Modeling and analysis of measurement error for a four-axis optical profilometer

Multi-axis optical profilometers are precision instruments used in optics and aerospace, where geometric errors critically impact measurement accuracy. This paper introduces an approach for error modeling and analysis for a four-axis optical profilometer. Utilizing MBS theory and the HTM method, a measurement error model with forty-five geometric errors is established. Based on the principle of measurement error, a new error sensitivity evaluation index-effective working distance error (WDE_e)-is proposed, taking into account the surface profile of the workpiece. Comparative experiments demonstrate that the measurement results compensated using the proposed method (3.189 µm) are closer to the LUPHOscan reference results (2.985 µm) than those obtained using conventional methods (3.320 µm), thus validating the effectiveness of the approach. This method replaces six traditional volumetric error indexes with a comprehensive index, improving sensitivity analysis and error compensation efficiency and effectiveness, thereby enhancing optical profilometer performance.