We demonstrate in experiment that the resolution of a conventional light microscope can be enhanced by 26% with the help of an image inverting interferometer. In order to prove this statement, we measured the point spread function of the system as well as the resolution of two-point objects. Additionally, the contrast transmission function of the interferometric setup was measured and compared to the results gained with a conventional wide-field microscope. Using the interferometric system, the spatial frequencies near the cutoff-frequency were far better transmitted than by the conventional microscope. Finally, we demonstrate the improved resolution with the help of images of two-dimensional structures.

The impact of the different reconstruction parameters in super-resolution structured illumination microscopy (SIM) onto artifacts is carefully analyzed. They comprise the Wiener filter parameter, an apodization function, zero-frequency suppression and modifications of the optical transfer function. A detailed investigation of the reconstructed image spectrum is concluded to be suitable for identifying artifacts. For this purpose, two samples, an artificial test slide and a more realistic biological system, were used to characterize the artifact classes and their correlation with the image spectra as well as the reconstruction parameters. In addition, a guideline for efficient parameter optimization is suggested and the implementation of the parameters in selected up-to-date processing packages (proprietary and open-source) is depicted.

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