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November 02, 2006

Breakthrough in focusing terahertz radiation

T-ray applications are presently limited by the relatively poor ability to focus the rays, which is achieved using the conventional means of lenses and mirrors to focus the radiation. This limits the spot size of focused T-rays to a substantial fraction of a millimetre and this has made studies of small objects such as biological cells with high resolution are virtually impossible.

Making a simple meta-material wire with grooves help focus the t-rays. The researchers found that although ordinary metal wire would not guide T-rays very well, if a series of tiny grooves was cut into the wire, it would do so much more effectively. If such a corrugated metal wire is then tapered to a point it becomes possible to very efficiently transport radiation to a point as small as a few millionths of a metre across.

This might, for example, lead to breakthroughs in examining very small objects such as the interior of biological cells where it might be possible to detect diseases or abnormalities. T-rays could also be directed to the interior of objects which could be useful in applications like endoscopic probing for cancerous cells or explosive detection.

Metal wire ordinarily has a limited ability to allow T-rays to flow along it, but this is overcome by corrugating its surface with a series of grooves, in effect creating an artificial material or ‘metamaterial’ as far as the T-rays are concerned.

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