CN109655931B - Millimeter wave/terahertz wave imaging device and method for detecting human body or article - Google Patents

Abstract

Disclosed is a millimeter wave/terahertz wave imaging device and a method for detecting human body or objects, including a quasi-optical component, including a Y-shaped reflective plate, and the Y-shaped reflective plate includes a first reflective plate, a second reflective plate and all The third reflective plate, the Y-shaped reflective plate can rotate around its rotation axis so that the first reflective surface of the first reflective plate, the first reflective surface of the second reflective plate and the third reflective surface of the third reflective plate A reflective surface is used in turn as the first working surface to receive and reflect millimeter waves/terahertz waves that are spontaneously emitted or reflected back by parts of the first object under inspection located at different positions in the first field of view; and a millimeter wave/terahertz wave detector array , suitable for receiving the beam from the quasi-optical component. The millimeter wave/terahertz wave imaging equipment has simple control and high stability.

Description

Millimeter wave/terahertz wave imaging equipment and detection method of human body or objects

Technical field

The present disclosure relates to the field of imaging technology, and in particular to a millimeter wave/terahertz wave imaging device and a method of detecting a human body or an object using the millimeter wave/terahertz wave imaging device.

Background technique

In the current increasingly severe situation of domestic and international terrorism prevention, terrorists use concealment methods to carry dangerous items such as knives, guns, and explosives with them, posing a serious threat to public security. Human body security inspection technology based on passive millimeter waves/terahertz waves has unique advantages. It achieves imaging by detecting the millimeter wave/terahertz wave radiation of the target itself, without the need for active radiation, to conduct security inspections on the human body, using millimeter waves/terahertz waves. Penetrating capability enables detection of hidden dangerous objects. However, existing millimeter wave/terahertz wave imaging equipment has low efficiency.

Contents of the invention

The present disclosure aims to solve at least one aspect of the above-mentioned problems and deficiencies existing in the prior art.

According to an embodiment of one aspect of the present disclosure, a millimeter wave/terahertz wave imaging device is provided, including:

Quasi-optical assembly, including a Y-shaped reflective plate, the Y-shaped reflective plate including a first reflective plate, a second reflective plate and a third reflective plate, the Y-shaped reflective plate can rotate around its rotation axis so that the first reflective plate The first reflective surface of the reflective plate, the first reflective surface of the second reflective plate and the first reflective surface of the third reflective plate take turns to be used as the first working surface to receive and reflect the first inspected object located in different first fields of view. Partially spontaneously radiated or reflected millimeter/terahertz waves at the location; and

A millimeter wave/terahertz wave detector array is adapted to receive the beam from the quasi-optical component.

In some embodiments, the quasi-optical assembly further includes a fourth reflective plate. When the Y-shaped reflective plate rotates, the second reflective surface and the third reflective surface of the first reflective plate that are opposite to the first reflective surface The second working surface of the second reflecting plate opposite to the first reflecting surface and the second working surface of the third reflecting plate opposite to the first reflecting surface are used in turn as the second working surface to receive and reflect the second Parts of the object under examination located at different positions in the second field of view spontaneously radiate or reflect millimeter waves/terahertz waves to the fourth reflective plate;

Chopper, the chopper is located on the reflection wave path of the first working surface and the reflection wave path of the fourth reflection plate, and the chopper is configured to only come from the first working surface at any time. The millimeter wave/terahertz wave or only the millimeter wave/terahertz wave from the fourth reflective plate is reflected or transmitted to the millimeter wave/terahertz wave detector array, and the chopper rotates around its central axis to The millimeter wave/terahertz wave from the first working surface of the Y-shaped reflection plate and the fourth reflection plate is alternately received by the millimeter wave/terahertz wave detector array.

In some embodiments, the quasi-optical assembly further includes a focusing lens located between the chopper and the millimeter wave/terahertz wave detector array.

In some embodiments, the quasi-optical component further includes a first focusing lens and a second focusing lens, the first focusing lens being adapted to focus on millimeter waves/mm from the first working surface of the Y-shaped reflective plate. Terahertz waves are focused, and the second focusing lens is suitable for focusing millimeter waves/terahertz waves from the second working surface of the Y-shaped reflecting plate.

In some embodiments, the millimeter wave/terahertz wave imaging device further includes a wave absorbing material adapted to absorb the millimeter wave/terahertz wave reflected from the first working surface via the chopper. waves, and millimeter waves/terahertz waves from the fourth reflective plate transmitted through the chopper.

In some embodiments, the angles between the three reflective plates and the rotation axis increase or decrease along the rotation direction of the Y-shaped reflective plate.

In some embodiments, the chopper includes at least one blade.

In some embodiments, a plurality of the blades are arranged at equal intervals around the central axis.

In some embodiments, the millimeter wave/terahertz wave imaging device further includes a housing, the quasi-optical component and the millimeter wave/terahertz wave detector array are located in the housing, and opposite sides of the housing A first window for the beam from the first subject to be inspected to pass through and a second window for the beam from the second subject to be inspected to pass through are respectively provided on the wall.

In some embodiments, the millimeter wave/terahertz wave imaging device further includes a first driving device adapted to drive the Y-shaped reflective plate to rotate.

In some embodiments, the millimeter wave/terahertz wave imaging device further includes a second driving device adapted to drive the chopper to rotate.

In some embodiments, the millimeter wave/terahertz wave imaging device further includes:

A data processing device, the data processing device is connected to the millimeter wave/terahertz wave detector array to respectively receive the image data of the first detected object from the millimeter wave/terahertz wave detector array and For the image data of the second subject to be inspected, millimeter wave/terahertz wave images are respectively generated; and

A display device connected to the data processing device and configured to receive and display millimeter wave/terahertz wave images from the data processing device.

In some embodiments, the millimeter wave/terahertz wave imaging device further includes an alarm device, the alarm device is connected to the data processing device, so that when the data processing device identifies the millimeter wave/terahertz wave When there is a suspicious object in the image, an alarm is issued indicating that there is a suspicious object in the millimeter wave/terahertz wave image.

In some embodiments, the millimeter wave/terahertz wave imaging device further includes a calibration source, the calibration source is located on the object surface of the quasi-optical component, and the data processing device receives data from the millimeter wave/terahertz wave. Calibration data of the detector array for the calibration source, and updating the image data of the first inspected object and the image data of the second inspected object based on the calibration data.

