No place to hide [millimeter wave imaging]

This paper discusses the potential of using millimeter-wave and terahertz (THz) radiation to provide a safe, non-ionizing solution to the problem of screening travellers passing through airports and crossing national boarders. These imaging technologies are capable of detecting hidden objects under clothes no matter what material they are made from. The paper describes the considerable progress made in the last few years and the efforts of several companies to develop prototype scanners in both the millimeter wave and THz regions of the spectrum.