CN109188547B - Total reflection type terahertz human body security inspection imaging device - Google Patents
Total reflection type terahertz human body security inspection imaging device Download PDFInfo
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- CN109188547B CN109188547B CN201810975207.9A CN201810975207A CN109188547B CN 109188547 B CN109188547 B CN 109188547B CN 201810975207 A CN201810975207 A CN 201810975207A CN 109188547 B CN109188547 B CN 109188547B
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- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
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Abstract
The embodiment of the invention provides a total reflection type terahertz human body security inspection imaging device which comprises a polyhedral scanning mirror, a terahertz focusing mirror group and a terahertz array detector, wherein the polyhedral scanning mirror rotates steadily at a high speed around a central shaft, so that N plane mirrors of the polyhedral scanning mirror are sequentially used as scanning mirrors to scan an image in the vertical direction, and terahertz waves radiated or reflected by an imaged target are reflected to the terahertz focusing mirror group; imaging terahertz waves reflected by a polyhedral scanning mirror of the terahertz focusing mirror group onto a terahertz array detector; the terahertz array detector converts terahertz waves into voltage signals and images according to the voltage signals, so that array scanning of an imaged object in the vertical direction is completed. The total reflection type terahertz human body security inspection imaging device can realize the scanning of the imaged target in the vertical direction through the high-speed stable rotation of the polyhedral scanning mirror around the central shaft, and has the advantages of simple and compact structure and high imaging speed.
Description
Technical Field
The embodiment of the invention relates to the technical field of terahertz, in particular to a total reflection type terahertz human body security inspection imaging device.
Background
The wavelength of the terahertz wave is between the wavelength of infrared rays and the wavelength of millimeter waves, so that the terahertz wave has good penetrability on materials such as textiles and leather, and the formed image has higher spatial resolution; the terahertz wave is lower than the X-ray energy by several orders of magnitude and does not cause ionization damage to biological tissues, so the terahertz wave is widely applied to security inspection, such as customs inspection, airport inspection, station inspection and other public place inspection.
In the prior art, a high-sensitivity array detector based on a terahertz waveband is expensive in manufacturing cost, and scanning imaging is mostly adopted in terahertz imaging. For example, in the non-contact, large-field-of-view, fast and high-resolution human terahertz scanning imaging meeting public places such as airports and stations, the scanning imaging adopting the terahertz array detector is a main method for realizing the human terahertz security inspection imaging. According to the method, terahertz imaging of the imaged human body is achieved by means of two-dimensional movement of the reflecting surface.
In the existing terahertz security inspection imaging system, the scanning imaging of the imaged human body is realized by adopting the two-dimensional motion of the reflecting surface, the imaging time is long, and the imaging quality is poor.
Disclosure of Invention
The invention provides a total reflection type terahertz human body security inspection imaging device, which aims to improve the imaging speed and the imaging quality based on terahertz wave imaging.
In a first aspect, an embodiment of the present invention provides a total reflection type terahertz human body security inspection imaging device, including: a polyhedron scanning mirror 1, a terahertz focusing mirror group 2 and a terahertz array detector 3, wherein,
the polyhedron scanning mirror 1 comprises N plane mirrors, each plane mirror is a rectangle with the same size, the N plane mirrors sequentially surround to form an N prism, the central axis of the N prism is parallel to each edge and has the same distance from each edge, N is not less than 3 and is an integer;
in an initial state, the polyhedral scanning mirror 1 is placed in front of an imaged object, the central axis of the polyhedral scanning mirror is parallel to an object plane where the imaged object is located, and a field of view of the terahertz focusing mirror group 2 covers a horizontal transverse range of the imaged object;
in a working state, the imaged target is located on an object plane of the terahertz focusing mirror group 2, and the terahertz array detector 3 is located on an image plane of the terahertz focusing mirror group 2; the polyhedral scanning mirror 1 rotates around the central axis, so that the N plane mirrors are sequentially used as scanning mirrors to scan the imaged object in the vertical direction, the terahertz waves radiated or reflected by the imaged object are reflected to the terahertz focusing mirror group 2, and the terahertz waves are imaged on the terahertz array detector 3 by the terahertz focusing mirror group 2; the terahertz array detector 3 is used for converting the terahertz waves into voltage signals and imaging according to the voltage signals.
