Terahertz security inspection instrument for real-time panoramic terahertz imaging

Abstract

The present application relates to a kind of terahertz security check instrument of real-time panoramic terahertz imaging, 360° panoramic scene from object side emits terahertz electromagnetic wave, after reflection by panoramic terahertz optical system, enter transmission type terahertz imaging system and gather, image on terahertz detector focal plane, like circular ring distribution.Makes that terahertz imaging system need not rotate and can directly complete 360° panoramic ring view, obtains annular panoramic terahertz image.Then through image processing software mapping transformation, it is changed into the cylindrical surface unfolded image that conforms to daily visual habit from annular image, so that the range of 360° around it can be imaged in real time by single terahertz system.

Description

Technical Field

[0001] This invention relates to a terahertz security inspection technology, and more particularly to a terahertz security inspection device with real-time panoramic terahertz imaging. Background Technology

[0002] Terahertz security scanners are currently at the forefront of security imaging technology, capable of detecting prohibited items concealed under a passenger's clothing. Most mainstream terahertz security scanners can typically image an area of ​​approximately 2 meters x 1 meter in front of them; this field of view precisely covers the body of an adult passenger. Figure 1a , 1b The images show the field of view of the terahertz security scanner from the side and top.

[0003] However, in many public places with high passenger traffic, it is impossible for passengers to concentrate only within the field of view directly in front of the terahertz security scanner. This means that the terahertz security scanner can only inspect a small number of passengers at a time, and the field of view of the terahertz security scanner has limitations such as... Figure 2 As shown.

[0004] Because existing terahertz security scanners all use the principle of scanning imaging, and are limited by the scanning angle and detector array, it is difficult to make the field of view of terahertz security scanners larger. Figure 3 The diagram shows the optical scanning imaging of a terahertz security scanner. Therefore, to perform security checks over a larger field of view, the terahertz scanner must either be rotated or passengers must be grouped within the field of view in front of it. The former, due to its limited rotation speed, cannot perform real-time checks on every passenger, making it easy to miss targets. The latter requires passengers to wait in long queues, reducing operational efficiency and impacting the user experience.

[0005] Therefore, if terahertz security scanners can achieve a large field of view or even panoramic imaging, their working efficiency can be greatly improved, making their practicality even more advanced. Summary of the Invention

[0006] To address the limited field of view issue of terahertz security scanners using scanning imaging, a real-time panoramic terahertz imaging terahertz security scanner is proposed.

[0007] The technical solution of the present invention is as follows: a terahertz security inspection device with real-time panoramic terahertz imaging. Terahertz electromagnetic waves emitted from the 360° panoramic scene from the object are reflected by the panoramic terahertz optical system and then enter the transmission terahertz imaging system for convergence, and are imaged on the focal plane of the terahertz detector, with the image distributed in a ring shape.

[0008] Preferably, the panoramic terahertz optical system is a terahertz reflector with a rotating hyperboloid, and the transmissive terahertz imaging system is a terahertz refractive lens composed of a positive lens or a group of positive lenses with high-order aspherical surfaces.

[0009] Preferably, it also includes a cylindrical terahertz security inspection device housing, with a terahertz reflector built into the housing. A cylindrical transmission window that allows terahertz electromagnetic waves to pass through is embedded on the housing at a position corresponding to the height of the terahertz reflector. Terahertz electromagnetic waves incident at any angle enter the reflecting surface of the terahertz reflector through the cylindrical transmission window.

[0010] Preferably, the terahertz refractive lens is made of high-density polyethylene or polytetrafluoroethylene, which can transmit and refract terahertz waves, further focusing the terahertz waves and correcting aberrations.

[0011] Preferably, the terahertz detector is a terahertz detector assembly composed of single-channel terahertz detection modules arranged in a combination. That is, one single-channel terahertz detection module corresponds to one terahertz image pixel, and a series of single-channel terahertz detection modules are arranged in a ring array according to the ring imaging range to form a terahertz detector assembly. The image receiving surface of the terahertz detector assembly coincides with the focal plane, thereby obtaining a ring-shaped terahertz image.

