Optimized coherence parameters for high-resolution holographic microscopy
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- Petruck, P., Riesenberg, R. & Kowarschik, R. Appl. Phys. B (2012) 106: 339. doi:10.1007/s00340-011-4787-6
A holographic in-line microscope setup with a glass sample carrier commonly uses a coherent laser light source, with the disadvantage of an incomplete suppression of disturbing interferences and coherence-induced noise.
We use temporally partially coherent and spatially partially coherent illumination in the micrometer range of 5 to 100 μm generated by spectrally and spatially filtered light-emitting diodes (LEDs) and tungsten filament lamps. It is shown how errors in reconstructed holograms are decreased by a factor of more than two and the spatial resolution reaches the limit as determined by the numerical aperture. A straightforward model is developed to investigate the effects of partial coherence. The optimization of the coherence parameters improves the imaging quality up to the limit of a conventional microscope.