Rapid, high-resolution phase reconstruction of off-axis holograms from rare samples

By applying digital holography, it is possible to examine a volume up to a hundred times larger than with a traditional microscope. Until now, we have used a Gábor Dénes type in-line hologram measurement setup for this purpose. Due to the geometry of the setup, the reconstructed image is always contaminated by the so-called twin image diffraction. In digital holography, these can be eliminated using phase reconstruction methods, thus recovering the phase and amplitude distribution of the objects. Unfortunately, the applicable mathematical procedures, especially in cases that allow high resolution, are very slow. This is why the so-called off-axis setups were introduced. In this case, phase recovery and filtering of the contaminating terms are simpler, but only a small part of the recorded hologram can be used for reconstruction, reducing the field of view and resolution. We previously developed a method whereby data from an off-axis measurement can be effectively used for fast phase reconstruction of the same object obtained with in-line measurement, resulting in significantly faster phase retrieval and thus much higher resolution and field of view. Until now, the algorithm required two measurements, making it impossible to measure moving objects.

The aim of the research is to develop a measurement setup and algorithm that allows for fast, accurate, and high-resolution phase retrieval of stationary objects using a single off-axis hologram. Our goal is to extend the applicability of our algorithm to other measurement setups, for example, for efficient shape measurement of transparent cells in tissue cultures.