Although traditional methods like X-ray, ultrasound, thermography, eddy current, and many others can be very useful, they have their limits when used for structural analysis and anomaly detection, especially, for sandwich or hollow constructions or modern fiber-reinforced or foamed plastics. For example, ultrasound cannot be used to inspect pipes directly after the extrusion process during manufacture; because of the high temperature of the material and the plastic fluid core of the not-yet solidified pipe.
Penetrating Thick Electrical Insulators
In comparison, terahertz technology is a relatively new, non-destructive testing method that is proving especially promising in the field of plastics. The terahertz frequency range is between 100 Gigahertz (GHz) and 10 Terahertz (THz), which corresponds to wavelengths of 3 mm to 30 μm. At this wavelength, special properties include the ability to penetrate electrical insulators made from ceramics, glass, and plastics.