Hand-held mail security check device based on reflection-type terahertz holographic imaging

Abstract

The utility model discloses a handheld mail security check device based on reflection-type terahertz holographic imaging, and relates to the technical field of mail detection, and the handheld mail security check device comprises a terahertz emission source which is used for emitting terahertz waves with a specific frequency; the terahertz beam splitter is used for dividing the terahertz beam emitted by the terahertz emission source into a reference beam and a detection beam; the terahertz emission window is used for transmitting a detection wave beam; the terahertz receiving window is used for transmitting scattered echoes formed by email reflection; the terahertz camera is used for converging the reference wave beam and the scattering echo to form holographic interference fringes carrying mail imaging information, converting the holographic interference fringes into electric signals and sending the electric signals; the data processing unit is used for generating a holographic image in the mail; and the switch trigger button is arranged on the handle structure and is used for controlling a switch of the mail security check device. The utility model provides the mail security check device which is portable, high in universality, high in detection precision, stable in work and free of damage and harm.

Description

Technical Field

[0001] The present application relates to the technical field of mail detection, and in particular to a handheld mail security inspection device based on reflective terahertz holographic imaging. Background Art

[0002] Mail security inspection is a necessary procedure for checking the contents of mail, mainly including inspection of flammable and explosive items, drugs, sharp objects, and suspicious marks or liquid leakage. Mail security inspection follows the principle of safety first, and usually requires the use of professional technology and equipment to conduct strict inspections without damaging the mail. With the rapid development of my country's Internet e-commerce and logistics industries, mail security inspection has gradually become one of the important work links in the logistics industry, which determines the safety and work efficiency of the logistics network.

[0003] Existing mail security inspection technologies mainly include the following categories:

[0004] (1) X-ray security inspection technology, the principle is to use X-rays to penetrate mail, and use the principle that different materials have different absorption abilities of X-rays to display the internal structure and items of the mail in the form of images. In actual use, X-ray security inspection technology has significant defects. Although X-ray security inspection technology can effectively detect most items in mail, its detection effect may not be good for some specific materials, such as plastics or certain types of explosives. In addition, X-ray security inspection equipment is usually large in size and not easy to carry and move. In addition, X-rays are high-energy ionizing radiation, which may cause irreversible damage to the delicate and fragile materials or structures inside the mail, seriously affecting the safety of mail security inspection.

[0005] (2) Metal detection technology uses the principle of metal interference with magnetic fields to determine the safety of mail by detecting metal objects in mail. Its disadvantage is that metal detection technology can only detect metal objects and cannot effectively detect explosives or dangerous goods made of non-metallic materials. In addition, metal detection equipment may also be interfered by other metal objects, resulting in a high false alarm rate.

[0006] (3) Biometric technology: by scanning the biometric information (such as fingerprints, irises, etc.) on the mail and comparing it with the pre-stored information, the security of the mail can be determined. The application of biometric technology in mail security is relatively rare, mainly because there is currently a lack of effective methods to embed biometric information on mail. In addition, biometric technology may also be threatened by forgery and deception.

[0007] (4) Intelligent image recognition technology can determine whether there are dangerous goods and contraband in the mail by intelligently analyzing and identifying the optical, infrared and even X-ray images of the mail. However, the accuracy of intelligent image recognition technology is affected by the image quality and algorithm performance. If the image quality is poor or the algorithm performance is insufficient, it may lead to false positives or false negatives. In addition, intelligent image recognition technology may also be interfered by complex background and noise.

[0008] In summary, the existing mail security inspection technology has many problems, such as single type of inspection materials, low inspection accuracy, susceptibility to camouflage interference, large size of inspection equipment and difficulty in moving, etc. At present, the logistics industry is still in urgent need of a portable, versatile, high-precision, stable and non-destructive mail security inspection technology and equipment to cope with the increasingly complex and heavy mail security inspection needs. Utility Model Content

[0009] The present application provides a handheld mail security inspection device based on reflective terahertz holographic imaging, which is used to overcome at least one technical problem existing in the prior art.

