Lasers are key to this new development as T-rays are produced by firing a near-IR laser pulse at a semiconductor optical switching device. Like X-rays they pass through some materials easily but are attenuated by others and can therefore be used much like X-rays for medical and security applications. It is always useful to have a variety of tools at your disposals and one major advantage that T-rays have over X-rays is that being nonionising they are far less hazardous to use. Getting images beyond the visible spectrum is also the topic of ourTutorialwhich deals with the very latest developments in infrared imaging. The early days of pyroelectric vidicons are now giving way to very exotic semiconductors and ferroelectric devices. Not only are the resolutions available from such devices increasing all the time but also the temperatures at which they can operate are getting closer to ambient levels. Devices that had previous required liquid nitrogen cooling can now be operated at 110 K which can be achieved with low cost, and much more user friendly, thermoelectric cooling. In the future it is hoped that operation at 190 K will be possible.

In much the same way that I do not believe anyone would have anticipated a fraction of the applications that have been found for lasers. I also suspect that the future will have much the same to say about Terahertz imaging.

Clive Loughlin

Previously published in: Sensor Review, Volume 23, Number 1, 2002  less