Single wave beam scanning imaging method of passive THz wave imaging system

Abstract

The invention relates to a fast scanning method based on the passive imaging of a single wave beam THz wave. Aiming at the problems of longer scanning time and overhigh system construction cost in an earlier scanning imaging method of the single beam THz wave, a rocker of a crank and rocker mechanism is adopted to drive a line scanning plane mirror to sway horizontally so as to achieve fast transverse scanning motion, and a field scanning plane mirror swaying vertically in a reciprocating way is utilized to realize longitudinal scanning motion, thereby realizing the two-dimensional scanning imaging over object space. On the premise of construction cost reduction, the invention greatly improves the scanning speed per se and simultaneously amplifies the scanning viewing field. In addition, the invention is not only suitable for the passive type THz wave single wave beam scanning imaging, but also suitable for the active type single wave beam scanning imaging of the THz wave.

Description

technical field [0001] The invention is a novel optical-mechanical scanning method aimed at THz security inspection imaging (imaging of concealed objects in the human body). By using the invention, only one receiver can be used to scan the antenna through a larger field of view scene through mechanical movement so as to obtain image information. Due to the use of this single-channel scanning imaging, the system greatly reduces the cost of imaging under the premise of ensuring the volume, and has a strong market prospect and competitiveness. Background technique [0002] Because THz waves have good penetration and high spatial resolution, THz wave radiometers can be used to image prohibited items (guns, knives, explosives, etc.) hidden under clothing, so as to achieve the purpose of detection and identification . [0003] In recent years, due to the continuous development of THz technology, the following imaging systems have been formed: ①Mechanical scanning imaging: it use...

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Problems solved by technology

[0003] In recent years, due to the continuous development of THz technology, the following imaging systems have been formed: ①Mechanical scanning imaging: it uses mechanical motion to obtain the target characteristics of scenes with a large field of view. For a certain period of time, it is difficult to achieve real-time imaging, but its biggest advantage is that it can realize imaging by scanning with as few receiving channels as possible, so the cost is relatively low, and it has strong market prospects and competitiveness; ② Phased array imaging: it It uses electronic scanning to replace mechanical scanning. The phased array antenna is composed of two-dimensional array units. Each receiving unit is connected to a phase shifter. By controlling the phase and amplitude of the receiving unit, the scanning of the antenna beam in the field of view is realized, but Because it is difficult to design an effective radiation unit and the loss of the feeding system is too large, there are not many applications in the THz band at present; ③ synthetic aperture imaging: mainly use N small antennas with real apertures arranged according to a certain rule, The signal is processed to obtain the effect equivalent to a synthetic large-aperture antenna. The imaging system is too complicated and expensive, and the space required for the interference array is large, so it is not suitable for imaging of hidden objects of the human body; ④ focal plane imaging : It is to arrange multiple receiving units on the focal plane of the focusing antenna, and use the different defocus of each feed source to generate multiple beams with different directions to cover the field of view. However, because the current THz wave device is still very expensive, the imaging There are not many applications of the system

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