of claim 11, wherein the quasi-optical assembly further comprises a focusing lens adapted to focus the beam from the reflecting plate, the focusing lens being located between the reflecting plate and the millimeter wave/terahertz wave detector array along the path of the beam.
13. The imaging apparatus of claim 12, further comprising a lens holder adapted to mount the focusing lens, the lens holder being disposed on a vertical portion of the L-shaped structure.
14. The imaging apparatus according to claim 1, wherein the quasi-optical assembly further comprises a focusing lens adapted to converge a beam from the object under examination, the focusing lens being located between the reflecting plate and the object under examination.
15. The imaging apparatus of claim 1, wherein a plurality of millimeter wave/terahertz wave detectors in the millimeter wave/terahertz wave detector array are in a linear distribution or a double-row staggered distribution.
16. The image forming apparatus according to claim 1, wherein a plurality of the reflection plates are equally spaced on an imaginary circle centered on a rotation axis of the rotation mechanism.
17. The imaging apparatus of any of claims 1-13, wherein the reflective plate is planar.
18. The imaging apparatus of claim 14, wherein the reflective plate employs a smooth metal surface or a metal grid.
19. The imaging apparatus of any of claims 1-13, wherein the reflective plate is a fresnel mirror or a parabolic mirror.
20. The image forming apparatus according to any one of claims 1 to 13, further comprising:
a data processing device connected with the millimeter wave/terahertz wave detector array to receive scan data for a detected object from the millimeter wave/terahertz wave detector array and generate a millimeter wave/terahertz wave image; and
and the display device is connected with the data processing device and is used for receiving and displaying millimeter wave/terahertz wave images from the data processing device.
21. A method for detecting a human body or an object by using millimeter wave/terahertz wave imaging apparatus, comprising the steps of:
step S1: the rotating mechanism drives the plurality of reflecting plates to rotate in the horizontal direction, so that the plurality of reflecting plates sequentially reflect part of spontaneous radiation or reflected millimeter wave/terahertz wave of the detected object at different vertical positions of the field of view, wherein the plurality of reflecting plates are arranged at intervals around the rotating axis of the rotating mechanism;
step S2: transmitting the scanning data of the detected object obtained by the millimeter wave/terahertz wave detector array to a data processing device; and
step S3: reconstructing the scan data with a data processing device to generate a millimeter wave/terahertz wave image of the object under examination.
22. The method of claim 21, wherein in step S1, the rotation mechanism drives a plurality of the reflection plates to rotate a predetermined angle in a horizontal direction, and the pitching mechanism drives at least one of the plurality of the reflection plates to oscillate a predetermined angle N in a vertical direction v Secondary to reflect the spontaneous radiation or reflected beam of the detected object in the corresponding vertical range of the field of view, and the rotating mechanism drives the reflecting plate to rotate in the horizontal direction by N h And secondly, the beam reflected by or spontaneous radiation of the part of the detected object in the horizontal range of the field of view is reflected.
23The method according to claim 21, wherein each of said reflecting plates performs a number of oscillations N required for reflection of the inspected object in a corresponding predetermined vertical range of said field of view v Calculated by the following formula:
wherein [ (formula) represents an upward rounding);
l is the distance from the center of the field of view to the center of the reflecting plate;
H 0 a static field of view arranged for millimeter wave/terahertz wave detectors;
θ pre-preparation A vertical range H of a preset visual field corresponding to each reflecting plate Pre-preparation The corresponding angle of the field of view.
24. The method of claim 21, wherein the number of rotations N required to complete reflection of the horizontal range of the field of view in which the subject is located h Calculated by the following formula:
wherein [ (formula) represents an upward rounding);
v is the horizontal range of the field of view;
d is the center-to-center distance between two adjacent millimeter wave/terahertz wave detectors;
L 1 is the object distance;
L 2 is the image distance.
25. The method according to any one of claims 21-24, further comprising step S4: after the millimeter wave/terahertz wave image of the object to be detected is generated, whether the object to be detected has suspicious objects and the positions of the suspicious objects are identified, and the result is output.
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