In a feasible implementation manner, the terahertz focusing lens group 2 comprises a first terahertz focusing lens 21, a second terahertz focusing lens 22 and a third terahertz focusing lens 23,
the first terahertz focusing mirror 21 is positioned in a reflection light path of the polyhedral scanning mirror 1;
the second terahertz focusing mirror 22 is positioned in a reflection light path of the first terahertz focusing mirror 21;
the third terahertz focusing mirror 23 is positioned in a reflection light path of the second terahertz focusing mirror 22;
the terahertz array detector 3 is positioned on the image plane of the third terahertz focusing mirror 23;
in a working state, the polyhedral scanning mirror 1 rotates around the central axis, so that the N plane mirrors sequentially serve as scanning mirrors to scan the imaged object in the vertical direction, and further the terahertz waves radiated or reflected by the imaged object are reflected to the first terahertz focusing mirror 21; the first terahertz focusing mirror 21 focuses the terahertz waves on the second terahertz focusing mirror 22, the second terahertz focusing mirror 22 focuses the terahertz waves on the third terahertz focusing mirror 23, and the third terahertz focusing mirror 23 images the terahertz waves on the terahertz array detector 3; in the process that the polyhedral scanning mirror 1 rotates around the central shaft, the center of the scanning mirror for imaging and the center of the first terahertz focusing mirror 21 are on the same straight line.
In a feasible implementation manner, in an operating state, the vertical distance between the center of the scanning mirror for imaging and the center of the first terahertz focusing mirror 21 is L1; the vertical distance between the centers of the first terahertz focusing mirror 21 and the third terahertz focusing mirror 23 is L2; the vertical distance between the centers of the first terahertz focusing mirror 21 and the second terahertz focusing mirror 22 is L3; the central horizontal distance between the first terahertz focusing mirror 21 and the third terahertz focusing mirror 23 is L4; the central horizontal distance between the first terahertz focusing mirror 21 and the second terahertz focusing mirror 22 is L5; the horizontal distance between the center of the third terahertz focusing mirror 23 and the terahertz array detector 3 is L6, the included angle between the incident beam and the emergent beam of the first terahertz focusing mirror 21 is β, the included angle between the incident beam and the emergent beam of the second terahertz focusing mirror 22 is α, the included angle between the incident beam and the emergent beam of the third terahertz focusing mirror 23 is θ,
l1 is more than twice the horizontal lateral dimension of the first terahertz focusing mirror 21;
l5 is larger than the horizontal transverse dimension of the first terahertz focusing mirror 21;
l3 is more than twice the horizontal lateral dimension of the first terahertz focusing mirror 21;
l4 is larger than the horizontal transverse dimension of the first terahertz focusing mirror 21;
l2 is more than twice the horizontal lateral dimension of the first terahertz focusing mirror 21;
in a feasible implementation manner, the N plane mirrors of the polygon mirror 1 are made by metal polishing, and the other parts of the polygon mirror 1 except the N plane mirrors are made of carbon fiber composite materials.
In a feasible implementation manner, the first terahertz focusing mirror 21, the second terahertz focusing mirror 22, and the third terahertz focusing mirror 23 are spherical or high-order aspheric surfaces.
In a feasible implementation manner, the number of the detection channels on the terahertz array detector 3 is greater than 2 times of the ratio of the width of the imaged target to the theoretical resolution of the terahertz focusing mirror group 2.
In a possible implementation, the apparatus further includes: protection device 4, polyhedron scanning mirror 1 terahertz focusing mirror group 2 and terahertz array detector 3 encapsulates in protection device 4, just be provided with the confession on the protection device 4 terahertz wave sees through window 41, window 41 sets up by the imaging target with between the polyhedron scanning mirror 1.
In a possible implementation, the apparatus further includes: a terahertz wave radiation source for irradiating the imaged object with a terahertz wave of 0.1-10 THz.
In a possible implementation, the polygon mirror 1 is a regular pentahedron or a regular hexahedron.
In a feasible implementation manner, the polyhedral scanning mirror 1, the first terahertz focusing mirror 21, the second terahertz focusing mirror 22 and the third terahertz focusing mirror 23 operate in a reflection mode.
