Passive millimetre wave imaging is now an established and accepted technology that is finding viable commercial
applications in many areas, particularly security and border control. The upper frequency of operation has largely been
governed by the availability of solid state uncooled detectors to around 100GHz. Passive operation at higher
frequencies potentially offers some unique features such as higher optical resolution for a given system size, increased
depth of focus and improved scene contrast. However, the technological challenges involved in realising arrays of
terahertz detectors with the required sensitivity, packing density, repeatability and reliability are considerable.
Nevertheless we have developed such detector arrays and these now provide the core technology base upon which to
explore many new commercial applications that require such benefits.
The first commercial application for this technology has been in the realisation of a compact passive real time imaging
system primarily aimed at the detection of concealed contraband and firearms at a remote distance. This paper describes
such an imager.
Some of the practical advantages of imagery at these wavelengths, such as the ability to operate un-illuminated either
outdoors or indoors, will be described as well as some of the practical system aspects such as bandwidth, scanning
methodology and optical design.
Examples of typical real time imagery is provided.