Characterization of a terahertz wave scanned imaging system for threat detection at standoff distances

A terahertz active scanned imaging system is developed in order to acquire images of various targets at stand-off distances. The images are analyzed with respect to the experimentally obtained beam profile at the target plane using a commercially available mm-wave/terahertz camera. The active scanning system utilizes a heterodyne, continuous wave transceiver unit operating at 340 GHz and 2-D opto-mechanical scanning of the target plane is performed using two large area mirror coupled galvanometers. 340 GHz working frequency allows standoff imaging with adequate resolution with the help of a suitable optical design. Results given here correspond to the imaging of various objects placed at least 120 cm away from the transceiver, with a 5 × cm2 field of view. Image resolution is about 0.6 cm in the horizontal, 0.3 cm in the vertical direction which was assessed by analyzing the measured beam profiles on the target plane with a commercial mm-wave/terahertz camera.