Passive 350 GHz Video Imaging Systems for Security

Authors: E Heinz T May D Born G Zieger S Anders V Zakosarenko HG Meyer C Schäffel

Publish Date: 2015/06/12

Volume: 36, Issue: 10, Pages: 879-895

PDF Link

Abstract

Passive submillimeterwave imaging is a concept that has been in the focus of interest as a promising technology for personal security screening for a number of years In contradiction to established portalbased millimeterwave scanning techniques it allows for scanning people from a distance in real time with high throughput and without a distinct inspection procedure This opens up new possibilities for scanning which directly address an urgent security need of modern societies protecting crowds and critical infrastructure from the growing threat of individual terror attacks Considering the low radiometric contrast of indoor scenes in the submillimeter range this objective calls for an extremely high detector sensitivity that can only be achieved using cooled detectors Our approach to this task is a series of passive standoff video cameras for the 350 GHz band that represent an evolving concept and a continuous development since 2007 Arrays of superconducting transitionedge sensors TES operated at temperatures below 1 K are used as radiation detectors By this means background limited performance BLIP mode is achieved providing the maximum possible signal to noise ratio At video rates this leads to a temperature resolution well below 1 K The imaging system is completed by reflector optics based on freeform mirrors For object distances of 5–25 m a field of view up to 2 m height and a diffractionlimited spatial resolution in the order of 1–2 cm is provided Optomechanical scanning systems are part of the optical setup and capable of frame rates of up to 25 frames per secondThe authors wish to thank Gerd Hechtfischer and Christian Evers from Rohde Schwarz GmbH Co KG in Munich as well as Karsten Müller from Institut für Konstruktion und Verbundbauweisen e V KVB in Chemnitz for valuable contributions This work has been funded by the German Federal Ministry of Education and Research BMBF under contract number 13N12023 and by the German Federal Ministry of Economic Affairs and Energy BMWI and contract number KF2318502

Keywords: