Terahertz Waves for Non-Destructive Evaluation (NDE)

Terahertz (THz) (0.1–30x10 12 Hz) imaging is a proven method for investigating a wide variety of materials and structures [1]. Its use has proven attractive for numerous application areas due to its non-contact and non-ionizing nature. The fact that terahertz (THz) imaging is non-destructive coupled with its ability to not only penetrate a wide variety of materials (Fig. 1), but also characterize them, yields a technique better suited for certain applications as compared to other competing technologies such as xray and ultrasound imaging. It has recently been demonstrated that the use of THz imaging can be advantageous in art renovation and restoration efforts [4]. The use of THz imaging for NDE purposes has also been demonstrated for use in materials and structures including fiberglass composites [5], paint coatings [6], and the foam insulation used on the space shuttle [7].