Approaches to millimeter-wave imaging of humans

Increasing demands for screening personnel for concealed objects lead to additional research efforts related to suitable imaging systems and their industrial realization. In this context millimeter-wave systems are a promising approach, because the radiation does not present a health hazard to people under surveillance and readily passes through many optically opaque materials such as clothing fabrics. A survey of existing and proposed systems as well as an assessment of potential methods is presented. The results of basic experiments applied to a mannequin carrying concealed objects using a lens for local focusing are given. The results of this method, which is not suitable for real-time imaging, allow to assess the system's imaging properties, which will be further developed to fulfill the data acquisition and processing time requirements for security checkpoints. The various applicable approaches to efficient imaging configurations allowing for fast data acquisition are compared.