Schneier on Security
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March 17, 2008
Camera that Sees Under Clothes
A British company has developed a camera that can detect weapons, drugs or explosives hidden under people's clothes from up to 25 meters away in what could be a breakthrough for the security industry.
The T5000 camera, created by a company called ThruVision, uses what it calls "passive imaging technology" to identify objects by the natural electromagnetic rays -- known as Terahertz or T-rays -- that they emit.
The high-powered camera can detect hidden objects from up to 80 feet away and is effective even when people are moving. It does not reveal physical body details and the screening is harmless, the company says.
If this is real, it seems much less invasive than backscatter X ray.
Posted on March 17, 2008 at 6:30 AM
• 35 Comments
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I work in the tolling industry and wonder whether this will be developed into something we can use, for example, to count the occupants of a vehicle. Currently, in a multi-lane environment, we can only count those seating on the front row.
Warning signs. "T-Rays"? Why not just have marketing write up stuff about the "high powered camera" being fed by di-lithium crystals, and call it a "tricorder" instead of a "T5000"? Or would that be too ridiculous?
The general description reads like a glorified thermal imaging camera.
The terahertz range covers from IR to visible light. I don't refer to either of these as "T-rays".
Insert usual rant about journalists who can't even be bothered to look up what the terahertz range is.
I checked the ThruVision website but found zilch there in the way of showing the potential.
I wonder if the (human) user could detect a Glock hidden behind a colostomy bag worn under the clothing.
Are 'people' reading the results of this camera or is it a computer? If it is people, we will run into the same problems of sleeping x-ray scanners at the airport.
The article mentions that cocaine emits its own wavelength - if it is effective, there are lots of uses for this thing.
If credibility were nutrition, the linked article would be a jelly donut.
From Wikipedia, this looks quite plausible, though it appears we've not heard about T-rays before, because they are hard to produce, and need a lot of cpu to back-processing, which until now has been restrictive.
Key points: Doesn't pass through even a few mm of water(or skin) but can accurately detect plastic explosives.
Wikipedia is worth reading.
Theoretical and technological uses under development
* Medical imaging:
o Terahertz radiation is non-ionizing, and thus is not expected to damage tissues and DNA, unlike X-rays. Some frequencies of terahertz radiation can penetrate several millimeters of tissue with low water content (e.g. fatty tissue) and reflect back. Terahertz radiation can also detect differences in water content and density of a tissue. Such methods could allow effective detection of epithelial cancer with a safer and less invasive or painful system using imaging.
o Some frequencies of terahertz radiation can be used for 3D imaging of teeth and may be more accurate and safer than conventional X-ray imaging in dentistry.
o Terahertz radiation can penetrate fabrics and plastics, so it can be used in surveillance, such as security screening, to uncover concealed weapons on a person, remotely. This is of particular interest because many materials of interest, such as plastic explosives, have unique spectral fingerprints in the terahertz range. This offers the possibility to combine spectral identification with imaging. Some controversy surrounds the privacy issues in using terahertz scanners for routine security checks due to the ability to produce detailed images of a subject's body through clothing, though this method is less invasive than a strip search.
before anyone else...
...all we need now is a device to remotely measure alcohol blood-level and I'm set for a great Friday night.
I worked on a terahertz source during my PhD research, and it's really an interesting mostly unused part of the spectrum. It falls between the IR and microwaves, not between IR and visible light. I have seen papers where THz scans can be used to distinguish aspirin from illegal drugs, and the sort of thing mentioned in the article is plausible.
Detecting THz (I have seen them called T-rays also) is not so easy -- the detector we worked with had to be cooled to liquid helium temperatures, for example. I know that the European Space Agency was indeed working on micromachined antenna arrays for detecting and imaging in the THz more easily.
Like any other new product, it's probable that Thruvision are exaggerating what it can do. I am especially interested in what they mean by "effective even when people are moving." But I would say that on first glance, it's not looney tunes.
More here: http://www.thruvision.com/products/
Assuming it works, and becomes depended upon ... how easily could a zillion false-positives be generated? A flood attack at a security choke point could become a real mess!
Note that the security section of the wikipedia entry references a BBC News article (http://news.bbc.co.uk/2/hi/technology/7287135.stm) which also references the same manufacturing company. It looks more like extra detail than corroboration.
Isn't it possible, in theory, to create a small portable broad-spectrum THz jammer? From there, how difficult could it be to create one which alters the "fingerprint" of whatever else you're carrying? And itself has the fingerprint of, I don't know, a pack of condoms.
from the discription, of what it penetrates and what it does not, it sounds like this technology can be easily blocked by many substances, includeing possibly a leather coat, (dosent penetrate flesh) various metalic fabrics and possibly metallized mylar. the passive infra red detectors can be blocked with a piece of corregated cardboard, this one should not be so much harder to foil, Almost so easy that it seems that for the proposed use, its not worth the development costs. It will pick up the uninformed and stupid, but will not deter the people who know the limits of the technology, and you will hear the people who are investing in the product telling of its infallibility, as propaganda to convince people that it works better than it possibly can.
