Abstract: The mirror comprises a multilayer structure, at least one of the component layers of which is made from a piezoelectric material, and electrodes for applying voltage to the multilayer structure. A free face of the multilayer structure carries the reflecting surface of the mirror. At least one of the outer faces of the mirror comprises at least one zone of curvature which is non-zero in the non-excited state of the multilayer structure.

Abstract: A method for eliminating small-scale, spatial intensity fluctuations in laser beams is disclosed comprising the steps of placing in the path of the laser beam at least one nonlinear filtering element constituted by a fluid medium, having an index of refraction increasing with the intensity of light passing through the fluid medium and focusing only the laser's small-scale, spatial intensity fluctuations above a predetermined power threshold at a focal point within the fluid medium whereby the energy contained in these fluctuations is dissipated. Alternatively, the nonlinear filter element can be constituted by a fluid medium wherein high-frequency sound waves propagate with low attenuation wherein only the small-scale, spatial intensity fluctuations above a stimulated Brillouin power threshold are back-reflected whereby the energy contained in those fluctuations is eliminated.