<title>Laterally modulated excitation microscopy: improvement of resolution by using a diffraction grating</title>

TLDR

High spatial frequencies in microscope illumination shift the detectable object spatial frequencies through the objective lens. The study aims to develop a simple method for generating a laterally modulated illumination pattern that, if properly evaluated, can yield higher‑resolution images than flat illumination. A custom diffraction grating was inserted at the conjugate object plane and projected through the objective, and microscopic beads were imaged and analyzed using a Fourier‑space algorithm. The results demonstrate improved resolution.

Abstract

High spatial frequencies in the illuminating light of microscopes lead to a shift of the object spatial frequencies detectable through the objective lens. If a suitable procedure is found for evaluation of the measured data, a microscopic image with a higher resolution than under flat illumination can be obtained. A simple method for generation of a laterally modulated illumination pattern is discussed here. A specially constructed diffraction grating was inserted in the illumination beam path at the conjugate object plane (position of the adjustable aperture) and projected through the objective into the object. Microscopic beads were imaged with this method and evaluated with an algorithm based on the structure of the Fourier space. The results indicate an improvement of resolution.