The total reflection type terahertz human body security inspection imaging device provided by the embodiment of the invention comprises a polyhedral scanning mirror, a terahertz focusing mirror group and a terahertz array detector, wherein the polyhedral scanning mirror rotates steadily at a high speed around a central shaft, so that N plane mirrors of the polyhedral scanning mirror are sequentially used as scanning mirrors to scan an image in the vertical direction, and terahertz waves radiated or reflected by an imaged target are reflected to the terahertz focusing mirror group; imaging terahertz waves reflected by a polyhedral scanning mirror of the terahertz focusing mirror group onto a terahertz array detector; the terahertz array detector converts terahertz waves into voltage signals and images according to the voltage signals, so that array scanning of an imaged object in the vertical direction is completed. The total reflection type terahertz human body security inspection imaging device can realize the scanning of the imaged target in the vertical direction through the high-speed stable rotation of the polyhedral scanning mirror around the central shaft, and has the advantages of simple and compact structure and high imaging speed. In addition, the total reflection type terahertz human body security inspection imaging device scans the imaged target in the vertical direction and simultaneously performs one-dimensional electrical scanning on the imaged target in the horizontal direction so as to scan the imaged target in the horizontal direction.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a total reflection type terahertz human body security inspection imaging device according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a polygon scanning mirror suitable for a total reflection type terahertz human body security inspection imaging device according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a total reflection type terahertz human body security inspection imaging device provided by another embodiment of the present invention;
fig. 4 is a schematic structural diagram of a terahertz array detector suitable for a total reflection type terahertz human body security inspection imaging device according to an embodiment of the present invention;
fig. 5 is a schematic view of a total reflection type terahertz human body security inspection imaging device according to another embodiment of the present invention.
Description of reference numerals:
1. a polygon scanning mirror;
2. a terahertz focusing lens group;
21. a first terahertz focusing mirror;
22. a second terahertz focusing mirror;
23. a third terahertz focusing mirror;
3. a terahertz array detector;
4. a protection device;
41. a window;
5. terahertz wave radiation source.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terms "first," "second," "third," "fourth," and the like in the description and in the claims, as well as in the drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The technical solution of the present invention will be described in detail below with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.
First, the terms in the examples of the present invention are briefly described as follows:
terahertz waves have quite important application prospects in the fields of basic research, industrial application, biomedicine, military and the like, and have the following characteristics: (a) the wavelength of the terahertz spectrum band is longer than that of the common optical spectrum and the near infrared spectrum, and the detected biological tissue sample is not easy to scatter; terahertz radiation has a shorter wavelength than microwaves, which enables terahertz spectroscopy to have higher spatial resolution and larger depth of field. (b) Terahertz waves are good in penetrability and can penetrate nonpolar liquid and a plurality of dielectric materials (clothes, plastics, wood, paper and the like), which means that people can detect objects in the packaging material by utilizing the terahertz waves to penetrate the packaging material. (c) Because the photon energy of the terahertz wave is very low (millielectron volt magnitude), when the terahertz wave penetrates through a substance, ionization is not easy to occur, so that the terahertz wave can be used for safe nondestructive detection, and the X-ray detection corresponding to the terahertz wave has considerable ionizing radiation danger. (d) Vibration and rotation frequency of a plurality of substance macromolecules such as biomacromolecules are in a terahertz wave band, so that strong absorption and resonance are shown in the terahertz wave band, which shows that the terahertz spectrum analysis technology can obviously see characteristic absorption peaks of a plurality of objects and materials in the terahertz wave band, and the terahertz waves can be used for carrying out non-contact component analysis on an object to be detected. (e) The time-domain spectrum signal-to-noise ratio of terahertz waves is high, so that terahertz waves are very suitable for imaging application. The typical pulse width of the terahertz pulse is in the picosecond order, and the terahertz pulse can be used for conveniently carrying out time-resolved research on various materials (including liquid, semiconductors, superconductors, biological samples and the like).
Fig. 1 is a schematic structural diagram of a total reflection type terahertz human body security inspection imaging device according to an embodiment of the present invention. As shown in fig. 1, the total reflection type terahertz human body security inspection imaging device provided by the embodiment of the present invention includes: the terahertz array detector comprises a polyhedral scanning mirror 1, a terahertz focusing mirror group 2 and a terahertz array detector 3, wherein the structure of each part and the relative position among the parts are as follows:
the polyhedron scanning mirror 1 comprises N plane mirrors, each plane mirror is a rectangle with the same size, the N plane mirrors sequentially surround to form an N prism, the central axis of the N prism is parallel to each edge and has the same distance from each edge, N is not less than 3 and is an integer;
in the above structure, the polygon mirror 1 is formed by N flat mirrors, an included angle between adjacent flat mirrors is 360/N degrees, N is an integer greater than or equal to 3, and the polygon mirror is a regular pentahedron or a hexahedron, for example. Fig. 2 is a schematic view of a polygon scanning mirror suitable for a total reflection type terahertz human body security inspection imaging device according to an embodiment of the present invention. As shown in fig. 2, the polygon mirror 1 is composed of 5 flat mirrors, and the center axis is the dashed line in the figure.
