基于正交双向迭代的自由曲面激光光束整形设计(特邀)  

Freeform surface design of laser beam shaping by iteration in two orthogonal directions(invited)

作　　者：叶井飞 朱钰 顾悠扬 詹浣湫 曹书琴 魏建民 宋真真 曹兆楼 郑改革 Ye Jingfei;Zhu Yu;Gu Youyang;Zhan Huanqiu;Cao Shuqin;Wei Jianmin;Song Zhenzhen;Cao Zhaolou;Zheng Gaige(School of Physics and Optoelectronic Engineering,Nanjing University of Information Science and Technology,Nanjing 210044,China)

机构地区：[1]南京信息工程大学物理与光电工程学院,江苏南京210044

出　　处：《红外与激光工程》2023年第7期84-93,共10页Infrared and Laser Engineering

基　　金：国家自然科学基金项目(62005124);江苏省自然科学基金项目(BK20180787);江苏省高校自然科学研究基金项目(18KJB140007);南京信息工程大学大学生实践创新训练项目(XJDC202210300221)。

摘　　要：激光光束整形技术在现代激光工业领域具有重要作用,为了克服传统激光光束整形自由曲面构造中存在法向矢量偏差的局限性,文中提出一种正交双向迭代的自由曲面设计方法。该方法基于能量守恒和斯涅尔定律建立光源与目标面的能量映射关系,通过正交方向坐标点迭代获得自由曲面数据点,同时利用相邻坐标点的均值进行曲面法向矢量修正,从而提高自由曲面的构造精度。设计实例表明,准直入射的激光光束经自由曲面整形反射镜,在特定目标区域内可形成高均匀度光斑。进一步从自由曲面的连续性、拟合精度与面形误差三个方面,与传统设计方法进行了详细对比分析。结果表明,所提设计方法得到的激光光束整形自由曲面连续性与平滑度更好,拟合精度更高;且在加工误差允许范围内,目标面的辐照度均匀性更稳定。Objective In many laser industrial applications,laser beam shaping is an important process to redistribute the laser energy,which is highly essential to obtain uniform or prescribed spatial energy distribution with high efficiency.At present,there are different methods for laser beam shaping,including the grouped aspheric lenses,microlens arrays,diffractive optical elements,liquid crystal spatial light modulator and freeform optical technology.Compared with other laser beam shaping methods,the method using freeform surfaces is beneficial to make the shaping optical system more simplified and more compact.In the current freeform surface construction method for laser beam shaping,the seed curve extension algorithm in one direction has the non-negligible normal vector deviation during the generation of surface sampling points.Therefore,in this paper,a method is proposed to reduce the normal errors to improve the construction precision of freeform reflector for obtaining the highly uniform spatial energy distribution in the target plane.Methods There are mainly three steps for constructing the freeform surface(Fig.2-3).At first,the incident beamand the target plane are divided in grids according to equal energy and equal area.The main purpose of this step isto obtain the one-to-one energy mapping between the light source and the target plane,which is based on theconservation of energy and Snell's law.Then,the initial constraint conditions are set according to therequirements,which are used to calculate the sampling data points of horizontal and vertical curves on thefreeform surface.Finally,according to the results of previous two steps,the sample data points on the unknownfreeform surface can be calculated by iteration together with normal error correction.The averaging approach ofcoordinates of adjacent sampling points in the orthogonal direction is applied to relieve the normal deviations,which is very useful for reducing the normal errors to obtain smooth freeform surface relatively.Results and Discussions The pr

关 键 词：激光光束整形 自由曲面设计 正交双向迭代 法矢修正 

分 类 号：O435.1[机械工程—光学工程]