Terahertz Imaging System for Composite Material Assessment

The goal of this project is to develop a terahertz-based instrument for performing Nondestructive Evaluation of composite structures that could be used during all phases of the life of the material. All phases of life of a composite part means – during manufacture (both pre- and post-cure), damage evaluation and bonded repair evaluation. Terahertz radiation, or “T-ray” imaging, offers a new approach for nondestructive evaluation (NDE) and detection of foreign objects in manually constructed composites. T-Rays possess many useful properties that prove advantageous over other NDE techniques. These characteristics include: the ability to "see-through" many opaque materials, non-ionizing emission, and no requirement for a coupling medium or index matching fluid. Furthermore, the coherent generation of the T-ray pulse permits multiple signal detection modes, including phase, amplitude, and spectral. A terahertz instrument has the potential for detecting a wide range of composite defects, including incipient heat damage, embedded debris, voids, delaminations, and blunt impact damage hidden beneath composite coatings such as paint and epoxy. This Phase II proposal focuses on addressing the technical challenges associated with developing new terahertz (THz) imaging techniques and constructing a field-testable prototype terahertz imaging device to be installed and tested at a composite manufacturing facility.