Based on the structure, the working principle of the total reflection type terahertz human body security inspection imaging device provided by the embodiment of the invention is as follows:
in an initial state, the polyhedral scanning mirror 1 is placed in front of an imaged object, the central axis of the polyhedral scanning mirror is parallel to an object plane where the imaged object is located, and a field of view of the terahertz focusing mirror group 2 covers a horizontal transverse range of the imaged object;
in a working state, the imaged target is located on an object plane of the terahertz focusing mirror group 2, and the terahertz array detector 3 is located on an image plane of the terahertz focusing mirror group 2; the polyhedral scanning mirror 1 rotates around the central axis, so that the N plane mirrors are sequentially used as scanning mirrors to scan the imaged object in the vertical direction, the terahertz waves radiated or reflected by the imaged object are reflected to the terahertz focusing mirror group 2, and the terahertz waves are imaged on the terahertz array detector 3 by the terahertz focusing mirror group 2; the terahertz array detector 3 is used for converting the terahertz waves into voltage signals and imaging according to the voltage signals.
Specifically, initially, the polygon mirror 1 is disposed in front of the object to be imaged such that the central axis of the polygon mirror 1 is in the horizontal plane and parallel to the object plane on which the object to be imaged is located. During passive scanning, the imaged object radiates or reflects terahertz waves, the terahertz waves are reflected to the terahertz focusing mirror group 2 by the scanning mirror of the polyhedral scanning mirror 1, and the terahertz waves are imaged on the terahertz array detector 3 through the terahertz focusing mirror group 2. In the scanning process, each scanning mirror of the polyhedral scanning mirror 1 completes scanning on the imaged target in the vertical direction, for example, when the imaged target is a human body, each scanning mirror of the polyhedral scanning mirror 1 completes scanning on the human body in the vertical direction by 2 meters, and the terahertz focusing mirror group images the terahertz waves radiated or reflected by the object point on the imaged target onto the image point corresponding to the terahertz array detector 3. In this way, when the polyhedral scanning mirror 1 rotates around the central axis, each plane mirror sequentially serves as a scanning mirror to scan the imaged target, so that the object points in the vertical direction of the imaged target are imaged one by one onto the corresponding positions of the terahertz array detector 3. The polyhedron scanning mirror 1 rotates around the central axis for a circle, and N frames of scanning imaging of the imaged object are completed.
In the process, when each scanning mirror finishes scanning the imaged target in the vertical direction, the terahertz waves radiated or reflected by the imaged target are reflected to the terahertz focusing lens group 2, so that the terahertz focusing lens group 2 images the terahertz waves to the terahertz array detector 3.
In the scanning process, when the polyhedral scanning mirror 1 does not rotate, terahertz waves radiated or reflected by an imaged target are reflected to the terahertz focusing mirror group 2 by a plane mirror on the polyhedral scanning mirror 1 as a scanning mirror; when the polyhedron 1 rotates around the central shaft stably at a high speed, when each scanning mirror on the polyhedron scanning mirror 1 rotates to a reflecting light path behind an imaged target, rapid scanning is completed in the vertical direction of the imaged target, meanwhile, the terahertz focusing mirror group 2 converges terahertz waves onto the terahertz array detector, and the terahertz waves are terahertz waves radiated or reflected by an object point of the imaged target corresponding to the terahertz array detector 3. In order to ensure the scanning of each object point of the imaged object in the vertical direction, the rotating scanning range of the scanning surface on the polyhedron scanning mirror 1 can cover all the object points of the imaged object in the vertical range. Wherein, the object point on the imaged object corresponds to the image point on the terahertz array detector. In order to ensure that the imaging target is scanned at each point in the horizontal range, the horizontal field of view of the terahertz focusing mirror group 2 should cover the horizontal lateral range of the imaged target. For example, when the imaged object is a human body, when the human body is facing the polygon mirror 1, the horizontal field of view of the terahertz focusing mirror group 2 should cover the maximum width of the human body, such as the width between two shoulders; for another example, when the imaged object is a human body, the horizontal field of view of the terahertz focusing mirror group 2 should cover the maximum width of the human body when the human body is faced to the polygon mirror 1, and the maximum width should be the thickness between the belly and the back of the maximum bulging part of the belly if the human body is a human body with beer belly.
