biostudies-literatureLi YNational Natural Science Foundation of China (National Science Foundation of China)93https://www.ebi.ac.uk/biostudies/studies/S-EPMC12852827biostudies-literatureUnknown15(1)Non-destructive and accurate characterization of high aspect ratio (HAR) and composite micro-trenches is critical for advanced microfabrication but remains a major challenge. Conventional coherence scanning interferometry (CSI), while widely adopted, suffers from low signal-to-noise ratio (SNR) and limited lateral resolution when applied to HAR and composite microstructures. Here, we present Fourier ptychographic coherence scanning interferometry (FP-CSI), the first transmissive CSI modality that integrates the aperture synthesis strategy of Fourier ptychographic microscopy with the quantitative phase-resolved capability of interferometry. FP-CSI enables robust three-dimensional morphology reconstruction with enhanced SNR and improved lateral resolution, without reliance on iterative phaseLight, science & applicationsFourier ptychographic coherence scanning interferometry for 3D morphology of high aspect ratio and composite micro-trenches.PMC1285282762327814, 62175107, 62205148Li YWang SYuan QHuo XHe HGao ZfalseFourier ptychographic coherence scanning interferometry for 3D morphology of high aspect ratio and composite micro-trenches.Non-destructive and accurate characterization of high aspect ratio (HAR) and composite micro-trenches is critical for advanced microfabrication but remains a major challenge. Conventional coherence scanning interferometry (CSI), while widely adopted, suffers from low signal-to-noise ratio (SNR) and limited lateral resolution when applied to HAR and composite microstructures. Here, we present Fourier ptychographic coherence scanning interferometry (FP-CSI), the first transmissive CSI modality that integrates the aperture synthesis strategy of Fourier ptychographic microscopy with the quantitative phase-resolved capability of interferometry. FP-CSI enables robust three-dimensional morphology reconstruction with enhanced SNR and improved lateral resolution, without reliance on iterative phase2026-01-01T00:00:00Z2026 Jan2026-06-17T07:05:44.835Z2026-06-17T03:10:24.449ZS-EPMC128528274160591210.1038/s41377-026-02189-6