Robust 3D topography measurement of large-range high-aspect-ratio structures based on dual-domain statistical...

Non-destructive topography measurement of high aspect ratio (HAR) microstructures (e.g., deep micro-holes) over a large dynamic range remains a major challenge in precision manufacturing. While spectral-domain optical coherence tomography (SD-OCT) offers a promising non-contact solution, its application is severely hindered by the complex background and noise inherent to HAR structures. To address this, this study proposes a dual-domain statistical filtering (DDSF) reconstruction method combined with a conventional longitudinal scanning (Z-scan) architecture. Utilizing the statistical features of interference signals, this method achieves the robust extraction of physical interfaces under extreme conditions through wavenumber-domain principal component analysis filtering and spatial-domain Bayesian filtering. DDSF successfully reconstructs the 3D topography of a highly reflective metal micro-hole with an aspect ratio exceeding 8:1, without complex hardware system modifications. Overall, DDSF effectively extends the geometric detection limits of traditional reflective SD-OCT and holds the potential to become a highly reliable, large dynamic range topography measurement tool for industrial HAR structures.