High-speed terahertz imaging system uses Rydberg atoms
(2 April 2019)
A new imaging system that uses a laser-excited, room-temperature atomic vapour to convert terahertz radiation to visible light has been created by researchers at the University of Durham in the UK. The system can acquire terahertz images rapidly and efficiently using a conventional high-speed camera and the new technique could make it easier to develop practical technologies that use terahertz radiation.
Terahertz radiation lies in the region of the electromagnetic spectrum between infrared light and microwaves. In principle, it has great promise for a wide range of applications including security screening, medical imaging and industrial quality control. However, generating and detecting electromagnetic radiation at 0.1-10 THz remains an ongoing challenge. Several competing techniques are used for different applications, but they all have disadvantages – and this lack of practical technologies is often referred to as the “terahertz gap”.
So why bother with terahertz radiation when the remaining electromagnetic spectrum is available? Durham’s Kevin Weatherill explains, “It’s a region in which many everyday materials such as paper, plastics and cloth are transparent so, as with X-rays, you can image things that are optically opaque. But being low-energy, the radiation is non-ionizing and therefore safe for biological and medical applications – though it still has a sufficiently short wavelength for reasonably high-resolution imaging.”