Remote Scanning Technology

I don’t know if this is real or fantasy:

Within the next year or two, the U.S. Department of Homeland Security will instantly know everything about your body, clothes, and luggage with a new laser-based molecular scanner fired from 164 feet (50 meters) away. From traces of drugs or gun powder on your clothes to what you had for breakfast to the adrenaline level in your body—agents will be able to get any information they want without even touching you.

The meta-point is less about this particular technology, and more about the arc of technological advancements in general. All sorts of remote surveillance technologies—facial recognition, remote fingerprint recognition, RFID/Bluetooth/cell phone tracking, license plate tracking—are becoming possible, cheaper, smaller, more reliable, etc. It’s wholesale surveillance, something I wrote about back in 2004.

We’re at a unique time in the history of surveillance: the cameras are everywhere, and we can still see them. Fifteen years ago, they weren’t everywhere. Fifteen years from now, they’ll be so small we won’t be able to see them. Similarly, all the debates we’ve had about national ID cards will become moot as soon as these surveillance technologies are able to recognize us without us even knowing it.

EDITED TO ADD (8/13): Related papers, and a video.

Posted on July 16, 2012 at 1:59 PM90 Comments


Geoffrey Kidd July 16, 2012 2:18 PM

Orwell was an optimist without enough imagination. Who needs telescreens?

phred14 July 16, 2012 2:19 PM

IF this is real technology, isn’t then the real problem then wading through this flood of data to find what you really want? Even if you’re specific about looking for “traces of drugs or gunpowder on your clothes,” even if you can handle the data volume, at some point you’re going to hit a “sorting problem.” You’ll find perhaps half the people on prescription medication, some fraction of the people on over-the-counter meds, “natural alternative therapies,” not to mention anyone who has shot a gun in the last week, perfectly legitimately at a perfectly legitimate firing range or hunting. Add “breakfast detection” and it gets that much worse.

The real problem is of course that there will be such a flood of information and such bumbling trying to store, access, and discriminate that information, that no doubt more real issues and threats will be missed than are missed today. Same for false positives.

Joe July 16, 2012 2:24 PM

“Behind Winston’s back the voice from the telescreen was still babbling away about pig-iron and the overfulfilment of the Ninth Three-Year Plan. The telescreen received and transmitted simultaneously. Any sound that Winston made, above the level of a very low whisper, would be picked up by it, moreover, so long as he remained within the field of vision which the metal plaque commanded, he could be seen as well as heard. There was of course no way of knowing whether you were being watched at any given moment. How often, or on what system, the Thought Police plugged in on any individual wire was guesswork. It was even conceivable that they watched everybody all the time. But at any rate they could plug in your wire whenever they wanted to. You had to live — did live, from habit that became instinct — in the assumption that every sound you made was overheard, and, except in darkness, every movement scrutinized.”

Bruce Schneier July 16, 2012 2:46 PM

“IF this is real technology, isn’t then the real problem then wading through this flood of data to find what you really want?”

I’ve read this argument a lot, and I don’t think it will be much of a big deal. Just as our surveillance technology is improving, so is our searching, sorting, and pattern matching technology. Sure, there’ll be all sorts of false positives when the system is set to do such vague things as “find suspicious patterns,” but it’ll work just fine when asked to produce a list of everyone who has attended a particular protest march or a history of a particular person’s movements for the past year. I presume this sort of thing is what the NSA’s Utah data center is designed to do.

Kevin Granade July 16, 2012 2:51 PM

Re: Information overload, as they make their systems more and more sensitive, it will be easier and easier to trip them, for example by powdering a explosive compound and broadcasting it around the (public) terminal entrances. No actual effect, but now every individual trips the explosives detector, potentially causing a terminal closure.

Patrick July 16, 2012 3:03 PM

Wear a hat and new kit – hope the store staff were not experimenting with fertilizer and eat fast food and you should get past.

Dominic July 16, 2012 3:14 PM

Until zero false positive software becomes materially affective, governments will argue they have the right to intrude remotely or otherwise. I’m off to Sweden.

Russell Johnson July 16, 2012 3:23 PM

When the false positive rate is already about 50%, they will push it to new heights with ever more sensitive equipment.

Clive Roobinson July 16, 2012 3:32 PM

@ Bruce,

Fifteen years from now, they’ll be so small we won’t be able to see them

I think you need to qualify that statment.

Taken literally you are saying that a camera will be physicaly so small it will not be visable to the naked eye at any range. Well physics is against you on that one.

If however you mean when the camera is installed that happened many years ago with fish eye and peephole lenses mounted in objects.

However any optical system of any use foocused to produce a clear image will suffer from the “cats eye” or “red eye” issue (they are not the same by the way). That is a light source close to your eye will go out to the lense be focused on the optics and will return on the 180degree path +- a small angle. This will enable you to see the flash back of the light coloured by the optics (we have discussed this before on this blog when talking about anti-photography systems).

Further all electronic systems are inefficient and the waste energy from the inefficiency will be radiated as heat. A sufficiently sensitive thermal imager will show the thermal disparity up to an observer.

Thus although surveillance technology improves all the time so does the coresponding antisurveillance technology.

It’s and endless war in just the same way ECM / ECCM / ECCCM / … was (and still is to a much lesser extent).

Fundementaly the war will resolve down to the point were the emmission or susceptance of a technology can not be differentiated from a “black body”. Not because it’s possible to get there in any meaningfull manner but the noise floor in the detectors etc has been reached. As this happens the detector bandwidth will be decreased untill the scanning process of a single detector will take to long to cover the required bandwidth. The next solution will be to use many sensors or some kind of pasive gain system (think antenna or lense) but this has physical limitations as does using Peltier or liquid nitrogen / helium cooling etc …

Dr. I. Needtob Athe July 16, 2012 3:36 PM

The first comment from Geoffrey Kidd sums it up quite nicely. In fact, I’d shorten it to simply “Orwell was an optimist.”

Unfortunately, it seems that suppressing any technology is impossible. There’s absolutely nothing that anyone can do about this.

Petréa Mitchell July 16, 2012 3:38 PM

I call BS.

The allegedly similar device created at GWU works like a real spectrometer; their claimed innovation is combining laser and mass spectrometry to broaden the range of applications.

The allegedly similar device created by the Russians claims to scan a volume of air for a specific limited range of substances. I think. Some of the pictures do not seem to match what the article is talking about. And it only works in a lab environment so far, which makes me dubious about the 50-meter range claim.

So neither of those is anything like this magic device that will scan everyone in a 50-meter radius and be able to pick up the kinds of massive detail the article is talking about.

OTOH, it appears this is all way overblown. Here’s the manufacturer’s product page with a photo matching the device in the article. According to the manufacturer, it’s just a laser generator. Not a scanner. Not a spectrometer. Not something capable of performing any analysis at all. They think it has great potential for such applications, but all they make is the laser.

Petréa Mitchell July 16, 2012 3:40 PM

I’m not arguing the meta-point of Bruce’s post, BTW. Just saying that this particular device is not something to be scared of anytime soon.

Brandioch Conner July 16, 2012 3:52 PM

This sounds similar to the M21 remote chemical agent sensor.

Similar, but the claimed capabilities are far beyond what the M21 can deliver. But then the M21 is almost 30 years old.

