Terahertz waves, a hand held device, privacy concerns, seeing through walls

By | December 18, 2009

Alexey Belyanin focuses his research on terahertz, otherwise known as THz or T-rays, which he says is the most under-developed and under-used part of the electromagnetic spectrum. It lies between microwave radiation and infrared (heat) radiation.

Belyanin, associate professor in the Texas A&M Physics Department, has collaborated with colleagues at Rice University and the National High Magnetic Field Laboratory to publish findings about their T-ray research in the renowned journal “Nature Physics.”

“THz radiation can penetrate through opaque dry materials. It is harmless and can be used to scan humans,” Belyanin says. “Unfortunately, until recently the progress in THz technology has been hampered by a lack of suitable sources and detectors.”

Belyanin and his team have offered hope: The researchers are able to control the T-rays by varying external parameters like temperature or magnetic field, making it possible to build THz sensors, cameras and other devices.

Traditionally, powerful photons from visible or near-infrared laser pulses are used to probe semiconductors, knocking electrons out of the atoms. Belyanin and collaborators use the less powerful T-rays instead, which only excite the waves in the electron gas because T-rays do not have enough energy to knock out electrons. …

via Physicist Sees With “T-rays” – Texas A&M University News & Information.

Related:

“T-rays” have been touted as the next breakthrough in sensing and imaging, but the need for bulky equipment has been an obstacle to reaching the field’s potential. Enter Brian Schulkin, winner of the first-ever $30,000 Lemelson-Rensselaer Student Prize. Schulkin has invented an ultralight, handheld terahertz spectrometer — an advance that could help catapult T-ray technology from the lab bench to the marketplace.

Related:

ScannerA camera that can “see” explosives, drugs and weapons hidden under clothing from 25 metres has been invented.

The ThruVision system could be deployed at airports, railway stations or other public spaces.

It is based on so-called “terahertz”, or T-ray, technology, normally used by astronomers to study dying stars.

Although it is able to see through clothes it does not reveal “body detail” or subject people to “harmful radiation”, according to the designers.

“It is totally and utterly passive – it receives only,” said a spokesperson for Thruvision.

The portable camera, which has already been sold to the Dubai Mercantile Exchange and Canary Wharf in London, will be shown off at the Home Office scientific development branch’s annual exhibition later this week.

“T-rays” may make X-rays obsolete as a means of detecting bombs on terrorists or illegal drugs on traffickers, among other uses, contends a Texas A&M physicist who is helping lay the theoretic groundwork to make the concept a reality. In addition to being more revealing than X-rays in some situations, T-rays do not have the cumulative possible harmful effects. – bbc

Related:

http://xenophilia.com/wp-content/uploads/2009/12/woman-scanned-with-terahertz.jpgX-ray cameras that would “undress” passers-by in a bid to thwart terrorists concealing weapons, could be coming to a street near you, according to reports.

Aside from the obvious privacy issues, would such a plan work?Leaked documents said to have been drawn up by the Home Office and seen by the Sun newspaper say cameras which can see through clothes could be built into lamp posts to “trap terror suspects”.

While Home Secretary John Reid has denied knowledge of the plans, the technology is not dissimilar to that already found in some UK airports. Currently, air security officials pick out individuals to stand in a booth while three pictures are taken of the person in slightly different positions.

Within seconds, an X-ray scanner produces an image of the body, minus the clothes. What shows up is the naked human form and anything that may be concealed on the person, such as coins, a gun or drugs.

There are other variations on the X-ray technology. Millimetre wave machines give more of a three-dimensional image, while terahertz radiation also penetrates clothing. …

the US military are trialling millimetre wave machines at military checkpoints to combat the threat of suicide bombers. The use of cables mean they can be operated from any distance.

bbc

I’ve long wondered how much can our best satellites can see. Can they spot and track individual people, even through walls?

When the Hubble Satellite was launched in 1990, the joke was that it was the third best optical satellite in space, but that the two better ones were pointed in the opposite direction. While it is still true today that more satellites are looking downward than upward, satellites are now much more likely to include sensors for other than just the optical portion of the electromagnetic spectrum. They now involve many other bands, including millimeter-waves, for specific data collection tasks. – encyclo

On the ground some devices may see through walls, but this device uses radar, not T-waves.

Regulars here know about the problems faced by innovators whose ideas do not conform to the FCC’s technical rules.A recent case in point is L-3 CyTerra, a division of L-3 Communications Corporation. Its new radar device, intended for police, fire, and homeland security personnel, can look through walls to detect people on the other side – even immobile hostages or unconscious fire victims.

Most civilian radars use the same principles worked out during World War II. They emit a short pulse of radio waves at some frequency and analyze the echo to deduce the direction, the distance, and possibly the speed of the target. The FCC routinely approves this kind of product.

But that approach would not do the job for L-3 CyTerra. It is easy enough to send a radar pulse through a wall and into a room on the other side. Coming back, though, would be dozens of echoes bouncing off multiple walls, furniture, and people, with no way to sort them out.

Instead, the L-3 CyTerra device sends pulses on 200 different frequencies, one at a time, ranging in sequence from 3101 to 3499 MHz at 2 MHz intervals. The whole cycle repeats 54 times per second. Each of the pulses still reflects from multiple surfaces. But the circuitry combines the echoes at different frequencies in such a way that the echoes from stationary objects fade into the background while those from moving objects stand out. The system is sensitive enough to detect the chest motions of a person who is unconscious but breathing, or the slight swaying of a person trying to stand perfectly still. … – link

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