Validation of the network method for evaluating uncertainty and improvement of geometry error parameters of a laser tracker.

Five National Metrology Institutes (NMIs) worked together to validate the assessment of laser tracker's (LT) uncertainty for large scale dimensional metrology in subsequent measurements using the network method. The LT uncertainty is assessed by measuring a set of a fixed network of targets from different LT positions. Afterward, we must perform a "bundled adjustment" of all the measurements to determine the transformations of the LT positions that minimize the residuals (differences) between a computed "virtual" group of targets, called composite points, and the redundant targets coming from the LT positions transformed to a unique LT position.