Infrared and millimeter-wave sensors for military special operations and law enforcement applications

We consider the application of infrared and millimeter-wave sensors, developed for the most part during the Cold War, to the solution of problems encountered by military special operations units and law enforcement personnel. These problems include detection of weapons concealed beneath clothing, through-the-wall surveillance, and wide-area surveillance under poor lighting conditions. Key sensors used in these applications are infrared cameras, millimeter-wave passive and active cameras, and millimeter-wave real-aperture and holographic radars. This paper discusses each type of sensor, describes its operation, and gives an example of its output, except in those cases where the device is early in its development phase and thus no outputs are available. All of these sensors form images, but the images are of varying quality. We conclude with a brief discussion of methods of using multiple sensors to improve performance.