Passive Millimeter Wave Imaging
Millimeter Waves (mmW) are the radiation band from 10 millimeters to one millimeter. As radio waves are considered low band frequency, millimeter waves are designated as very high frequency. Regardless of the frequency of the radiation, just like light, radio waves and millimeter waves are all around us in the atmosphere. The use of this "passive" or "always there" radiation for imaging is a method that has been incorporated into high technology equipment. AEI was involved in the development of two passive millimeter wave imagers for detecting explosive devices hidden on people. The advantages of this method of imaging is obvious. First, the person is not exposed to any radiation that is not already all around them so there is no concern that the device is harmful (like the x-ray machine). Further, the length of the millimeter wave is large, so there is no possibility of invading personal privacy.
AEI was contracted to develop both a hand held mmW device and a "whole body" imaging system. Both were developed within a very short (6 month) product development cycle and the resulting first generation systems were introduced at a security trade shows. AEI was subsequently involved in initial product commercialization improvements.
The hand held imager detects millimeter waves as the unit is passed from head to toe. Just like a person emits infrared radiation and can be seen at night with infrared goggles, the same person emits more millimeter waves than guns or other explosive devices. The whole body scanner technology is similar to the hand held with the exception that an operator is not required. These systems hold future the promise of protecting our personal right to privacy while allowing the detection of dangerous devices.