Showing posts with label Peter Siegel.. Show all posts
Showing posts with label Peter Siegel.. Show all posts

Monday, January 20, 2014

Plenary Talk-Peter Siegal, "THz Imaging: What You See and What you Don’t"

http://www.radiowirelessweek.org/highlights/plenary-talk/

Abstract

THz technology has developed to the point at which we can now begin to use customized-off-the-shelf components to construct near-real time imagers. However traditional imaging at these wavelengths is extremely challenging. Most materials, and the atmosphere itself, have extremely high loss, limiting transmission measurements. Contrast from scattered energy is generally low, as the frequency and amplitude sensitivity to reflected power from most environmental objects is poor. Thermal contrast is limited by high background temperatures (generally above the energy range of THz signals). However, as advances in solid-state source and receiver technology push ever upwards in frequency, more and more proposals are aimed at using this new found capability for active and passive imaging. It turns out that there are at least a few tricks that one can play to help integrate millimeter and submillimeter wavelength transceivers into traditional imaging applications. One of the first application areas to take advantage is undergarment threat detection.
This talk will discuss current techniques in active THz scanning, both to introduce the phenomenology of what we see reflected off the body, as well as the hidden phenomenology of what THz radiation may be stimulating in the body

Speaker

Dr. Peter SiegelPeter H. Siegel (BA Colgate 1976, PhD Columbia, 1983, IEEE member since 1975) has held appointments as Faculty Associate in Electrical Engineering and Senior Scientist in Biology at Caltech and Senior Research Scientist at the NASA Jet Propulsion Laboratory. At JPL, he founded and led for 25 years, the Submillimeter Wave Advanced Technology (SWAT) team, a group of 20+ scientists and engineers developing THz technology for NASA’s near and long term space missions. This included delivering key components for four major satellite missions and leading more than 75 smaller R&D programs for NASA and the US department of defence. At Caltech, Dr. Siegel has been involved in new biological and medical applications of THz, especially low power effects on neurons and most recently, millimetre-wave monitoring of blood chemistry. Among many other functions, he serves as founding Editor-in-Chief of the IEEE Transactions on Terahertz Science and Technology and the General Secretary of the International Society of Infrared, Millimeter, and Terahertz Waves, the world’s largest society devoted exclusively to THz science and technology, which he founded in 2009. He is also an IEEE Fellow, and has served as an IEEE Distinguished lecturer, vice-chair and chair of IEEE MTTS Committee 4 – THz Technology, and an ad-hoc member of the MTTS AdCom. Dr. Siegel has published more than 300 articles on THz components and technology and has given more than 200 invited talks on this subject throughout his career of 38 years in THz. Web Pages: http://www.thz.caltech.edu/http://www.irmmw-thz.orghttp://www.thz.ieee.org, Email: mailto:phs@caltech.edu

Monday, December 19, 2011

Terahertz Radar “Maps” Targets In Long-Distance Pat-Down




http://www.mwrf.com/Article/ArticleID/23809/23809.html
Due to concerns over privacy, efficiency, and accuracy, security screening at airports and other public places is constantly being improved. At NASA’s Jet Propulsion Laboratory, a 675-GHz imaging radar with the potential to perform such screenings from a distance has been proposed by Ken B. Cooper, Robert J. Dengler, Nuria Llombart, Bertrand Thomas, Goutam Chattopadhyay, and Peter H. Siegel. This radar can conduct rapid “frisk” or “pat-down” types of searches of persons as far away as 25 m via a focused, low-energy terahertz beam.
The team picked the 675-GHz band because it benefits from low atmospheric attenuation. At the same time, it provides sufficiently high spatial resolution for a favorable tradeoff between antenna size and standoff range. To achieve sub-centimeter-range resolution, the radar relies on the frequency-modulated-continuous-wave (FMCW) radar technique in combination with a bandwidth of nearly 30 GHz. To optimize the radar’s range resolution, a software-calibration procedure compensates for signal distortion from radar waveform nonlinearities.
The radar achieves low-noise, high-dynamic-range detection with a combination of a heterodyne RF architecture, low-noise chirp source, and 675-GHz transceiver. With its quasi-optical design, it allows low-distortion, fast beam scanning for single-pixel imaging. The portable laboratory prototype operates in FMCW mode over a 28.8-GHz bandwidth, currently centered at 676.7 GHz. With peak output power below 1 mW, it is well within health safety limits. See “THz Imaging Radar for Standoff Personnel Screening,” IEEE Transactions On Terahertz Science And Technology, Sept. 2011, p. 169.