Sound-to-light converting devices could detect cancer and terrorists

May 27th, 2010 - 4:25 pm ICT by ANI  

London, May 27 (ANI): Semiconductor devices could one day convert sound into light at tetra hertz frequencies, to provide a privacy-protecting alternative to naked body scanners in airports, according to scientists.

Terahertz radiation occupies the region between infrared and microwave frequencies - a range that can detect skin cancers before they are visible on the surface.

Its sub millimetre-long waves can penetrate fabrics and plastics, but they reflect off explosives and metallic weapons in a characteristic way that can be used to detect such objects hidden beneath clothing - without generating a privacy-compromising image.

It can also identify density differences in tissue caused by nascent skin or epithelial cancers.

Mark Fromhold at the University of Nottingham, UK, and his colleagues have developed a theoretical model which shows how blasting a tiny piece of semiconductor material with high-frequency sound waves could generate such radiation.

The team produced Bloch oscillations, which are usually induced by applying a voltage across the crystal. But in this case they are caused purely by the incident sound in a process that the researchers say has the potential to be much more efficient.

Such a device would require a suitably intense source of sound waves, such as a saser - the acoustic equivalent of a laser - the technology for which has already been developed by Tony Kent, Fromhold’s colleague at Nottingham.

The work is theoretical but commercial applications, while a long way off, are possible in principle, says Arkadii Krokhin, who studies the structure and electronic properties of solids at the University of North Texas in Denton.

“The mathematics is beautiful,” New Scientist quoted him as saying.

“The idea is completely new. I had never heard about making terahertz frequency [light] from sound.” (ANI)

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