Side-lobe free 4Pi-Microscopy

In 4Pi-microscopy, the wavefronts of two opposing high aperture objective lenses are coherently added in the focal plane and/or at a common detector point. The net result is a 3-7 times sharper main focal maximum representing a similar improvement of the axial resolution of far-field fluorescence microscopy. However, the main maximum is also accompanied by axial sidelobes of 25-50 % height that lead to imaging artefacts, unless the image data is mathematically postprocessed for sidelobe removal. Therefore 4Pi-imaging has always required the mathematical postprocessing of its raw image data. Here we will discuss a new implementation of 4Pi-microscopy that synergistically combines high aperture angle lenses with a new embedding medium. The observed side-lobes are < 10% of the main maximum, meaning that deconvolution is basically no longer required. As a side-effect, phase adjustment is greatly simplified due to the strongly peaking intensity at the preferred constructive-constructive 4Pi mode of type C.