But that is besides the point. I think the real issue is the ubiquitous tracking that Bruce mentioned. Even without the facial recognition and such. Just saving your cell phone data for 25 years would be enough to track almost everyone.

John F July 16, 2012 3:55 PM

@Petrea: It almost certainly is BS.

But if the general public thinks it’s real, it will still have a deterring effect. It’s just basic psychology, and lets face it – it’s not all that hard to fool the American public.

All you really need is an ‘anonymous source’, a sound bite, a ‘leaked’ document, and for good measure maybe some mocked up ‘screen shots’ taken from a cell phone camera and the CNN/Fox/AP ‘news’ will do the rest for you…

Sad, but true.

ex-TSA K band tech nerd July 16, 2012 4:07 PM

This is complete BS. Even if the technology worked, the DHS/TSA large system integrator contractors would break it in the field. And there is no such technology at the present time.

kashmarek July 16, 2012 4:15 PM

Over the past couple of years, there has been lots of hyperbole about this device or that device being able to recognize you in may different ways. This “announcement” is just one more such device intended to gain relevance in the realm of securiity theater, and what problem does it solve?

I don’t have a problem if they recognize me. I do think there is a problem if they monitor me and collect data about me that is unnecessary. In particular, while Bruce says technologies are improving, such technologies DON’T LAST VERY LONG.

And, when we move to the next technology, what happens to all that data collected under the previous technology? Storage of the data is the issue. Soon, storage technology won’t be able to hold all the data that can be generated and there won’t be time to convert all the OLD data to the new technology (for use), thus rendering most of the data collected, obsolete before much of it gets used.

When they can’t store ALL the data, they will only collect the “damaging” data, thus achieving nirvana in that everything bad about you is collected to be used against you but nothing good about you is collected to be used for your defense.

FUD is still alive and well. What is revealed is good for “them” and can mostly be called progaganda. What they don’t reveal is troublesome because it generally is not good for “them” and we can use it (if we find out about it) to our advantage.

Wael July 16, 2012 4:24 PM

The only possible unrealistic thing I see about this is the time frame. A laser source illuminating a target could “somehow” be modulated by the characteristics of the reflector (body) and spectral analysis can be conducted to analyze the characteristics of the reflecting materials. Different wavelength (whether Continuous Wave or Pulsed, single beam or Multi-beam) laser can be used for different materials (clothes, skin, traces of explosives, …)

Similar remote sensing technologies have been used to analyze the surface structure and materials of remote planets and stars. Microwaves were used long ago for characterizing the ground for potential Oil-well locations.. Man! Lasers can even be used to cool down materials as well!

LASER was a solution looking for a problem when it was first invented. The solutions today are many… Eye surgeries, Remote sound reconnaissance (laser hitting a window), Welding, rifle targeting…

I don’t see this as science fiction at all! The only science fiction I see now is a “Beam me up Scottie” device. That will not happen any time soon.

Mooooouuuuuuh (a long smooch) your privacy goodbye… For the users of this technology, they can add a hand gesture to that kiss, with their hand touching thier mouth… Just like when an Italian chef tastes a dish he cooked, and liked…

Dave C. July 16, 2012 4:31 PM

The main problem I see is the gap between technology and the law. Technology is years ahead of where the law needs to be and the government takes advantage of this gap to keep tabs on people. “If you havent done anything wrong what should you be worried about?”

Clive Robinson July 16, 2012 5:25 PM

Having read through the article it contains some inaccuracies 0.1-10THz (3mm-30μm) is not realy considered “light” which is usually considered to cover the bottom end of UV to the top end of near infrared. The range covered is the top end of microwaves and the bottom of IR or “far infrared” so Laser is not the correct term (Maser would be, but then most people don’t know what the term means).

Untill fairly recently broad band detectors in the THz range have been slow because they have often used bolometric techniques to convert to near infrared. Put simply you focus the THz input onto an ultra thin “broadband absorber” which converts the THz energy to heat energy which can be seen by a thermal imager or photo-multiplier tube working in that range.

There are however other techniques that can be used such as optical parametric amplifiers as pump up converters. Put overly simply you have a long cavity tuned to to widley seperate frequencies and in the cavity you have a nonlinear “reactance” element. You inject a much higher idler/pump frequency into the cavity, the lower frequency then gets superimposed onto this pump frequency by changing the nonlinear elements reactence and in the process it also gets significantly amplified in level at the same time.

The amplication can be in theory noisless because it is done by a reactive not resistive element. To see how this works think of a simple two plate capacitor, it’s capacitance is inversly proportional to the distance between the two plates. The voltage (V) across a capacitor is related to the charge (Q) held within the given capacitance (C) as,

V = Q / C

So you increase the charge (Q) or decrease the capacitance (C) the voltage goes up.

So let us assume the plates start very close together and the capacitor is charged from the very low voltage input signal. The capacitor is then disconected from the input and the capacitor plates are moved a reasonable distance apart, the capacitance drops by a factor of say 100, thus as Q remains constant the voltage goes up one hundred times. Provided you do the moving of the capacitor plates several times (ten or more) during the minimum period (maximum frequency) of the input signal you get a reasonably faithful representation of the input signal at one hundred times the level envelop modulated (ie AM) onto the resulting high frequency signal that drives the capacitor plates. In most microwave systems the variable capacitor element is a Varactor diode and it is driven by the “pump frequency” in effect the circuit also acts like a mixer as a result of the envelope modulation and the output is (Pf-If) + (Pf+If) where Pf is the pump frequency and If the input frequency. Due to the way things work the input signal is fed into the bottom low impeadence end of a parallel tuned circuit with the varactor connected to the top or high impedence end. The pump frequency is effectivly fed to the varactor via a series tuned circuit and the output frequency selected is taken via another parallel tuned circuit to step down the effective impedence. Now just to make it all fun the tuned circuits can also be “tuned via varicap diodes” thus the whole amplifier can be very rapidly tuned across a desired band which can with the right design cover a couple of decades or more.

The same applies to the Optical Paremetric Amplifier (OPA) / up converter. For more details have a look at the Wikipedia page,

I suspect that their ideas are based on this or similar techniques.

Petréa Mitchell July 16, 2012 5:25 PM


Similar remote sensing technologies have been used to analyze the surface structure and materials of remote planets and stars.

If you mean lidar, (a) that hasn’t been used outside the inner solar system yet, as it requires actually sending the instrument package to the object being examined, and (b) it’s mainly used either for ground mapping or tracking aerosols and water in the atmosphere– nothing like the kind of massively detailed comprehensive chemical examination this alleged TSA device is supposed to provide is.

bcs July 16, 2012 6:31 PM

There is already something like this. In fact they are shipping it to mars:

They just need to run it a bit longer and they can get as much data as they want. Down side? It’s kinda hard on the subject, but when has that ever stopped the TSA?

MingoV July 16, 2012 6:37 PM

“I don’t know if this is real or fantasy”

It’s fantasy. I’m a clinical pathologist and a chemist who has much experience with spectrophotometric identification of chemicals. The laser wavelengths in the scanner are much longer (lower energy) than the visible and ultraviolet light wavelengths commonly used to identify molecules. The pattern of laser-emitted photons reflected back from the distant object cannot possibly provide accurate identification of chemicals. At best, the reflection patterns will be “consistent with” a particular chemical of interest. Essentially, these expensive scanners will be the technological equivalent of the drug sniffer dogs that are trained to respond to almost anything. Law enforcement agents will be pleased with the high rate of false positives because any positive result will be the “probable cause” to perform strip searches.