[0012] Preferably, it also includes an image processing unit, through which the annular terahertz image received by the terahertz detector is mapped into a cylindrical surface and expanded into a rectangular image.

[0013] The beneficial effects of the present invention are as follows: The terahertz security inspection instrument with real-time panoramic terahertz imaging of the present invention can realize real-time security inspection of a 360° range around it through a single terahertz security inspection instrument. Attached Figure Description

[0014] Figure 1a This is a side view of the field of view of a terahertz security scanner.

[0015] Figure 1b This is a top view of the field of view of the terahertz security scanner.

[0016] Figure 2 A schematic diagram illustrating the limitations of the field of view of a terahertz security scanner;

[0017] Figure 3 This is a schematic diagram of the optical scanning imaging of a terahertz security scanner.

[0018] Figure 4 This is a schematic diagram of the folding panoramic terahertz security inspection device of the present invention;

[0019] Figure 5This is a top-view schematic diagram of the foldback terahertz panoramic imaging of the present invention;

[0020] Figure 6 This is a schematic diagram of the software processing and cylindrical unfolding mapping of the annular panoramic terahertz image of the present invention.

[0021] Figure 7 This is a schematic diagram of the structure of an embodiment of the panoramic imaging terahertz security inspection instrument of the present invention;

[0022] Figure 8 This is a schematic diagram of a ring terahertz detection array composed of a single-channel terahertz detection module of the present invention. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0024] This invention employs a folding panoramic imaging optical scheme, combined with a ring-shaped terahertz detector array, enabling the terahertz security scanner to directly achieve a 360° panoramic view without rotation, obtaining a ring-shaped panoramic terahertz image. Then, image processing software performs a mapping transformation, converting the ring-shaped image into a cylindrical unfolded image that conforms to everyday visual habits. This allows a single terahertz security scanner to perform real-time security checks over a 360° area. The 360° panoramic image obtained by this invention has no temporal or spatial blind spots, and its image refresh rate and prohibited item detection rate are far superior to methods that obtain panoramic views by rotating the terahertz security scanner.

[0025] Specifically, the system composition of the folding panoramic terahertz security scanner is as follows: Figure 4 Terahertz electromagnetic waves 1 emitted from the 360° panoramic scene are reflected by the panoramic terahertz optical system 2 and then converged into the transmission terahertz imaging system 2', finally forming an image on the focal plane of the terahertz detector 3.

[0026] Furthermore, its imaging principle can be explained as follows:

[0027] like Figure 5 As shown, taking four points a, b, c, and d as an example, these four points are distributed in a 360° pattern around the terahertz security scanner and are equidistant from it. Therefore, these four points can be regarded as being located on a cylindrical surface 1' centered on the terahertz security scanner. After passing through the panoramic terahertz reflection system 2 and the transmission terahertz imaging system 2', the four points a, b, c, and d are imaged on the detector's focal plane 3' and distributed in a ring shape.

[0028] Therefore, it can be seen that the imaging process of the folding panoramic terahertz security scanner is the process of mapping the cylindrical object surface 1' into the annular image surface 3'.

[0029] like Figure 6 As shown, since the ring-shaped image does not conform to everyday visual habits, it poses a significant challenge to image discrimination. Therefore, it needs to be processed by image processing software 4 to remap the ring-shaped terahertz panoramic image 5 into a cylindrical surface. Since the cylindrical surface can be easily unfolded into a rectangular image 6, a 360° panoramic real-time terahertz image that conforms to everyday visual habits can be obtained.

