Composite wavelet decomposition algorithm combined with correlation analysis in white-light scanning interferometry

Abstract

White-light scanning interferometry (WLSI) is a mature and efficient technique that is widely used in the field of high-precision three-dimensional measurements. However, coherence and phase information in the WLSI technique are inconsistent, false height jumps, such as batwings artifact and ghost steps, are typical obstacles in applying WLSI, which distort measurement results and reduce the measurement accuracy. In this study, we proposed a composite wavelet decomposition algorithm combined with a correlation analysis to solve the above two obstacles without having any prior knowledge about the tested sample. Two calibration step plates with heights of 459.8 ± 3.0 nm and 90.5 ± 2.8 nm were used to evaluate the accuracy of the proposed algorithm, and the results were compared with those of Centroid and Fourier transform algorithms. Consequently, the proposed algorithm exhibited a higher correction effect, and the accuracy was improved by more than two times, which proved that our approach could effectively suppress the batwings effect and eliminate the ghost steps.

Keywords

• White-light interference
• Batwings effect
• Wavelet transform
• Correlation analysis