Enhancement of light intensity related to distribution of defects in the final optics assembly

Abstract

Laser induced damage in the final optics assembly is one of the bottleneck problems in high power laser systems for the inertial confinement fusion. Defects on the optical elements can cause optical intensity intensification and therefore damage the optical elements in the downstream. However, only single defect is considered for most cases. In this paper, physical models are established to study enhancement of light intensity related to distribution of defects in the final optics assembly. Results show that, when the distance of two localized defects reduces to a certain distance, there will be a stronger light intensity intensification duo to the interference effect. What’s more, it will be much more serious when the nonlinear effect is taken into consideration. Meanwhile, the interaction of two kinds of different defects are also studied, i.e., the periodic defect and the localized defect. The optical field will be enhanced to a certain extent at the overlapped area. Thus, we can see that single defect may not cause optical damage. But when there are more than one defect with a certain distribution, light field may be further enhanced, thus damaging the optical element. As a conclusion, the distribution of defects also needs strict constraints. The results could give some references to the mitigation of damage caused by defects in the final optics assembly.