T-rays vs. terrorists

This paper discusses terahertz radiation technology (T-ray) that will probably find its first big uses in security-related applications, an enormous fast-growing business because of recent high-profile terrorist attacks.The technology appeal here is undeniable: in a terahertz image, a gun or a knife shines through whatever clothing it´s concealed in - even a plastic knife shows up, because of the way its sharp edges scatter the radiation. And yet, unlike X-rays, T-ray screeners could be used routinely on people, because the radiation is harmless.