Passive stand-off THz imaging using lock-in phase information

A method for directly detecting edges in images which are obtained with a passive stand-off terahertz (THz) imaging system is presented. This novel method can improve the signal-to-noise ratio of THz images as well as it may contribute to solving the privacy problem of body scanners. In addition the proposed method when used with a suitable Spatial Light Modulator (SLM) allows imaging in the lock-in phase space where the trade-off between detection robustness and temperature resolution can be adapted to the situation at hand.