In some embodiments, the millimeter wave/terahertz wave imaging device further includes an optical camera device, and the optical camera device includes a first optical camera device adapted to collect an optical image of the first object to be inspected and a first optical camera device adapted to collect an optical image of the first subject. The second optical camera device of the optical image of the second object to be inspected, the first optical camera device and the second optical camera device are respectively connected to the display device.

In some embodiments, the display device includes a display screen, the display screen includes a first display area adapted to display the millimeter wave/terahertz wave image and an optical image collected by the optical camera device. the second display area.

In some embodiments, the distance between the first reflective plate and the second reflective plate, the second reflective plate and the third reflective plate, and the third reflective plate and the first reflective plate is The included angles are all 120°.

In some embodiments, the millimeter wave/terahertz wave imaging device further includes a fifth reflective plate that swings back and forth around its central axis to receive and reflect the self-radiated or reflected light from the first subject. The millimeter wave/terahertz wave reaches the first working surface and is received by the millimeter wave/terahertz wave detector array after being reflected by the first working surface. The swing period T1 of the fifth reflecting plate is 2m times the rotation period of the Y-shaped reflecting plate, where m is an integer greater than or equal to 1.

In some embodiments, the millimeter wave/terahertz wave imaging device further includes a third driving device adapted to drive the fifth reflective plate to swing back and forth.

According to another aspect of the present disclosure, a method for detecting a human body or an object using the above-mentioned millimeter wave/terahertz wave imaging device is also provided, including the following steps:

S1: Drive the Y-shaped reflecting plate to rotate so that the first reflecting surface of the first reflecting plate, the first reflecting surface of the second reflecting plate and the first reflecting surface of the third reflecting plate take turns to be used as the first working surface to receive and reflect Millimeter waves/terahertz waves that are spontaneously radiated or reflected back by the first subject; passing through the second reflective surface of the first reflective plate, the second reflective surface of the second reflective plate and the second reflective surface of the third reflective plate It is used as a second working surface in turn to receive and reflect millimeter waves/terahertz waves that are spontaneously radiated or reflected back by the second subject to be inspected; while the Y-shaped reflecting plate rotates, the chopper rotates around its central axis to alternately The millimeter wave/terahertz wave from the first working surface and the millimeter wave/terahertz wave from the second working surface reflected by the fourth reflecting plate are received by the millimeter wave/terahertz wave detector array. ;

S2: Send the image data about the first inspected object and the second inspected object received by the millimeter wave/terahertz wave detector array to a data processing device; and

S3: Use the data processing device to reconstruct the image data of the first inspected object and the image data of the second inspected object respectively to generate the first inspected object and the second inspected object. Millimeter/terahertz wave images.

According to the millimeter wave/terahertz wave imaging equipment and the method for detecting human body or objects according to the above various embodiments of the present disclosure, a Y-shaped reflective plate is used. The Y-shaped reflective plate includes a first reflective plate, a second reflective plate and a third reflective plate. Three reflecting plates, driving the Y-shaped reflecting plate to rotate around the connection of the first reflecting plate, the second reflecting plate and the third reflecting plate so that the first reflecting surface of the first reflecting plate, the first reflecting surface of the second reflecting plate and The first reflective surface of the third reflective plate is used in turn as the first working surface to receive and reflect the millimeter waves/terahertz waves that are spontaneously emitted or reflected back by parts of the first subject located at different positions in the first field of view, thereby achieving detection of the subject. The inspection object is imaged, and the control is simple and the cost is low.

Description of the drawings

Figure 1 is a schematic structural diagram of a millimeter wave/terahertz wave imaging device according to an embodiment of the present disclosure;

Figure 2 is a schematic structural diagram of a millimeter wave/terahertz wave imaging device after removing the housing according to another embodiment of the present disclosure;

Figure 3 is a schematic diagram of the installation of a Y-shaped reflective plate of a millimeter wave/terahertz wave imaging device according to an exemplary embodiment of the present disclosure;

Figure 4 is a side view of the Y-shaped reflective plate shown in Figure 3;

5 is a schematic diagram of the angles between each reflecting plate and the rotation axis of a polyhedral rotating mirror according to another embodiment of the present disclosure;

Figure 6 is a schematic structural diagram of an exemplary embodiment of a chopper of a millimeter wave/terahertz wave imaging device according to the present disclosure;

7 is a schematic structural diagram of another exemplary embodiment of a chopper of a millimeter wave/terahertz wave imaging device according to the present disclosure;

Figure 8 is a schematic structural diagram of yet another exemplary embodiment of a chopper of a millimeter wave/terahertz wave imaging device according to the present disclosure;

Figure 9 is a schematic structural diagram of another exemplary embodiment of a chopper of a millimeter wave/terahertz wave imaging device according to the present disclosure;

Figure 10 is a schematic diagram of lens imaging;

Figure 11 is a schematic structural diagram of a millimeter wave/terahertz wave imaging device according to yet another embodiment of the present disclosure;

Figure 12 is a schematic structural diagram of a millimeter wave/terahertz wave imaging device according to yet another embodiment of the present disclosure;

Figure 13 is a schematic diagram of the total pixels of the millimeter wave/terahertz wave imaging device, the scanning pixels of each reflector, and the sparsely arranged millimeter wave/terahertz wave detector array according to one embodiment of the present disclosure;

Figure 14 is a flow chart of a method for inspecting a human body or an object using a millimeter wave/terahertz wave imaging device according to an embodiment of the present disclosure; and

Figure 15 is an application scenario diagram of a millimeter wave/terahertz wave imaging device according to an embodiment of the present disclosure.

Detailed ways

Although the present disclosure will be fully described with reference to the accompanying drawings containing preferred embodiments of the present disclosure, it should be understood before this description that one of ordinary skill in the art can modify the disclosure described herein while obtaining the technical effects of the present disclosure. Therefore, it is to be understood that the above description is a broad disclosure to those of ordinary skill in the art, and its content is not intended to limit the exemplary embodiments described in the present disclosure.

Additionally, in the following detailed description, for convenience of explanation, numerous specific details are set forth to provide a comprehensive understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are illustrated in order to simplify the drawings.