This is unrelated to the post, but I noticed my RSS feed hasn't been finding any new posts. Has anyone else had a similar problem?
A Friend of mine worked on the imaging side of this for a couple of years and I can confirm that it's real.
There was a trial machine in use at Heathrow airport for a while.
From what I can recall the image wasn't quite as good as backscatter X ray.
One of there paper's ( Image analysis for object detection in millimetre-wave images) (PDF) is here: http://www.ece.eps.hw.ac.uk/~arharvey/...
There was a group working on this at my university. I walked past their labs almost every day. This is indeed real.
> It does not reveal physical body details
Oh yes it does! A lot!
If it "sees" through clothes, it "sees" your physical details. The amount of distortion in your physical appearance is what matters. If it shows even close to anatomically correct images, then they will end up in the tabloid press for any persons of notoriety.
We're spending an awful lot of time, money, and resources attacking a haystack to find a needle which isn't even there. In the process we're trouncing the good will and alienating everyone around the world who might wish to come spend their appreciating currency here in America, while still not preventing even 80% of the test case guns and bombs from making it past the TSA. Why?
Sounds a lot like the device Arnold passed through in Total Recall.
I seem to remember ads on the back of adolescent-male-targeted comic books that promised glasses that could look through (girl) clothes. Didn't say anything about terrorists that I can recall, though.
red squad radiates civilians to glow and spectate them, meanwhile tempest smiles near them as they use computers with drone cameras waiting in the wings, be sure they are there always
Use of active Terahertz imaging is well documented and mostly does what it claims on the box.
What these people seem to be claiming is purely passive THz imaging. I have problems with believing this would work in anything other than very tight laboratory conditions or in space with large targets. (The whole edge of the Universe, for instance).
The temperature of a black body radiating at its peak wavelength in the THz region (300GHz - 3 THz, or if you prefer wavelengths 1mm - 100um) is between approximately 2.9 - 29 Kelvin. i.e. close to absolute zero. The energy emitted at that wavelength is tiny. Peak emissions at these temperatures range from 3.9 uW/m2 to 39 mW/m2.
But a warm, everyday object doesn't have its emissions peak at near absolute zero, it is right up at 290-300 Kelvin, meaning the emissions at Terahertz wavelength are off on the very tail of its spectrum at truly tiny energy densities. Add to that we're talking about objects with lower emissivities than a perfect black body and the figures get worse still.
Unless I've missed something crucial that's the physics of it and the physics says it can't work, or at least it can't work passively from "Naturally occurring terahertz waves emitted by people and objects".
My suspicion is that it's a passive infrared system and they're using the "Terahertz" word because it's had some positive press in some quarters in the past couple of years. After all, infrared at 10,000 nm is technically at 30 THz, its just that the rest of us call that the infrared band, not the Terahertz band. "Thermal Imaging Camera Announced" wouldn't get more than a tiny mention in the trade press and wouldn't get us talking.
Obviously if they are using detectors made out of ultra-chilled Oleum Serpens then it would work flawlessly and I would be proved wrong.
@derf: "In the process we're trouncing the good will and alienating everyone around the world who might wish to come spend their appreciating currency here in America..."
Embarrassingly, it's a British company we're talking about.
I'll bet dollars to doughnuts that the "T-Rays" aren't really THz radiation but rather in the 100-500 GHz range where a lot of promising imaging work has been done, and where useful things like cloth and paper are transparent (even at 1 THz, dry cotton cloth is pretty opaque, at it gets worse as you go up in frequency). There is, as far as I can tell, no spectral information in this regime, at least for solids or atmospheric pressure gasses.
Super hero x-ray vision or high technology tool of the future when dealing with security screening perception can as important as fact. A simple warning sign stating T-Ray's now at use at an entry point to any port may well increase the nervous tension a wrong-doer may be experiencing thus exposing themselves more readily to the trained and/or experienced eyes of on-site screeners. I say "have at it!"
I too doubt that the system works as advertised, but I could be wrong, so here's a protocol that will be a big help in evaluating this and future surveillance inventions.
When the backers announce how wonderful the new system is, they should invite skeptical experts to come into the lab, play with the device and try to beat it. If they fail, that won't prove that the system works, but it will at least allay suspicions that it's trivially beatable. For instance, I suspect that this THz device can't detect plastic explosives wrapped in sliced ham, an idea that an expert could test in seconds.
"I have problems with believing this would work in anything other than ... in space with large targets. (The whole edge of the Universe, for instance)."
Warm objects should emit more terahertz radiation than very cold objects, it's just that the terahertz radiation will be a smaller fraction of the total.
Even if they cannot see any anatomical details, it is still a search of my person.
Seems like it would be fairly easy to defeat since it doesn't see thru water.
Might this lead to a revival in sequined clothing?
"...it may also increase concerns that Britain is becoming a surveillance society"
I'm reading more and more statements like this, isn't it already a surveillance society?
How do you jam a terahertz camera that someone is using to spy on me. where can i get the jammer?
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