Application of partially coherent light in live cell imaging with digital holographic microscopy

The main drawbacks of laser-based digital holographic microscopy (DHM) are coherent noise and disturbances due to parasitic reflections in the experimental setup. To overcome some of these problems, investigations on the performance of partially coherent light in DHM-based live cell imaging were carried out. First, the impact of different partially coherent light sources on the formation and the reconstruction of digital off-axis holograms was analyzed. Therefore, the achieved lateral resolution and the accuracy for the detection of optical path length changes were compared to results obtained with laser light. In additional experiments, we investigated if partial coherent light can be utilized in DHM for quantitative phase contrast imaging of living cells in incident light configuration by using light from specifically selected reflective sample interfaces. The obtained results show the applicability of partially coherent light in off-axis DHM and its use to for the reduction of disturbances due to coherence effects. Furthermore, it is demonstrated that quantitative DHM phase contrast imaging of phase objects can be performed with experimental arrangements in which an illumination of the sample in transmission due to geometric conditions is not possible.