The special properties of terahertz waves include the ability to penetrate electrical insulators such as ceramics, glass, and plastics. This ability has an advantage over the established methods based on x-rays, ultrasound, or thermography, which all have limitations, especially, when assessing modern fiber reinforced plastics. A solution is now available in the form of the mobile, terahertz handheld scanner, which can also examine structures in hard to access places and detect defects in plastics.
Overcoming the Limits of Ultrasound Systems
Many applications demand measuring methods that are suitable for rapid and mobile use. Often, ultrasound is chosen for this reason. Water and gel are common coupling media to minimize the high losses when passing from air to a material. However, this is not possible for ceramics and foams. Fortunately, terahertz-measuring systems are non-contact, require no coupling medium and can even be used to examine hollow structures.