Abstract: An optical element is provided, which is transparent at a wavelength of use ?, and which has a super-hydrophobic nanostructured surface that has an anti-reflection property, the surface having an array of pads. —The pads have a nanoscale width, a height h, an aspect ratio of less than 1/2, and the pitch p of the array is such that p<h and the element comprises a top layer of thickness less than h/5 which covers without discontinuity and conformally the nanostructured surface, the top layer being obtained via a step of annealing at a temperature comprised between 500° C. and 1200° C. and being in a material of a hardness greater than the hardness of the material of said nanostructured surface.