Si Jia, Feng Zexin, Cheng Dewen, Wang Yongtian
Opt Express. 2021 Sep 13;29(19):29918-29935. doi: 10.1364/OE.431899.
Laser beam splitting by freeform optics is promising but less studied. Instead of directly forming a target spot array, we propose to first convert the input beam into a closely connected Gaussian sub-beam array. All the Gaussian sub-beams have the same optical field distributions which thus can produce identical discrete spots on the target plane. Such a design concept is very beneficial to ensure the consistency for laser processing. Importantly, the introduction of an intermediate Gaussian sub-beam array can reduce diffraction effects when the size of each Gaussian sub-beam is sufficiently larger than that of the corresponding sub-area within the input beam. The desired transformation can be achieved by two typical systems. The first system consists of two plano-freeform lenses. The second system is composed of a plano-freeform lens and a lens with an entrance freeform surface and an exit surface of freeform lens array. The two freeform beam splitting systems can be determined based on appropriate ray mappings among the input, intermediate and target irradiance distributions and a subsequent double-surface construction. Geometrical and physical simulations verify the effectivenesses of the two beam splitting systems.
利用自由曲面光学元件进行激光束分束很有前景，但相关研究较少。我们提议先将输入光束转换为紧密相连的高斯子光束阵列，而不是直接形成目标光斑阵列。所有高斯子光束具有相同的光场分布，因此能在目标平面上产生相同的离散光斑。这种设计理念对确保激光加工的一致性非常有益。重要的是，当每个高斯子光束的尺寸足够大于输入光束内相应子区域的尺寸时，引入中间高斯子光束阵列可减少衍射效应。可通过两种典型系统实现所需的变换。第一种系统由两个平自由曲面透镜组成。第二种系统由一个平自由曲面透镜以及一个具有自由曲面入射面和自由曲面透镜阵列出射面的透镜组成。可基于输入、中间和目标辐照度分布之间的适当光线映射以及随后的双面构造来确定这两种自由曲面分束系统。几何和物理模拟验证了这两种分束系统的有效性。
