Large area terahertz imaging and non-destructive evaluation applications

Terahertz (THz) imaging is being adopted for non-destructive evaluation (NDE) applications in aerospace and other government and industrial settings([1-3]). NASA is currently employing THz reflection NDE to examine the space shuttle external tank sprayed on foam insulation (SON) for voids and disbonds. Homeland security applications such as the inspection of personnel([2]), the detection of concealed explosives([2]), biological agents, chemical weapons, flammables, metallic and non-metallic weapons, and other potentially dangerous items are the subject of active investigation. Advancement of many of these applications beyond small table top experimentation had been limited by slow imaging speed (tens of minutes or hours), small scan areas (<10 square cm) and in many cases the requirement that the sample itself be mechanically raster scanned. We report the development and applications of a high-speed large-area time domain terahertz non-destructive evaluation imaging system.