Lensless digital holographic microscopy (LDHM), as one of key computational microscopy techniques, performs high throughput in silico imaging. Numerical propagation of digitally recorded in-line Gabor holograms allows for accessing both amplitude (absorption) and phase (refraction) contrast, devoid of microscope objective limitations, e.g., in depth of field and field of view. The in-line coherent holographic framework induces inherent twin image errors and various coherent artifacts, however. The signal-to-noise ratio of reconstructed holograms additionally deteriorates due to low photon budget environment, favorable in terms of time-lapse photostimulation-free bioimaging of live cells. In this contribution, we discuss several techniques for minimization of LDHM reconstruction errors, with the emphasis on simultaneous validation of phase measurement fidelity via calibration target testing. Crafted using two-photon polymerization, our targets enable large field of view phase imaging verification and assess the efficacy of the 3D printing method itself. We also present bio-applications of enhanced LDHM in dynamic (migrating neural cells) and static (brain tissue slices) scenarios.
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