Dealing with Missing Angular Sections in NanoCT Reconstructions of Low Contrast Polymeric Samples Employing a Mechanical In Situ Loading Stage

While in situ experiments are gaining importance for the (mechanical) assessment of metamaterials or materials with complexmicrostructures, imaging conditions in such experiments are often challenging. The lab-based computed tomography systemXradia 810 Ultra allows for the in situ (time-lapsed) mechanical testing of samples. However, the in situ loading setup of thissystem limits the image acquisition angle to 140°. For low contrast polymeric materials, this limited acquisition angle leads toregions of low information gain, thus preventing an accurate reconstruction of the data using a filtered back projection algorithmresulting in erroneous microstructures. Here, we demonstrate how the information gain can be improved by selecting an appro-priate position of the sample. A low contrast polymeric tetrahedral microlattice sample and a structured sample with specificmarkers, both scanned over 140° and 180°, demonstrate that the missing structural details in the 140° reconstruction are limitedto an angular wedge of about 20°. Depending on the sample geometry and microstructure, applying simple strategies for the insitu experiments allows accurate reconstruction of the data. ... mehrFor the tetrahedral microlattice, a simple rotation of the sample by90° rotates all relevant surfaces by about 30° to the original illumination direction, creating a more even X-ray illumination forall the projections, thus providing enough X-ray absorption for an accurate reconstruction of the geometry.