3D Non-Line-of-Sight Terahertz Imaging Using Mirror Folding

We experimentally verify a reconstruction method for terahertz (THz) non-line-of-sight (NLoS) 3D imaging. In the THz band, common building surfaces exhibit both diffuse scattering and strong specular reflections. These properties can be combined to distinguish between line-of-sight (LoS) and NLoS objects. However, the multi-reflection propagation of THz waves in a typical scene can clutter the image with ghost objects, thus the raw image obtained from a THz imaging system lacks an accurate representation of the scene geometry. With the proposed mirror folding method, we exploit the multipath propagation to 1) correct the image from cluttering and 2) see around occlusions. To further validate the feasibility of THz NLoS imaging, we carried out an around-the-corner imaging experiment in the 270–300 GHz band achieving centimeter-scale resolution.