Nondestructive Inspection of Glass-Fiber Reinforced Plastic (GFRP) Composites with Photonic Terahertz Radar

We present high-resolution thickness measurement and volumetric imaging of multilayer glass fiber-reinforced plastics (GFRP) composites. For our investigations, we use a previously developed, broadband terahertz photonic frequency-modulated continuous wave (FMCW) radar with 1.65THz modulation bandwidth. The performance of the terahertz photonic FMCW radar has previously been shown to exhibit submillimeter precision for layer thickness measurements with a range resolution of 90 m in vacuum. Here we combine multilayer thickness measurements with volumetric imaging for defect detection purposes, for example, for the detection of delaminations of the individual layers of sandwich radomes for 5G applications.