针对惯性约束聚变(ICF)激光等离子体诊断系统应用的需求,提出一种采用非线性相位拟合法设计单透镜代替理想对数轴锥镜的方法。对所要得到的球面透镜与理想对数轴锥镜的相位进行拟合,求解得出所需要的球面透镜参量。设计了用于激光等离子体诊断系统的长焦深透镜,并对透镜的焦深、轴向光场均匀性、横向均匀性、焦斑旁瓣等指标进行分析。数值分析结果表明,长焦深透镜具有与理想对数轴锥镜相同的相位分布,焦深、轴向光场均匀性、横向均匀性、焦斑旁瓣均符合设计要求,验证了非线性相位拟合法的正确性。

For requriement of plasma diagnostic system in inertial confinement fusion (ICF) drivers, simple lens which can be substituted for logarithmic axicon is designed by nonlinear-phase fitting method. Required sperhical lens parameters are determined by fitting the phase of sperhical lens and logarithmic axicon. A long-focal-depth lens applied for plasma diagnostic system is designed, and the optical performance of lens is analyzed, such as long focal depth, homogeneous axial , transverse intensity distribution and side lobe of focal spot. Numerical results show that long-focal-depth lens has the same phase distribution with logarithmic axicon, its optical performance can satisfy the requirements of plasma diagnostic system, so the nonlinear phase fitting method is valid.