Dave X July 16, 2012 9:11 PM

If it is true, it seems like an invitation for false-ish positives.

A small sprinkling of gunpowder or cocaine could contaminate thousands of passengers with traces and clog checkpoints for hours.

Wael July 16, 2012 9:42 PM

@ MingoV

The laser wavelengths in the scanner are much longer (lower energy) than the visible and ultraviolet light wavelengths commonly used to identify molecules.

Is that your only reason?

Figureitout July 17, 2012 12:11 AM

What if I smell burnt marijuana coming from the car that just passed me as I am running? –Those molecules will stick to my sweat-soaked shirt and body (False Positive).

What if I just fired off 8 shots of a ’22 rifle and 2 shots of a ’20 gauge shotgun for the hell of it on my private property?–Which I “may” do, maybe there are rabbits chewing on my crops 🙂

What if I’m feeding all my crops with store-bought fertilizer?–Whoops, got some of that on my hands and shirt; yep I’m purifying the elements and making a bomb (SARCASM).

I can deal with electronic surveillance (it’s to be expected these days, no?), it’s the physical surveillance that I’ve been sensing lately that really irks me and puts me in my “trolly-polly” mode. From the creepy/weird/awkward/cigarette-smoking neighbors that have moved in recently to the sight of my fellow coworkers while on a run and someone not even trying to hide and wearing a “CIA” shirt; they seem to be trying to make it obvious to me now. I don’t know why TLA’s would want to waste time with me, but I certainly will give them their money’s worth; i.e. leading them on a fruitless goose-chase.

In fact, in case they didn’t know; one of my favorite games as a kid was playing the “neighborhood spy”. My parents bought me a “kiddy-spykit”, with a listening device, and a wristband where we could tap-out coded messages with a red-laser in the dark. We had multiple bases set up, and managed to “spy” on just about everyone on our street and cul-de-sac. The one time we got caught, was when spying on the “odd” family of the neighborhood (I still remember seeing the dad’s face), the man called my parents and we got reprimanded; sort of :).

Well, my father was and still is an avid amateur radio operator; and back when cell phone traffic could be picked up with commercial radio equipment, he happened to pick up a conversation with that man and someone else besides his wife; come to find out he was cheating on his wife. So you can see why he got so upset at some little kids playing spy in the neighborhood. :/

The point of that story being, I’ve enjoyed playing the “spy games” since I was a kid; so game on..(expletive deleted).

Nick N July 17, 2012 12:18 AM

IANA chemist or physicist, but it appears they are referring to Raman and Mid-IR spectroscopy. From what I have read about them, you could only use these techniques to identify compounds in a tightly controlled lab environment.

It also looks like you need lasers in the many hundred mW range, shining these at people would be incredibly dangerous.

Wael July 17, 2012 12:37 AM

@ Nick N

“It also looks like you need lasers in the many hundred mW range, shining these at people would be incredibly dangerous.”

Not if it’s for a few pico seconds. You can buy a 3 watt laser and your skin will stand a fast burst — Exposure time is important. If it hits your eye, it would not be good.

Related subject: I remember that my Microwaves prof told us once that you can kill someone with a 9 volt battery if you connect it to their temples or ear lobes – I forgot. I don’t believe him, but I am scared to try…

@ Clive Robinson
Is there any truth to that ?

Clive Robinson July 17, 2012 2:54 AM

@ Wael,

All chemicals have charecteristic spectra, normaly we talk about the spectra when we have the chemicals in one of the four natural states (solid, liquid, gas, plasma). However the spectra vary also dependant on how you are messuring (emmission, reflection, absorbtion, transmission).

For instance plain old water has two atoms of hydrogen and one atom of oxygen. However you can also view it as being an OH bond which is quite common in organic chemicals such as our food.

Now the OH bond has a spectral charecteristic well well down in the low microwave region around two and a half gigs. It is known that if you pump the OH bond at that frequency it vibrates in sympathy and in the process converts the RF energy to thermal energy.

Now millons of people a day use this in a practical way (ie to “microwave their food”) but very very few of them know the specifics.

So…. untill we know by what method they plan to use to measure the spectra and in what part of the frequency range it’s not possible to call BS or NOT BS, So… we just need to continue digging for further information, and as you say the people behind the idea do have a reasonable “pedigree” in this area.

A little story, prior to WWII Dr R.V.Jones (of the 1973 book Most Secret War) was investigating detectors for IR and he hoped it could be used for detecting the side effects of aircraft engines. Well it did not work out for various reasons. However things change specificaly the aircraft engines and various types of aerosol both of which ment that just a few years after WWII we had our first IR anti-aircraft devices more than capable of doing what Dr Jones envisaged.

As I said further up untill fairly recently THz radiation detection was by bolometric absorbtion devices, however things have changed considerably in this respect fairly rapidly, partly due to the “War on Terror” and partly due to “usable spectrum shortages” for communications…

With regards the 9V battery, people have been killed with less than half that voltage and people have survived many tens of thousands times that voltage. Which indicates it’s not the voltage that kills but a side effect of it’s measurable pressence. There is a saying from years back,

It’s the Volts that jolts! But the Mils that Kills.

Strictly this is not true either it’s the energy against time which in turn is dependent on the resistance in circuit. And it’s contact resistance and the path the current takes that decide is you live or die…

If you put your tounge on top of a small 9V battery you will jump simply because the path of least resistance involves the nerves in your tounge. Now if you hold the probes of an old Avo Meter set to resistance you will find the reading changes a lot depending on how tightly you hold the probes and how damp you are. It is the change in skin resistance that is used to indicate potential sweating as one of the source readings in the standing joke of technology called the “lie detector” (Oh and what the Scientologists use in their stress measuring device they claim uses secret technology “of the stars” etc…).

So a very low voltage when applied directly to a critical nerve path (think those going to the heart) can cause malfunctioning that can either stop the heart (if the potential is high enough) or block the nerves to induce other malfunctions in the heart that will lead quite rapidly to death. However the trick works in reverse a sufficiently large charge of energy will quite litteraly “shock the heart back into normal operation” which is the technique used in de-fibs.

As for applying electric currents to the brain via the ears etc, this belongs to the “dark ages” of Victorian medicine that gave rise in turn to the now much discredited Electro Convulsive Therapy which could induce all sorts of spasms and other effects including death. In more recent times people developing electronic eyes for the blind have to do things in very timey steps because the optical nerves they connect to are a direct connection into the brain and they have had some early patients have siezures and fits because the brain is very nonlinear in it’s response to energy.

Oh and of more recent times there is work underway which uses magnetic fields to cause changes in neural activity this has shown very odd but interesting side effects that are now being developed as therapies. The question is is it the magnetic field or the currents it induces that are causing the changes…

Bill July 17, 2012 3:31 AM

It’s technical snake oil. A Star Trek Tricorder by another name.

Spectroscopy via laser is simply not that sophisticated yet. The nuclear powered Mars Robot that lands in a few weeks has one which can just about figure out minerals in rocks.

