Real-time terahertz imaging of nonmetallic objects for security screening and anti-counterfeiting applications

The article of record as published may be found at http://dx.doi.org/10.1117/12.800632We report the use of a 160×120 pixel microbolometer camera, under illumination by a milliwatt-scale 3.6 THz quantum cascade laser, for real-time imaging of materials which are exclusively nonmetallic in character. By minimizing diffraction effects suffered by the camera system and operating the laser at bias currents approaching saturation values, an imaging scheme was developed in which overlapping samples of nonmetallic materials can be imaged with high fidelity and long persistence times. Furthermore, an examination of various security features embedded within domestic and foreign currency notes suggests that this imaging scheme could serve a future role in detection of assorted counterfeiting practices.Air Force Office of Scientific Research (AFOSR)