Illumination coherence engineering and quantitative phase imaging.

Partially coherent illumination provides significant advantages such as speckle-free imaging and enhanced optical sectioning in optical microscopy. The knowledge of the spatial and temporal coherence is crucial to obtain accurate quantitative phase imaging (QPI) of specimens such as live cells, micrometer-sized particles, etc. In this Letter, we propose a novel technique for illumination coherence engineering. It is based on a DMD projector providing fast switchable both multi-wavelength and spatial coherence design. Its performance is experimentally demonstrated for QPI with different spatial coherence states.