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光束取样光栅(BSG)是一种重要的用于光束取样诊断的衍射光学元件.在惯性约束聚变(ICF)终端光学系统中所使用的BSG,强激光产生的近场调制可能导致其自身的激光诱导损伤从而造成元件不能继续正常工作,为了对其在强激光条件下的正常运行提供分析的依据,采用傅里叶模式理论对BSG内部的近场调制特性进行了模拟计算.计算结果表明,BSG基片内部调制度较小,但仍然存在光强分布不均的情况,增加了这些位置产生激光诱导损伤的风险.另外,通过对BSG制作误差分析得出了其近场调制随各种制作误差的变化关系,结果表明BSG刻槽深度误差比占空比误差对光束近场调制的影响更大,但只要刻槽深度误差不超过一定值,其调制度仍然保持在较小的水平,因此BSG仍能较好地在ICF驱动器中工作.
The Beam Sampling Grating (BSG) is an important diffractive optical element for beam sampling diagnostics. The BSG used in inertial confinement fusion (ICF) termination optics, the intense laser-induced near-field modulation, may cause its own laser In order to provide the basis for the analysis of its normal operation under strong laser conditions, the near-field modulation characteristics of the BSG are simulated by using the Fourier mode theory.The calculation results show that the BSG The internal modulation of the substrate is small, but there is still the uneven distribution of light intensity, which increases the risk of laser-induced damage at these positions. In addition, the errors of BSG fabrication are analyzed and the errors of near-field modulation The results show that BSG notch depth error has more influence on beam near field modulation than duty cycle error, but the modulation degree of BSG remains at a small level as long as the groove depth error does not exceed a certain value. Therefore, Still working well in ICF drives.