Also CCTV cameras to be effective must have a useful angular resolution (not to be confused with pixels) and that’s a physics limit. Lenses for visible wavelengths or longer will ALWAYS be visible (almost by definition).

Unless cameras adopt synthetic aperture means (e.g. interferometer).

But yeah, it’s not technology that’s the problem …

Kevin July 17, 2012 4:07 AM

It’s unfortunate that the article is drenched in hyperbole (and I’m not surprised that the author won’t put his name to it). However, doing a patent search for Genia Photonics brings up a lot of interesting patents on tunable, mode-locking fibre lasers and some of them mention being able to tune the wavelength within ranges of 100GHz which makes it plausible that they do have terhertz laser producing capability now.

The article is full of juvenile, breathless excitement and with orders of magnitude bandied around with gay abandon it’s difficult to see through the smoke, but I think what’s happened is that the author has taken the molecular “scanning” capability and let his mind run riot.

It looks to me like the laser can be tuned to specific resonant wavelengths of known molecules so that presumably a suitable imaging or detection device will be able to pick up signals that exceed a baseline reading. To my mind this is much more preferable to remote-control strip-searching as it would be targeted and looking for specific marker molecules in a non-invasive manner. I certainly don’t believe the claims in the article that it can tell you what you had for breakfast (unless you can tune the laser to detect the aromatic compounds and fat molecules that comprise a fry-up) but this is still very specific. It can’t tell you that you had scrambled egg unless it scans specifically for the molecular components of that egg left in your mouth.

It certainly looks like it could be used to detect cancerous cells so that they could be individually targeted (how deep they can be targeted within tissues remains to be seen).

If I was a cynic, my suspicion would be that the author recently bought shares in the company and is trying to make a quick buck on his investment by deliberately inflating the scope of the technology.

Wael July 17, 2012 4:18 AM

@ Clive Robinson
Thank you.

@ Kevin
It can’t tell you that you had scrambled egg unless it scans specifically for the molecular components of that egg left in your mouth.

Or from perspiration. If you eat raw garlic you can smell it after a few hours on your skin, and it can last a day or so.

Is there a way we can invite one of the founders for a Q/A session on this blog? I have a USB stick that we can drop in his parking lot…

Autolykos July 17, 2012 5:00 AM

Law enforcement agents will be pleased with the high rate of false positives because any positive result will be the “probable cause” to perform strip searches.
That probably nailed it. They don’t care how reliable the technology actually is, as long as the guy selling it can make up enough technobabble to convince the judge. They’d use dowsing rods if they could get away with it (heck, in some countries they do).

Clive Robinson July 17, 2012 5:09 AM

@ Figureitout,

What if I smell burnt marijuana coming from the car that just passed me as I am running? –Those molecules will stick to my sweat-soaked shirt and body (False Positive).

It’s already happened not with cloaths but with hair.

A test was developed to show “drug use” and aproximatly when by taking a hair sample (roots and all in some cases). Originaly it did not “wash the hair” before analaysis, as it was not an issue (the test was for offenders to show parol violation of use or contact).

Well Ronnie “Starwars Ray Gun”‘s wife Nancy was a bit hot on “drugs in the work place” and the unions etc kicked off about urine and other more invasive testing… So some bright spark suggested the hair test. So corporate America got on the case and produced many different (but dirt cheap) hair testing kits… Well the rules were slightly different for employees it was “use” not “use or contact” and in the fullness of time it happened a non user failed the hair test because of “contacct” which was due not to “social choice” but to the area they lived in (people openly smoking on street cornorss and on public transport etc). So the test became a lot more complicated in that the sample had to be chemicaly washed… This was to difficult for those “HR Types” so what they were (supposedly) suposed to do was take a sample divide it into two and give one to the person being tested. The other sample was then divided in two again and one goes into the old unwashed test and if positive the other sample gets sent to a lab to have the proper test done on it…

Well there is another issue with the hair test that Motorola found out, it does not indicate the source or quantity of the “drug” only that it is present… And it is quite legal to use and sell some opiate sources.

A number of employes in a UK office were found guilty via the lab test on the hair. They were adament they were not “drug users” it got quite frought for a while till it was found out the “staff canteen” were the “drug pushers” via the bread rolls that had poppy seeds on them.

It turns out that quite a few foods contain natural sources of drugs, lettuce stems for instance contain small quantities of “laudinum” another opiate. Likewise hemp used for making any number of craft products and the seeds are used in cooking as either “oil” or “flour” contain trace quantities of the same drug found in the commonly used plant used for making joints…

As for explosives and food there is a significant connection via preserved meats and meats that contain certain improvers and it’s the old favourite from the midden “potash” or other nitrates which make good oxidizers and thus preservatives.

Oh and some washing products contain other chemicals that would show up as explosives and there is also the good old “pre-plastics” that are actually explosives… These are the nitro-celuloses. Still used to “finish playing cards” make “bone handles” on cutlery and keys on pianos. There is a lovely story (supposadly true) of an inventor using them to make “billiard balls” (which is true) as they aged from light and use and other chemicals in the environment in bars and saloons would change their composition from one type of nitrated cotton to another and apparently would if hit sufficiently strongly cause the ball to explode…

The point is if just cooking the nitrate loaded bacon and adding the opiate laden lettuce for your morning BLT roll with opiate carrying poppy seeds and spread with your chosen fat via that old nitro celulose bone handle butter knife means that you look like a heavily armed, explosive totting drug dealer, who is going to be innocent?

Guy July 17, 2012 7:25 AM

@Geoffrey Kidd: The watchers need telescreens. The telescreens give you the false assurance that there are times and places where you can’t be seen.

phred14 July 17, 2012 8:05 AM


LASER was a solution looking for a problem when it was first invented. The solutions
today are many… Eye surgeries, Remote sound reconnaissance (laser hitting a
window), Welding, rifle targeting…

The laser is one of those things that gives me some faith in the world. When it was invented one of the first things on peoples’ minds was “death ray,” but despite much effort and money, that’s one thing it hasn’t become – yet. Yes, there are laser “death rays” in existence, but so far none of them have been practical. Even if someday they do manage to make a practical death ray out of one, and even if there are military uses like targeting, surveillance, etc, that doesn’t even start to tip the scale.

For all of it’s imagined roots as a “death ray,” the laser has been an incredibly useful device in remarkably peaceful ways.

vasiliy pupkin July 17, 2012 8:10 AM

@Dave C.
Laws have different level of ‘generality’.
On the top level they may codify principles which apply to usage of any new future technology in differnt types of relationships: citizen2citizen, private corporation2citizen and vice versa, business2business, governmet(not law enforcement)2citizen,
law enforcement2citizen including usage in a court as evidence not only for operational usage (when technology gets such capability? any robust scientific criteria or just opinion 5 by 4 majority of nine Justices to affect several hundred people?), etc.
Then it’ll be less problem with time gap between new technology usage and specific law addressing usage of that particular technology. In short, it is switch to deductive approach versus inductive/precedent approach.
I guess it’ll be possible after accepting ISO system of measures as the rest of all civilized world in the day-by-day life(that is just bitter joke!)

M.V. July 17, 2012 8:11 AM

Now the OH bond has a spectral charecteristic well well down in the low microwave region around two and a half gigs. It is known that if you pump the OH bond at that frequency it vibrates in sympathy and in the process converts the RF energy to thermal energy.

