TY - GEN A1 - Spranger, Holger T1 - THz-TOF saft & ola for the detection of inherent discontinuities in dielectric materials N2 - T-rays are electromagnetic waves with frequencies between 0.3 and 10 THz. The ability to penetrate dielectric materials makes them attractive to reveal discontinuities in polymer and ceramic materials. THz-Time Domain Spectroscopy Systems (THz-TDS) are available which operates with THz-pulses. In THz-TDS the travelling time (ToF) and shape of the pulse changes if it interacts with the basic material and its discontinuities. Several reconstruction techniques have been already demonstrated in the context of THz-ToF. Nevertheless, tomographic reconstruction procedures, developed for x-ray computed tomography (CT) ap-plications, have been preferably applied. As a result, reliable tomograms could be presented in case of existing minor refraction property differences between the defect and its surrounding material. Nevertheless geometric artefacts could be observed. The strong restriction of the CT application for the inspection of dielectric plastics that engaged us to develop a recon-struction technique that takes refraction into account. A time domain SAFT based algorithm will be presented, which is able to visualize discontinuities properly in dimension and location, if the base materials shape and its refractive index are considered. The algorithm became more challenging in case of multilayer composites. For that reason an Optical Layer algorithm was developed. Measurements on representative samples with a variety of artificially produced small and large size defects will be shown. The calculated tomograms will be demonstrated to discuss and evaluate the benefits and limits of the two different reconstruction approaches. T2 - QNDE 2016 CY - Atlanta, G.A, USA DA - 17.07.2016 KW - THz KW - Synthetic Aperture Focusing KW - Layer Reconstruction KW - FMM PY - 2016 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/37246 AN - OPUS4-37246 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany