A new conversion approach between different characterization methods to measure the spot size of micro computed tomography systems

Up to date, several different approaches are proposed in standards and guidelines to determine the spatial resolution and the focal spot size of micro X-ray sources. From a metrological point of view, the precise measurement of the focal spot is essential, as this is one of the main factors determining the uncertainty of computed tomography dimensional measurements. Besides the fact that the available standards and guidelines are only specified for spot sizes down to 5 μm, there is no consistency among the results of the different approaches. In this work, two commonly adopted approaches, one using a knife edge and the other one using a resolution test chart with line and radial features, are used to evaluate the focal spot size of a micro X-ray computed tomography system. With the combination of these two methods, it is possible to characterize the focal spot of micro X-ray sources over a broad range of the input parameters consistently. The obtained results show the evolution of the focal spot for different source parameters and can be used to determine the optimal source parameters to be set for a desired resolution. © 2018 CURRAN-CONFERENCE. All rights reserved.