An on-axis self-calibration approach for precision rotary metrology stages based on an angular artifact plate

摘要

Precision rotary metrology stages need calibration technology to determine the stage error for the compensation and improvement of angle measurement accuracy. Departing from previous perspectives, we present an on-axis angle self-calibration approach for rotary metrology stages with the utilization of an angular artifact plate. Specifically, the artifact plate with angular mark lines, whose accuracy is not precisely known, is first presented as the assistant tool. Then, the artifact plate is placed in the uncalibrated rotary metrology stage with different alignments to construct independent measurement views. The measurement deviation of each mark line from its nominal angle position is rigidly modeled as a combination of stage error, artifact error, misalignment error and random measurement noise. Based on the circle closure principle and the mathematical definition of axis orientation, the misalignment error of each measurement view can be directly determined by algebraic processing. With the comparison of the different measurement views, transitivity and redundancy can be obtained, and a least-squares calculation law is synthesized to determine the stage error and to meet the challenge of random measurement noise. The designed artifact plate is developed for the explanation of a standard angle self-calibration procedure, and a practical description of how to measure the angular marks of different measurement views is also provided in detail. Computer simulation finally validates that the proposed method can realize the stage error accurately even when there exist various random measurement noises. The proposed strategy essentially provides a novel on-axis angle self-calibration approach with accuracy, simplicity and robustness orientation to meet industrial requirements.