Various fields of experimental science are constantly requiring smaller resolution for optical microscopy. In this thesis are presented several works for improving resolution in fluorescence microscopy and in Tomographic Diffraction Microscopy (TDM), an emerging phase microscopy technique. In the first part it is shown that one can improve the axial resolution in depositing the sample on a mirror. In confocal fluorescence microscopy, this is done by shaping the illumination beam with a Spatial Light Modulator. In TDM this is done by adapting the reconstruction method. Then algorithms are proposed for reconstructing high-resolution images from structured illumination measurements with unknown illumination fields, both in fluorescence imaging (blind-SIM algorithm) and in TDM. This allows a dramatical simplification of the experimental set-ups in fluorescence structured illumination and the image reconstruction of high optical index samples in TDM.
