Surrounded by a crowd of people, some friendly and some hostile, a soldier in Iraq has no way to determine which individuals are carrying concealed weapons short of frisking or X-raying everyone in sight. Engineer Rick Blum and a group of colleagues at Lehigh University in Pennsylvania are working on a better option. Their "image fusion" system, funded by the U. S. Army Research Office, uses software to combine a digital snapshot of a scene with an image of the same area taken by a millimeter-wave camera. The millimeter-wave camera, an experimental device that detects rays longer than infrared, highlights differences in the way substances give off heat. Metal objects emit heat poorly and reflect millimeter waves well, so weapons stand out in the composite image, even if hidden under clothing.
The hard part is building an affordable device that quickly delivers a high-resolution composite image. Although Blum's tests show the fusion technique works in laboratory settings, the dishwasher-size prototype millimeter-wave camerabeing developed by Bernard Clarke and his team at Rome Labs in Rome, New Yorkis far from field-ready. The main issues are image quality and cost. Clarke estimates the current version of the camera costs more than $100,000, and its resolution is still quite grainy, which complicates making a positive ID. Nevertheless, Blum reports that several companies are interested in manufacturing image-fusion devices, potentially making them cheap enough for police use.