Airport security scanner for safer skies
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In the futuristic action film Total Recall, the character played by Arnold Schwarznegger tries to sneak hidden weapons past a security checkpoint only to find that the high-tech detector quickly spots the hardware concealed under his clothing. The movie takes place in 2084, but at Pacific Northwest National Laboratory, researchers already have spent more than 12 years developing a Personal Security Scanner that allows security guards to "see" concealed weapons, including plastic explosives and other nonmetallic threats.
Looking much like a conventional metal detector, the Personal Security Scanner projects ultrahigh frequency, low-powered radio waves onto the front and back of the person being screened. These harmless waves—known as millimeter or centimeter waves because they have wavelengths of about one centimeter—penetrate clothing and bounce off the person and the items he or she may be carrying.
An array sensor captures the reflected waves and sends the information to a high-speed image-processing computer. The computer produces a high-resolution, three-dimensional image from the signals.
Pacific Northwest's expertise in three-dimensional holograph imagery is based on a program established at the Laboratory in the 1970s to develop nondestructive evaluation technologies for nuclear reactors.
As these capabilities are applied in new ways, some new challenges have arisen. "The images show human features, so we are developing processing techniques that we call privacy algorithms," said Doug McMakin, an engineer who helped develop the technology. "We're working toward converting the images into gender-neutral, wire-frame images or silhouettes," he said.
Eventually the system may be fully automated so that it would detect and identify a concealed object and then alert security guards to the threat. At this point, however, the human brain is still needed to interpret the image. "We're exploring different methods to help operators accurately identify risks, and to do so in a way that also addresses privacy concerns," McMakin said.
Over the last few years, McMakin and his colleagues also have focused on reducing the time it takes for the system to scan a person and process the data to avoid bottlenecks at security checkpoints. In recent years they have cut the time down to less than 10 seconds per person.
Federal agencies have funded this research and development since 1985 and in 1989 the Federal Aviation Administration became interested in the technology's potential for screening airline passengers. The Personal Security Scanner could possibly be used at points of entry for mass transit systems; government buildings such as courtrooms, embassies and prisons; and crowded public places such as sports arenas and concert halls. It was originally developed to identify dangerous objects that people might bring into a facility, but it also could protect against theft by identifying concealed items that people might try to sneak out of a museum or nuclear facility.
With continuing changes in security laws and regulations driven by the terrorist attacks on Sept. 11, Pacific Northwest is actively negotiating with several parties to commercialize this technology. Commercialization and licensing efforts may result in the establishment of a locally based product engineering operation using third-party manufacturing to enlarge the FAA's supply chain for security products.