FIG. 1 schematically illustrates a millimeter wave/terahertz wave imaging device according to an exemplary embodiment of the present disclosure. As shown in the figure, the millimeter wave/terahertz wave imaging device 100 includes a quasi-optical component, a millimeter wave/terahertz wave detector array 2 and a chopper 8, wherein the quasi-optical component includes a Y-shaped reflective plate 1, a Y-shaped The reflection plate 1 includes a first reflection plate 1A, a second reflection plate 1B and a third reflection plate 1C. The Y-shaped reflection plate 1 can surround the connection point ( That is, the rotation axis o) rotates so that the first reflective surface of the first reflective plate 1A, the first reflective surface of the second reflective plate 1B, and the first reflective surface of the third reflective plate 1C take turns to be used as the first working surface to receive and reflect Parts of the first inspected object 31A located at different positions in the first field of view 3A spontaneously radiate or reflect millimeter waves/terahertz waves; the quasi-optical component also includes a fourth reflective plate 7. When the Y-shaped reflective plate 1 rotates, the A second reflective surface of a reflective plate 1A opposite to the first reflective surface, a second working surface of a second reflective plate 1B opposite to the first reflective surface, and a second reflective surface of a third reflective plate 1C opposite to the first reflective surface. The working surface is in turn used as the second working surface to receive and reflect some of the millimeter/terahertz waves that are spontaneously emitted or reflected back by the second object 31B located at different positions in the second field of view 3B to the fourth reflecting plate 7 . The quasi-optical element also includes a first focusing lens 4A and a second focusing lens 4B. The first focusing lens 4A is suitable for converging the beam from the first working surface, and the second focusing lens 4B is suitable for converging the wave beam from the second working surface. . The chopper 8 is located on the reflection wave path of the first working surface and the reflection wave path of the fourth reflection plate 7. The chopper 8 is configured to transmit only the millimeter wave/terahertz wave from the first working surface to the millimeter wave at any time. /terahertz wave detector array 2 or only the millimeter wave/terahertz wave from the fourth reflection plate 7 is reflected to the millimeter wave/terahertz wave detector array 2, and the chopper 8 rotates around its central axis to alternately make the wave from The millimeter wave/terahertz waves of the first working surface of the Y-shaped reflection plate 1 and the fourth reflection plate 7 are received by the millimeter wave/terahertz wave detector array 2 . The millimeter wave/terahertz wave detector array 2 is suitable for receiving the reflected and converged wave beam from the quasi-optical component; the number of detectors in the millimeter wave/terahertz wave detector array 2 is based on the required fields of view 3A and 3B. The size and required resolution are determined. Its arrangement direction is perpendicular to the normal line of the field of view and parallel to the horizontal plane. The size of the detector is determined according to the wavelength, processing technology and required sampling density.

According to the millimeter wave/terahertz wave imaging device 100 according to the embodiment of the present disclosure, the Y-shaped reflection plate 1 is driven to rotate around the connection of the first reflection plate 1A, the second reflection plate 1B and the third reflection plate 1C to complete respectively For data collection of the first field of view 3A and the second field of view 3B, during the rotation of the Y-shaped reflecting plate 1, the chopper 8 is used to convert the millimeter wave/terabytes from the first field of view 3A and the second field of view 3B. The Hertzian wave is alternately switched to the same millimeter wave/terahertz wave detector array 2, thereby achieving imaging of the two inspected objects 31A and 31B located in the two fields of view 3A and 3B while reducing the millimeter wave/terahertz wave detector array 2. The number of Hertzian wave detectors can reduce equipment costs, with high stability and small footprint.

In this embodiment, the focusing lens 4 includes a first focusing lens 4A and a second focusing lens 4B. The first focusing lens 4A is located between the Y-shaped reflecting plate 1 and the chopper 8 and is suitable for analyzing the signals coming from the Y-shaped reflecting plate. The second focusing lens 4B is located between the Y-shaped reflective plate 1 and the fourth reflective plate 7 and is suitable for focusing the millimeter wave/terahertz wave from the Y-shaped reflective plate 1. The millimeter wave/terahertz wave of the second working surface is focused. The focal lengths of the two focusing lenses 4A and 4B are f1 and f2 respectively, and the sizes of f1 and f2 may be the same or different. Since the chopper 8 is placed in the wave path focused by the focusing lenses 4A and 4B, the size of the blades 82 of the chopper 8 can be smaller. In this case, the specific size of the blades 82 of the chopper 8 is given by The size of the beam spot at the place where the chopper 8 is pre-placed after being focused by the focusing lenses 4A and 4B is determined. Assuming that the beam spot radius at the place where the chopper 8 is pre-placed after being focused by the focusing lenses 4A and 4B is w _cut , then the size (area) of the blade 82 of the chopper 8 is selected as

It should be noted that those skilled in the art should understand that in other embodiments of the present disclosure, as shown in FIG. 2 , a focusing lens 4 may also be used, and the focusing lens 4 is located between the chopper 8 and the millimeter wave/ between the terahertz wave detector array 2. In this case, since the chopper 8 is placed in an unfocused wave path, the size of its blades 82 should match the reflecting surface of the Y-shaped reflecting plate 1 .

In the exemplary embodiment shown in FIGS. 1 and 2 , the millimeter wave/terahertz wave imaging device further includes a wave absorbing material 9 , which is suitable for absorbing the wave reflected from the first working wave via the chopper 8 . millimeter waves/terahertz waves from the surface, and millimeter waves/terahertz waves from the fourth reflective plate 7 transmitted through the chopper 8 .

In the exemplary embodiment shown in FIGS. 1 and 2 , the angle θ between the first reflective plate 1A, the second reflective plate 1B and the second reflective plate 1C is 120°. It should be noted that those skilled in the art should understand that in other embodiments of the present disclosure, the angle θ of two adjacent ones of the first reflecting plate 1A, the second reflecting plate 1B and the second reflecting plate 1C is also Can be other values.

In the exemplary embodiment shown in FIGS. 1 and 2 , the first reflective plate 1A, the second reflective plate 1B, and the third reflective plate 1C are rectangular, and their length and width should match the corresponding focusing lens 4. Generally, In this case, the widths of the first reflective plate 1A, the second reflective plate 1B, and the third reflective plate 1C are greater than or equal to the diameter of the corresponding focusing lens 4. The first reflective plate 1A, the second reflective plate 1B, and the third reflective plate 1C should have a length equal to its width times, the diameter of the focusing lens 4 may be, for example, 3cm-50cm.

In the exemplary embodiment shown in FIGS. 1 to 4 , the first reflective plate 1A, the second reflective plate 1B, and the third reflective plate 1C are all parallel to the rotation axis o. It should be noted that those skilled in the art should understand that in other embodiments of the present disclosure, the angle between the first reflection plate 1A, the second reflection plate 1B, the third reflection plate 1C and the rotation axis o can be along the The rotation direction of the Y-shaped reflective plate 1 increases or decreases in increments of α to achieve pixel difference, so that the detectors of the millimeter wave/terahertz wave detector array 2 can be sparsely distributed, thereby reducing the number of detectors.

where d is calculated from the following equation:

In the formula, λ is the wavelength of millimeter wave/terahertz wave,

D is the diameter of the focusing lens 4.

