Although the tiny downward-peering video cameras seen in public buildings and spaces may be amassing volumes of visual data about the people passing beneath them, most do not speedily detect and identify potential threats to public safety. In response to today's heightened sensitivity to threats, technologists are extending the reach of imaging security systems to more fully exploit the electromagnetic spectrum. For those in the field of optoelectronics, this is a boon. Investigative imaging is under intense development and will be for some time to come.
The approaches described in this special report vary widely, as they should. In the first article, Art Stout presents an improvement to an existing type of imaging system (in this case, a laser illuminator for infrared surveillance systems). Intelligently engineered improvements will be the approach many technical groups will pursue, delivering immediate and useful results. In the second article, Paul Reep introduces a type of image processing that combines two disparate techniques—visual imaging and magnetic detection—to provide effective screening of passengers at airports. Benefiting from powerful computers and innovative software, combinations of optoelectronics with other technologies will result in ever-more-comprehensive ways to uncover threats.
A third approach is to push the electromagnetic envelope. The relatively new field of terahertz imaging is flourishing, thanks to the increasing need to leave nothing covered. These longer wavelengths can pass through packages and clothing, revealing what is underneath. In the third article, contributing editor Kathy Kincade gives an overview of this field, outlining both the most recent research and the path to its commercialization. And in the last article, Igor Minin and Oleg Minin explain how optical techniques can be extended all the way into the millimeter-wave (subterahertz) region; they highlight Russian research in this area and present very practical results relating to the detection of concealed weapons.