Journal ArticleDOI
Passive terahertz camera for standoff security screening
Erich N. Grossman,Charles Dietlein,Juha Ala-Laurinaho,Mikko Leivo,Leif Grönberg,Markus Gronholm,Petteri Lappalainen,Anssi Rautiainen,Aleksi Tamminen,A. Luukanen +9 more
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TLDR
The construction and performance of a passive, real-time terahertz camera based on a modular, 64-element linear array of cryogenic hotspot microbolometers, which detects signals on free-standing bridges of superconducting Nb or NbN at the feeds of broadband planar spiral antennas is described.Abstract:
We describe the construction and performance of a passive, real-time terahertz camera based on a modular, 64-element linear array of cryogenic hotspot microbolometers. A reflective conical scanner sweeps out a 2 m x 4 m (vertical x horizontal) field of view (FOV) at a standoff range of 8 m. The focal plane array is cooled to 4 K in a closed cycle refrigerator, and the signals are detected on free-standing bridges of superconducting Nb or NbN at the feeds of broadband planar spiral antennas. The NETD of the focal-plane array, referred to the target plane and to a frame rate of 5 s(-1), is 1.25 K near the center of the array and 2 K overall.read more
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Journal Article
Bolometer noise: nonequilibrium theory
TL;DR: Basic results on bolometer responsivity, time constant, and thermal properties are presented in a new and convenient form and photon noise in the Rayleigh-Jeans limit is computed with attention to the attenuation of photon correlations in the light beam.
Journal ArticleDOI
Quality control and authentication of packaged integrated circuits using enhanced-spatial-resolution terahertz time-domain spectroscopy and imaging
TL;DR: In this paper, a comprehensive set of techniques for quality control and authentication of packaged integrated circuits (IC) using terahertz (THz) time-domain spectroscopy (TDS) is developed.
Journal ArticleDOI
Terahertz imaging for early screening of diabetic foot syndrome: A proof of concept.
G. G. Hernandez-Cardoso,S. C. Rojas-Landeros,Mariana Alfaro-Gomez,Mariana Alfaro-Gomez,A. I. Hernandez-Serrano,I. Salas-Gutierrez,E. Lemus-Bedolla,A. R. Castillo-Guzman,H. L. Lopez-Lemus,Enrique Castro-Camus +9 more
TL;DR: Terahertz imaging is proposed as a method for the evaluation of deterioration of diabetic foot syndrome and this screening method could aid the prevention and medical treatment of this condition in the future.
Journal ArticleDOI
Mathematical Modeling of THz Point Spread Function and Simulation of THz Imaging Systems
TL;DR: A comprehensive theory for cohesive mathematical modeling and simulation of THz imaging systems and simulated transmission THz images, showing great accuracy in terms of the location of the details and structural similarity are presented.
Journal ArticleDOI
THz Metrology and Instrumentation
Zoya Popovic,Erich N. Grossman +1 more
TL;DR: An overview of measurement techniques used in the THz region of the electromagnetic spectrum, from about 100 GHz to several THz currently available components necessary for THz metrology, such as sources, detectors and passives, are briefly described.
References
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Journal ArticleDOI
Convergence Properties of the Nelder--Mead Simplex Method in Low Dimensions
TL;DR: This paper presents convergence properties of the Nelder--Mead algorithm applied to strictly convex functions in dimensions 1 and 2, and proves convergence to a minimizer for dimension 1, and various limited convergence results for dimension 2.
Journal ArticleDOI
An application of electrothermal feedback for high resolution cryogenic particle detection
TL;DR: In this paper, a superconducting transition edge sensor is proposed, where the temperature of a superconding film is held constant by feeding back to its position on the resistive transition edge.
Journal ArticleDOI
Standoff Detection of Weapons and Contraband in the 100 GHz to 1 THz Region
R. Appleby,H.B. Wallace +1 more
TL;DR: The techniques and technologies currently being investigated to detect weapons and contraband concealed on persons under clothing are reviewed and the basic phenomenology of the atmosphere and materials that must be understood in order to realize such a system are discussed.
Journal Article
Bolometer noise: nonequilibrium theory
TL;DR: Basic results on bolometer responsivity, time constant, and thermal properties are presented in a new and convenient form and photon noise in the Rayleigh-Jeans limit is computed with attention to the attenuation of photon correlations in the light beam.