Abstract : This PhD work focuses on the resolution improvement of far-field optical microscopy. We have studied and developed different techniques that take advantage of the relationship between the sample, the illumination and the diffracted (or emitted) field, in order to increase the final band-pass of the image beyond that imposed by the diffraction phenomenon. In In these approaches, several images of the same sample are recorded under different illuminations. An inversion algorithm in then used to reconstruct a super-resolved map of the sample from the set of measurements. This concept is first applied to coherent microscopy. In tomographic diffraction microscopy, many holograms of the same unstained sample are obtained under various incidences and the quantitative map of permittivity of the sample is reconstructed numerically from the set of data. The resolution is usually better than that of classical wide-field microscopy. We show theoretically and experimentally that, far from being a drawback, the presence of multiple scattering within the sample can, if properly accounted for, lead a to an even better resolution. We then study structured illumination fluorescence microscopy. We present two different ways for improving this method. The first one takes advantage of an inversion algorithm, which is able to retrieve the fluorescence density without knowing the illumination patterns. This algorithm permits one to replace the periodic light pattern classically used in structured illumination microscopy by unknown random speckle patterns. The implementation of the technique is thus considerably simplified while the resolution improvement remains. In the second approach, we propose to replace the coverslip on which the sample usually lays, by a sub-lambda grating. The latter is used to form, in near field, a light grid with sub-diffraction period that is able to probe the finest details of the sample. The design, fabrication and optical characterization of this key structure are detailed.