[0010] The present application embodiment provides a handheld mail security inspection device based on reflective terahertz holographic imaging, comprising:

[0011] A main body module, wherein the main body module is a hexahedral structure with a hollow interior;

[0012] A terahertz emission source is arranged inside the main module and is used to emit terahertz waves of a specific frequency;

[0013] A terahertz beam splitter is arranged inside the main module and located on the terahertz wave emission path of the terahertz emission source, and is used to split the terahertz beam emitted by the terahertz emission source into a reference beam and a detection beam;

[0014] A terahertz emission window, fixed on the first surface of the main module, for transmitting the detection beam;

[0015] A terahertz receiving window, fixed on the first surface, for transmitting scattered echoes formed by reflection of mail;

[0016] A terahertz camera is arranged inside the main module, and is used to converge the reference beam and the scattered echo, so that the reference beam and the scattered echo interfere with each other to form holographic interference fringes carrying the imaging information of the mail; and is also used to convert the holographic interference fringes into electrical signals and then transmit them;

[0017] A data processing unit, used for receiving the electrical signal and processing the electrical signal to generate a holographic image inside the mail;

[0018] A handle structure, fixed to a second surface of the main body module, wherein the second surface is adjacent to the first surface;

[0019] A switch trigger button is arranged on the handle structure and is used to control the switch of the mail security inspection device.

[0020] Optionally, it also includes:

[0021] A display screen is fixed on the third surface of the main body module, and the first surface and the third surface are arranged opposite to each other; the display screen is used to display the holographic image inside the mail.

[0022] Optionally, the handle structure is a rectangular parallelepiped or cylindrical structure made of metal material, and the length of the handle structure is 10-20 cm.

[0023] Optionally, it further includes a base, which is fixedly connected to the handle structure, and the base is located at one end of the handle structure away from the main body module.

[0024] Optionally, it further includes a data storage unit;

[0025] The data storage unit is located in the base and is used for storing the holographic image inside the mail.

[0026] Optionally, a USB data interface is also included;

[0027] The USB data interface is located on the base and is used to copy the holographic image inside the mail.

[0028] Optionally, the data processing unit is deployed locally or remotely.

[0029] Optionally, the terahertz beam splitter comprises high-resistance floating region silicon.

[0030] Optionally, the terahertz emission window and the terahertz receiving window are made of terahertz high-transmittance materials.

[0031] Optionally, the mail security inspection device weighs less than 3 kg.

[0032] The innovative features of the embodiments of the present application include:

[0033] 1. In this embodiment, narrow linewidth reflective terahertz holographic imaging technology is used to generate high-resolution images to display the details of items inside the mail, including shape, size, and material, etc., thereby helping security personnel to accurately identify possible contraband or dangerous goods, which is one of the innovative features of the embodiment of the present application.

[0034] 2. In this embodiment, the narrow linewidth reflective terahertz holographic imaging technology can realize real-time imaging and automated processing, so that the security inspection process can be carried out quickly, and suspicious items can be automatically identified and marked through computer algorithms, thereby reducing the need for manual intervention and improving the accuracy and efficiency of security inspections. This is one of the innovative points of the embodiments of the present application.

[0035] 3. In this embodiment, a non-contact detection method is adopted, and inspection can be carried out without opening the mail, thereby reducing the risk of damage to the mail during the security inspection process and improving the security inspection efficiency; at the same time, since it is a non-contact detection, it can handle mail of various shapes and sizes, including fragile or sealed packages, which is one of the innovative points of the embodiment of the present application.

[0036] 4. In this embodiment, a portable structure design is adopted. During use, the security personnel can use it by hand to realize on-site rapid detection and analysis, which overcomes the problem that traditional security equipment is bulky and difficult to use flexibly; and the detection results can be directly displayed on the display screen in real time, which greatly improves the efficiency and safety of mail security inspection, which is one of the innovative points of the embodiment of this application. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 A schematic diagram of a three-dimensional structure of a handheld mail security inspection device based on reflective terahertz holographic imaging provided in an embodiment of the present application;

[0039] Figure 2 A schematic diagram of the planar structure of a handheld mail security inspection device based on reflective terahertz holographic imaging provided in an embodiment of the present application. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] It should be noted that the terms "including" and "having" and any variations thereof in the embodiments of the present application and the accompanying drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0042] The embodiment of the present application discloses a handheld mail security inspection device based on reflective terahertz holographic imaging, which is described in detail below.

