Portable terahertz real-time imaging system based on terahertz camera

Abstract

The invention relates to the technical field of terahertz camera real-time imaging, and discloses a terahertz camera-based portable terahertz real-time imaging system, which comprises an optical part, a circuit part and a control part, the optical portion includes a terahertz photoconductive antenna for emitting pulsed terahertz radiation. Through the arrangement of the optical part, the circuit part and the control part, a complete and stable imaging system can be formed, and through the arrangement of the terahertz photoconductive antenna and the TPX lens group in the optical part, the purpose of greatly reducing the loss of terahertz radiation in the transmission process can be achieved; and optical images can be orderly presented on the sensor array of the terahertz camera through the terahertz lens, so that the purpose of better imaging effect is achieved, and the whole terahertz imaging technology has the effects of low cost and portability along with the arrangement of the circuit part and the control part.

Description

Technical Field

[0001] The present invention relates to the technical field related to terahertz camera real-time imaging, and in particular to a portable terahertz real-time imaging system based on a terahertz camera. Background Art

[0002] The wavelength range of terahertz waves is between infrared and microwaves, and can penetrate materials such as rubber, paper and clothing. It is an ideal wavelength for biomedicine, material testing and security inspection. Among them, terahertz imaging is one of the most important forms of terahertz technology application. Emerging terahertz imaging technology often relies on terahertz cameras. Terahertz cameras are a type of terahertz radiation power sensor array that can detect the field intensity distribution of terahertz waves in space. With the corresponding terahertz lens, terahertz imaging can be achieved. However, existing terahertz imaging technology relies on high-power terahertz radiation sources, such as terahertz cascade lasers (THz-QCL) and carbon dioxide terahertz lasers. These light sources are often large in size and weight, expensive, and rely on laboratory environments, which is not conducive to the popularization of terahertz imaging.

[0003] The existing terahertz imaging systems are mainly divided into pulsed terahertz time-domain imaging systems and continuous terahertz imaging systems. The time-domain pulsed terahertz imaging system usually adopts a combination of large nonlinear crystals and high-power femtosecond lasers. The disadvantages of this system are high cost and complex optical path. The system is too large and highly dependent on the laboratory environment, so it is very inconvenient to build, debug and move. There is also an active or passive terahertz imaging system based on a terahertz camera, but this system does not have time resolution. In order to solve this problem, a portable terahertz real-time imaging system based on a terahertz camera is proposed. Summary of the invention

[0004] The present invention provides a portable terahertz real-time imaging system based on a terahertz camera, which solves the problems in the above-mentioned background technology.

[0005] The present invention solves the technical problem by adopting the following technical solutions:

[0006] A portable terahertz real-time imaging system based on a terahertz camera, comprising an optical part, a circuit part and a control part;

[0007] The optical part includes a terahertz photoconductive antenna for emitting pulsed terahertz radiation, and the terahertz radiation will pass through the sample and be modulated by the spatial image information of the sample. A terahertz lens for forming an image and adjusting the focal length is provided on the opposite side of the terahertz photoconductive antenna, and a TPX lens group for collimating the terahertz beam is provided between the terahertz photoconductive antenna and the terahertz lens. The focal length and size selection of the TPX lens group determine the numerical aperture of the imaging system. The terahertz lens presents the terahertz optical image of the sample on the sensor array of the terahertz camera to form a terahertz imaging.

[0008] The circuit part includes a power supply system for powering the terahertz camera and a bias power supply for powering the terahertz photoconductive antenna;

[0009] The control part includes software for cooperatively controlling the laser and the terahertz transmitter for the bias power supply of the photoconductive antenna and software for real-time acquisition of terahertz camera imaging.

[0010] Preferably, the optical part further comprises a femtosecond fiber laser for exciting the terahertz photoconductive antenna.

[0011] Preferably, the power supply system is a universal 5V1A DC power supply module, which is connected to the computer by a micro-usb to USB type-A data cable that takes into account both power supply and data transmission, and is powered by the computer's serial port power supply.

