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通过数值模拟研究了高功率激光驱动器的光束均匀辐照情况,分析了三倍频激光辐照下小焦斑的光强分布及空间功率谱.采用透镜列阵可降低光束近场畸变的影响并控制靶面焦斑的包络形状;采用二维光谱色散匀滑技术可明显地消除焦斑内部大反衬度的强度调制,且该方法在焦斑非常小的情况下也仍然有效.大量的数值模拟结果表明,光谱色散匀滑技术应用于尺寸不同的焦斑时,其效果是有差异的.对大焦斑而言,光谱色散匀滑主要抹平其内部细密的条纹,即消除中高空间频率范围的强度调制;对小焦斑而言,光谱色散匀滑主要消除中低空间频率范围的强度调制,故将影响焦斑的整体包络形状.本文所得的数值结果对间接驱动实验中激光束匀滑方案的选择和优化具有参考价值.
The uniform beam irradiation of high power laser driver was studied by numerical simulation and the light intensity distribution and spatial power spectrum of the small focal spot irradiated by triple frequency laser were analyzed.The influence of the beam near field distortion Control the envelope shape of the focal spot of the target surface, and the intensity modulation of the large contrast inside the focal spot can be obviously eliminated by adopting the two-dimensional spectral dispersion smoothing technique, and the method is still effective when the focal spot is very small. The simulation results show that the effect of spectral dispersion smoothing technique is different when applied to different size of focal spots.For large focal spot, the dispersion of spectral dispersion mainly smoothes its internal fine stripes, that is, eliminates the middle and high spatial frequency For the small focal spot, the dispersive dispersion of the spectrum mainly eliminates the intensity modulation in the middle and low spatial frequency range, so it will affect the overall envelope shape of the focal spot.The numerical results obtained in this paper are useful for the analysis of the laser beam The selection and optimization of the smoothing scheme have reference value.