Self-referenced digital holographic microscopy

By developing a self referenced digital holographic microscope it becomes possible to record holograms and numerically reconstruct volumetric images of low coherence fluorescent objects such as (auto)fluorescent biological samples (e.g. algae). Our goal was to develop and construct a simple, compact portable device. In contrast to the common holographic approaches where there is a conventional reference beam, a reference beam should be produced together with the object beam from the same fluorescent source via imaging it by two separate optical paths (with near zero path length differences) to get interferences fringes. These interference forms separate holograms of all the point sources. The waves coming from the separate sources are mutually incoherent but have an inherent short coherence length. Initially we have tested the self referenced digital holographic microscope setup with test objects illuminated by LED light source that has similar spectral bandwidth as the fluorescence sources like chlorophyll. Digital reconstructions of the measured holograms need considerable processing. To accelerate the hologram processing a parallel implementation of processing seems essential. Using GPU-s we were able to enhance the algorithm's speed considerably, without the loss of the reconstruction accuracy.