连续相位板面形特性对远场分布的影响

惯性约束聚变(ICF)系统打靶对焦斑的大小及能量分布均匀性都有明确的要求,在连续相位板设计过程中要同时兼顾这两个方面。研究了连续相位板的面形与远场焦斑光强均匀性间的关系,从理论上推导了元件表面调制深度与焦斑尺寸的关系,并进行了定量计算。结果表明,焦斑半径随连续相位板的面形调制深度线性增加。鉴于连续相位板具有的随机特性,比较了不同相位板远场特性的区别,研究了面形调制深度对其光强峰谷值和均方根值的影响,结果表明不同设计的连续相位板,远场特性有较大的不同。当面形调制深度在5~15个波长时,焦斑具有较低的光强峰谷值和均方根值,连续相位板具有较好的束匀滑效果。

Influence of surface characteristics of continuous phase plate on far field distribution

The ICF system has strict requirements on the focal spot size and intensity distribution uniformity during the design process of continuous phase plate(CPP). The relationship between CPPs surface and the light intensity uniformity of far field focal spot is studied, and the influences of CPPs surface modulation depth on the size of focal spot are analyzed and calculated theoretically. Results show that the growth of the radius of focal spot is in direct proportion to the increase of the surface modulation depth of CPP. For the sake of random behavior of CPP, the difference of far field characteristics between CPPs is compared, and the influences of modulation depth on the peak-valley and root mean square value of light intensity are studied, which shows that the differently designed CPP has different behavior in far field. When the modulation depth is around 5 to 15, the focal spot could have a relatively low peak-valley and low root mean square value, which means that the CPP is in good smoothing performance.