基于曲柄摇杆机构的被动太赫兹波成像系统

Passive THz Imaging System Based on the Crank-Rocker Mechanism

针对传统单通道被动太赫兹波成像系统的效率低、结构复杂的缺点,设计了一种基于曲柄摇杆机构的光机扫描太赫兹波成像系统。使用曲柄摇杆机构对行扫描镜实现快速驱动,同时配合场反射镜的运动完成对成像目标的二维扫描。通过使用390mm口径的卡塞格林天线以及94GHz太赫兹波辐射计完成对目标的快速成像。实验表明,系统单帧成像时间为20s,成像视场角为30°×36°,角分辨率可达0.6°。在室内条件下,可以很好地对人体进行成像,并能有效地探测隐藏在衣物下的危险物品。该系统具有成本低、效率高、结构简单等特点,对实现被动太赫兹成像系统的小型化、快速化有较高的参考价值。

In order to solve the problem of low efficiency and high complexity in traditional single channel passive THz imaging system, a novel passive terahentz （THz） imaging system with single channel and optical-mechanical scanning is designed. A crank-rocker mechanism is employed to realize the fact movement of the line scanning mirror, and the two-dimensional imaging is achieved through the cooperation of the line scanning mirror and the frame scanning mirror. A Cassegrain antenna of 390 mm in diameter and 94 GHz Schottky diodes are used in this system to help to accomplish the fast scanning imaging of the objects. The single frame imaging time of the system is only 20 s, the field of view （FOV） is 30°×36°, and the angular resolution is up to 0.6°. The experimental results show that the system can image the human body, and effectively detect dangerous items concealed under the clothes. The system of fast scanning has many advantages such as low cost, high efficiency and simple structure, and provides a useful reference for the development of passive THz imager in miniaturization and high-speed.