It should be noted that the above formula is only an estimation formula of angular resolution under ideal focusing of a lens. In the actual system, the size of α should be fine-tuned based on the experimental results so that the final pixel arrangement is as uniform as possible without overlap and gaps. That is to say, the angle between the reflecting plates 1A, 1B, and 1C on the Y-shaped reflecting plate 1 and the rotation axis o can be finely adjusted.

As shown in FIG. 5 , in an exemplary embodiment, the angle between the first reflecting plate 1A, the second reflecting plate 1B, the third reflecting plate 1C and the rotation axis o is along the rotation of the Y-shaped reflecting plate 1 The direction increases. The angle θ between the first reflection plate 1A and the rotation axis o is 0°, the angle θ between the second reflection plate 1B and the rotation axis o is +α, and the angle θ between the third reflection plate 1C and the rotation axis o is is -α. It should be noted that those skilled in the art should understand that in other embodiments of the present disclosure, the angle between the first reflection plate 1A, the second reflection plate 1B, the third reflection plate 1C and the rotation axis o is along the The rotation direction of the Y-shaped reflecting plate 1 decreases gradually.

Figures 6 to 9 respectively show the structural schematic diagrams of several choppers. The chopper 8 includes at least one blade, such as 1, 2, 3, 4, etc., and a plurality of blades 82 are equally spaced around the center. Axis 81 is set. During the rotation of the chopper 8 around its central axis 81, at any moment when the millimeter wave/terahertz wave from the first working surface is incident on the blades 82 of the chopper 8, the blades 82 will come from the first working surface. The millimeter wave/terahertz wave on the surface is reflected to the wave absorbing material 9 to be absorbed by the wave absorbing material 9, and at the same time, the millimeter wave/terahertz wave from the fourth reflection plate 7 is reflected to the millimeter wave/terahertz wave detector array 2 . As the chopper 8 rotates around its central axis 81, at the next moment, the millimeter wave/terahertz wave from the first working surface is incident on the part of the chopper 8 that is not provided with blades 82 (i.e., the empty part), In order to transmit to the millimeter wave/terahertz wave detector array 2, the part of the chopper 8 not provided with blades 82 simultaneously transmits the millimeter wave/terahertz wave from the fourth reflection plate 7 to the wave absorbing material 9, so as to be formed by The absorbing material 9 absorbs, and the cycle continues.

It should be noted that the chopper 8 can also be replaced by other devices that can quickly switch to high reflection and high transmission states.

In the exemplary embodiment shown in FIGS. 1 and 2 , the chopper 8 is placed at an angle of 45 degrees to both the wave path from the first working surface and the wave path from the fourth reflective plate 7 . It should be noted that those skilled in the art should understand that in other embodiments of the present disclosure, the chopper 8 and the wave path from the first working surface and the wave path from the fourth reflection plate 7 can also be placed at other angles. .

As shown in Figure 1, in an exemplary embodiment, the millimeter wave/terahertz wave imaging device further includes a housing 6, in which the quasi-optical component and the millimeter wave/terahertz wave detector array 2 are located, Opposite side walls of the housing 6 are respectively provided with a first window 61A for the millimeter wave/terahertz wave to be spontaneously radiated or reflected by the first subject 31A to pass through, and a millimeter wave for the second subject 31B to be spontaneously radiated or reflected. The second window 61B through which the wave/terahertz wave passes.

As shown in Figures 3 and 4, in an exemplary embodiment, a rotating shaft 11 is provided at the connection between the first reflecting plate 1A, the second reflecting plate 1B and the second reflecting plate 1C, and both ends of the rotating shaft 11 are connected through bearings. 10A, 10B are rotatably connected to the housing 6, so that the Y-shaped reflective plate can rotate, thereby making the first reflective surface of the first reflective plate 1A, the first reflective surface of the second reflective plate 1B and the second reflective plate 1C The first reflective surfaces respectively reflect the beams from parts of the inspected object 31A located at different vertical positions in the field of view 3A. At the same time, the second reflective surfaces of the first reflective plate 1A, the second reflective surface of the second reflective plate 1B and The second reflective surface of the second reflective plate 1C reflects the beams from the portions of the inspected object 31B located at different vertical positions in the field of view 3B respectively.

As shown in FIGS. 3 and 4 , in an exemplary embodiment, the millimeter wave/terahertz wave imaging device further includes a first driving device 13 suitable for driving the Y-shaped reflective plate 1 to rotate, such as a servo motor.

As shown in Figures 3 and 4, in an exemplary embodiment, the millimeter wave/terahertz wave imaging device also includes an angular displacement measurement mechanism 12 that detects the angular displacement of the Y-shaped reflective plate in real time, such as a photoelectric code disk, In order to accurately calculate the attitude of the Y-shaped reflector, this can reduce the difficulty of developing control algorithms and imaging algorithms to a considerable extent.

As in an exemplary embodiment not shown, the millimeter wave/terahertz wave imaging device further includes a second driving device suitable for driving the chopper 8 to rotate, such as a servo motor, to drive the chopper 8 around it. The central axis 81 rotates at high speed, and the rotation period of the chopper 8 should match the scanning period of the Y-shaped reflective plate 1, so that the millimeter wave/terahertz wave imaging device can simultaneously image both fields of view 3A and 3B. The objects 31A and 31B to be inspected are imaged respectively. It is preferable that the rotation period of the chopper 8 is 1/1000-1/2 of the scanning period of the Y-shaped reflecting plate.

In this embodiment, the static field of view of the detector is a horizontal field of view. Assume that the number of detectors is N and the center distance between two adjacent detectors is d, then the maximum offset distance y _m of the detector is, but

From this, it can be calculated that the static field of view of the millimeter wave/terahertz wave detector array 2 is H ₀ . As shown in Figure 10, the static field of view H ₀ of the millimeter wave/terahertz wave detector array 2, the object distance L ₁ and the image distance L ₂ need to satisfy the following relationships:

The Y-shaped reflective plate 1 rotates around its rotation axis o. The angle of data collection is determined by the field of view in the height direction of the objects 31A and 31B that need to be scanned. Assume that the angle of view corresponding to the required imaging field of view in the height direction is is θ _m , then the corresponding scanning field of view angle is θ _rot =θ _m /2.

