Real-time high-resolution terahertz imaging for concealed object detection

Terahertz (THz) radiation can penetrate most non-metallic and non-polar materials without causing damage to biological tissues, making THz imaging a promising technique for applications in security screening, biomedical diagnostics, and concealed object detection. In this study, we present a real-time THz transmission imaging system. Using this system, we conducted imaging experiments on English letters concealed within multiple layers of paper, as well as pharmaceutical pills hidden inside an envelope. The results show that the system can effectively penetrate five layers of paper and a double-layer envelope, clearly revealing the hidden letters "THZ" and the concealed pills. Moreover, by optimizing the alignment between the sample and the imaging system, we achieved transmission imaging of centimeter-scale samples within milliseconds, significantly reducing acquisition time and enabling real-time imaging of large-area samples.