X-Ray Computed Tomography for Dimensional Metrology

X-ray computed tomography (CT) has emerged over the last years as an innovative dimensional measuring technique and has been increasingly applied in industry. This chapter describes the state of the art, the main technical characteristics, and examples of applications of CT in industrial dimensional metrology. Although still in its youth, metrological CT offers unique solutions and provides several advantages in comparison to other coordinate measuring systems such as tactile coordinate measuring machines. In particular, CT systems allow reconstructing holistic three-dimensional models of the scanned workpieces, which are then used to obtain nondestructive and noncontact measurements of outer as well as inner features. However, important drawbacks still limit a wider acceptance of CT in industrial metrology. One of the most critical aspects is the establishment of metrological traceability, which is often challenging due to many and complex error sources that affect CT measurements and complicate the evaluation of metrological performances and of task-specific uncertainties.