Among them, the number of swings N _v required for the Y-shaped reflecting plate 1 to complete the reflection of the vertical range of the field of view where the corresponding subject 31A (31B) is located is calculated by the following formula:

In the formula, [] means rounding up;

L is the distance from the center of the field of view 3A (3B) to the center of the first working surface (second working surface 1B);

δ represents the object-space resolution;

θ _m is the field of view angle corresponding to the vertical field of view range H.

The Y-shaped reflecting plate 1 rotates in one cycle to complete the collection of three images for each field of view.

The sampling density in the height direction is determined by the beam dwell time. The Y-shaped reflector 1 rotates for one cycle, and each field of view outputs three images. Assuming that the angular resolution of the detector is θ _res , the number of 3dB beams contained in one rotation of the Y-shaped reflector 1 is

n＝360°/θ _res (5)

Assuming that the imaging rate requirement is mHz, the average residence time τ _d of each sampling beam in the height direction is

Taking the imaging distance of the system as 3000mm, the angular resolution θ _res = 0.57°, the object-space resolution as δ = 30mm, and the imaging rate of 10Hz as an example, the number of steps collected in the height direction can be calculated to be approximately 67, with an average of each beam The dwell time is τ _d =100ms/67=1.47ms. The first driving device 13 controls the Y-shaped reflecting plate 1 to rotate with a period of 0.05s.

In an exemplary embodiment, a millimeter wave/terahertz wave imaging device operating at a center frequency of 94 GHz, the number of detectors N = 30, arranged in a row, the center distance of the detectors d = 7 mm, the detector array Length 2y _m = 21cm. The object distance L ₁ =3.5m, the image distance L ₂ =0.7m, the static field of view H ₀ =105cm can be calculated according to formula (3). Assuming that the size of the imaging area in the height direction is 1.8m, the scanning angle in the height direction used to reconstruct the image is θ _m =34°.

In another exemplary embodiment, a millimeter wave/terahertz wave imaging device operating at a center frequency of 220 GHz, the number of detectors is N=48, arranged in a row, the center distance between detectors is d=3mm, and the detector array The length is 2y _m =14.4cm. The object distance L ₁ =5m, the image distance L ₂ =0.7m, the static field of view H ₀ =103cm can be calculated according to formula (3). Assuming that the size of the imaging area in the height direction is 1.8m, the scanning angle in the height direction used to reconstruct the image is θ _m =20°.

In an exemplary embodiment, the millimeter wave/terahertz wave imaging device further includes a data processing device (not shown). The data processing device is connected wirelessly or wiredly to the millimeter wave/terahertz wave detector array 2 to respectively receive the first detected object 31A and the second detected object received by the millimeter wave/terahertz wave detector array 2 31B of image data.

In an exemplary embodiment, the imaging device may further include a display device connected to the data processing device for receiving and displaying millimeter wave/terahertz wave images from the data processing device.

As shown in Figure 1, in an exemplary embodiment, the millimeter wave/terahertz wave imaging device further includes a calibration source 5, which is located in the housing 6 and on the object surface of the quasi-optical component, to So that when the first working surface rotates to the calibration area, the calibration data about the calibration source 5 is received through the millimeter wave/terahertz wave detector array 2, and the data processing device receives the calibration data about the calibration source 5 received by the millimeter wave/terahertz wave detector array 2. The calibration data of the source 5 is calibrated, and the image data of the first inspected object 31A and the second inspected object 31B are updated in real time based on the calibration data. Since the calibration source 5 is packaged inside the housing 1, the millimeter wave/terahertz wave imaging device is more stable and reliable than using remote air for calibration.

In this embodiment, the calibration source 5 is located obliquely above the Y-shaped reflecting plate 1. It should be noted that the position of the calibration source 5 only needs to enable the millimeter wave/terahertz wave detector array 2 to receive the calibration data about the calibration source 5 and As long as the image data of the objects 31A and 31B do not interfere with each other, the beam radiated by the calibration source 5 is reflected to the millimeter wave/terahertz wave detector array 2 through the first working surface and/or the second working surface, so that alignment can be achieved. The calibration of the complete receiving channel including focusing lens 4 and detector further ensures the consistency of the channel.

In the exemplary embodiment shown in FIGS. 1 and 2 , the rotation axis 11 of the Y-shaped reflective plate 1 is set horizontally, so that the first working surface and the second working surface are located in the field of view from the corresponding inspected objects 31A, 31B. Parts of the beam at different vertical positions are reflected. It should be noted that those skilled in the art should understand that in other embodiments of the present disclosure, the rotation axis 11 of the Y-shaped reflection plate 1 can also be arranged vertically, so that the first working surface and the second working surface come from The beams corresponding to the portions of the inspected objects 31A and 31B located at different horizontal positions in the field of view are reflected. In addition, the calibration source 5 can be an absorbing material with an emissivity close to 1, such as plastic or foam, or a blackbody or semiconductor refrigerator.

According to the Nyquist sampling law, at least two sampling points are required within a half-power beam width to fully restore the image. The arrangement direction of the millimeter wave/terahertz wave detector array 2 in this embodiment is perpendicular to the normal line of the field of view and parallel to the horizontal plane to sample the field of view in the height direction. The millimeter wave/terahertz wave detector array 2 The arrangement density determines the sampling density. The images produced by the millimeter-wave imaging system are actually grayscale images. When the spatial sampling rate cannot meet the Nyquist sampling requirements (undersampling), the target scene can still be imaged, but the imaging effect is relatively poor. In order to compensate for the missing pixels caused by undersampling, an interpolation algorithm can be used to increase data density during post-signal processing.

As shown in Figure 1, in an exemplary embodiment, the length direction of the calibration source 5 is parallel to the rotation axis 11 of the Y-shaped reflection plate, and the length of the calibration source 5 is greater than or equal to the millimeter wave/terahertz wave detector array 2 in parallel. The size of the field of view in the direction of the rotation axis 11, the width of the calibration source 5 is 10 times the antenna beam width of the millimeter wave/terahertz wave detector 2. However, it should be noted that those skilled in the art will understand that the width of the calibration source 5 may also be 1 time, 2 times or other multiples of the antenna beam width of the millimeter wave/terahertz wave detector.

In one embodiment, the millimeter wave/terahertz wave imaging device further includes an optical camera device. The optical camera device includes a first optical camera device adapted to collect an optical image of the first subject 31A and a first optical camera device adapted to collect the second optical image. A second optical camera device for optical images of the two inspected objects 31B. The optical camera device is connected to the display device. The optical camera device can realize visible light real-time imaging and provide images of the first inspected object 31A and the second inspected object 31B. Image information to compare with millimeter wave/terahertz wave images for user reference.

