Study on detection and identification model of passive Terahertz imaging system for extended target

Detection and identification performance prediction is an important part in designing the passive terahertz imaging system. This paper presents a novel detection and identification model of passive terahertz imaging system for concealed extended target. In the modeling process we take into account main factors such as radiation principle of target and background, the characteristics of atmospheric transmission, and imaging detecting system. Firstly we research interaction principle of terahertz radiation for object based radiation principle of low temperatures terahertz blackbody. We calculate target and background terahertz radiation power. So target-to-background contrast is described in different fields and ranges. Secondly, we research the effect of terahertz beam attenuation in atmospheric environment, and choose the best terahertz atmospheric absorption frequency. So we can account target radiation power in the surface of detector. Lastly we research passive terahertz imaging detecting method for improving THz radiometric resolution. Due to testing target is extended, the two dimensional real-time scanning method is adopted. So we account identification probability of passive terahertz imaging system in different distance. The paper shows results in different distances and is useful to design and evaluate the passive terahertz imaging system for concealed object detection and identification.