Evaluating the geometrical error of dimensional X-ray CT to enhance the measurement accuracy

Dimensional X-ray computed tomography (DXCT) is widely used in the manufacturing field because it is the only technology that enables nondestructive measurement of products’ internal features. However, DXCT is less accurate than tactile coordinate measuring machines (CMMs) because DXCT has many error factors. A large influencing factor is the geometrical error of computed tomography (CT) systems. The error sources of DXCT instruments should be evaluated, compensated, and mechanically adjusted to enhance their accuracy. In this paper, the current performance of a CT system was evaluated. The geometrical error of the system was assessed using a laser interferometer. The translational errors of the magnification axis were±4 μm, and its rotational errors were±2 arcsec. Furthermore, the angle error of the rotation axis was ±6 arcsec. These errors will be used for numerical correction and mechanical modification in future research.