Threats to our personal and collective safety abound in our society. The STG conducts and performs research to advance the technology and measurement science of concealed threat and contraband sensing and imaging. This work includes the establishment of test and evaluation tools, reference test beds, test artifacts, and documentary standards through leadership in standardization bodies. The STG currently has detection projects in millimeter-wave imaging, x-ray imaging, infrared imaging, through-barrier radar sensing and imaging, and metal detection.
Millimeter-wave technology for application in security screening and imaging has been an area of intense research over the last few years because of the possibility to confer both acceptable spatial resolution (mm-level) and penetration of clothing and some packaging materials. There are both active and passive designs. The STG in collaboration with NIST Div. 687 has developed a state-of-the-art passive millimeter-wave imaging system based on cryoelectronic sensor arrays. This system will be the basis for the development of NIST’s millimeter-wave imager metrology, including the development of test artifacts, test and evaluation protocols, and international documentary standards.
X-ray imaging is used is used throughout the country by law enforcement officers, at the borders, in the military and in transportation security to detect concealed objects, including threats and contraband. Perhaps the most prevalent use of security and safety imaging is made in aviation security. In US airports alone, millions of bags are scanned every week using x-ray systems. Domestic bomb squads and military explosive ordinance disposal teams also use x-ray imaging as a key tool in their efforts to identify explosive devices and render them safe. The NIST Security Technologies Group conducts research and develops standards and metrological tools to assist these stakeholders as they continue to use x-ray imaging technology for security purposes.
Infrared imaging is a very common safety, security, surveillance, and intelligence-gathering imaging technology. Although the infrared (IR) range is large, from about 700 nm (near IR) to 1 mm (far IR), the STG addresses those IR bands of the greatest importance to the safety and security communities. These bands are the near IR (NIR, about 750 nm to 1.5 μm), typically used for perimeter/site/building security, both indoor and outdoor; and the long-wave IR (LWIR, about 7 μm to 15 μm), typically used in outdoor security applications, long-range surveillance and intelligence gathering, and firefighter applications. NIST is developing the metrology to establish objective test and evaluation protocols for these imagers and, in collaboration with the University of Texas – Austin, possibly developing new objective image quality metrics, and develop methods for correlating these new metrics or traditional image quality metrics to human task performance.
The ability to see through nonmetallic optically opaque barriers, such as walls or rubble, for location and tracking of people and imaging of behind-barrier scenes, can be achieved using radar-based through-barrier detection and imaging systems. Applications and users of through-barrier radar include law enforcement, military, and emergency response. NIST is conducting research in through-barrier radar to advance metrology associated with this technology that will ultimately lead to the development of performance standards. Through collaboration with industry and the user community, NIST is identifying the critical parameters which may be used to quantify the performance of through-barrier radar systems. NIST operates laboratory based through-barrier radar detection and imaging systems to develop test methods and test objects to measure these critical parameters. Additionally, NIST is developing a library of sample walls that are representative of commercial/industrial and residential construction for use in through-barrier radar testing and measurement.
Metal detection is the most common technology used in the detection of metallic threats concealed on people. Metal detection is used at almost all security checkpoints worldwide and includes both the hand-held metal detector and the walk-through metal detector…