[0043] Figure 1 A schematic diagram of a three-dimensional structure of a handheld mail security inspection device based on reflective terahertz holographic imaging provided in an embodiment of the present application, Figure 2 A schematic diagram of a planar structure of a handheld mail security inspection device based on reflective terahertz holographic imaging provided in an embodiment of the present application is provided in FIG. Figure 1-Figure 2 The present application provides a handheld mail security inspection device 100 based on reflective terahertz holographic imaging, comprising:

[0044] The main body module 1 is a hexahedral structure with a hollow interior;

[0045] The terahertz emission source 8 is arranged inside the main module 1 and is used to emit terahertz waves of a specific frequency;

[0046] The terahertz beam splitter 9 is arranged inside the main module 1 and located on the terahertz wave emission path of the terahertz emission source 8, and is used to split the terahertz beam emitted by the terahertz emission source 8 into a reference beam and a detection beam;

[0047] A terahertz emission window 4 is fixed on the first surface of the main module 1 and is used to transmit the detection beam;

[0048] A terahertz receiving window 5, fixed on the first surface, for transmitting scattered echoes formed by reflection of mail;

[0049] The terahertz camera 10 is arranged inside the main module 1, and is used to converge the reference beam and the scattered echo, and the reference beam and the scattered echo interfere to form holographic interference fringes carrying the imaging information of the mail; and is also used to convert the holographic interference fringes into electrical signals and then send them;

[0050] The data processing unit 11 is used to receive the electrical signal and process the electrical signal to generate a holographic image inside the mail;

[0051] The handle structure 2 is fixed to the second surface of the main body module 1, and the second surface is adjacent to the first surface;

[0052] The switch trigger button 7 is arranged on the handle structure 2 and is used to control the switch of the mail security inspection device 100 .

[0053] Specifically, please refer to Figure 1-Figure 2 The handheld mail security inspection device 100 based on reflective terahertz holographic imaging provided in the embodiment of the present application includes a main body module 1. The main body module 1 is a hexahedral structure with a length of about 20-40 cm, a width of about 15-30 cm, and a height of about 30-50 cm. The shell of the main body module 1 is made of metal materials such as aluminum, magnesium, steel, stainless steel, and various types of common shell packaging materials such as plastics and ceramics.

[0054] The mail security inspection device 100 also includes a terahertz emission source 8, a terahertz beam splitter 9, a terahertz emission window 4, a terahertz receiving window 5, a terahertz camera 10 and a data processing unit 11. The above components are used to collect mail information and generate a holographic image of the mail information. In order to facilitate mail detection, in this embodiment, the interior of the main body module 1 is set to be hollow, so that the terahertz emission source 8, the terahertz beam splitter 9, the terahertz emission window 4, the terahertz receiving window 5, the terahertz camera 10 and the data processing unit 11 can be placed in the main body module 1.

[0055] The terahertz emission source 8 may be realized by common terahertz sources such as a solid-state avalanche diode, a vacuum tube integrated circuit, a terahertz antenna or a terahertz laser, and terahertz waves of a specific frequency may be emitted by the terahertz emission source 8 .

[0056] Here, it should be noted that the line width of the terahertz wave generated by the terahertz emission source 8 is one of the important indicators that affect the performance of holographic imaging. During the transmission of terahertz waves, the narrower the line width, the better the consistency of the response of each component in the optical path, and the more accurate the focusing and positioning alignment of the terahertz wave; the narrow line width terahertz wave will significantly weaken the dispersion effect during the propagation of the terahertz signal, making the amplitude and phase properties of the terahertz wave more stable during imaging, greatly improving the imaging accuracy and resolution; by selecting a suitable narrow line width terahertz frequency, customized imaging detection can be effectively performed for mails of different material systems, thereby improving the imaging quality and stability; the narrow line width terahertz wave can effectively shield the influence of environmental factors on the holographic imaging effect, reduce imaging noise, and improve imaging resolution and stability. Therefore, in order to ensure the accuracy and quality of coherent imaging, this embodiment adopts a narrow line width terahertz emission source 8, and its emission line width needs to be less than the kHz level. By selecting a suitable narrow line width terahertz frequency, customized imaging detection can be effectively performed for mails of different material systems, thereby improving the imaging quality and stability.

