Gap-matching algorithm with the impCEEMDAN in scanning white-light interference microscopy

Coherence scanning interferometry (CSI) is a common optical measurement method for measuring three-dimensional surface profiles. However, batwings and ghost steps are common obstacles in CSI. In this paper, we proposed a gap-matching algorithm with the improved complete ensemble empirical mode decomposition with adaptive noise (impCEEMDAN) to solve the above two obstacles without any priori knowledge of the surface geometry from the tested sample. A micro-component with 500 nm and 1200 nm step heights and a 10 µm standard step of were used as test samples to evaluate the accuracy of the proposed method. Simulations and experimental results show that this approach can effectively suppress the batwings effect and eliminate the ghost steps. Experiments also confirm that the approach has good accuracy and repeatability.