A self-calibration algorithm is described that allows testing the out-of-plane error motion of two-dimensional profiling stages by using a flat artifact whose accuracy is unknown. The algorithm suppresses artifact-related calibration errors in consideration of the geometrical congruence of three separate profile measurements taken with different orientations of a single artifact. Usefulness of the self-calibration algorithm is verified through computer simulation as well as actual experimental testing. Test results show that the calibration accuracy is free from artifact imperfection and only minimally affected by random measurement errors encountered during the process of calibration. (C) 2004 Elsevier Ltd. All rights reserved.