In an exemplary embodiment not shown, the display device includes a display screen, and the display screen includes a first display adapted to display millimeter wave/terahertz wave images of the first subject 31A and the second subject 31B. area and a second display area suitable for displaying the optical images of the first object 31A and the second object 31B collected by the optical camera, so that the user can combine the optical images collected by the optical camera with millimeter-wave/ Terahertz wave images for comparison.

In an exemplary embodiment not shown, the millimeter wave/terahertz wave imaging device further includes an alarm device connected to the data processing device so that when the first inspected object 31A and/or When there is a suspicious object in the millimeter wave/terahertz wave image of the second inspected object 31B, for example, an alarm is issued below the millimeter wave/terahertz wave image corresponding to the corresponding inspected object, for example, the alarm light lights up. It should be explained. Yes, the alarm method with sound prompt can also be used.

In an exemplary embodiment, the data processing device may be used to generate a control signal and send the control signal to the first driving device 13 and the second driving device to drive the Y-shaped reflective plate 1 and the chopper 8 to rotate respectively. In another exemplary embodiment, the imaging apparatus may also include a control device independent of the data processing device.

Figure 11 is a schematic structural diagram of a millimeter wave/terahertz wave imaging device according to yet another embodiment of the present disclosure. As shown in Figure 11, the millimeter wave/terahertz wave imaging device includes a Y-shaped reflective plate 1 and a focusing lens 4. By driving the Y-shaped reflective plate 1 to rotate, the first reflective surface of the first reflective plate 1A, The first reflective surface of the two reflective plates 1B and the first reflective surface of the second reflective plate 1C respectively reflect the beams from the parts of the object 31A located at different positions in the field of view 3A, thereby achieving imaging of a single field of view, Y The reflection plate 1 rotates once to complete the collection of three images.

Figure 12 is a schematic structural diagram of a millimeter wave/terahertz wave imaging device according to yet another embodiment of the present disclosure. As shown in Figure 12, it also includes a Y-shaped reflection plate 1, a focusing lens 4 and a fifth reflection plate 14. The fifth reflection plate 14 swings back and forth around its central axis to receive and reflect the spontaneous movement of the first subject 31A. The millimeter wave/terahertz wave radiated or reflected back to the first working surface is received by the millimeter wave/terahertz wave detector array 2 after being reflected by the first working surface. The fifth reflection plate 14 The swing period T1 is 2m times the rotation period of the Y-shaped reflecting plate 1, where m is an integer greater than or equal to 1. In this embodiment, the fifth reflective plate 14 is driven to swing back and forth around its central axis to increase the number of scanning columns in the horizontal direction of the object 31 to be measured. Since the swing range of the fifth reflective plate 14 is just enough to allow the object to be measured to be The moving range of the image formed by the object on the image plane is the distance between two adjacent detection units. Therefore, when the fifth reflection plate 14 swings back and forth around its central axis, it can detect millimeter waves/terahertz waves. The pixels adjacent to the detection units in the detector array 2 are sent to each detection unit successively.

When the fifth reflective plate 14 does not swing, the millimeter wave/terahertz wave emitted or reflected by the object 31A is reflected to the Y-shaped reflective plate 1 through the fifth reflective plate 14, and the Y-shaped reflective plate 1 rotates around its axis. o Perform high-speed and stable rotation. When the first reflecting plate 1A, the second reflecting plate 1B and the third reflecting plate 1C in the Y-shaped reflecting plate 1 turn into the wave path behind the fifth reflecting plate 14, they will all affect the object 31A being inspected. One-dimensional multi-column rapid scanning is completed in the vertical column direction, and then is converged by the focusing lens 4 to form an image of the object to be inspected 31A, which is finally received by the millimeter wave/terahertz wave detector array 2 arranged in the image plane. The number of detected columns on the object 31A is consistent with the number of detection units in the millimeter wave/terahertz wave detector array 2 .

When the fifth reflective plate 14 deflects by an angle around its central axis, the image plane of the object 31A behind the focusing lens 4 also moves by a certain angle accordingly. Each detection unit in the millimeter wave/terahertz wave detector array 2 A certain column of pixels that was originally located to the left or right of its position will be detected. If the fifth reflective plate 14 rotates at an appropriate angle, each detection unit can receive any pixels before the fifth reflective plate 14 rotates. The pixel points not received by the detection unit are the pixel points between the original two adjacent detection units, as shown in Figure 13. Therefore, by deflecting the fifth reflecting plate 14 at a certain angle, the number of scanning columns of the measured object 31A can be increased without adding additional detection units in the millimeter wave/terahertz wave detector array 2, that is, the horizontal scanning column number of the measured object 31A can be increased. The number of pixels in the row direction can be increased, thereby increasing the scanning speed. In addition, since the swing angle of the fifth reflective plate 14 is small, the system stability is relatively high.

Before starting the imaging equipment, arrange each device in the system as required so that the fifth reflective plate 14 is placed at the maximum angle to the left or right side of its central axis. The first reflective plate 1A and the third reflective plate 1A in the Y-shaped reflective plate 1 The second reflecting plate 1B and the third reflecting plate 1C are parallel to the central axis of the fifth reflecting plate 14 . After the imaging equipment is started, the fifth reflective plate 14 and the Y-shaped reflective plate 1 move synchronously, and the millimeter wave/terahertz wave detector array 2 begins to receive the millimeter wave/terahertz wave transmitted by the focusing lens 4. The millimeter wave/terahertz wave The wave detector array 2 converts millimeter wave/terahertz wave signals into DC voltage signals.

As shown in Figure 14, the present disclosure also provides a method for detecting human bodies or objects using millimeter wave/terahertz wave imaging equipment, including the following steps:

S1: Drive the Y-shaped reflecting plate 1 to rotate, so that the first reflecting surface of the first reflecting plate 1A, the first reflecting surface of the second reflecting plate 1B and the first reflecting surface of the third reflecting plate 1C take turns to receive and reflect the first The millimeter wave/terahertz wave that the subject 31A radiates spontaneously or reflects back; passes through the second reflective surface of the first reflective plate 1A, the second reflective surface of the second reflective plate 1B and the second reflective surface of the third reflective plate 1C. The reflective surface takes turns to receive and reflect the millimeter/terahertz waves that are spontaneously radiated or reflected back by the second subject 31B; while the Y-shaped reflective plate 1 rotates, the chopper 8 rotates around its central axis to alternately make the waves from the second subject 31B The millimeter wave/terahertz wave from one working surface and the millimeter wave/terahertz wave from the second working surface reflected by the fourth reflecting plate 7 are received by the millimeter wave/terahertz wave detector array 2;

S2: Send the image data about the first subject 31A and the image data about the second subject 31B obtained by the millimeter wave/terahertz wave detector array 2 to the data processing device; and

S3: Use the data processing device to reconstruct the image data of the first subject 31A and the image data of the second subject 31B respectively to generate millimeter waves/terahertz of the first subject 31A and the second subject 31B. wave image.

