离轴双反射自由曲面激光整形系统的设计

Design of Off-Axis Two-Mirror Laser-ShapingSystem with Freeform Surface

设计了一种离轴双反射自由曲面激光整形系统,不仅可以使输出光束辐照度分布变均匀,而且可以控制输出波前和扩束率。通过设置两个约束条件和初始条件,获得自由曲面上相邻采样点之间的迭代关系,从而计算整个自由曲面上所有采样点。利用软件对系统进行验证,将16mm×16mm的方形高斯束分别整形为80mm×80mm的方形均匀光斑和120mm×20mm的矩形均匀光斑,出射光束均为准直光束。结果表明:方形光斑均匀度为90.74%,光束扩束率为5;矩形光斑均匀度为94.75%,水平方向扩束率为7.5,竖直方向扩束率为1.25。

In this paper,an off-axis two-mirror system that can not only make the output beam irradiance distribution uniform,but also control the output beam wave-front and beam-expansion ratio,is designed for laser shaping.By setting two constraints and initial conditions,the iterative relationship between the adjacent sampling points on the free surface can be obtained,and all the sampling points on the whole free surface can be calculated.We use a software to verify the system,and the 16 mm×16 mm square aperture is transformed into an 80 mm×80 mm square aperture and a 120 mm×20 mm rectangular aperture;the outgoing beams are all collimated beams.The results show that the square spot uniformity is 90.74%,and the beam expansion ratio is 5;the rectangular aperture spot uniformity is 94.75%,and the beam expansion ratios in the horizontal and vertical directions are 7.5 and 1.25,respectively.