[0012] Preferably, the focal length and size selection of the TPX lens group determines the numerical aperture of the imaging system. The larger the numerical aperture, the better the imaging quality of the image focal plane, but the larger numerical aperture will also cause the depth of the image focal plane along the Z axis to be shallower.

[0013] The advantages and positive effects of the present invention are: a complete and stable imaging system can be formed by arranging the optical part, the circuit part and the control part, and the terahertz photoconductive antenna and the TPX lens group in the optical part can greatly reduce the loss of terahertz radiation in the transmission process, and the optical image can be orderly presented on the sensor array of the terahertz camera through the terahertz lens, so as to achieve the purpose of better imaging effect, and with the arrangement of the circuit part and the control part, the entire terahertz imaging technology presents the effect of low cost and portability. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0015] Figure 1 Schematic diagram of the structure of the single-lens imaging system of the present invention;

[0016] Figure 2 It is a schematic structural diagram of a dual-lens imaging system of the present invention;

[0017] The symbols in the accompanying drawings are described as follows:

[0018] 1. Terahertz camera;

[0019] 2. Terahertz lens;

[0020] 3. TPX lens group;

[0021] 4. Terahertz photoconductive antenna;

[0022] 5. Computer;

[0023] 6. Bias power supply;

[0024] 7. Femtosecond fiber laser;

[0025] 8. Data cable;

[0026] 9. Fiber optic cable. DETAILED DESCRIPTION

[0027] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0028] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings:

[0029] Reference Figure 1 and Figure 2As shown in the figure, the wavelength range of terahertz waves is between infrared and microwaves, and it can penetrate materials such as rubber, paper and clothes. It is an ideal wavelength for biomedicine, material testing and security inspection. Among them, terahertz imaging is one of the most important forms of terahertz technology application. The emerging terahertz imaging technology often relies on terahertz cameras 1. The terahertz camera 1 is a terahertz radiation power sensor array that can detect the field intensity distribution of spatial terahertz waves. With the corresponding terahertz lens 2, terahertz imaging can be achieved. However, the existing terahertz imaging technology relies on high-power terahertz radiation sources, such as terahertz cascade lasers (THz-QCL) and carbon dioxide terahertz lasers. These light sources are often large in size and weight, and are expensive. Expensive and dependent on laboratory environment, which is not conducive to the popularization of terahertz imaging. The existing terahertz imaging systems are mainly divided into pulsed terahertz time-domain imaging systems and continuous terahertz imaging systems. Among them, the time-domain pulsed terahertz imaging system usually adopts a combination of large nonlinear crystals and high-power femtosecond lasers. The disadvantages of this system are high cost and complex optical path. The system is too large and highly dependent on the laboratory environment, so it is very inconvenient to build, debug and move; there is also an active or passive terahertz imaging system based on the terahertz camera 1, but this system does not have time resolution. In order to solve this kind of problem, a portable terahertz real-time imaging system based on the terahertz camera 1 is proposed, including an optical part, a circuit part and a control part;

[0030] The optical part includes a terahertz photoconductive antenna 4 for emitting pulsed terahertz radiation, and the terahertz radiation will pass through the sample and be modulated by the spatial image information of the sample. A terahertz lens 2 for forming an image and adjusting the focal length is provided on the opposite side of the terahertz photoconductive antenna 4, and a TPX lens group 3 for collimating the terahertz beam is provided between the terahertz photoconductive antenna 4 and the terahertz lens 2. The focal length and size selection of the TPX lens group 3 determine the numerical aperture of the imaging system. The terahertz lens 2 presents the terahertz optical image of the sample on the sensor array of the terahertz camera 1 to form a terahertz imaging.