This is a common believe which is actually wrong. The microwave oven works with dielectrical heating on liquid water (and other substances). You don’t need water, it is just more effective (probably because it is liquid).
Also the frequency doesn’t need to be 2.45 GHz. It is just a regulation requirement for the microwave ovens to use that.

Mind you, till a few month ago i also didn’t know that.

Dick Alstein July 17, 2012 8:16 AM

It detects gun powder traces? Great!

Imagine how much fun you can have, walking around in the departure hall of the airport, spreading the contents of a small firecracker over the clothes of hundreds of travellers, and watching the ensuing chaos.

phred14 July 17, 2012 8:17 AM

@Bruce Schneier

There is a bit of a conundrum, when we look at the TSA and the apparent incompetence, and then try to resolve that with competent management of information overload. I would hope that there are other parties in the government that are much more competent than the TSA.

Once again, the real question is whether the holders of that information will themselves ask the right questions. You cite one sensible query, but it is indeed easier to make less sensible queries that will generate far more results – and political hay. “Political” also being shop-politics, not necessarily the national partisan variety. Unfortunately the latter can be a factor too, when the top brass typically tend to be political appointees and the career underlings have to keep them placated.

Anthony Fiorito July 17, 2012 9:11 AM

Gun powder traces are meaningless. More Americans shoot at gun ranges than play golf. The bigger issue is data volume. Trying to store, sort, and collate this mess will be a horrendously difficult problem. Add in millions of records with non-zero false positive and false negative rates means an incredibly dirty, horrendously difficult problem. Smells like BS to me.

Mike July 17, 2012 9:53 AM

I suspect the false positives are a benefit, not a negative to these types of technology. The volume of data is irrelevant. It would cost next to nothing to store billions of false positives. Trying to find meaningful data in such a mess would be nearly impossible, as many people have pointed out.

However, once a suspect is chosen, the plethora of false positives can be used to pressure them into confessing. I recently was an observer where a police officer tried to intimidate a person into confessing to a crime they did not commit. I have no doubt that a false positive database would make the process even easier.

Could any of us explain why we had dozens of hits from various scans that weren’t mentioned when they occurred? I’d be surprised if anything in my house didn’t have traces of dog hair or gunpowder. Of course, the database wouldn’t reflect that reloading ammo is perfectly legal, and I doubt the dog hair would be noticed since it doesn’t suggest some imaginary criminal activity.

karrde July 17, 2012 10:03 AM

@Clive July 17, 2012 5:09 AM

I’ve heard stories of people failing urine-tests due to a diet heavy in poppy-seed muffins/bagels. I was unfamiliar with the hair-tests, though.

On a more prosaic level: i’ve heard from multiple sources that the average piece of American paper money has trace amounts of cocaine on it.

The cause could be that lots of bills pass through the hands of drug dealers…or it could be that cocaine is a fine powder, and transfer easily from bill to bill. (Especially when being processed through any sort of money-stacking/money-counting system as used by a bank.)

Whatever the cause, it is not hard to find detectable quantities of cocaine in the pocket of anyone who carries cash. (At least, in the U.S. Is the same true in Britain?)

Fred P July 17, 2012 11:42 AM

My immediate thought is fantasy, but if even a much more limited version of this is feasible, think of the implications for medical devices.

mcb July 17, 2012 11:46 AM

This trend toward a molecular surveillance state is not going to stop until we tell our overlords (“Did I say overlords, I meant protectors”) that gut-ripping the Constitution in order to defend us from butt-bombs at bankrupting levels of public expense serves only fill the coffers of the military-industrial-global-war-on-terror-and-still-with-the-ballistic-missile-defense-security complex, and that we’ve had enough. Yup, that’s all it will take…

kashmarek July 17, 2012 11:55 AM

This device (?) doesn’t have to be accurate and it doesn’t have to even be real. It only needs stories like this to get spread around so it can be sufficiently intimidating for DHS and/or TSA use to “buffalo” you into submission. It is more likely that your reaction will make you guilty of something that will take you out. The TSA is just training grounds for the old cold war iron curtain “your papers please” agenda, so everyone (prisoners and guards) know how to behave in such situations.

kashmarek July 17, 2012 11:57 AM

By the way, we are beyond the stage of using technology for good and into the stage of using technology for evil, be it by criminals or government overlords.

Wael July 17, 2012 12:09 PM

@ phred14

For all of it’s imagined roots as a “death ray,” the laser has been an incredibly useful device in remarkably peaceful ways.

Couldn’t agree more…
However, any new technology, or old for that matter, will find it’s way in all purposes — good or evil.

Northern Realist July 17, 2012 12:12 PM

Sounds like BS but if ture, there are several simple defenses:

  • wear gloves
  • walk with your hands close to your side so the underside of your fingers cannot be seen
  • use pastes or creams to alter the ridge patterns
  • saok your hands in warm water until they become “prunish”

Wael July 17, 2012 12:19 PM

@ karrde

Whatever the cause, it is not hard to find detectable quantities of cocaine in the pocket of anyone who carries cash. (At least, in the U.S. Is the same true in Britain?)

If they found sniffles Cocaine in King Tuts’ mummy, chances are they can “find” it anywhere.

Clive Robinson July 17, 2012 2:16 PM

@ Karrde,

Whatever the cause, it is not hard to find detectable quantities of cocaine in the pocket of anyone who carries cash. (At least, in the U.S. I the same true in Britain?)

The “responsable authorities in the UK” (ie the Home Office) don’t tend to make that sort of information as readily apparent as they might (they tend to be very sniffy about things that might potentialy low drug dealer convictions).

That said I’m told that the UK 20GBP note is the one of choice to roll up for “white line” duty as 50GBP notes are treated with great suspicion by the authorities as most places don’t or won’t take them, their main use is money transfer for the black economy or criminal activities.

Now nearly every body in the UK from about the age of 10 has twenties in their pocket, wallet, purse or piggy bank, so contact transmission would be expected to be high.

However I’ve been told (but have no way to verify) that the main cross contamination vector involves the warmth and sweat of the human body as this apparently goes quite happily through the cloth and leather of clothes, wallets/purses and the note paper and takes the cocaine molecules aloong with it very easily…

Wael July 17, 2012 4:11 PM

In light of this information, seems these detection mechanisms could serve as pretext for incriminating anyone — since we all have a detectable trace of molecules of controlled substances…

@ Clive Robinson Messin’ with Clive, and asking for it

I have noticed you may have inadvertantly opened a side channel and briefly leaked some information about your social habits. I latched on your clock like an Alabama tick.

they tend to be very sniffy
Hmmm. Sniffy? Cocaine? “Home Office” consumes the powder?

That said I’m told that the UK 20GBP note is the one of choice to roll up for “white line” duty
However I’ve been told (but have no way to verify) that the main cross contamination vector involves the warmth…

How exactly did you verify the first “I’m told”, Clive? Huh?
Your comments, sir! ducking underneath the desk, in fetal position

MingoV July 17, 2012 4:49 PM

@Clive Robertson: “…So…. untill we know by what method they plan to use to measure the spectra and in what part of the frequency range it’s not possible to call BS or NOT BS…”

They already indicated that they will use lasers in the terahertz range that will pass through clothing. As I noted in my previous comment, the reflected photon patterns of radiation in that range cannot identify specific chemicals. (I did research in my undergrad days on laser raman infrared spectroscopy, and I understand its limitations. The scanner will have more limitations than laser raman IR.)

