Passive Submillimeter-wave Stand-off Video Camera for Security Applications
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Passive Submillimeter-wave Stand-off Video Camera for Security Applications Erik Heinz · Torsten May · Gabriel Zieger · Detlef Born · Solveig Anders · Günter Thorwirth · Viatcheslav Zakosarenko · Marco Schubert · Torsten Krause · Michael Starkloff · André Krüger · Marco Schulz · Frank Bauer · Hans-Georg Meyer Received: 18 May 2010 / Accepted: 14 September 2010 / Published online: 28 September 2010 © Springer Science+Business Media, LLC 2010
Abstract We present the concept and experimental set-up of a passive submillimeter-wave stand-off imaging system for security applications. Our ambition is the design of an application-ready and user-friendly camera providing high sensitivity and high spatial resolution at video frame rates. As an intermediate step towards this goal, the current prototype already achieves a frame rate of 10 frames per second and a spatial resolution below 2 cm at 8 m distance. The camera is the result of a continuous development and a unique concept that yielded first high-resolution passive submillimeter-wave images provided by cryogenic sensors in May et al. (2007). It is based on an array of 20 superconducting transition-edge sensors operated at a temperature of 450 mK, a closed-cycle cooling system, a Cassegrain-type optics with a 50 cm main mirror, and an opto-mechanical scanner. Its outstanding features are the scanning solution allowing for high frame rates and the compact and integrated system design. Keywords THz · Submillimeter-wave · Imaging · Camera · Bolometer · TES
E. Heinz (B) · T. May · D. Born · G. Zieger · S. Anders · G. Thorwirth · V. Zakosarenko · T. Krause · A. Krüger · M. Schulz · F. Bauer · H.-G. Meyer Institute of Photonic Technology, Albert-Einstein-Str. 9, 07745 Jena, Germany e-mail: [email protected] M. Schubert · M. Starkloff Supracon AG, Wildenbruchstr. 15, 07745 Jena, Germany
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J Infrared Milli Terahz Waves (2010) 31:1355–1369
1 Introduction Screening of persons to detect concealed hazardous objects is a common task arising from various security threats to contemporary societies. In the context of recent aircraft attack attempts conventional solutions like metal detectors and manual scanning are no longer regarded as sufficiently secure. Novel fullbody scanning techniques based on x-rays on the other side raise questions of privacy and health issues, thus limiting their acceptance by the public. Other important security requirements like for instance recognizing suicide bombers from a safe distance are not met at all by existing technologies. Utilizing submillimeter-wave (i. e. terahertz) radiation as already suggested long ago [2] may provide an answer to these demands. It is able to penetrate clothing materials [3] while due to the high absorption coefficient of water, the human body resembles a nearly perfect black body in the submillimeter-wave range. This allows for a technique called passive imaging [4] which provides thermal images, that is, yields information on the temperature distribution on the body surface. Against the background of the radi
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