Based on the above working principle, when the polygon mirror 1 rotates around the central axis, the object point on the object to be imaged moves in the vertical direction with respect to the terahertz array detector 3, so that the terahertz array detector 3 can receive the terahertz waves reflected or radiated by the object point on the object to be imaged, which are different from those before. In the process, the polyhedron scanning mirror 1 uses a plurality of scanning surfaces to scan the imaged object in the rotating process, so that the scanning frame frequency is improved.
Fig. 3 is a schematic structural diagram of a total reflection type terahertz human body security inspection imaging device according to another embodiment of the present invention. In the figure, the position relationship of each terahertz focusing mirror in the terahertz focusing mirror group 2 is illustrated in detail. Referring to fig. 3, the terahertz focusing lens assembly 2 includes a first terahertz focusing lens 21, a second terahertz focusing lens 22 and a third terahertz focusing lens 23, wherein,
the first terahertz focusing mirror 21 is positioned in a reflection light path of the polyhedral scanning mirror 1;
the second terahertz focusing mirror 22 is positioned in a reflection light path of the first terahertz focusing mirror 21;
the third terahertz focusing mirror 23 is positioned in a reflection light path of the second terahertz focusing mirror 22;
the terahertz array detector 3 is positioned on the image plane of the third terahertz focusing mirror 23;
in a working state, the polyhedral scanning mirror 1 rotates around the central axis, so that the N plane mirrors sequentially serve as scanning mirrors to scan the imaged object in the vertical direction, and further the terahertz waves radiated or reflected by the imaged object are reflected to the first terahertz focusing mirror 21; the first terahertz focusing mirror 21 focuses the terahertz waves on the second terahertz focusing mirror 22, the second terahertz focusing mirror 22 focuses the terahertz waves on the third terahertz focusing mirror 23, and the third terahertz focusing mirror 23 images the terahertz waves on the terahertz array detector 3; in the process that the polyhedral scanning mirror 1 rotates around the central shaft, the center of the scanning mirror for imaging and the center of the first terahertz focusing mirror 21 are on the same straight line.
Further, referring to fig. 3 again, in an operating state, a vertical distance between a center of the scanning mirror for imaging and a center of the first terahertz focusing mirror 21 is L1; the vertical distance between the centers of the first terahertz focusing mirror 21 and the third terahertz focusing mirror 23 is L2; the vertical distance between the centers of the first terahertz focusing mirror 21 and the second terahertz focusing mirror 22 is L3; the central horizontal distance between the first terahertz focusing mirror 21 and the third terahertz focusing mirror 23 is L4; the central horizontal distance between the first terahertz focusing mirror 21 and the second terahertz focusing mirror 22 is L5; the horizontal distance between the center of the third terahertz focusing mirror 23 and the terahertz array detector 3 is L6, the included angle between the incident beam and the emergent beam of the first terahertz focusing mirror 21 is β, the included angle between the incident beam and the emergent beam of the second terahertz focusing mirror 22 is α, the included angle between the incident beam and the emergent beam of the third terahertz focusing mirror 23 is θ,
l1 is more than twice the horizontal lateral dimension of the first terahertz focusing mirror 21;
l5 is larger than the horizontal transverse dimension of the first terahertz focusing mirror 21;
l3 is more than twice the horizontal lateral dimension of the first terahertz focusing mirror 21;
l4 is larger than the horizontal transverse dimension of the first terahertz focusing mirror 21;
l2 is more than twice the horizontal lateral dimension of the first terahertz focusing mirror 21;
in the above embodiment, the lateral dimension refers to the maximum dimension of the first terahertz focusing mirror 21 in the lateral direction, as indicated by the black double-headed arrow in the figure.
Fig. 4 is a schematic structural diagram of a terahertz array detector suitable for a total reflection type terahertz human body security inspection imaging device according to an embodiment of the present invention. Referring to fig. 4, the detection channels of the terahertz array detector 3 are arranged in a staggered arrangement in two rows, and adjacent detection channels between the upper and lower rows are staggered by half. The number of the detection channels on the terahertz array detector 3 is determined according to the theoretical resolution of the terahertz focusing mirror group 2 and the width of the imaged target. For example, the number is more than 2 times of the ratio of the width of the imaged target to the theoretical resolution of the terahertz focusing mirror group 2. Assuming that the object to be imaged is a human body, when the front of the human body faces the polygon mirror 1, the width of the object to be imaged is, for example, 0.5 m, and the theoretical resolution of the terahertz focusing mirror assembly 2 is 2 cm, and 2 times the ratio of the width of the object to be imaged to the theoretical resolution of the terahertz focusing mirror assembly 2 is 0.5 m/2 cm × 2, which is 50, the number of detection channels on the terahertz array detector 3 is greater than 50.
