Refocusing a THz reflector imaging system

In this work, the design of a reflector system that can rapidly scan and refocus a terahertz beam for high-resolution standoff imaging applications is presented. The design is based in a Gregorian Confocal geometry and a small mechanical fast rotating mirror is used in order to scan the beam. The system is able to scan the beam over 0.5 m in cross-range at a 8 m standoff distance. The beam refocusing at variable ranges is obtained by shaping the mirror surface in order to compensate the phase aberrations for each target distance. The shaped surface can be achieved by simply replacing the mirror by a curved one or by constructing a flexible surface with the necessary actuators. Geometrical and Physical Optics analysis methods are used to show the refocusing capabilities of the antenna system.