The term Autocorrection was coined by the Werth Messtechnik company with the introduction of the first coordinate measuring machines with computed tomography (CT) in 2005. Thanks to the greatly improved precision of CT, the original multisensor method is now used only for submicron precision measurements, such as for automotive fuel injection systems. Workpieces made of metal are sometimes difficult to capture tomographically since artifacts from beam hardening, cone beam effects, or scattered radiation often have a great influence on the measurement uncertainty. For reasons of efficiency, a somewhat greater measurement uncertainty is often tolerated, or conventional measurement is used.
With Virtual Artifact Correction (VAC), Werth Messtechnik now has a solution for this problem. The comparative measurement using multisensor systems is replaced with calculated simulations under ideal (without artifacts) and actual (with artifacts) conditions. The difference between the two simulations provides the artifact-induced systematic measurement deviations used for correcting the measurement results. The method also leads to good results even if alternative methods (characteristic curve-based Empirical Artifact Correction, or Multisensor Autocorrection) cannot be used due to insufficient initial data. While computed tomography is already an ideal tool for both fast metrological first article inspection, and for general inspection tasks, this new correction methodology opens even more areas of application.