After the terahertz wave reflected or radiated by the imaged target is imaged on the terahertz array detector 3 by the terahertz focusing mirror group 2, imaging of the imaged target in the vertical direction is completed. The terahertz wave array detector 3 acquires pixels for imaging the imaged object in the horizontal direction by one-dimensional electrical scanning. Therefore, under the condition that the terahertz array detector 3 is not moved and other devices are added, the two-dimensional scanning imaging of the imaged target can be realized. The one-dimensional continuous scanning motion and the array electrical scanning are combined, so that the structure of the total reflection type terahertz human body security inspection imaging device is simplified, and the terahertz imaging speed is improved to a great extent.
The total reflection type terahertz human body security inspection imaging device provided by the embodiment of the invention comprises a polyhedral scanning mirror, a terahertz focusing mirror group and a terahertz array detector, wherein the polyhedral scanning mirror rotates steadily at a high speed around a central shaft, so that N plane mirrors of the polyhedral scanning mirror are sequentially used as scanning mirrors to scan an image in the vertical direction, and terahertz waves radiated or reflected by an imaged target are reflected to the terahertz focusing mirror group; imaging terahertz waves reflected by a polyhedral scanning mirror of the terahertz focusing mirror group onto a terahertz array detector; the terahertz array detector converts terahertz waves into voltage signals and images according to the voltage signals, so that array scanning of an imaged object in the vertical direction is completed. The total reflection type terahertz human body security inspection imaging device can realize the scanning of the imaged target in the vertical direction through the high-speed stable rotation of the polyhedral scanning mirror around the central shaft, and has the advantages of simple and compact structure and high imaging speed. In addition, the total reflection type terahertz human body security inspection imaging device scans the imaged target in the vertical direction and simultaneously performs one-dimensional electrical scanning on the imaged target in the horizontal direction so as to scan the imaged target in the horizontal direction.
In a feasible implementation manner, the N plane mirrors of the polyhedral scanning mirror 1 are made by metal polishing, and other parts except the N plane mirrors in the polyhedral scanning mirror 1 are made of carbon fiber composite materials.
Specifically, in the embodiment of the present invention, the polygon scanning mirror 1 adopts a reflection working mode, N plane mirrors constituting the polygon scanning mirror 1 are manufactured by metal polishing, and the quality of the surface of each plane mirror is improved by an optical cold working method after the manufacturing, so that each plane mirror has a high reflectivity when being used as a scanning mirror; the other two parallel surfaces of the polygon mirror 1, such as the hexagonal part shown in fig. 2, are made of carbon fiber composite material, which is light, so that the polygon mirror 1 has a smaller moment of inertia during the rotation process.
In a possible implementation manner, the polyhedral scanning mirror 1, the first terahertz focusing mirror 21, the second terahertz focusing mirror 22 and the third terahertz focusing mirror 23 described above operate in a reflection mode.
In a feasible implementation manner, the surface of the terahertz focusing lens group 2 is a spherical surface or a high-order aspheric surface.
In a feasible implementation manner, the total reflection type terahertz human body security inspection imaging device further includes: and a protection device 4. In particular, see fig. 5.
Fig. 5 is a schematic view of a total reflection type terahertz human body security inspection imaging device according to another embodiment of the present invention. As shown in fig. 5, the total reflection type terahertz human body security inspection imaging device provided in this embodiment further includes a protection device 4, the polyhedral scanning mirror 1, the terahertz focusing mirror group 2, and the terahertz array detector 3 are packaged in the protection device, and a window 41 for transmitting terahertz waves is disposed on the protection device 4, and the window 41 is disposed between the imaged object and the polyhedral scanning mirror 1.
In the embodiment, by arranging the protection device and the window, dust and stray light can be prevented from entering, the cleanliness and the sensitivity of each part of the total reflection type terahertz human body security inspection imaging device are improved, and the service life of the total reflection type terahertz human body security inspection imaging device is prolonged.
