39th Int. Conf. on Infrared, Millimeter, and THz Waves
September 14-19, 2014
The University of Arizona, Tucson, AZ
M3/C - 10. Defense and Security Applications
Monday, September 15, 2014 2:00 pm to 3:30 pm
Room: Tucson Room
Chairperson: Lee Mosbacker
2:00 pm 2:00 pm : Terahertz Circuits, Systems, And Imaging Instruments
Presenter: Goutam Chattopadhyay

O VER the past several years, rapid strides has been made in the area of terahertz imaging system developments. Even though multi-pixel video rate terahertz imaging systems similar to optical digital cameras are still not available, it is now possible to have systems which can produce high fidelity imaging scans at close to video rate. Obviously, the design of a specific imaging system depends on the target applications. However, it is becoming apparent that for stand-off imaging application of security purposes, terahertz radar imagers have several advantages [1]. In case of terahertz passive imagers, the main challenge has been to overcome the lack of sufficient contrast of the imaging objects compared to the background due the high atmospheric absorptions at these frequencies [2]. Since radar based imagers mostly use the range information to construct a three-dimensional image of the object, they do not suffer from this low-contrast of the scene. However, all these imagers face the same challenge of imaging objects in a highly cluttered environment. Terahertz imaging systems also have applications in the scientific fields, especially in the space-based instruments. They include potential orbital debris mapping, remote radar spectroscopy imaging on planetary moons, and Doppler radar imaging for planetary sand dynamics and volcanisms. In this article, we will discuss different terahertz imaging applications and provide details of circuits and systems that drive these instrument developments. We have designed a radar system also has the potential to be used in studies of Doppler radar based planetary sand dynamics. Since terahertz radar is highly sensitive to scattering from <100 µm particle sizes present in dust storms, dust devils, dune saltation, planetary sputtering, and explosive volcanic eruptions, by simultaneous measurements of range discrimination and Doppler characteristics through coherent signal generation and processing, it is possible to quantify spatially inhomogeneous sand processes and their dynamics. Using the 675 GHz radar system in our laboratory, we were able to perform range-Doppler detection of sands falling from a vessel, blown in single burst along an inclined tray, and sand blown from a series of dunes created along a specially designed tray.

Author(s):
Goutam Chattopadhyay - Jet Propulsion Laboratory, California Inst. Technology
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2:30 pm 2:30 pm : Identification Of Substances By THz Spectroscopy And Multivariate Analysis
Presenter: Andreas Pohl

The identification of different substances based on terahertz transmittance spectra and multivariate analysis (MVA) is demonstrated. Transmittance spectra are obtained by the use of a Fourier transform infrared spectrometer (FTIR). By means of principal component analysis (PCA) and partial least squares regression (PLS) the spectral data were analyzed in order to discriminate and to identify the substances from each other.

Author(s):
Andreas Pohl - Technische Universit‰t Berlin
Nils Deflmann - Technische Universit‰t Berlin
Katja Dutzi - German Aerospace Center
Heinz-Wilhelm H¸bers - German Aerospace Center / TU Berlin
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2:45 pm 2:45 pm : Terahertz Imaging Spectroscopy - Towards Robust Identification Of Concealed Dangerous Substances
Presenter: Arthur D. van Rheenen

Spectral angle mapping is used to identify materials in Terahertz images. We test the performance of several spectral characteristics derived from the measured spectra. Robustness is studied by investigating the Receiver-Operating-Characteristics.

Author(s):
Arthur D. van Rheenen - Norwegian Defense Research Establishment
Magnus W. Haakestad - Norwegian Defense Research Establishment
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3:00 pm 3:00 pm : A Fast Tracking 60 GHz Radar Using A Frequency Scanning Antenna
Presenter: Alexander Hommes

A FMCW broadband radar system with a center frequency of 60 GHz has been setup and demonstrated by using frequency scanning antennas and low cost hardware components. It was shown, that the chosen approach is well suited for the real time detection of slow and fast moving objects and for mobile use in rough environment.

Author(s):
Alexander Hommes - Fraunhofer Institute for High Frequency Physics and Radar Techiques FHR
Alex Shoykhetbrod - Fraunhofer Institute for High Frequency Physics and Radar Techiques FHR
Nils Pohl - Fraunhofer Institute for High Frequency Physics and Radar Techiques FHR
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3:15 pm 3:15 pm : THz Spectroscopy Of Amines And Aminoacids Intercalated In Clays
Presenter: John Molloy

THz optical constants were measured for layered clay minerals from the smectite group with different chemical compositions (hectorite and montmorillonite) and modified with intercalated alkylamines or amino acids. These were compared with spectra from pure alkylamines and amino acids.

Author(s):
Marian Janek - Slovak University of Technology
Daniel Zich - Comenius University
Mira Naftaly - National Physical Laboratory
John Molloy - National Physical Laboratory
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