For lensless digital in-line holographic microscopy a new state-of-the-art spatial resolution corresponding to an NA of 0.8 is shown based on the tile superposition propagation. The result is proved using a common glass sample carrier with a refraction index of 1.52. Single-shot high-resolution imaging is possible by suppression of coherent reflections in an optimized arrangement using partially coherent laser light illumination.

In lensless digital in-line holographic microscopy, currently applied fast reconstruction techniques use approximations limiting the usable NA for optical resolution. The computational effort for an exact scalar reconstruction with straightforward algorithms depends on the relation between the desired resolution and the given pixel pitch of the detector. So there is a trade-off between achievable image resolution and required computation time. We present an exact reconstruction algorithm that guaranties optimum resolution with affordable computation time. Experimental results show a realized NA of at least 0.62. A 1 megapixel hologram was reconstructed in about 1.5 s.

Digital inline holographic microscopy using a pinhole for sample illumination allows lensless imaging. To overcome restrictions of the sample size and density in the setup additional reference waves are generated by extending the single pinhole to a regular 2D pinhole array illumination. A technique is presented that uses phase shifting between the pinhole waves. Multiple foci with stable phase differences and a phase error (rms) of 0.027 rad generate pinhole waves which illuminate an undiluted, dense blood smear sample. Amplitude and phase images of the blood sample were successfully reconstructed.

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