Improvement of the resolution in optical imaging systems by interference of against each other inverted image fields

Based on the proposal of Wicker and Heintzmann we demonstrate first for our knowlegde the experimental realization of the improvement of the lateral resolution by adding an interferometer with partial image inversion to the detection pathway of an optical imaging system. Using first a sodium (λ = 589 nm, Δλ = 0.6 nm), further a mercury (λ = 546 nm, Δλ = 6 nm) vapor discharge lamp and finally an arbitrary white light source λ = 625 nm Δλ ca. 300 nm) we could show that the radius of the Point Spread Funktion (PSF) reduces from 1.53 µm by a wide field detection without an interferometer to approx. 0.95 µm applying our system with a numerical aperture of NA = 0.25 of the used microobjective.