NJIT physicist sees terahertz imaging as ultimate defense against terrorism

John Federici, a physics professor at NJIT, sees the use of terahertz rays as a critical technology in the defense against suicide bombers and other terrorist activities. Federici and his research team recently described experimental results from a digital video camera invented in their laboratory that uses a terahertz imaging system. One day such a device could be used to scan airport passengers quickly and efficiently.

"Video-Rate terahertz Interferometric and Imaging" appeared in Applied Optics (July, 2009).

The article examined experimental results from a video-rate device. The device uses terahertz (THz) rays that emit a continuous narrow bandwidth radiation of 0.1 (THz). The instrument creates a two-dimensional image of a point in an object. The image is reconstructed at a rate of 16 milliseconds per frame with a four-element detector array. The number of detectors, the configuration of the detection array and how well the baselines are calibrated affects the image resolution and quality.

"Scientists favor terahertz radiation because it can transmit through most non-metallic and non-polar mediums," said Federici. "When a terahertz system is used correctly, people can see through concealing barriers such as packaging, corrugated cardboard, walls, clothing, shoes, book bags, pill coatings, etc. in order to probe for concealed or falsified materials."

Once the rays penetrate those materials, they can also characterize what might be hidden-be they explosives, chemical agents or more—based on a spectral fingerprint the rays will sense which can identify the material. terahertz radiation also poses minimal or no health risk to either the person being scanned or the THz system operator.

At this time, instruments using terahertz imaging are widely used in laboratories and have shown some limited use in commercial applications. However, a THz for security screening of people has not yet reached the market. Researchers say that such a system is at least five years away. The NJIT device, however, has great promise. According to Federici, THz imaging systems have an inherent advantage over millimeter wave imaging systems due to the intrinsically improved spatial resolution that one can achieve with the shorter wavelength THz systems (typically 300 micrometer wavelength) compared to longer wavelength millimeter wave systems. However, video-rate THz imaging systems are not as well advanced as their millimeter wave counterparts.

One technical limitation in developing video-rate THz imaging is the cost of THz hardware components including detectors. Consequently, THz imaging systems create images using a very small number of detectors in contrast to the million or more detectors that are used in digital cameras. According to Federici, one can use advanced imaging techniques, such as synthetic aperture imaging methods, to compensate for the relatively few number of THz detectors in an imaging system.

"The idea has been to apply different methods of imaging with radio waves, where many of the ideas for synthetic aperture imaging originated, to terahertz rays," said Federici. His research team has focused in particular on applications of synthetic aperture imaging to the terahertz range. "The advantage of this particular method is the ability to generate terahertz images with a large number of pixels using a limited number of terahertz detectors. This imaging method should also be capable of video-rate imaging, thereby enabling the real-time monitoring of people hiding concealed explosives or other dangers." A typical imaging system would be analogous to a still or video camera designed for this purpose.

In 2005, Federici and his research team received a U.S. patent for a terahertz imaging system and method that enables video-rate THz imaging with a limited number of detectors. Since 1995, terahertz imaging has grown in importance as new and sophisticated devices and equipment have empowered scientists to understand its potential. The U.S. Department of Homeland Security, the Army Research Office, Department of Defense, and the National Science Foundation support Federici's work.

While researchers have focused on the potential applications of terahertz rays for directly detecting and imaging concealed weapons and explosives, they say another application is the remote detection of chemical and biological agents in the atmosphere.

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Apr 12, 2010
I went to a few talks on THz at a recent conference. One interesting point the speakers indicated was that the price of THz emitters and detectors are dropping - so new applications are opening all the time.

This article is about security applications of the technology and implied the chemical analysis application.

Another interesting application is in the field of art - analysis of old art for restoration (THz is non destruction and has been applied for determining composition of media) as well as discovering techniques and artwork hidden behind existing art (in the old days canvas were expensive so many artists would paint over their own and other artists' work). Nice thing is that pigments such as lead are transparent to T-Hz so this method is a complement to X-ray imaging.

Right now in a church in Italy there is a wall with a master's painting on it.
But the wall is suspected to cover another (perhaps greater) work, and they are looking to THz to find out what is there.

Apr 12, 2010
Terrorists can still transfer lotta stuff inside of body cavities, which terahertz waves cannot penetrate. They can wear reflective underwear and straps, too.

Apr 14, 2010
If you are wearing specially constructed, THz image shielding underwear, you should be arrested.

Apr 16, 2010
The best bet is to get rid of the corporate rule that makes and creates the 'terry-wrists' in the first place.

The game is a little known Latin phrase of 'Casus Belli', which is the idea of a 'self created' lie to use and be thrust upon the public as an excuse for running a war and scaring people into believing what the hidden hand of control -says.

Hitler knew and used the aspect of exciting people's emotions to rally them to the direction he desired. What we see these days is that exact level of manipulation, on a global scale. He knew it mattered not what logic or truth was presented to them, if it was mythical and emotional, they would believe that aspect wholly instead, and enough belief that they could then run whatever program they wanted upon and with the public.

Scanning people in airports for non-existent bombs under the guise of saving you from fearful things, is simply more of the same.

For all the fear generated -death on the highway is 1000 times more likely.

Apr 16, 2010
He knew it mattered not what logic or truth was presented to them, if it was mythical and emotional, they would believe that aspect wholly instead, and enough belief that they could then run whatever program they wanted upon and with the public.

He also knew that he could draw on thousands of years of indoctrination against semites provided courtesy of the Christian faith. Hence why he utilized the phrase "Christian Nation" in a majority of his speeches.

Apr 20, 2010
The title of this article is misleading. The ultimate defense against terrorism is barbaric punishment (televised death penalties, threat and consummate act of tactical nuclear strikes). I didn't say it was pretty or nice, but certainly more effective than waiting for them to get over here with a bomb to roll the dice and try to detect it.

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