Multi-energy image stack fusion in computed tomography

Abstract

In the past years computed tomography (CT) was adopted to manufacturing metrology rapidly. Due to the main benefit that lies in the volumetric model generated for each measurement object, many application possibilities from non-destructive testing to coordinate measurements of inner and outer features are possible in much shorter time without destroying the sample. However, some limitations apply to the application of CT. First, it is not possible to measure objects of high aspect ratios (ratio width to thickness) as the changing material thickness influences the remaining intensity after the radiation passed through the workpiece. Secondly, parts consisting of different absorbing materials cannot be measured as only the high absorbing components are acquired with a good signal-to-noise ratio, i.e. with high accuracy and low measurement uncertainty. As high radiation energies are necessary to assure remaining intensities greater than zero in the radiographs, low absorbing components are outshone and not visible after reconstruction. The fusion of multi-energy stacks has been developed to deal with these issues. The approach and first measurement results are shown here.