Breaking the Resolution Barrier in Incoherent Structured Illumination Microscopy via High‐Modulation Coefficient Mapping and Principal Component Analysis (PCA‐iSIM)

Abstract Structured illumination microscopy (SIM) is a widely used super‐resolution technique that provides sub‐diffraction resolution with low phototoxicity and high photon efficiency. While incoherent SIM based on digital micromirror devices (DMDs) enables compact and cost‐effective system design, it traditionally emphasizes sectioning over lateral resolution and faces a fundamental barrier: due to severe attenuation of high spatial frequency components by the system's optical transfer function (OTF), fringe visibility and modulation depth are significantly reduced. As a result, the achievable resolution enhancement in practical incoherent SIM is typically capped at , falling short of the demands of modern super‐resolution microscopy. In this work, this barrier is broken by introducing PCA‐iSIM, a novel reconstruction framework based on high‐modulation coefficient mapping with principal component analysis (PCA). PCA‐iSIM effectively resolves the challenge of illumination parameter estimation under weak fringe modulation, substantially improving reconstruction performance, particularly under high spatial frequency illumination. Moreover, by leveraging PCA's dimensionality reduction and noise suppression capabilities, PCA‐iSIM enables efficient, real‐time super‐resolution imaging even in complex experimental conditions. Experimental results demonstrate that PCA‐iSIM achieves a resolution gain exceeding 1.9 (corresponding to an effective resolution of 100 nm), along with real‐time reconstruction at 30 Hz on a compact optical platform. With its compact footprint, algorithmic robustness, and low hardware complexity, PCA‐iSIM offers a flexible and cost‐effective solution for high‐performance super‐resolution imaging in resource‐limited and field‐deployable environments.