Terahertz Imaging System for Concealed Weapon Detection

This Small Business Innovation Research Phase I project is aimed at developing an entirely new terahertz imaging system capable of detecting hidden weapons and explosives on subjects at safe distances. Compact and efficient semiconductor terahertz quantum cascade lasers are currently being developed by several companies (including Spire) and will soon be commercially available. Using these sources as illuminators, a small and portable imaging system utilizing one of several candidate imaging detector configurations is proposed. Terahertz radiation, with wavelengths in the submillimeter spectral region, is non-ionizing and low in energy, avoiding environmental safety issues. Working with the University of Massachusetts Lowell¿s Submillimeter-Wave Technology Laboratory (STL) as a subcontractor, Phase I will investigate candidate imaging detection schemes and carry out calculations of anticipated system sensitivity and laser power requirements, with the goal of defining a technically feasible, portable concealed weapon detection system. The STL group has already demonstrated non-portable terahertz-based hidden weapon detection systems using gas lasers and heterodyne receivers. The proposed design of a portable THz imaging system will utilize THz atmospheric transmission data, and attenuation coefficients of relevant materials. During Phase II, a breadboard imaging system will be fabricated and demonstrated with surrogate hidden weapons and explosives. Anticipated Benefit/Potential Commercial Applications of the Research or Development. Terahertz radiation is absorbed by water-containing and biological materials but relatively transparent in other materials such as paper and clothing. The commercial availability of terahertz imaging systems will have a strong impact on homeland defense, military surveillance, biomedical technology, agricultural inspection, transportation monitoring, analytical instruments, and high-resolution spectroscopy applications. Medical applications include non-ionizing dental diagnostics, DNA identification, chemical agent detection and analysis, and non-invasive monitoring of blood glucose levels in diabetics. Transportation applications include detection-at-a-distance moisture (rain and fog) sensors on highways and rail tracks.