Scattered light noise in gravitational wave interferometric detectors: Coherent effects

Large interferometric detectors of gravitational waves involve high power light beams stored in optical resonators or Fabry-Perot cavities, installed in km long vacuum pipes. Scattering of light by mirrors, interaction of the scattered light with the walls of the vacuum vessel, and final rescattering on any mirror is a source of noise in such antennas. We present some results obtained within the framework of a coherent approach of scattered light propagation using a coherence function allowing us to study, namely, the effects of small reflecting surfaces along the tube, of diffraction, and of reflection by eventual baffle edges.