Scared July 17, 2012 5:31 PM

It was only a matter of time before a couple of tailors arrived and offered the emperors at DHS a device so fantastic they simply had to have it and they paid the tailors more and more money because a lot of research had to be done and anybody that didn’t like the idea must be stupid or unfit for their position.

Wael July 17, 2012 5:57 PM

@ Mingov

(I did research in my undergrad days on laser raman infrared spectroscopy, and I understand its limitations. The scanner will have more limitations than laser raman IR.)

Apparently these technologies have advanced since your undergrad days.
Check out the four suppliers on this link:

Specifically, look at the Proof of concept they claim on this link

If someone claimed they would have such a device ready in two years, I would not call that BS. Your milage may vary…

RobertT July 17, 2012 10:29 PM

@ Mingov

(I did research in my undergrad days on laser raman infrared spectroscopy, and I understand its limitations. The scanner will have more limitations than laser raman IR.)

Mingov, this is not Raman spectroscopy, because you are not looking for stokes / anti stokes lines.

Think about simple vibrational spectroscopy, using absorption spectra to identify compounds. Now I’m not saying this is possible, I’m also inclined to agree that the laser power needed to detect anything at 50 m is enough to literally cook the test subject. BUT this type technology can work in a controlled environment over much shorter distances than the stated 50m.

The real enabler for this technology is shrinking geometries in Semiconductor manufacture. At 45nm get length you can easily get Ft’s of 300Ghz or higher if you use lattice stressing techniques. At the moment 45nm is standard technology for making Cell phone chips (a cell phone chipset sells for under $4)
so today we have cheap CMOS technology that can be used to make amplifiers for the 100Ghz band, within a few years the newer technologies will increase the speed to enable 1000Ghz amplifiers to be easily designed.

Combining low cost Thz processes / amplifiers and high resolution ADC’s with various forms of down-converting detectors will make this whole Thz sensing technology easy within 15 years. Think about how incredible todays cell phones are compared with the candy-bar phones from 1997 (that’s only 15 years ago)

The technology is coming that much is certain, the sensitivity is the only thing in question.

AC2 July 18, 2012 3:27 AM

“The DHS has announced the Next Big Thing in remote scanning. This involves flash-incineration of carefully selected travellers, with subsequent spectroscopic analysis confirming the DHS’ suspicions.

In the unlikely event that nothing suspicious is found an apology and travel refund (less taxes) will be issued.

DHS: Working to make travel safer”

Clive Robinson July 18, 2012 4:34 AM

@ M.V.

This is a common believe which is actually wrong.The microwave oven works with dielectrical heating on liquid water (and other substances). You don’t need water, it is just more effective (probably because it is liquid). Also the frequency doesn’t need to be 2.45 GHz.

The way it was explained to me many years ago was,

“it’s all to do with polar molecules, the H-bond causes an uneven distribution of electrons and the two bonds due to the oxegen atom cause asymitary in the molecule which means that it has a nonsymetrical charge distrubution in one dimension. This causes the molecule where it can to align it’s self with the electric field (dipolar polarisation) of the RF source which as it rotates causes the water molecule to rotate in sympathy. It’s the delay between the field and the molecular rotation that acts as the transducer that causes the RF energy to be released as thermal energy. Whilst the molecule will align with other frequencies below 1×10^10Hz the conversion works best at those that corespond to it’s absorbtion spectrum.”

The explanation went on at some length and mentioned the curious fact that sugar likewise is polar but in it’s usual crystalline form does not have the freedom to align it’s self strongly with the electric field. However when disolved in water it does and the absorbtion spectra changes appropriately, but sugar also disolves in some non polar organic solvents which alows it’s absorbtion spectrum to be more easily seen, importantly this demonstrates it is not an electricaly conductive effect as they are effectivly insulators.

But the important point is the Dipolar Polarisation is one of the underlying mechanisms of the dielectric effect. That is the effect of the electric field on the Polar Molecule and the delay between the field and the molecules rotation, in effect causes temporary energy storage localy (like a streatched spring) it is not an electricly conductive effect like resistive heating (hence it is a property found in many but not all insulators).

Other dielectric effects that cause energy absorbtion from an electric field are ion-drag, distortion polarisation, ionic polarisation and electronic polarisation.

So the dipolar polarisation caused by the OH bond charge asymmitry combind with the bond asymmetry of the oxygen atom (104 degrees if memory serve me right) is a “specific case” of the more general dielectric heating so we are sort of talking about the same thing.

However how the energy stored in a dielectric is released amongst other things determins how effective the electric field heating is in various ways and of what use it may be for other technologies (for instance if the electric field is applied the polarisation occurs when the field is removed “instantaniously” some forms of de-polarisation will just like a spring with a weight on the end oscillate. This oscillitory effect can be used in the likes of imaging technology some what analogusly to MRI. It is an area of research interest currently and I suspect what is of interest in the equipment in question. In paticular ionic and electrical polarisation show this effect from IR to low UV somewhere around 1×10^15Hz all these dielectric effects cease and the constant of free space prevails.

Importantly when ever there is oscillitory behaviour you will find a “resonator” determaning the natural frequency. One of the side effects of resonators is their energy storage effects and the resulting efect the frequency of excitation has on this storage. If you have an “unquenched” resonator and you excite it at it’s resonant frequency the energy stored in the resonantor will increase indefinatly, or in the real world untill some other nonlinear effect comes into play (and quite often the energy is released destructivly). However if the excitation frequency is not that of the resonator natural frequency (or it’s harmonics) the energy will build up and decay at a rate determined by the difference between the two frequencies (which has other interesting side effects as if a very small amount of this energy is “tapped off” it looks just like an amplitude modulated signal). One argument to describe this effect is that the resonator pushes back against the exciting field and in effect puts energy back into the field (some what analogus to the back emf on DC motors also acting as generators etc limiting it’s speed)

However it appearss it is dependant on what is in effect the phase difference between the frequency of the energy stored in the resonator and that of the frequency of the field. This likewise could in theory be used as another method to get information back that could be used for imaging purposes.

Anyway one of the problems with the dielectric effect is it is very complex but subscribes to that bad habit of “having some easy models” that work in some but by nomeans all circumstances and as is often the case in physics they teach you the simple lies (models) first and work up to the more difficult lies as you gain experiance…

Any way if you look back at my original comment to Wael you will note the little story about Dr Jones, and if you read RobrtT’s post above you will note that the technology is moving on a pace. Importantly the result as always will be an improvment in instrumentation. After all think how slow the progress of physics would have been if we were stuck with only the “gold leaf electroscope” and the “moving coil galvonometer”…

Sometimes the problems are quite obscure, for instance currently there are issues to do with the manufacture of broad band artifficial thermal noise sources in the THz range (as well as usable connectors and transmission lines). These are a necesary bit of kit when you are designing and testing low noise amplifers, mixers and other devices that will be needed to efficiently exploit the THz bands. A lack of test equipment in these bands means using up or down converters of known good characteristics which in turn need the LNA’s and mixers etc…

For those new to the field of endevor it’s all exciting stuff and potentialy has many advanatages for niche startups to make it big with the assistance of “angels” (Venture capatalists that supposadly are not “venture vultures”). For some of us older folks we shrug our sholders and let them get on with it as we’ve sort of seen it all befor and we instead look for the interesting oddities that sometimes occure that we’ve not seen before to see if there is anything we can “reflect back” into what we still do. It is this odd mindset which also alows us to make some odd apparently off the wall engeneering predictions which bring forth all sorts of antisurveillance ideas that confound those young whipersnappers and their claims 😉

As was once observed (in French) “the more things change, the more they stay the same”.

