Experiments: X-ray Tomography
A powerful technique in determining the internal structure of closed objects is X-ray computed tomography (CT) or simply, tomography or CT scan. A beam of X-rays is projected on the desired specimen. The radiation transmitted by the specimen is captured by an optical receiver. Images are captured for each discrete rotation of the specimen, and they are reconstructed into a 3-dimensional density map. This map can be used to observe the internal structure and determine its flaws and structural inhomogeneity [5,12,16]. It can also be used to determine minute morphological variations. A Bruker Skyscan 1172 Micro-CT scanner was used to perform this experiment. The specimen here is the 3D printed PLA object using the FFF printer. This is placed using a mount and a paraffin film, so that there is no movement. This film is transparent to X-rays.
It was important to choose an appropriate voltage to keep the power supplied very close to 10 W, so that the X-ray source and the transmitted X-rays from the specimen remains high. A low voltage would result in an inefficient capture of images by the receiver [5,16]. The voltage chosen here was 44 kV. The corresponding current was 222 mA.
When objects were scanned, the captured dataset had 631 horizontal cross section and 1000 vertical cross section slices of images. When it came to the scanning the outer shell, 641 images were captured for pink cones and cylinders, whereas 901 images were captured for the transparent cylinders. The resolution of the obtained images was set to 1K (1000 x 666 ppi for the outer shell, 1000 x 632 ppi for the vertical cross section, and 1000 x 1000 ppi for the horizontal cross sections). The images were captured for all 4 infill levels for natural cylinders, and for both pink cones and cylinders.
References can be found in the Introduction section.