基于粒子群算法离轴多反光学系统设计

Design of off-axis multi-reflective optical system based on particle swarm optimization

满足像差平衡和多约束控制的初始结构构建,是实现极小像差离轴多反光学系统的设计关键。本文基于空间光线追迹与像差矫正相结合的分组设计方法建立离轴多反的初始结构计算数学模型,提出了一种改进的粒子群算法用以解决离轴多反光学系统的初始结构问题,采用带收缩因子的自然选择的粒子群算法提高了计算精度,提升了设计效率,获取了离轴多反光学系统的初始结构。最后,本文以离轴六反的极紫外光刻投影物镜为例,验证此方法的可靠性和有效性,实现了0.33NA极紫外光刻物镜综合波像差优于1/80λRMS光学系统设计。

An initial construction satisfying aberration balance and multi-constraint control is essential for the design of an off-axis multi-reflective optical system with minimal aberration.In this paper,a mathematical model for calculating the initial structure of off-axis multi-reflective is established based on the grouping design method combining spatial ray tracing and aberration correction,and an improved Particle Swarm Op-timization(PSO)is proposed to solve the initial structure problem of an off-axis multi-reflective optical sys-tem.The PSO of natural selection with shrinkage factor is applied to improve calculation accuracy and design efficiency,so as to obtain the initial structure of the off-axis multi-reflection optical system.In the last part of this paper,taking an Extreme UltraViolet(EUV)lithography projection objective with six-mirror reflective aspheric mirrors as an example,the reliability and effectiveness of this method are verified.A 0.33 numeric-al aperture EUV lithographic objective with wave-front error better than 1/80λ(λ=13.5 nm)RMS is achieved.