Prof. Federici's Web Page

Short  Cuts  

THz Reflection Spectroscopy of Composition C-4 and its detection through interferometric imaging

 Amartya Sengupta¹, Aparajita Bandyopadhyay¹, Robert B Barat², Dale E Gary¹ and John F Federici¹

¹Department of Physics, New Jersey Institute of Technology, Newark, NJ 07103

²Otto York Center for Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07103

 Previous reports using THz transmission spectroscopy and FTIR spectroscopy have suggested that C-4 explosives (~90% RDX mixed with plastic composites) have an intrinsic absorption peak around 0.8 THz using which efforts have been made to predict the reflection spectra of C-4 in THz frequencies. However, in applications like security screening and non-invasive inspection, reflection geometry plays a major role and the lack of any experimental work on the same limits the scope of such applications. In this study we report a direct measurement of reflection spectra of composition C-4 using THz time domain spectroscopic techniques. The experimental spectra are diffuse in nature as the surface of the sample was not optically flat in THz frequencies and a contrast of around 8% was observed between the neighboring frequencies of 0.7 THz and 0.9 THz. The spectral data have been used to create realistic synthetic images for use in simulations of interferometric detection in a stand-off THz imaging system. The results of the same show the effective contrast needed for positive classification of lethal agents using an interferometric array of few detectors in near field mode.