[0057] The terahertz beam splitter 9 is located on the terahertz wave emission path of the terahertz emission source 8. After the terahertz wave emitted by the terahertz emission source 8 reaches the terahertz beam splitter 9, since the terahertz beam splitter 9 is semi-reflective and semi-transparent, the terahertz wave beam emitted by the terahertz emission source 8 can be split into two, specifically a reference beam (such as Figure 2 middle dashed line) and the detection beam (e.g. Figure 2 In this embodiment, the main material of the terahertz beam splitter 9 is high resistance floating zone silicon (HRFZ-Si).

[0058] The terahertz emission window 4 is fixed on the first surface of the main body module 1, and the terahertz emission window 4 is made of a terahertz high-transmittance material, such as polymethylpentene (TPX), polyethylene (PE) or polytetrafluoroethylene (PTFE). In this way, the detection beam can be transmitted from the terahertz emission window 4 and irradiated to the mail to be detected. Since the terahertz wave has a strong penetrating power and can penetrate objects of different materials, including paper, plastic, wood and ceramics, after the detection beam is irradiated to the mail, it can penetrate into the mail to be tested. Through the reflection and scattering of the terahertz wave by the mail, the intensity and phase of the returned scattered echo will be modulated, so it carries the image information of the internal structure of the object. This allows security personnel to easily detect objects hidden inside the mail, no matter how they are wrapped or hidden.

[0059] After being reflected by the mail, the scattered echo reaches the terahertz receiving window 5 fixed on the first surface. Here, the terahertz receiving window 5 is also made of a terahertz high-transmittance material, such as polymethylpentene (TPX), polyethylene (PE) or polytetrafluoroethylene (PTFE), so that the scattered echo can pass through the terahertz receiving window 5.

[0060] The scattered echo and reference beam transmitted from the terahertz receiving window 5 converge to the terahertz camera 10. In order to achieve the convergence of as many scattered echoes and reference beams as possible, an array terahertz camera 10 is used here. The scattered echo and the reference beam interfere with each other on the surface of the terahertz camera 10, thereby forming holographic interference fringes carrying the imaging information of the mail. The interference fringes contain the amplitude and phase information about the mail under test carried by the detection light. Since different materials respond differently to terahertz waves, the material type of the items inside the mail can be identified by analyzing the reflected scattered echo signal. In this way, by analyzing the material characteristics, it can be determined whether there are contraband items in the mail under test. After obtaining the holographic interference fringes carrying the imaging information of the mail, the terahertz camera 10 records and converts the holographic interference fringes into electrical signals and sends them to the data processing unit 11.

[0061] After the data processing unit 11 receives the electrical signal converted by the terahertz camera 10, it processes the electrical signal using a holographic algorithm to obtain complete holographic complex amplitude information inside the mail under test. By converting the complex amplitude digital information into image information, the holographic image inside the mail can be restored for inspection by security personnel.

[0062] In addition to the various components used in the above-mentioned imaging process, the present application also provides a handle structure 2. The handle structure 2 is fixed to the second surface of the main body module 1, and the second surface is adjacent to the first surface. In this way, when performing mail inspection, the handle structure 2 can be grasped. Since the main body module 1 has a small structure, it is easy to hold the mail security inspection device 100, which solves the problems of the existing mail security inspection equipment being large in size and difficult to move or carry.

[0063] Furthermore, the handle structure 2 is a rectangular parallelepiped or cylindrical structure of a metal material. By setting the handle structure 2 to be a cylinder or rectangular parallelepiped that is easy to grasp, its portability can be further improved. In addition, when the length of the handle structure 2 is too short, it cannot be grasped, and when the length is too long, the volume of the entire device will be increased, which is not conducive to carrying. Therefore, in this embodiment, the length of the handle structure 2 is set to 10-20 cm.

