Terahertz imaging has been around for a long time. In fact, around 15 years.
The frequency band for terahertz radiation is located between microwaves and infrared (100GHz to 10THz) and this technique has one important difference to ordinary spectroscopy. Whereas standard spectroscopic techniques only look at amplitude changes, terahertz imaging examines both the amplitude and the phase. This allows more information about the target to be extracted. However, it is far from being applicable to the long-range location of buried objects.
|