Reduction of the influence of parasitic interferences and coherence induced disturbances in digital holography-based quantitative phase microscopy by modulation of the object illumination with an electrically focus tunable lens

In digital holographic microscopy (DHM) scattering patterns and parasitic interference fringes due to internal reflections that are caused by coherent laser light affect quantitative phase imaging (QPI). We present an approach for the reduction coherence induced disturbances. Therefore, the sample illumination is modulated by an electrically focus tunable lens while a series of digital off-axis holograms is recorded from which subsequently averaged QPI images are retrieved. The principle is compatible with Mach-Zehnder interferometer-based off-axis DHM and capable to be integrated into commercial research microscopes. The performance of our approach is demonstrated by results from living porcine epithelia cells and mouse fibroblasts.