在惯性约束聚变(ICF)终端光学聚焦系统中,采用取样光栅将透射的高功率三倍频光按约0.5%的效率进行聚焦采样,送入能量计中进行诊断。提出了用取样光栅对结构取代单取样光栅,通过合理选择系统参数,包括两块光栅的距离、光栅倾斜角度等,设计出的消像差取样光栅可同时进行能量诊断、光脉冲响应测量、以及远场光斑质量的检测。计算结果显示:光程差从8.3 cm降低到8.7 mm,像点的均方根半径为0.777 μm,达到衍射极限和使用要求。这为ICF系统中激光能量、波前畸变的诊断提供了一种可供选择的新诊断装置。

Beam sampling gratings are used to sample the high-power transmitted light with an efficiency of 5% which is sent into an energy meter for energy diagnostics in the final optical focusing system of ICF.This paper proposes the structure of grating pair instead of single one.The designed grating is aberration-free by choosing system parameters properly,including the distance between two gratings,inclination angle,etc.and can be used for energy diagnostics as well as pulse response and far-field image quality measurements.The calculated results show that the optical path difference decreases from 8.3 cm in the case of single grating to 8.7 mm,and the root mean square radius of image point is 0.777 μm,which reaches the diffraction limit and can meet application requirements.