340 GHz imaging system for detection of concealed threat objects at 5 meters stand-off distance (Conference Presentation)

A THz active scanned imaging system is developed for detection of concealed threat objects at a stand-off distance of 5 meters. Single pixel, active imaging system utilizes a continuous wave transceiver unit operating at 340 GHz, based on RF components and Schottky diode rectifiers. The transceiver has a heterodyne detection geometry and has 7 mW total power output which is derived from a 3dB directional coupler (25 dB directivity) and a horn antenna. 2D opto-mechanical scanning is performed using two mirror coupled galvanometer scanners to scan 50x50 cm2 field of view at 5 meters stand-off distance. 2 cm resolution is achieved on the target plane. Based on the opto-mechanical scan speed, frame rate is 2 Hz. 340 GHz provides penetration to common barrier objects such as clothing for detection of concealed threats. Here we present imaging capability of the system and its penetration abilities. Effect of barrier objects to the dynamic range is also investigated. To provide real time screening of the target scene for potential threat objects, its visual image is combined with the acquired THz image of the field of view by using image fusion technique