A revolutionary breakthrough in terahertz remote sensing

Jul 11, 2010
Photo Credit: Rensselaer/Daria Robbins

(PhysOrg.com) -- A major breakthrough in remote wave sensing by a team of Rensselaer Polytechnic Institute researchers opens the way for detecting hidden explosives, chemical, biological agents and illegal drugs from a distance of 20 meters.

The new, all-optical system, using (THz) wave technology, has great potential for homeland security and military uses because it can "see through" clothing and packaging materials and can identify immediately the unique THz "fingerprints" of any hidden materials.

Terahertz waves occupy a large segment of the between the infrared and microwave bands which can provide imaging and sensing technologies not available through conventional technologies such as x-ray and microwave.

"The potential of THz wave remote sensing has been recognized for years, but practical application has been blocked by the fact that ambient moisture interferes with wave transmission," says Xi-Cheng Zhang, Ph.D., director of the Center for THz Research at Rensselaer.

Dr. Zhang, the J. Erik Jonsson Professor of Science at Rensselaer, is lead author of a paper to be published next week in the journal . Titled "Broadband terahertz wave remote sensing using coherent manipulation of fluorescence from asymmetrically ionized gases," the paper describes the new system in detail.

The "all optical" technique for remote THz sensing uses laser induced fluorescence, essentially focusing two laser beams together into the air to remotely create a plasma that interacts with a generated THz wave. The plasma fluorescence carries information from a target material to a detector where it is instantly compared with material spectrum in the THz "library," making possible immediate identification of a target material.

"We have shown that you can focus a 800 nm and a 400 nm laser beam together into the air to remotely create a plasma interacting with the THz wave, and use the plasma fluorescence to convey the information of the THz wave back to the local detector," explains Dr. Zhang.

Repeated terrorist threats and the thwarted Christmas Eve bombing attempt aboard a Delta airline heightened interest in developing THz remote sensing capabilities, especially from Homeland Security and the Defense Department, which have funded much of the Rensselaer research.

Because THz radiation transmits through almost anything that is not metal or liquid, the waves can "see" through most materials that might be used to conceal explosives or other dangerous materials, such as packaging, corrugated cardboard, clothing, shoes, backpacks and book bags.

Unlike x-rays, THz radiation poses little or no health threat. However, the technique cannot detect materials that might be concealed in body cavities.

"Our technology would not work for owners of an African diamond mine who are interested in the system to stop workers from smuggling out diamonds by swallowing them," Dr. Zhang says.

Though most of the research has been conducted in a laboratory setting, the technology is portable and eventually could be used to check out backpacks or luggage abandoned in an airport for explosives, other dangerous materials or for illegal drugs. On battlefields, it could detect where explosives are hidden.

The fact that each substance has its own unique THz "fingerprint" will show exactly what compound or compounds are being hidden, a capability that is expected to have multiple important and unexpected uses. In the event of a chemical spill, for instance, could identify the composition of the toxic mix. Since sensing is remote, no individuals will be needlessly endangered.

"I think I can predict that, within a few years, the THz science and technology will become more available and ready for industrial and defense-related use," predicts Dr. Zhang.

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User comments : 9

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axemaster
3.8 / 5 (5) Jul 11, 2010
You shouldn't call it "remote sensing" because that tends to attract the loony crowd... or perhaps that's your intent?

Good 'ol physorg.
Taps
1 / 5 (8) Jul 11, 2010
"You shouldn't call it "remote sensing" because that tends to attract the loony crowd... or perhaps that's your intent?"

Haven't you heard of CIA remote sensing using people's minds? Or is that loony as well?

It's name calling like this that creates dogma and the status quo. Anything that is said or done outside of these lines becomes the norm for ridicule.

There are many brilliant, and I mean brilliant people, that simply get passed by by this type of dogma.

Your dogmatic remark is truly one out of ignorance.
jonnyboy
2.4 / 5 (5) Jul 11, 2010
"You shouldn't call it "remote sensing" because that tends to attract the loony crowd... or perhaps that's your intent?"

Haven't you heard of CIA remote sensing using people's minds? Or is that loony as well?

It's name calling like this that creates dogma and the status quo. Anything that is said or done outside of these lines becomes the norm for ridicule.

There are many brilliant, and I mean brilliant people, that simply get passed by by this type of dogma.

Your dogmatic remark is truly one out of ignorance.

exactly his point, loon
Shootist
1 / 5 (2) Jul 11, 2010
It is a tricorder™ yet?
slaveunit
2.5 / 5 (2) Jul 11, 2010
How is that exactly his point? nothing in what he said says what taps had to say, to any normal person sensing explosives from 20 metres is 'remote' at least in so far as existing tech is concerned it is also far enough away from a normal grenade to give a reasonable chance of survival so this tech could save lives. Less name calling/trolling and the world would be a better place start by not being part of the problem.
DaveGee
3 / 5 (1) Jul 11, 2010
Maybe it's me but what value is a detection device when it can be foiled by immersing said contraband in a volume of water? Unless the detection can identify the 'blind spots' water or metal and alert the inspector that more inspection is necessary.

That being said, this still has some enormous potential WRT spills as noted in the story and maybe even mine field detection, a VERY real problem in MANY parts of our world. However, the idea that this would be any form of magic bullet to protect us from drug, bomb, etc transporting evil doers leaves a lot of loopholes but still it's another tool that can be added to the toolbox...
antialias
5 / 5 (1) Jul 11, 2010
Might not be useful for airlines.

If a bomber goes in he's expecting to die, anyways. What's to stop him from swallowing (or inserting recttally) a condom full of liquid explosive with a small timer chip for detonation?

Mine detectors are worth a thought (though I bet the mine producing industry will simply build their mines with a thin double wall containing water once such tech becomes wide-spread.
kevinrtrs
1.7 / 5 (6) Jul 12, 2010
Will human beings ever evolve from being the inventors of evil that they are?

Will they actually get to a point where no-one steals, lies, plans to rob, murder, rape, abuse and mistreat other human beings?

What exactly will it take, because it seems that the more we prevent one kind of misuse of technology, the sooner some technological loophole or circumvention is found. Computer viruses are a case in point.

And so evil continues.

Unabated.

How to evolve out of it??????

pauljpease
not rated yet Jul 12, 2010
Will human beings ever evolve from being the inventors of evil that they are?

Will they actually get to a point where no-one steals, lies, plans to rob, murder, rape, abuse and mistreat other human beings?

What exactly will it take, because it seems that the more we prevent one kind of misuse of technology, the sooner some technological loophole or circumvention is found. Computer viruses are a case in point.

And so evil continues.

Unabated.

How to evolve out of it??????



I doubt it is possible for humans to "evolve out of it"? But if you can elevate your perspective to something beyond humans, some kind of meta-organism, I think it's possible. For example, even while individual organisms on Earth commit violent acts, Earth as a whole is still innocent on that larger scale.