Improving the quality of active millimeter wave standoff imaging by incorporating the cross-polarized scattering.

In this paper, we report a polarimetry-based THz imaging technique that highly benefits from backscatter data reflected from PEC hidden objects, considering the edge diffractions of the object as a key point. First, based on physical optic principles, we investigate the cross-polarized reflections of PEC objects in order to show the superiority of reflections of the edges to other parts of the object. Next, we represent the results of a near filed simulation using Feko to study the differences between cross and co-polarized reflections of a PEC object and the human body beneath it. To a further illustration, our experimental results are presented in which we utilized a THz imaging system consisting of a semiconductor-based THz camera and a horn antenna operating at 100 GHz as the source. Cross-polarized backscatter data is analyzed to distinguish PEC objects from the human body. Besides, we used two orthogonal linear polarizations of the source to maximize backscattering from orthogonal edges. Experimental results show a noticeable improvement in edge detection of hidden objects indicating that this method can result in high accuracy in THz real-time imaging.