Gravitational wave scintillation by a stellar cluster
  The diffraction effects on gravitational waves propagating through a stellar cluster are analyzed in the relevant approximation of Fresnel diffraction limit. We find that a gravitational wave scintillation effect - similar to the radio source scintillation effect - comes out naturally, implying that the gravitational wave intensity changes in a characteristic way as the observer moves. 
G. Congedo, F. De Paolis, P. Longo, A. A. Nucita, D. Vetrugno