Early Warning Chemical Sensing

The nation faces a growing concern that terrorists or state actors will resort to the use of chemical or biological warfare agents against military or civilian targets. The primary defensive action available for this threat is to detect the deadly agents before they contact their intended victims. Given advance warning, people can evacuate a contaminated area, administer prophylactic medication, or don protective equipment. Moreover, timely awareness of an attack will make it more likely that victims who are exposed will receive appropriate treatment. Chemical agents may be delivered either as a vapor or aerosol or in combination, depending on their physical properties, and various agents will have different persistence following an attack. Military countermeasures may be developed for fixed sites or to be deployed during tactical operations. Normally, tactical deployment implies protecting a moving force, which has proven to be more difficult than protecting a fixed site. Attacks may be either overt, using chemical munitions, or covert, using a variety of improvised methods. Attacks may also be either exterior or interior, with exterior attacks classified as either on target or off target (localized or from a point upwind). When the chemical target is a military installation or other outdoor target, a variety of atmospheric and other relevant considerations also come into play, including the type of location (urban, rural, desert, or maritime), time of year, and local topography. Chemical sensors can be categorized as either " point, " meaning that they sense local conditions, or " standoff, " meaning that they sense threats at a distance. While point sensors have been demonstrated to have very high sensitivities , they have a significant drawback: protection over a wide area requires deployment of a large number of The threat of chemical weapon attacks has prompted the defense community's development of standoff chemical sensors, designed to provide advance warning of an attack from a distance. Lincoln Laboratory has assessed the mission requirements for two relevant applications—wide-area chemical surveillance and inexpensive fixed-site protection—and developed sensor concepts optimized for each mission. EARLY WARNING CHEMICAL SENSING individual sensors. Standoff systems make it more practical to monitor a wide area with fewer sensors and make it possible to detect chemical releases from remote locations such as aircraft. Lincoln Laboratory has developed two long-wave infrared (LWIR) standoff chemical-sensor concepts, optimized for two particular missions: one for wide-area chemical surveillance, the other for inexpensive protection of fixed sites—particularly civilian …