[0031] The circuit part includes a power supply system for powering the terahertz camera 1 and a bias power supply 6 for powering the terahertz photoconductive antenna 4;

[0032] The control part includes software for cooperatively controlling the laser and the terahertz transmitter for the bias power supply 6 of the photoconductive antenna, and software for real-time acquisition of the imaging of the terahertz camera 1; a complete and stable imaging system can be formed by the arrangement of the optical part, the circuit part and the control part, and the arrangement of the terahertz photoconductive antenna 4 and the TPX lens group 3 in the optical part can greatly reduce the loss of terahertz radiation during the transmission process, and the optical image can be orderly presented on the sensor array of the terahertz camera 1 through the terahertz lens 2, so as to achieve the purpose of better imaging effect, and with the arrangement of the circuit part and the control part, the entire terahertz imaging technology presents the effect of low cost and portability.

[0033] It should be noted that the focal length and size selection of the above-mentioned TPX lens group 3 determine the numerical aperture of the imaging system. The larger the numerical aperture, the better the imaging quality of the image focal plane. However, a larger numerical aperture will also cause the depth of the image focal plane along the Z-axis direction to be shallower. The selection of this part of the focal length and size is distinguished by single lens and double lens.

[0034] Further, the single lens imaging system is set up with reference to Figure 1 As shown, the sample to be imaged is placed between the TPX lens and the terahertz photoconductive antenna 4, and the femtosecond fiber laser 7 and the bias power supply 6 are turned on. The control software of the terahertz camera 1 is used to perform real-time imaging preview on the computer 5. This imaging method is conducive to imaging a larger imaging area.

[0035] In addition, when using Figure 2 In the 4f imaging system shown in the figure, the sample is placed at the common focal position of two TPX lenses. This imaging method can control the terahertz transmission in a direction perpendicular to the sample, but the sample size is limited by the size of the lens group, and the image acquisition method and Figure 1 The cases shown are identical.

[0036] It should also be noted that the use of the terahertz camera 1 and the terahertz lens 2, as well as the ingenious optical settings, allows the terahertz signal emitted by the PCA to be received by the terahertz camera 1 to the maximum extent, so as to achieve the purpose of high-quality terahertz imaging using a low-power terahertz light source.

[0037] Furthermore, an optical fiber line 9 is provided between the bias power supply 6 and the terahertz photoconductive antenna 4 for connection and transmission.

[0038] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive, and therefore the present invention is not limited to the embodiments described in the specific implementation manners. Any other implementation manners derived by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.

Claims

1. A portable terahertz real-time imaging system based on a terahertz camera, characterized in that: Including optical part, circuit part and control part; The optical part comprises a terahertz photoconductive antenna (4) for emitting pulsed terahertz radiation, and the terahertz radiation will pass through the sample and be modulated by the spatial image information of the sample. A terahertz lens (2) for forming an image and adjusting the focal length is provided on the opposite side of the terahertz photoconductive antenna (4), and a TPX lens group (3) for collimating the terahertz beam is provided between the terahertz photoconductive antenna (4) and the terahertz lens (2). The focal length and size of the TPX lens group (3) determine the numerical aperture of the imaging system. The terahertz lens (2) presents the terahertz optical image of the sample on the sensor array of the terahertz camera (1), forming a terahertz imaging. The circuit part comprises a power supply system for powering the terahertz camera (1) and a bias power supply (6) for powering the terahertz photoconductive antenna (4); The control part includes software for cooperatively controlling the laser and the terahertz transmitting end for the photoconductive antenna bias power supply (6) and software for real-time acquisition of images from the terahertz camera (1).

2. A portable terahertz real-time imaging system based on a terahertz camera according to claim 1, characterized in that: The optical part also includes a femtosecond fiber laser (7) for exciting the terahertz photoconductive antenna (4).

3. A portable terahertz real-time imaging system based on a terahertz camera according to claim 1, characterized in that: The power supply system is a universal 5V1A DC power supply module, which is connected to the computer (5) by a micro-usb to USB type-A data cable (8) that takes into account both power supply and data transmission, and is powered by the serial port power supply of the computer (5).

4. The portable terahertz real-time imaging system based on a terahertz camera according to claim 1, characterized in that: The focal length and size of the TPX lens group (3) determine the numerical aperture of the imaging system. The larger the numerical aperture, the better the imaging quality of the image focal plane. However, the larger the numerical aperture, the shallower the depth of the image focal plane along the Z-axis direction.

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