University of St Andrews

The ability to detect person-borne concealed threats is an ongoing and pressing requirement in many scenarios such as border crossings, airports and military checkpoints. Submillimetre wave imaging is a promising modality for such future security screening applications as it offers the ability to see through clothing with high spatial resolution using systems of a practical size. It is possibly the only solution to concealed object detection at stand-off distances of many to tens of metres where diffraction limited resolution is achievable with a reasonably sized antenna. Passive imagers detect radiometric brightness temperature which reveals concealed objects through temperature differences caused by differences in physical temperature and/or emissivity. Active imagers use radar measurements to make 3D maps plus reflectivity and polarisation images of the subject which can be used to distinguish concealed objects. It is the latter approach which is the subject of this colloquium. Since the first demonstration of concealed object detection using submillimetre wave imaging radar by JPL in 2007 many groups including ours have sought to develop a practical solution. The goal is to image a 3D volume big enough to encompass a person with ~cm3 voxel resolution to reveal small objects and do so at a frame rate of at least 10 Hz to cope with subject movement. I will review the work done in the Millimetre Wave & EPR Group to tackle this challenge under projects funded by the MoD and UK Home Office for stand-off detection, and under the EU FP7 CONSORTIS project for next generation, walk-by aviation security.