Terahertz Interferometric Imaging Systems (THS) for Detection of Weapons and Explosives

We propose to develop a continuous wave terahertz interferometric imaging spectrometer tunable from 0.2 to 3 THz in order to remotely detect concealed explosives and other weapons. The fully realized system will consist of a high brightness THz sourceilluminating the region of interest and detected by a tunable THz interferometric imaging array. The array will consist of a multiple spaced THz semiconductor heterodyne photomixers driven by a common fiber optic coupled frequency stabilized tunableoptical heterodyne source. Phase I demonstrated tunable narrow band THz generation and detection system employing a derivation of our commercial THz photomixing modules. We have collected single element interferograms. The THz spectra of RDX wascollected and the detection properties of N element array was simulated. In Phase II, we will construct and test a multiple element array THz detector, and develop photomixing local oscillator heterodyne. The array will be tuned to demonstratedifferential image detection of spectroscopic signatures. Artificial neural network algorithms will be further developed to recognize explosive image spectra to automatically identify dangerous vs. harmless objects. The designs of rotating and fixedimaging arrays will be evaluated. A database of required THz-frequency spectral signatures for target explosives will be further developed.A successful Phase II will result in a benchtop prototype demonstration of all substantial elements of a compacttunable THz remote detection system for concealed explosives and weapons. No such interferometric imaging THz spectrometer is currently commercially available. The proposed system will be useful not only in defense applications as a stationary perimeterdefense system and outward looking remote surveillance system, but for civilian security applications as well, such as airport screening for explosives, biological agents, and other contraband. In addition, the components designed will have commercialapplications manufacturing, process control, medical, and environmental diagnostics.