The next generation of airport security

The next generation of scanners, based on terahertz lasers, may be far more efficient, but also raises some privacy concerns


Ever since the rise of “skyjackers” in the 1970s and much more so after 9/11, airport security and efforts to screen out harmful materials have seen several generations of technology come and go. Simple (and sometimes unmanned) magnetron metal detectors have given way to baggage X-Ray machines and backscatter scanners, all of which are arguably ineffective in keeping out unwanted materials.

The next generation of scanners, based on terahertz lasers, may be far more efficient, but also raises some privacy concerns.

Terahertz radiation is on the extreme upper limit of the portion of the electromagnetic spectrum associated with light, almost into the microwave band. As used in this application, it’s very low power and non-ionizing (read: it won’t give you cancer), so it’s reasonably safe. It uses a variation on Raman spectroscopy called coherent anti-stokes Raman scattering (CARS) to interact with molecules which give off detectable vibrations consistent with their composition.

In short, it identifies substances by light alone, and at a distance.

Typical Raman spectroscopy applications have the scanner a few inches from the target, but terahertz lasers can work from as far as 50 meters (164 feet) away. This technology would allow security personnel to check not only people coming through the checkpoint on the way to a plane, but potentially everyone who entered the airport facility. It also is not limited to explosives or another narrow category of materials. Terahertz lasers can potentially find a single flake of cocaine or virtually any other substance, even if it’s hidden under a layer of clothing or two.

Placed at the entrance to a stadium or a courthouse, the system could identify people showing traces of contraband materials, to include the components of a cell phone or recording device.

At the current stage of development, it’s more likely the device would alert the operator on who to search, rather than exactly where on their person the target substance was located. Of course, this could get a lot better as the technology is packaged for marketing and refined.

There are other possible applications for this technology, especially in medicine. Certain cancers and other diseases produce metabolic byproducts that are barely detectable, even if you know what you’re looking for. A terahertz scanner could look for all of them, non-invasively, and possibly without even having to undress. Hello, Star Trek.

Expect the invasion-of-privacy community to condemn these machines. People going through a metal detector or backscatter imaging system know they are being scanned. It’s entirely possible that people whose pocket and purse contents were inventoried by terahertz lasers wouldn’t know about it until the cop taps them on the shoulder. It’s a scenario not too far removed from the film Minority Report, where scanners at storefronts captured the retinal patterns of people passing by, and instantly tailored ads enticing them to come into the store.

If implemented, this technology will almost certainly be tested on a constitutional basis. In the 2001 case of Kyllo v. U.S., the U.S. Supreme Court banned the use of thermal imaging devices to detect heat patterns indicative of a marijuana grow operation from outside the home. One could argue that the same legal theory applied to a non-consensual search of one’s person while in a public place, using a terahertz laser scanner.

Another concern is one of cost.

When the Transportation Security Administration (TSA) was created in the wake of the Twin Towers, Pentagon, and Shanksville attacks, billions were spent on X-Ray and magnetron metal detector equipment that wasn’t thoroughly vetted and tested prior to purchase.

In the intervening 11 years, much of this equipment has been scrapped and replaced, sometimes by equipment that also has not been sufficiently tested and evaluated for suitability. It’s been a horribly wasteful process that many critics say has not done anything to improve aviation security, although it’s been highly successful in creating angst and resentment among the traveling public. Depending on how costly these new systems turn out to be, we could be looking at yet another generation of discarded equipment replaced by still-unsuitable gear.

I can only hope the TSA and other early adopters will be a bit more cautious this time.

About the author

Tim Dees is a retired police officer and criminal justice professor. He has been writing on criminal justice technology issues for virtually every U.S. police publication and commercial website since 1988. Tim holds a bachelor’s degree in biological science from San José State University, and a master’s degree in criminal justice from The University of Alabama. He serves on the executive board of the Public Safety Writers Association.

He can be reached at tim.dees@policeone.com.

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