An investigation and review into microwave thermography for NDT and SHM

Infrared (IR) thermography is a fast-growing Nondestructive Testing (NDT) technique. Various sources can be used as the thermal stimulation, such as flash lamps, laser, ultrasound, and eddy current etc. Currently, various quantification methods for defect depth estimation are built based on the surface heating, heat conduction or thermal wave diffusion. Microwave heating is a new heating technique, which has a lot of advantages, such as strong penetrability, selective heating, volumetric heating, significant energy savings, uniform heating, and good thermal efficiency. In this work, the basic principle of microwave thermography (MWT) is introduced. The developments and case studies of microwave thermography are reviewed.