[0064] The present application also provides a switch trigger button 7 on the handle structure 2, and the switch trigger button 7 can be used to control the opening and closing of the mail security inspection device 100. When the trigger is turned on, the terahertz emission source 8 starts to emit terahertz waves, and the array terahertz camera 10 starts to receive signals; when the trigger is turned off, the optical path is in a closed state.

[0065] The handheld mail security inspection device 100 based on reflective terahertz holographic imaging provided by the present application adopts narrow linewidth reflective terahertz holographic imaging technology to generate high-resolution images to display the details of the items inside the mail, including shape, size and material, etc., so as to help security inspectors accurately identify possible contraband or dangerous goods. In addition, narrow linewidth reflective terahertz holographic imaging technology can realize real-time imaging and automated processing, so that the security inspection process can be carried out quickly, and suspicious items can be automatically identified and marked by computer algorithms, thereby reducing the need for manual intervention and improving the accuracy and efficiency of security inspection. This technology adopts a non-contact detection method, and can be inspected without opening the mail, thereby reducing the risk of damage to the mail during the security inspection process, and also improving the efficiency of security inspection; at the same time, because it is a non-contact detection, it can handle mail of various shapes and sizes, including fragile or sealed packages.

[0066] It should be noted that the mail 12 mentioned in this application refers to various types of mail, parcels, etc., including but not limited to letters, cards, express parcels, luggage, packaged liquids, etc. This application is not limited to a specific type of mail.

[0067] Optionally, refer to Figure 1 , Figure 2 The mail security inspection device 100 further includes: a display screen 6 fixed on the third surface of the main body module 1, the first surface and the third surface are arranged opposite to each other; the display screen 6 is used to display the holographic image inside the mail.

[0068] Specifically, please refer to Figure 1 , Figure 2 In this embodiment, a display screen 6 is further provided on the third surface of the main body module 1, wherein the third surface is arranged opposite to the first surface. After the data processing unit 11 processes and obtains the holographic image inside the mail, the holographic image inside the mail is sent to the display screen 6, and the holographic image inside the mail can be intuitively displayed through the display screen 6, so as to facilitate the inspection by the security inspectors.

[0069] Optionally, refer to Figure 1 , Figure 2 The mail security inspection device 100 also includes a base 3 , which is fixedly connected to the handle structure 2 . The base 3 is located at one end of the handle structure 2 away from the main module 1 .

[0070] Specifically, please refer to Figure 1 , Figure 2 In this embodiment, a base 3 fixedly connected to the handle structure 2 is provided at the bottom of the handle structure 2, and the base 3 is a rectangular parallelepiped structure made of metal material, with a length and width of about 10-15 cm and a height of about 2-5 cm. By providing the base 3, when the mail security inspection device 100 is not in use, the base 3 can be used to fix it, thereby avoiding the problem that the mail security inspection device 100 cannot be fixed and placed, resulting in damage.

[0071] It should be noted that, in addition to being configured as a rectangular parallelepiped structure, the base 3 may also be configured as other shapes, such as a disc shape, etc., and this application does not make any specific limitation to this.

[0072] Optionally, refer to Figure 2 , and also includes a data storage unit (not marked in the figure); the data storage unit is located in the base 3 and is used to store the holographic image inside the mail. Figure 2 In this embodiment, a data storage unit is provided in the base 3, and the holographic image inside the mail can be stored in the data storage unit.

[0073] Optionally, refer to Figure 2, and also includes a USB data interface (not marked in the figure); the USB data interface is located on the base 3 and is used to copy the holographic image inside the mail. For details, please refer to Figure 2 In this embodiment, a USB data interface is provided on the base 3. When the holographic image inside the mail needs to be copied to other devices, the holographic image inside the mail can be copied by connecting to other devices through the USB data interface.

[0074] Optionally, the data processing unit 11 is deployed locally or remotely.