M.V. July 18, 2012 5:16 AM


As usual you are a great source of knowledge.
However the dielectric spectrum is very broad and there is no advantage of using excatly 2.45 GHz. You can be cooked in front of an UHF Transmitter quite as well. The 2.45 GHz is just down to regulation. Of course technical reason like the size of the Transmitter have also played a role. To do the same at 500 MHz is just a bit to big for a kitchen appliance.

M.V. July 18, 2012 5:44 AM

Whatever the cause, it is not hard to find detectable quantities of cocaine in the pocket of anyone who carries cash. (At least, in the U.S. Is the same true in Britain?)
The “responsable authorities in the UK” (ie the Home Office) don’t tend to make that sort of information as readily apparent as they might (they tend to be very sniffy about things that might potentialy low drug dealer convictions)

A short google session throws up some data.

One reasearch (from 1999/2000) claims that 99% of all pound notes in London are contamined.

A later research claim that about 40-50% of all pound notes in the UK have traces.
But of course a % number is just a question there you put the limit.

Another research (arround 2007/2008) on the Euro shows that there can be big local differences.

In Spain the Euro notes have an average of 155 µg cocaine, in Germany 30 µg and in Ireland less than 1 µg on them.

I bet that also in the US are big regional differences. In the age of plastic money the bills don’t travel very fast when used in legit trades. These bills have than only small amounts when compared to the bills used by the drug traffikers. (Spain is the main entry point for cocaine into Europe).

Tom July 18, 2012 6:56 AM

In 2008 I was able to follow a lecture on laser physics. The professor was amongst the most-respected in his field. At that time, he held a few records in laser physics. He was also doing a lot of research on THz lasers. And by “a lot” I’m talking about >50 articles.

I’m sure if something like the described device would’ve been remotely possible at that time, he’d have told us. (And he even explained in detail how he was looking for russian MIG engines to build one of the possibly most powerful lasers ever made).

Yes, this was 4 years ago, but I highly doubt progress was made that fast. Thus I call BS!

bob July 18, 2012 6:57 AM

1) Just because its snake oil does NOT mean its not going to become US policy.

2) If there are lots of false positives triggered by legal behaviors you will either a] stop exhibiting those behaviors to stop getting hassled, b] go to jail anyway because they have unlimited amounts of [your!] money to prosecute you with or c] they will outlaw those behaviors for “security reasons”; then goto b.

The only way to fix this is to get it firmly codified in law beforehand that reducing liberty in the name of security is not acceptable. Like that thing we used to have here, what was it called, the constellation, constipation? Something like that.

And as long as people would rather watch NASCAR than CSPAN [although, to be honest, given my choice I’d rather watch yeast rise than our legislator’s doing what they call “work”] what’s left of the country will be stolen right out from under us. I’m not even claiming its the fault of either party, just that the end result is deviating logarithmically from what the Founders had in mind when they set it up.

jacob July 18, 2012 3:19 PM

@bruce. I respectfully disagree. Information filtering and human understanding of what the filter provides limits the application.

Sounds like snake oil to me. Kind of like facial recognition in a moving crowd. It was sold as a way to catch a lot of felons. Not so much. It’s good for a still looking into a camera. Not for moving crowd of faces, hats, sunglasses, etc.

I will believe it is possible when they can tell the difference between baby lotion and explosives from a distance…old news story.

Farts generate methane, a carbon complex…? Shut down a terminal because someone ate eggs and beer? There’s a deadly combination. Or a whiskey drinker expells ketones/etc. on skin? Just random thoughts.

Dirk Praet July 18, 2012 6:42 PM

The real issue here isn’t whether or not this is feasible, but to which extent it is desirable, and at what cost both in terms of money and the type of society we are heading to. As usual, it is not technology that is the main problem, it’s humans.

The rise of a military-surveillance industrial complex is exactly what former president Eisenhower in his exit speech and visionaries like George Orwell warned us about decades ago. Just like German author Heinrich Mann in his 1919 novel “Der Untertan” not only explained how Germany’s political system inevitably had to lead to WWI, but also unwittingly predicted the rise of madman like Hitler as a direct consequence of the average German’s disposition towards authority. It’s pretty much the same as that of the average American today.

I’m often surprised to which point history classes in school have been deprecated in favour of “more useful things”. Forgetting about the past, the inability to recognise the precursors of and the mechanisms behind the birth of an authoritarian state is and always has been the best guarantee for the rise to power of tyrants and their minions.

RobertT July 18, 2012 7:02 PM


Capacitors actually do contribute noise to the signals. As a matter of fact the noise called “kT/C noise” usually sets the resolution limit for most modern ADC’s.

Leading edge High speed ADC’s today have 14bit resolution at say 300Mhz, so you can calculate the minimum cap size (required for matching reasons) and you will see how much noise comes from the cap.

The source impedance sets the maximum size of the sample cap because the input impedance needs to be matched to the source for power transfer reasons. Do then sums and you will see that kT/C noise is a big problem.

At frequencies above about 50Ghz the resistor noise also increases and hooks up noticeably at above 100Ghz. I’m not sure anyone understands the source of this noise properly. I’ve heard lots of hand waving descriptions of this HF noise but nothing that fits the measurements exactly.

Autolykos July 19, 2012 5:04 AM

@Dirk Praet: I’m not sure how effective history classes really are in making people learn from past mistakes. Most people learn the specific cases, but precious few understand the general concepts.
From my history lessons (in Germany), I’m reasonably sure that a blatant Hitler-Ripoff, complete with swastikas and speeches about killing Jews wouldn’t work ever again in Germany. But a more subtle form of fascism and/or racism might still gather lots of followers. Most people won’t see or understand the similarities and/or rationalize them away (“But he is on good terms with Israel.” “I don’t see any swastikas, he can’t possibly be a Nazi.”).

Sam July 19, 2012 3:46 PM

I would mention that while the obfuscation technique suggested by several posters of scattering one of the trigger substances over the wide audience of travelers and employees appears sound in theory, being observed sprinkling any kind of “faerie dust” around an airport facility is likely to have consequences of a terminal nature…

Brian July 19, 2012 6:09 PM

There seems to be a lot of hype about this new terahertz laser lately. It does have the ability to see “through” items and get a depth profile. Is this technology real? yes most definitely, we use it in lab daily. Let us take a step back and ask, what is this, and how does it work.

The Raman effect is an inelastic scattering event. What does that mean? When you hit something with a photon it can do 1 of 3 things, pass through it, be elastically scattered by it (Rayleigh or Raman or Mie scattering), or be absorbed by it. Right now let us ignore pass though and absorbed and look only at scattering. The photon can be elastically scattered, which means the photon leaves with the same energy it came in with. Conversly the photon can be inelastically scattered. In this inelastic scattering, or Raman scattering, the photon leaves with a little less energy (stokes) or a little more energy (anti-stokes) than it had before interacting. The amount of energy it gains or loses are the energies of internal vibrations of the molecule. This Raman spectrum is a molecular fingerprint of the molecule. You cannot fake it. Raman can even detect the presence of isotopes because the extra mass effects the vibrational frequencies.