[0030] A specific implementation plan for a panoramic imaging terahertz security inspection device is as follows: Figure 7 As shown, the terahertz security inspection device has a cylindrical housing 7, which houses a terahertz reflector 9. A cylindrical transmission window 8, capable of transmitting terahertz electromagnetic waves, is embedded in the housing 7 at a height corresponding to the terahertz reflector 9. Terahertz electromagnetic waves incident at any angle enter the reflecting surface of the terahertz reflector 9 through the cylindrical transmission window 8. The panoramic terahertz optical imaging system consists of the terahertz reflector 9 and a terahertz refractive lens 10. The terahertz reflector 9 has a hyperboloidal surface and is coated with an aluminum film with high reflectivity for terahertz waves, ensuring that all terahertz waves from the object are reflected into the terahertz refractive lens 10. The terahertz refractive lens 10 is a high-order aspherical positive lens or a group of positive lenses, made of high-density polyethylene (HDPE) or polytetrafluoroethylene (PTFE) that can transmit and refract terahertz waves, further converging the terahertz waves and correcting aberrations. The terahertz detector is the terahertz detector component 12, which is used to receive terahertz images.

[0031] Specifically, in order to obtain a ring-shaped terahertz image, such as Figure 8 As shown, the terahertz detector assembly 12 is composed of single-channel terahertz detection modules 11 arranged in a circular array. Each single-channel terahertz detection module 11 corresponds to one terahertz image pixel. The modules are generally cylindrical in shape, with a square or rectangular cross-section. A series of single-channel terahertz detection modules 11 are arranged in a circular array according to the annular imaging range of the folded panoramic terahertz optical system to form the terahertz detector assembly 12. During installation, the image receiving surface 13 of the terahertz detector assembly 12 is aligned with the focal plane of the folded panoramic terahertz optical system to obtain an annular terahertz image. Figure 6 5. A panoramic terahertz image of the central ring.

[0032] By employing a folding panoramic imaging optical scheme and combining it with a ring-shaped terahertz detector array, the terahertz imaging system can directly achieve a 360° panoramic view without rotation, obtaining a ring-shaped panoramic terahertz image. Then, image processing software performs mapping transformation, converting the ring-shaped image into a cylindrical unfolded image that conforms to everyday visual habits. This allows for real-time imaging of the surrounding 360° area using a single terahertz system.

[0033] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A terahertz security inspection device with real-time panoramic terahertz imaging, characterized in that, Terahertz electromagnetic waves emitted from a 360° panoramic view are reflected by the panoramic terahertz optical system and then converged by the transmissive terahertz imaging system, forming an image on the focal plane of the terahertz detector in a ring shape. The panoramic terahertz optical system is a hyperboloid terahertz reflector, the surface of which is coated with an aluminum film with high reflectivity for terahertz waves. The transmissive terahertz imaging system is a terahertz refractive lens composed of high-order aspherical positive lenses or groups of positive lenses, made of high-density polyethylene or polytetrafluoroethylene that can transmit and refract terahertz waves, used to further converge the terahertz waves and correct aberrations. It also includes a cylindrical terahertz security inspection equipment housing, with a built-in terahertz reflector. A cylindrical transmission window that can transmit terahertz electromagnetic waves is embedded on the terahertz security inspection equipment housing at a height position corresponding to the terahertz reflector. Terahertz electromagnetic waves incident at any angle enter the reflecting surface of the terahertz reflector through the cylindrical transmission window. The terahertz detector is a terahertz detector assembly composed of single-channel terahertz detection modules arranged in a circular array. That is, one single-channel terahertz detection module corresponds to one terahertz image pixel. A series of single-channel terahertz detection modules are arranged in a circular array according to the circular imaging range to form a terahertz detector assembly. The image receiving surface of the terahertz detector assembly coincides with the focal plane, thereby obtaining a circular terahertz image.

2. The terahertz security inspection device with real-time panoramic terahertz imaging according to claim 1, characterized in that, It also includes an image processing unit. The ring-shaped terahertz image received by the terahertz detector is processed by the image processing unit to map the ring-shaped terahertz panoramic image into a cylindrical surface and unfold it into a rectangular image.

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