[0075] Specifically, in the present application, the data processing unit 11 can be implemented in a local deployment or remote deployment manner. If it is a local deployment, the data processing unit 11 is an industrial control host or a miniaturized computer host, which directly implements holographic image processing and result display locally. If it is a remote deployment, the data processing unit 11 is a wireless transmission module, which transmits electrical signals to a remote computer to complete algorithm processing, and receives the results sent back by the computer for display.

[0076] Optionally, refer to Figure 1 , the weight of the mail security inspection device 100 is less than 3 kg. Figure 1 When the mail security inspection device 100 is too heavy, it is not convenient to perform hand-held operation. Therefore, in this embodiment, the weight of the mail security inspection device 100 is set to be less than 3 kg. In this way, hand-held operation can be achieved, which is convenient for security inspectors to hold the device for mail security inspection.

[0077] Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of one embodiment, and the modules or processes in the accompanying drawings are not necessarily required to implement the present application.

[0078] Those skilled in the art can understand that the modules in the system in the embodiment can be distributed in the system of the embodiment according to the description of the embodiment, or can be changed accordingly and located in one or more systems different from the embodiment. The modules in the above embodiment can be combined into one module, or can be further divided into multiple sub-modules.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A handheld mail security inspection device based on reflective terahertz holographic imaging, characterized in that: include: A main body module, wherein the main body module is a hexahedral structure with a hollow interior; A terahertz emission source is arranged inside the main module and is used to emit terahertz waves of a specific frequency; A terahertz beam splitter is arranged inside the main module and located on the terahertz wave emission path of the terahertz emission source, and is used to split the terahertz beam emitted by the terahertz emission source into a reference beam and a detection beam; A terahertz emission window, fixed on the first surface of the main module, for transmitting the detection beam; A terahertz receiving window, fixed on the first surface, for transmitting scattered echoes formed by reflection of mail; A terahertz camera is arranged inside the main module, and is used to converge the reference beam and the scattered echo, so that the reference beam and the scattered echo interfere with each other to form holographic interference fringes carrying the imaging information of the mail; and is also used to convert the holographic interference fringes into electrical signals and then transmit them; A data processing unit, used for receiving the electrical signal and processing the electrical signal to generate a holographic image inside the mail; A handle structure, fixed to a second surface of the main body module, wherein the second surface is adjacent to the first surface; A switch trigger button is arranged on the handle structure and is used to control the switch of the mail security inspection device.

2. The handheld mail security inspection device based on reflective terahertz holographic imaging according to claim 1 is characterized in that: Also includes: A display screen is fixed on the third surface of the main module, and the first surface and the third surface are arranged opposite to each other; The display screen is used to display the holographic image inside the mail.

3. The handheld mail security inspection device based on reflective terahertz holographic imaging according to claim 1 is characterized in that: The handle structure is a rectangular parallelepiped or cylindrical structure made of metal material, and the length of the handle structure is 10-20 cm.

4. The handheld mail security inspection device based on reflective terahertz holographic imaging according to claim 3 is characterized in that: It also includes a base, which is fixedly connected to the handle structure and is located at one end of the handle structure away from the main body module.

5. The handheld mail security inspection device based on reflective terahertz holographic imaging according to claim 4 is characterized in that: Also included is a data storage unit; The data storage unit is located in the base and is used for storing the holographic image inside the mail.

6. The handheld mail security inspection device based on reflective terahertz holographic imaging according to claim 4 is characterized in that: Also includes a USB data interface; The USB data interface is located on the base and is used to copy the holographic image inside the mail.

7. The handheld mail security inspection device based on reflective terahertz holographic imaging according to claim 1 is characterized in that: The data processing unit is deployed locally or remotely.

8. The handheld mail security inspection device based on reflective terahertz holographic imaging according to claim 1 is characterized in that: The terahertz beam splitter includes a high-resistance floating region of silicon.

9. The handheld mail security inspection device based on reflective terahertz holographic imaging according to claim 1 is characterized in that: The terahertz emission window and the terahertz receiving window are made of terahertz high-transmittance materials.

10. The handheld mail security inspection device based on reflective terahertz holographic imaging according to claim 1, characterized in that: The weight of the mail security inspection device is less than 3kg.

Images