Three-dimensional(3D) model of Gaussian repaired site contained crack or bubble is establishd,and 3D finite-difference timedomain method is used to simulate near-field modulation of 355 nm laser incidence by those defects on fused silica rear-surface.The results show that we should avoid any unrepaired cracks,especially cracks with incident angle of 65°,and the size of bubbles should be less than 5 A.All of the above can contribute to the weakening of the modulation around repaired pit.When crack or bubble ...