Microscopic 3D Surface Imaging With Annular Spectrum Sampling Parallel Single‐Pixel Imaging: Resistant to Global Illumination

ABSTRACT The trend toward device miniaturization and precision manufacturing poses challenges for microscopic 3D surface imaging under global illumination, due to the strong inter‐reflections and subsurface scattering. Conventional structured‐light methods often fail in dealing with such conditions because of their inherent point‐to‐point triangulation rule. Here, we propose a global illumination‐resistant microscopic 3D surface imaging technique based on annular spectrum sampling parallel single‐pixel imaging (ASS‐PSI). By exploiting the point‐to‐plane imaging ability of single‐pixel detection and establishing the global illumination response (GIR) model, the mixed direct and global illumination components can be effectively separated at each camera pixel. Furthermore, an annular spectrum sampling strategy is proposed to mitigate the impact of structured light on illumination interference while enhancing measurement efficiency. With discarding unstable low‐frequency illumination, fewer spectrum coefficients yield higher accuracy, turning “less” into “more” under harsh conditions. Experimental results under strong inter‐reflection and subsurface scattering conditions demonstrate that ASS‐PSI achieves superior robustness compared to the conventional approaches. These advances make ASS‐PSI a promising solution for robust microscopic 3D imaging in advanced manufacturing and biomedical applications.