Terahertz (THz) waves are rays with a frequency between 0.1-10 THz and are commonly referred to as ‘T-rays”.  THz waves can be used throughout a portion of the electromagnetic spectrum between infrared and microwave bands.  Recent advances in high-powered terahertz emitters and sensors have allowed THz imaging to be used for widespread applications.

One of the benefits of using Terahertz imaging as opposed to X-rays is that THz frequencies have low photon energies.  For example, a 1 THz signal has a typical photon energy of 4 meV compared to the range of keV for x-rays, which are on the order of 1 million times greater. T-rays do not subject biological tissue to harmful ionizing radiation, thus making it suitable for medical applications.  Another benefit of THz imaging is that T-rays provide spectroscopic information within the terahertz frequency range, whereas x-rays only provide density images.  The unique vibrational, rotational, and translational responses between the interaction of T-rays and different materials can provided information that is not normally seen in optical, x-ray, and nuclear magnetic resonance (NMR) images.