Additive manufacturing (AM) technology is not only used to make 3D objects but also for rapid prototyping. In industry and laboratories, quality controls for these objects are necessary though difficult to implement compared to classical methods of fabrication because the layer-by-layer printing allows for very complex object manufacturing that is unachievable with standard tools. Furthermore, AM can induce unknown or unexpected defects. Consequently, we demonstrate terahertz (THz) imaging as an innovative method for 2D inspection of polymer materials. Moreover, THz tomography may be considered as an alternative to x-ray tomography and cheaper 3D imaging for routine control. This paper proposes an experimental study of 3D polymer objects obtained by additive manufacturing techniques. This approach allows us to characterize defects and to control dimensions by volumetric measurements on 3D data reconstructed by tomography.

International audience—In this paper, we present an advanced image processing sequence to perform nondestructive inspection from 3-D terahertz (THz) images. We develop all the steps starting from a 3-D tomographic reconstruction of a sample from radiographs acquired with a monochromatic millimeter-wave imaging system to an automated segmentation, extracting the different volumes of interest (VOI) composing the sample. This leads to 3-D visualiza-tion and dimensional measurements. This inspection is completed by a skeletonization and caliber analysis providing an accurate assessment of the structure, geometry, and morphology of the acquired object. Overall sequence is implemented onto an unique software and validated through different sample analysis

International audienceArt painting diagnostic is commonly performed using electromagnetic waves at wavelengths from terahertz to X-ray. These former techniques are essential in conservation and art history research, but they could be also very useful for restoring artwork. While most studies use time domain imaging technique, in this study, a painting has been investigated using both time domain imaging (TDI) and frequency-modulated continuous wave (FMCW) system in the millimeter frequency range. By applying these systems to a painting of the eighteenth century, we detect and analyze the structure of some defects. This study underlines the differences between FMCW and TDI. We present the advantages and disadvantages of each technique on a real artwork