Contents I. Introduction
The problem of detecting person-borne concealed weapons or contraband from a long distance is very difficult, and no highly effective solution currently exists despite the urgent national security need. Compared to the booth-sized portal-based screening systems now in operation at many airports, a standoff personnel screening technology would have several advantages: At checkpoint approaches, it could provide early warning of a threat, possibly from outside the blast radius of an improvised explosive device (IED). For screening of unstructured crowds, a standoff sensor would add flexibility with its ability to point in any direction from a high vantage point. A long-range IED imager might also be easily concealed or camouflaged for covert surveillance. Its deployment in a given situation also needs to be weighed against obvious privacy concerns.