This method can perform all-round imaging and detection of two inspected objects 31A and 31B at the same time, where the inspected object 31 can be a human body or an object. When the objects to be inspected 31A and 31B are human bodies, the millimeter wave/terahertz wave imaging device 100 can be used in conjunction with the object imaging device 200. As shown in Figure 15, the two objects to be inspected 31A and 31B are respectively at the left side to be inspected. and the right side to be inspected, or, after an inspected object 31A completes the front inspection at the left side to be inspected, it can walk along the path shown by the arrow to the right side to be inspected, and complete the back side detection, so that all-round detection can be completed without the need for the subject 31A to turn around.

In an exemplary embodiment, the method further includes the following steps before step S3: when the Y-shaped reflection plate 1 rotates to the calibration area, receive calibration about the calibration source 5 through the millimeter wave/terahertz wave detector array 2 data; and the received image data of the first inspected object 31A and the second inspected object 31B are updated in real time based on the calibration data of the calibration source 5 .

The antenna temperature corresponding to the detected output voltage V _out is T _A , which should satisfy the following relationship,

T _A =(V _out -b)/a (7)

In the formula, a is the gain scaling coefficient,

b is the bias scaling coefficient.

Therefore, updating the received image data of the subject 31 based on the calibration data of the calibration source 5 includes correction of the offset scaling coefficient b and correction of the gain scaling coefficient a.

Within the calibration area, the radiation brightness temperature of the calibration source 5 and its surrounding environment can be regarded as uniform, that is, the antenna temperature _TA of all channels is consistent. When the channels are completely consistent, the output V _{out of} the focal plane array receiving channel should be completely consistent. If the outputs are inconsistent, the gain scaling coefficient a and offset scaling coefficient b of each channel need to be adjusted to make the output of all channels consistent, thereby achieving Channel consistency adjustment. The gain scaling parameter a reflects the total gain and equivalent bandwidth of the channel. This part has been carefully adjusted during channel debugging. It can be considered that the gain scaling coefficient a of each channel is approximately equal, so the correction is adjusted during normal use. This is done by offsetting the scaling coefficient b.

In an exemplary embodiment, updating the received image data of the subject 31 based on the calibration data of the calibration source 5 mainly includes the correction of the offset scaling coefficient b, including the following steps:

A1: Calculate the average of the multiple measured output voltages of all channels of the millimeter wave/terahertz wave detector array in the calibration area

A2: The calibrated data of the detection area of each channel is the data V _i collected in the detection area of each channel minus the average value Then divide by the gain scaling coefficient a _i of each channel.

This method can perform overall calibration on the receiving channel array of the focal plane array system. The calibration algorithm only requires simple calculations, takes very little time, and can achieve real-time calibration; channel consistency calibration is performed on each image.

When the equipment is operated for a long time or the place of use is changed, the system performance deteriorates due to system temperature drift, and the gain scaling coefficient a of each channel usually changes. At this time, it is necessary to adjust the gain scaling coefficient a and offset scaling coefficient b of the channel, including the following steps:

B1: Use the millimeter wave/terahertz wave detector array to measure the voltage value V _air (i) of the air, i∈[1, number of channels], and calculate the average voltage value of the air in all channels

B2: Set the temperature of the calibration source to have a difference with the temperature of the air, and use the millimeter wave/terahertz wave detector array to measure the voltage value V _cal (i) of the calibration source, i∈[1, number of channels ], and calculate the average voltage value of the calibration source for all channels And calculate the gain scaling coefficient a _i and offset scaling coefficient b _i of each channel through the following equations:

B3: The calibrated data of the detection area of each channel is The absolute value of , where _Vi is the data collected in the detection area of each channel.

The data processing device collects twice in each 3dB beam direction, so that in the embodiment shown in Figure 1, each channel obtains at least 10 collected data in the calibration area. The output voltage data in the calibration area and the output voltage data in the detection area are stored in the same data table of the data processing device.

As an exemplary embodiment, the method may further include S4: after generating millimeter wave/terahertz wave images of the first subject 31A and the second subject 31B, It identifies whether the inspection object 31B contains suspicious objects and the location of the suspicious objects, and outputs the results.

In the above steps, the identification of suspicious objects and their locations can be carried out through automatic computer identification or manual identification or a combination of both. The result output can be realized by, for example, displaying a mark on the display device to directly indicate whether there is a conclusion containing suspicious objects. The detection result can be directly printed or sent.

The security personnel who perform the detection can confirm whether the human body or object contains suspicious objects and the location of the suspicious objects based on the detection results given in step S4 above, or they can conduct a review through manual inspection.

Those skilled in the art can understand that the above-described embodiments are exemplary and can be improved by those skilled in the art. The structures described in the various embodiments do not conflict in structure or principle. can be freely combined.

After describing the preferred embodiments of the present disclosure in detail, those skilled in the art can clearly understand that various changes and modifications can be made without departing from the scope and spirit of the appended claims, and the present disclosure is not limited to Implementations limited to the exemplary embodiments set forth in the specification.

Claims (20)

1. A millimeter wave/terahertz wave imaging apparatus comprising:

the quasi-optical assembly comprises a Y-shaped reflecting plate, wherein the Y-shaped reflecting plate comprises a first reflecting plate, a second reflecting plate and a third reflecting plate, and the Y-shaped reflecting plate can rotate around the rotation axis of the Y-shaped reflecting plate so that a first reflecting surface of the first reflecting plate, a first reflecting surface of the second reflecting plate and a first reflecting surface wheel flow of the third reflecting plate are used as a first working surface to receive and reflect millimeter wave/terahertz waves spontaneously radiated or reflected by parts of a first detected object, which are positioned at different positions of a first view field; and

A millimeter wave/terahertz wave detector array adapted to receive a beam from the quasi-optical assembly.

