Analysis of stray light reflected from multi-beam laser focusing surface

Abstract

In the current research of solving the energy problem, the Inertial Confinement Fusion (ICF) has been studied for many years, which drives the occurrence of nuclear reaction in a multi-beam laser focusing system. And in this system, multiple laser beams in different directions are focused at the same surface to produce sufficient light energy. Generally, if the stray light reflected by the focusing surface returns back toward one of the laser systems and then is focused into ghosts with high energy, the optical components near the ghosts will be influenced or damaged. For each laser in the multi-beam laser focusing system, the influence of internal stray light and the effect of stray light generated by other laser need to be considered. Based on the study of the National Ignition Facility (NIF), analysis of stray light reflected from multi-beam laser focusing surface was proposed in this paper. Modeling and simulation based on the law of light propagation and Monte Carlo analysis were demonstrated. Ray tracing and the analysis of stray light were carried out in the focusing system. The distribution of stray light on the observation sphere and the optimization rules of array structure were obtained. Finally, we got the optimal structure with d = 2 mm and R = 3 mm, which can better meet the requirements of uniformity and back-to-hole energy.