Mapping and correcting residual flatness errors in optical metrology for high precision surface measurements (Conference Presentation)

Residual flatness errors in optical metrology arise from the dependence of measurements on the sample local slope and position in the field of view, presenting serious challenges for accurate surface characterization of tilted samples. This study maps these errors using measurements of a flat mirror at various tilt angles, correlating residual flatness errors with local slope and position. Models are developed to estimate and correct these errors for arbitrary sample geometries. Experimental validation using a confocal optical profilometer demonstrates the effectiveness of each model in enhancing measurement accuracy and reliability. Our approach improves surface characterization, advancing precision in optical metrology.