Active millimeter-wave standoff and portal imaging techniques for personnel screening

Active millimeter-wave imaging systems can be configured as personnel screening portals or standoff systems that can operate at ranges of up to 20 meters or more. The Pacific Northwest National Laboratory (PNNL) has developed a variety of active millimeter-wave imaging systems and technologies including the cylindrical imaging technique that has been successfully commercialized with L3-Communications/Safeview, and has continued to advance the cylindrical imaging technology using higher frequency ranges up to 100 GHz, and polarimetric imaging techniques. In addition, a standoff, three-dimensional imaging technique and prototype that operates near 350 GHz has been developed. This prototype system uses focusing optics coupled to a high-speed mirror scanning system and can obtain an image in 10 seconds, which is sufficiently fast to conduct extensive imaging tests on cooperative subjects. In this paper, these advanced imaging techniques are described in detail and numerous experimental imaging results are shown.