ACCURACY STUDY OF A 450 KV CT SYSTEM WITH A CALIBRATED TEST OBJECT

Computed tomography is already a well established technology in medical and material analysis. Also for dimensional metrology applications, CT is a promising technique for measuring internal and external geometries. Nowadays, most industrial CT scanners, use 120 to 225 kV sources. To scan thicker and more absorbing materials, more power is needed. The Nikon Metrology XT H450 has a range up to 450 kV. However the accuracy of these new, more powerful machines has to be investigated. This accuracy study uses a calibrated reference object and simulations, to get a better understanding of the existing errors. This reference object is developed and produced by fixing CMM probing styli on a socket. It has been produced in several materials and used together with simulations to analyze the accuracy of single and multi-material CT measurements. For single material, accuracies up to 10-15 µm are achieved. In the case of multi material this accuracy deteriorates to 70-80 µm. Besides some mechanical errors which cause these deviations, the main factor is the edge detection.