Referring to fig. 5 again, in a feasible implementation manner, the total reflection type terahertz human body security inspection imaging device can also be used for active terahertz wave scanning imaging, and when active terahertz wave scanning imaging is adopted, terahertz wave radiation 5 with the frequency range of 0.1THZ to 10THZ is selected to illuminate an imaged target.
It should be noted that, in the above embodiment, before starting the total reflection type terahertz human body security inspection imaging device, each component in the terahertz imaging system needs to be arranged as required, so that the relative position of each component meets the requirement. Specifically, the scanning angle of the scanning mirror of the polygon scanning mirror 1 is the largest, and the central axis of the polygon scanning mirror 1 is parallel to the object plane where the imaged object is located. After the total reflection type terahertz human body security inspection imaging device is started, the face body scanning mirror 1 stably rotates around the central shaft at a high speed, the terahertz array detector 3 receives terahertz waves reflected by each scanning mirror on the polyhedral scanning mirror 1 while performing one-dimensional electrical scanning, the terahertz focusing mirror group 2 images the terahertz waves onto the terahertz detector 3, the terahertz detector 3 converts the detected terahertz waves into direct-current voltage signals, then the direct-current voltage signals are sent to the data processing device, and the data processing device performs filtering, amplification, high-speed acquisition and other processing on the direct-current voltage signals. And then, the data processing device collects and splices the processed direct current voltage signals according to the synchronous signals of the polyhedral scanning mirror 1 and the arrangement positions of all detection channels in the terahertz array detector 3, and finally displays the image of the imaged target. The data processing device can be arranged on a total reflection type terahertz human body security inspection imaging device, and is not shown in the figure.
In summary, the total reflection type terahertz human body security inspection imaging device provided by the embodiment of the invention comprises a polyhedral scanning mirror, a terahertz focusing mirror group and a terahertz array detector, wherein the polyhedral scanning mirror rotates steadily at a high speed around a central axis, so that N plane mirrors of the polyhedral scanning mirror are sequentially used as scanning mirrors to scan an image in the vertical direction, and terahertz waves radiated or reflected by an imaged target are reflected to the terahertz focusing mirror group; imaging terahertz waves reflected by a polyhedral scanning mirror of the terahertz focusing mirror group onto a terahertz array detector; the terahertz array detector converts terahertz waves into voltage signals and images according to the voltage signals, so that array scanning of an imaged object in the vertical direction is completed. The total reflection type terahertz human body security inspection imaging device can realize the scanning of the imaged target in the vertical direction through the high-speed stable rotation of the polyhedral scanning mirror around the central shaft, and has the advantages of simple and compact structure and high imaging speed. In addition, the total reflection type terahertz human body security inspection imaging device scans the imaged target in the vertical direction and simultaneously performs one-dimensional electrical scanning on the imaged target in the horizontal direction so as to scan the imaged target in the horizontal direction.
Those of ordinary skill in the art will understand that: all or a portion of the steps of implementing the above-described method embodiments may be performed by hardware associated with program instructions. The program may be stored in a computer-readable storage medium. When executed, the program performs steps comprising the method embodiments described above; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (8)
1. A total reflection type terahertz human body security inspection imaging device is characterized by comprising: a polyhedron scanning mirror (1), a terahertz focusing mirror group (2) and a terahertz array detector (3), wherein,
the polyhedron scanning mirror (1) comprises N plane mirrors, each plane mirror is a rectangle with the same size, the N plane mirrors sequentially surround to form an N prism, the central axis of the N prism is parallel to each edge and has the same distance from each edge, N is not less than 3 and is an integer;
in an initial state, the polyhedron scanning mirror (1) is placed in front of an imaged target, the central axis is parallel to an object plane where the imaged target is located, and a field of view of the terahertz focusing mirror group (2) covers a horizontal transverse range of an imaged object;
in a working state, the imaged target is located on an object plane of the terahertz focusing mirror group (2), and the terahertz array detector (3) is located on an image plane of the terahertz focusing mirror group (2); the polyhedral scanning mirror (1) rotates around the central shaft, so that the N plane mirrors are sequentially used as scanning mirrors to scan the imaged object in the vertical direction, the terahertz waves radiated or reflected by the imaged object are reflected to the terahertz focusing mirror group (2), and the terahertz waves are imaged on the terahertz array detector (3) by the terahertz focusing mirror group (2); the terahertz array detector (3) is used for converting the terahertz waves into voltage signals and imaging according to the voltage signals;
