Passive terahertz camera for standoff security screening.

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.

[1]  J. Mather.  Bolometer noise: nonequilibrium theory. , 1982, Applied optics.

[2]  D. Rutledge,et al.  INTEGRATED-CIRCUIT ANTENNAS. , 1983 .

[3]  Dean P. Neikirk,et al.  Air-bridge microbolometer for far-infrared detection , 1984 .

[4]  K. Irwin.  An application of electrothermal feedback for high resolution cryogenic particle detection , 1995 .

[5]  Gabriel M. Rebeiz,et al.  Off-axis properties of silicon and quartz dielectric lens antennas , 1997 .

[6]  Jeffrey C. Lagarias,et al.  Convergence Properties of the Nelder-Mead Simplex Method in Low Dimensions , 1998, SIAM J. Optim..

[7]  Erik L. Kollberg,et al.  Conversion gain and fluctuation noise of phonon-cooled hot-electron bolometers in hot-spot regime , 2000 .

[8]  Arttu Luukanen,et al.  A superconducting antenna-coupled hot-spot microbolometer , 2003 .

[9]  E. Brown,et al.  Millimeter-wave, terahertz, and mid-infrared transmissionthrough common clothing , 2004 .

[10]  Chris Mann,et al.  A compact real time passive terahertz imager , 2006, SPIE Defense + Commercial Sensing.

[11]  H. Sipola,et al.  An Ultra-Low Noise Superconducting Antenna-Coupled Microbolometer With a Room-Temperature Read-Out , 2006, IEEE Microwave and Wireless Components Letters.

[12]  Charles Dietlein,et al.  Phenomenology of Passive Broadband Terahertz Images | NIST , 2006 .

[13]  Panu Helistö,et al.  Low-noise readout of superconducting bolometers based on electrothermal feedback , 2006 .

[14]  Z. Popovic,et al.  Integrated Microbolometer Antenna Characterization from 95-650 GHz , 2007, 2007 IEEE/MTT-S International Microwave Symposium.

[15]  H.B. Wallace,et al.  Standoff Detection of Weapons and Contraband in the 100 GHz to 1 THz Region , 2007, IEEE Transactions on Antennas and Propagation.

[16]  Charles Dietlein,et al.  Spectral decomposition of ultra-wide-band terahertz imagery , 2007, SPIE Defense + Commercial Sensing.

[17]  Charles Dietlein,et al.  Broadband THz aqueous blackbody calibration source , 2007, SPIE Defense + Commercial Sensing.

[18]  Erich N. Grossman,et al.  Passive Euro-American terahertz camera (PEAT-CAM): passive indoor THz imaging at video rates for security applications , 2007, SPIE Defense + Commercial Sensing.

[19]  A. Luukanen,et al.  Performance comparison of Nb and NbN antenna-coupled microbolometers , 2007, SPIE Defense + Commercial Sensing.

[20]  Nitin M. Vaidya,et al.  A novel approach to automatic threat detection in MMW imagery of people scanned in portals , 2008, SPIE Defense + Commercial Sensing.

[21]  A. Luukanen,et al.  Passive THz imaging system for stand-off identification of concealed objects: results from a turn-key 16 pixel imager , 2008, SPIE Defense + Commercial Sensing.

[22]  Torsten May,et al.  Passive stand-off terahertz imaging with 1 hertz frame rate , 2008, SPIE Defense + Commercial Sensing.

[23]  A. Luukanen,et al.  Imaging with modular linear arrays of cryogenic Nb microbolometers , 2008, SPIE Defense + Commercial Sensing.

[24]  Charles Dietlein,et al.  Aqueous blackbody calibration source for millimeter-wave/terahertz metrology. , 2008, Applied optics.

[25]  Mikko Leivo,et al.  Stand-off passive THz imaging at 8-meter stand-off distance: results from a 64-channel real-time imager , 2009, Defense + Commercial Sensing.

[26]  Patrick Lj Valdez,et al.  Active wideband 350GHz imaging system for concealed-weapon detection , 2009, Defense + Commercial Sensing.

[27]  Aleksi Tamminen,et al.  Characterization of antenna-coupled microbolometers for THz-imaging , 2009 .

[28]  M. Leivo,et al.  A passive, real-time, terahertz camera for security screening, using superconducting microbolometers , 2009, 2009 IEEE MTT-S International Microwave Symposium Digest.

[29]  Mikko Leivo,et al.  Real-time passive terahertz imaging system for standoff concealed weapons imaging , 2010, Defense + Commercial Sensing.