Dynamic focusing in low-coherence quantitative phase imaging with decoupling of spatio-temporal coherence gating and geometric focusing

Abstract

We describe an approach for arbitrarily adjusting the focal positions in quantitative phase imaging (QPI) based on a Linnik interferometer. Our setup employs a unique sample configuration in which transparent objects are imaged by a Linnik interferometer. By introducing a focus-tunable lens on top of the Linnik interferometer, we successfully decoupled the spatio-temporal coherence gating from the focal positioning and achieved dynamic focusing without disturbing the optical path length. Depth-sectioned quantitative phase images of polystyrene beads and live cultured cells were obtained without mechanical scanning.