the terahertz focusing mirror group (2) comprises a first terahertz focusing mirror (21), a second terahertz focusing mirror (22) and a third terahertz focusing mirror (23),
the first terahertz focusing mirror (21) is positioned in a reflection light path of the polyhedral scanning mirror (1);
the second terahertz focusing mirror (22) is positioned in a reflection optical path of the first terahertz focusing mirror (21);
the third terahertz focusing mirror (23) is positioned in a reflection optical path of the second terahertz focusing mirror (22);
the terahertz array detector (3) is positioned on an image plane of the third terahertz focusing mirror (23);
in a working state, the polyhedron scanning mirror (1) rotates around the central shaft, so that the N plane mirrors are sequentially used as scanning mirrors to scan the imaged target in the vertical direction, and further terahertz waves radiated or reflected by the imaged target are reflected to the first terahertz focusing mirror (21); the first terahertz focusing mirror (21) focuses the terahertz waves on the second terahertz focusing mirror (22), the second terahertz focusing mirror (22) focuses the terahertz waves on the third terahertz focusing mirror (23), and the third terahertz focusing mirror (23) images the terahertz waves on the terahertz array detector (3); in the process that the polyhedron scanning mirror (1) rotates around the central shaft, the center of the scanning mirror used for imaging and the center of the first terahertz focusing mirror (21) are on the same straight line;
in the working state, the vertical distance between the center of a scanning mirror used for imaging and the center of the first terahertz focusing mirror (21) is L1; the vertical distance between the centers of the first terahertz focusing mirror (21) and the third terahertz focusing mirror (23) is L2; the vertical distance between the centers of the first terahertz focusing mirror (21) and the second terahertz focusing mirror (22) is L3; the central horizontal distance between the first terahertz focusing mirror (21) and the third terahertz focusing mirror (23) is L4; the central horizontal distance between the first terahertz focusing mirror (21) and the second terahertz focusing mirror (22) is L5; the horizontal distance between the center of the third terahertz focusing mirror (23) and the terahertz array detector (3) is L6, the included angle between the incident beam and the emergent beam of the first terahertz focusing mirror (21) is beta, the included angle between the incident beam and the emergent beam of the second terahertz focusing mirror (22) is alpha, the included angle between the incident beam and the emergent beam of the third terahertz focusing mirror (23) is theta, wherein,
l1 is more than twice of the horizontal transverse dimension of the first terahertz focusing mirror (21);
l5 is larger than the horizontal transverse dimension of the first terahertz focusing mirror (21);
l3 is more than twice of the horizontal transverse dimension of the first terahertz focusing mirror (21);
l4 is larger than the horizontal transverse dimension of the first terahertz focusing mirror (21);
l2 is more than twice of the horizontal transverse dimension of the first terahertz focusing mirror (21);
2. the apparatus according to claim 1, characterized in that the N flat mirrors of the polygon mirror (1) are made by metal polishing, and the other parts of the polygon mirror (1) than the N flat mirrors are made of carbon fiber composite material.
3. The device according to claim 1, characterized in that the first terahertz focusing mirror (21), the second terahertz focusing mirror (22) and the third terahertz focusing mirror (23) are spherical or high-order aspheric in surface shape.
4. The device according to claim 1, wherein the number of detection channels on the terahertz array detector (3) is greater than 2 times of the ratio of the width of the imaged object to the theoretical resolution of the terahertz focusing mirror group (2).
5. The apparatus of any one of claims 1 to 4, further comprising: protection device (4), polyhedron scanning mirror (1), terahertz focusing mirror group (2) and terahertz array detector (3) encapsulation are in protection device (4), just be provided with the confession on protection device (4) window (41) that the terahertz wave sees through, window (41) set up by the imaging target with between polyhedron scanning mirror (1).
6. The apparatus of any one of claims 1 to 4, further comprising: a terahertz wave radiation source for irradiating the imaged object with a terahertz wave of 0.1-10 THz.
7. The apparatus according to any one of claims 1 to 4, characterized in that the polygon mirror (1) is a regular pentahedron or a regular hexahedron.
8. The device according to any one of claims 1 to 4, characterized in that the polyhedral scanning mirror (1), the first terahertz focusing mirror (21), the second terahertz focusing mirror (22) and the third terahertz focusing mirror (23) work in a reflection mode.
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| JP2008224452A (en) * | 2007-03-13 | 2008-09-25 | Hamamatsu Photonics Kk | Device for measuring totally reflected terahertz wave |
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