Local Optimization of Wave-fronts for optimal sensitivity PHase Imaging (LowPhi)

Phase contrast microscopy is an invaluable tool in the biosciences and in clinical diagnostics. However, its sensitivity varies significantly across a given sample because it is optimized for one specific mean value of the sample induced phase shifts. Here, we demonstrate a technique based on wavefront shaping that optimizes the sensitivity across the field of view and for arbitrary phase objects. We show significant sensitivity enhancements, both for engineered test samples and red blood cells. Our technique adds on naturally to commercial phase contrast microscopes, reduces imaging artifacts, and, once initialized, allows for quantitative single-frame phase microscopy.