ROCS microscopy with distinct zero-order blocking

Research in modern light microscopy continuously seeks to improve spatial and temporal resolution in combination with user-friendly, cost-effective imaging systems. Among different label-free imaging approaches, Rotating Coherent Scattering (ROCS) microscopy in darkfield mode achieves superior resolution and contrast without image reconstructions, which is especially helpful in life cell experiments. Here we demonstrate how to achieve 145 nm resolution with an amplitude transmission mask for spatial filtering. This mask blocks the reflected 0-th order focus at 12 distinct positions, thereby increasing the effective aperture for the light back-scattered from the object. We further show how angular correlation analysis between coherent raw images helps to estimate the information content from different illumination directions.