Gravitational waves have been predicted by Einstein in his General Relativity theory. They are perturbation of the space-time metric and we try to reveal them by laser interferometry. More precisely, gravitational wave detectors are km long Michelson interferometers combined with Fabry-Perot cavities. The network of first generation detectors (Virgo, LIGO, GEO) did not permit a direct detection after several observational runs in coincidence at the nominal sensitivity. A second generation of detectors is in preparation with in particular the European project Advanced Virgo which should have a sensitivity increased by an order of magnitude compared to Virgo. The interferometer mirrors play a crucial role in the Advanced Virgo sensitivity. This thesis is interested first in the thermal lensing effect induced by the high power circulating in the Fabry-Perot cavities for different optical configurations of the interferometer. Then we are interested in the mirrors composing the Fabry-Perot arm cavity from the calculation of the requirements in terms of flatness to the realization of the mirrors flatness and its measurement. The mirror flatness should be sub-nanometric in order to limit the optical losses in the Fabry-Perot cavities to reduce the effect of the shot noise and of the diffused light. We will see the correction of the substrates flatness by the so-called corrective coating technique. Finally, we study the uniformity of the dielectric multilayer coating deposition necessary to obtained high-reflective mirrors. We study in particular the planetary motion of the substrates in the coating machine.
