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Production sequence of Si-spheres and interferometrical determination of the sphere volume

Improving the application range and increasing the accuracy of industrial computed tomography (ICT) by radiographic image correction.


In ICT, the usable dynamic range of the X-ray images, i.e. the useful contrast, limits the maximum material thickness and the accuracy of the surface determination. In the EMPIR project "AdvanCT", various influences on radiographic imaging, such as parasitic source regions and light scattering in the scintillator of the detector, were checked and model-based corrections were implemented to then calculate them out of the 2D X-ray projections. The following figure shows exemplary a radiograph of an injection nozzle (material: steel, diameter: 5 mm) before and after correction in color-coded representation. The improvement in the area around the object is clearly visible.

Fig. 1: Radiograph of an injection nozzle (5 mm diameter) without (left) and with correction (right). The color-coded representation highlights the gray value differences in the area around the object to show that there are significantly smaller gray value differences in the corrected image.

The influence of the image corrections on the 3D measurement is currently being investigated. First evaluations showed a significant improvement in the measurement of strongly absorbing objects and the material separation in the multi-material case. For example, it became possible to determine the surfaces accurately down to 1/10 of the voxel size even in the case of an arrangement of overlapping steel gauge blocks.



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