In order for you to get a good spectrum, you need a narrow bandwidth source. This means you need photons of just 1 wavelength +/- a small amount. The more that +/- grows, the broader the features become until they are no longer observable above the noise.

In 1930 C.V. Raman won the Nobel prize for demonstrating this effect, but it was not very widely used until the advent of lasers (narrow bandwidth light source). This technology is not new. We just have access to a new laser in a new region of the spectrum (terahertz). I am waiting to see the first spectra from it, but has it been done already in the visible? Yes! Standoff? Commercially available from Intevac, named the ObserveR (this is Raman standoff, but not in the terahertz region, its in the IR).

@Petréa Mitchell
“The allegedly similar device created by the Russians claims to scan a volume of air for a specific limited range of substances.” This technology has been around for a while. Infact it has a name LIBS, and it is also Raman based. Here is a good recent article, please read Anal Bioanal Chem. 2011 Jul;400(10):3353-65.

RobertT July 19, 2012 10:00 PM

Are you certain this is Raman spectroscopy?
The problem with Raman is that it is a non-linear effect of the material. This means we need very high intensity excitation signals just to create sufficient inelastic scattering that any measurable amount of Stokes photons are created. On top of this you have a probability of detection problem because the detector covers a small angular area (especially at 50Meters). assuming the stokes / anti stokes photon is expelled into a 4 pie steradian space.

Seems to me that it is easier to look at absorption spectra and intentionally place the detector behind the person.
At the low end of the THz band most clothing would be reasonably transparent. Additionally you could measure the diffraction of the probe beam, this is similar to the way that a medical CT scanner works.

I must admit I haven’t studied this problem so I might be missing something, but for reasons of minimizing the individuals exposure to high field strength THz RF, I’m inclined to believe that Raman is a bad starting point.

John Galt III July 20, 2012 12:57 AM

Some netizens are concerned that this technology would allow the government to subvert privacy in novel ways. That’s probably true, but it has some awesome and legitimate security applications. The laser technology is real, but poorly described. This link was the clearest that I could find: Genia Photonics was founded by folks from the Centre d’Optique Photonique et Laser at Universite Laval. The whole department are really bright. At the Optical Society of America (OSA) meeting in Sante Fe in 2007, one of the COPL folks described a relatively wideband method of generating a laser frequency comb a million times brighter than a blackbody source (incandescent lamp). Such a laser plus a detector is a spectrometer; the detector signal only needs to be decoded to find the intensity as a function of wavelength (a spectrum). The Genia technology mainly involves fiber lasers generating picosecond pulses at telecom wavelengths (1.3 and 1.5 microns) as did the work described in 2007 at the OSA meeting. The magical part is that Genia can tune the wavelength over an 80 nm range at 50 million wavelengths per second, which allows identification of a large number of molecules. These wavelengths really aren’t perfect for detecting molecules, because they are resonant with overtones and harmonics of the molecular vibrations, which are much weaker than the fundamental absorptions in the 8 to 12 micron atmospheric window. Some molecules can be detected with useful limits, but the traces of energetic materials are better left to ion mobility spectrometers (the part where they swab your knapsack and stick the cloth in a machine). To the extent that the TSA are empowered to perform only administrative searches for items dangerous to the operation of aircraft and they follow the rules, I don’t have a big problem with it. Scanning people walking on the street generally would be an unwarranted invasion of privacy. Sorry that I don’t have time to critique the whole thread. There is a lot more to say on many topics, but this will have to do for now.

Richard Heaters July 20, 2012 7:57 AM

Quite apart from the fascinating technical debate, this kind of technology is adding to the slow death of Habeas Corpus and the assumption that people are innocent until they are proven guilty. It also goes against the idea that the authorities should at least have a reasonable suspicion of wrong doing before invading a person’s privacy.

Brian July 20, 2012 1:19 PM


Absolutely positive its Raman. The information from the manufacturer states it in the open.

First, you will not look at the anti-stokes. It is far too weak. An advantage to anti-stokes in the visible is it does avoid contamination from fluorescence. In the terahertz range you are much farther into the red than any electronic transition, fluorescence is not a problem.

As far as power goes, you can get non-first order effects with too much power. Standard procedure is to actually do a power dependence curve for work you are going to publish. We run 1 to 3 mW in the visible normally. That is more than enough to see a signal with a cooled CCD and an efficient spectrograph. Because most explosive materials are white, (in the pure form – I am not discussing plasticizers or other binding reagents) that means they absorb in the UV, so all of the terahertz Raman will be off resonance and the ability to detect one type of molecule over another will be proportional to their Raman cross sections.

Brian July 20, 2012 1:41 PM


They state they use CARS, so I will talk a little about it. CARS (which is just pre saturating specific vibrations to enhance the anti-stokes signal), is a type of Raman. Terahertz is ripe to saturate these vibrations and produce a CARS signal. In fact SINGLE MOLCULE detection has been done with CARS. A big leader in the field is Sunney Xie from Harvard J. Phys. Chem. B 2004, 108, 827-840

The only CARS I have used is Raman shifting. While single molecule spectroscopy has been done in several labs, I do not believe it has reached the commercial level, it is still the realm of research only.

RobertT July 21, 2012 3:11 AM

Thanks for the information. I must admit I’m a bit of a novice when it comes to Raman effects in the THz band.

Unfortunately I’m in the middle of moving house / country, so I have very little free time, and my wife will literally go ballistic if she sees me fiddling with a THz Raman test setup.

I’ve done some CARS experiments in the past and I just happen to have a cooled Hamamutsu CCD camera at home (dont even ask).

Hmmm sounds like an interesting way to spend some quality free time.

jerry July 28, 2012 9:40 PM

I just added a few lines to a blog page
that I titled, “Beyond Orwell’s Room 101 –
Remote Neural Monitoring”. I keep
reminding myself to google anything that
debunks something called the microwave
auditory effect. According to Wiki it has
been expanded over and above just
hearing your own thoughts seemingly
amplified and has been around for many
years. Aka Voice of God tech b/c it is used
to simulate schizophrenia. This is not
urban myth or subliminal suggestion.

Nathanael October 21, 2012 5:54 AM

The key thing, though, is how cheap surveillance is going to get. Governments who are awake are freaking out with the realization that everyone will have this stuff. The “1984”-type possibilities are pretty minor compared to the implication that every single disaffected person or group will have access to these things; they can’t be locked down.

That poses far more threat to governments than it does to citizens. Many of them haven’t noticed; many have noticed and are trying to do the impossible (you can’t make cheap, popular, useful technology illegal; it just doesn’t work).

I don’t really know what the implications of universal surveillance are, but they imply major changes in social attitudes.

Gary Lighting April 25, 2013 5:23 AM

In my opinion the only reason people should fear government surveillance is if they are doing something wrong. Ultimately this is what its for not to check up on peoples day to day lives and little things like dropping litter. Its to pick up patterns of behavior and make the community safer. The more the better IMO.

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