Combining Commercially Available Active and Passive Sensors Into a Millimeter-Wave Imager for Concealed Weapon Detection

Current imaging technology for concealed weapon detection in the millimeter-wave (mm-wave) and terahertz ranges is traditionally limited to a single type of sensor. In this paper, a system combining active and passive mm-wave sensors along with a depth-sensing camera is presented. These sensors are combined at a hardware stage (being integrated into a single imager) as well as at software level (via simultaneous processing and sensor fusion). The resulting images of the individual sensors are combined via image fusion techniques, using a consumer-grade optical sensor as an image noise-removing tool and highlighting the threat over the subject's body. Each sensor is able to compensate some of the imaging limitations of the others, thus offering better overall detection capabilities. Furthermore, the final imager has been formed by combining commercially available devices, which provides a reduced-cost alternative to custom-made equipment.