2. The imaging apparatus according to claim 1, wherein the quasi-optical assembly further includes a fourth reflection plate to which a second reflection surface of the first reflection plate opposite to the first reflection surface, a second working surface of the second reflection plate opposite to the first reflection surface, and a second working surface wheel flow of the third reflection plate opposite to the first reflection surface serve as a portion of the second working surface that receives and reflects spontaneous radiation or reflected millimeter wave/terahertz wave of a second object to be inspected at a different position of a second field of view when the Y-shaped reflection plate rotates;

a chopper on the reflection wave path of the first working face and the reflection wave path of the fourth reflecting plate, the chopper being configured to reflect or transmit only millimeter wave/terahertz waves from the first working face or only millimeter wave/terahertz waves from the fourth reflecting plate to the millimeter wave/terahertz wave detector array at any one time, the chopper rotating about its central axis so that millimeter wave/terahertz waves from the first working face and the fourth reflecting plate of the Y-shaped reflecting plate are alternately received by the millimeter wave/terahertz wave detector array.

3. The millimeter wave/terahertz wave imaging device of claim 2, wherein the quasi-optical assembly further comprises a focusing lens located between the chopper and the millimeter wave/terahertz wave detector array.

4. The millimeter wave/terahertz wave imaging apparatus according to claim 2, wherein the quasi-optical assembly further comprises a first focusing lens adapted to focus millimeter wave/terahertz waves from the first working face of the Y-shaped reflecting plate and a second focusing lens adapted to focus millimeter wave/terahertz waves from the second working face of the Y-shaped reflecting plate.

5. The millimeter wave/terahertz wave imaging apparatus according to claim 2, further comprising a wave absorbing material adapted to absorb millimeter wave/terahertz waves from the first working face reflected via the chopper and millimeter wave/terahertz waves from the fourth reflecting plate transmitted via the chopper.

6. The millimeter wave/terahertz wave imaging apparatus according to claim 2, wherein angles between 3 of the reflection plates and the rotation axis are increased or decreased in an increasing or decreasing direction along the rotation direction of the Y-shaped reflection plate.

7. The millimeter wave/terahertz wave imaging apparatus according to claim 2, wherein the chopper includes at least one blade.

8. The millimeter wave/terahertz wave imaging apparatus as set forth in claim 7, wherein a plurality of the blades are disposed around the central axis at equal intervals.

9. The millimeter wave/terahertz wave imaging apparatus according to claim 2, further comprising a housing in which the quasi-optical assembly and the millimeter wave/terahertz wave detector array are located, a first window through which a beam from the first object to be inspected passes and a second window through which a beam from the second object to be inspected passes being provided on opposite side walls of the housing, respectively.

10. The millimeter wave/terahertz wave imaging apparatus as set forth in claim 9, further comprising a first driving device adapted to drive the Y-shaped reflecting plate to rotate.

11. The millimeter wave/terahertz wave imaging apparatus according to claim 2, further comprising a second driving device adapted to drive the chopper to rotate.

12. The millimeter wave/terahertz wave imaging device according to any one of claims 2 to 11, wherein further comprising:

A data processing device connected with the millimeter wave/terahertz wave detector array to respectively receive image data for the first inspected object and image data for the second inspected object from the millimeter wave/terahertz wave detector array and respectively generate millimeter wave/terahertz wave images; 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.

13. The millimeter wave/terahertz wave imaging apparatus according to claim 12, further comprising an alarm device connected to the data processing device so that an alarm indicating that a suspicious item is present in the millimeter wave/terahertz wave image is issued when the data processing device recognizes the suspicious item in the millimeter wave/terahertz wave image.

14. The millimeter wave/terahertz wave imaging apparatus according to claim 12, further comprising a calibration source located on an object plane of the quasi-optical assembly, the data processing device receiving calibration data for the calibration source from the millimeter wave/terahertz wave detector array and updating image data of the first subject and image data of the second subject based on the calibration data.

15. The millimeter wave/terahertz wave imaging apparatus according to claim 12, further comprising an optical imaging device including a first optical imaging device adapted to acquire an optical image of the first object to be inspected and a second optical imaging device adapted to acquire an optical image of the second object to be inspected, the first and second optical imaging devices being connected to the display device, respectively.

16. The millimeter wave/terahertz wave imaging apparatus according to claim 15, wherein the display device includes a display screen including a first display area adapted to display the millimeter wave/terahertz wave image and a second display area adapted to display an optical image acquired by the optical image pickup device.

17. The millimeter wave/terahertz wave imaging apparatus according to claim 1, wherein the first and second reflection plates, the second and third reflection plates, and the third and first reflection plates each have an included angle of 120 °.

18. The millimeter wave/terahertz wave imaging apparatus as set forth in claim 16, further comprising a fifth reflecting plate that swings reciprocally around its center axis to receive and reflect millimeter wave/terahertz wave spontaneously radiated or reflected back by a first object to be inspected onto the first working face to be received by a millimeter wave/terahertz wave detector array after reflection via the first working face, the swing period T1 of the fifth reflecting plate being 2m times the rotation period of the Y-shaped reflecting plate, where m is an integer of 1 or more.

19. The millimeter wave/terahertz wave imaging apparatus as set forth in claim 18, further comprising a third driving device adapted to drive the fifth reflecting plate to oscillate reciprocally.

20. A method of detecting a human body or an article using the millimeter wave/terahertz wave imaging apparatus according to any one of claims 2 to 15, comprising the steps of:

s1: driving the Y-shaped reflecting plate to rotate, so that the first reflecting surface of the first reflecting plate, the first reflecting surface of the second reflecting plate and the first reflecting surface of the third reflecting plate are used as a first working surface to receive and reflect millimeter wave/terahertz wave spontaneously radiated or reflected back by the first detected object; the millimeter wave/terahertz wave spontaneously radiated or reflected by the second detected object is alternately formed by the second reflecting surface of the first reflecting plate, the second reflecting surface of the second reflecting plate and the second reflecting surface of the third reflecting plate to be received and reflected by the second working surface; while the Y-shaped reflecting plate rotates, a chopper rotates around a central axis thereof to alternately enable the millimeter wave/terahertz wave from the first working face and the millimeter wave/terahertz wave from the second working face reflected by a fourth reflecting plate to be received by the millimeter wave/terahertz wave detector array;

S2: transmitting image data received by the millimeter wave/terahertz wave detector array with respect to the first object and with respect to the second object to a data processing apparatus; and

s3: reconstructing image data of the first object and image data of the second object with the data processing apparatus to generate millimeter wave/terahertz wave images of the first object and the second object, respectively.