Characterization of a terahertz wave scanned imaging system for threat detection at standoff distances İ. Ozan Yıldırım 1 · V. Ali Özkan 1 · Fırat İdikut 1 · Taylan Takan 1 · A. Behzat Şahin 2 · Hakan Altan 1 Received: 25 November 2015 / Accepted: 14 June 2016 / Published online: 30 June 2016 © Springer Science+Business Media New York 2016 Abstract 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 9 cm 2 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. Keywords Terahertz radiation · Scanned imaging · Threat detection 1 Introduction Millimeter wave to terahertz region of the spectrum is considered to be promising for imaging and sensing applications in various areas such as material characterization, bio- medicine and security. Due to its non-destructive character and penetration abilities, THz This article is part of the Topical Collection on Advances in the Science of Light. Guest Edited by Jelena Radovanovic, Milutin Stepic, Mikhail Sumetsky, Mauro Pereira and Dragan Indjin. & I ˙ . Ozan Yıldırım ozany@metu.edu.tr 1 Physics Department, Middle East Technical University, 06800 Ankara, Turkey 2 Electronics and Communication Engineering Department, Yildirim Beyazit University, Ankara, Turkey 123 Opt Quant Electron (2016) 48:367 DOI 10.1007/s11082-016-0631-x