基于组合光栅的光束整形方法研究  

Beam Shaping Method Based on Combined Gratings

作　　者：翟中生[1] 张艺 吕清花[2] 王选择[1] 冯维[1] 熊芝[1] Zhai Zhongsheng;Zhang Yi;Lü Qinghua;Wang Xuanze;Feng Wei;Xiong Zhi(Hubei Key Laboratory of Modern Manufacturing Quantity Engineering,School of Mechanical Engineering,Hubei University of Technology,Wuhan 430068,Hubei,China;School of Science,Hubei University of Technology,Wuhan 430068,Hubei,China)

机构地区：[1]湖北工业大学机械工程学院现代制造质量工程湖北省重点实验室,湖北武汉430068 [2]湖北工业大学理学院,湖北武汉430068

出　　处：《中国激光》2022年第13期60-68,共9页Chinese Journal of Lasers

基　　金：国家自然科学基金(32071457)。

摘　　要：提出了一种基于组合光栅的任意形状光束整形方法。在需要整形的几何形状的内外分别设计不同的光栅并形成相位全息图,将相位全息图加载到相应的光路上就可整形出想要的形状。其中:外部闪耀光栅将入射高斯光束分成0级和非0衍射级,利用光阑阻挡非0级光束,获得所需形状的0级光束;内部光栅分别采用了渐变二元光栅和渐变正交光栅,它们能够改善几何掩模内部区域的能量分布,获得均匀性较好的平顶光束。实验结果表明,该方法可以获得任意形状、边缘陡峭、均匀性高的平顶光束,能量利用率可达43.71%,最小不均匀性为2.12%。该方法在激光加工领域具有良好的应用前景。Objective In most laser processing,Gaussian beam is used,but in high-precision laser processing,shaping beam,as an unconventional beam,can sometimes outperform Gaussian beam.Traditional shaping techniques include using a deformable mirror,a nonpixel optical addressing light valve,and a spatial light modulator(SLM).The nonpixel optical addressing light valve method can generate flattop,ring,square,and triangular beams at the focal plane.Beam shaping with SLM can use Gerchberg-Saxton(GS)method,imaging method,and hybrid holograms.However,simultaneously ensuring the energy efficiency and uniformity of the shaping beam using these methods is difficult.The larger the geometric mask size in the hybrid holograms method,the worse the uniformity.Only when the mask area is small can a flat-top beam with better uniformity be obtained.It is worthwhile to investigate how to implement the shaping method while maintaining high energy efficiency and uniformity.In this paper,we propose a beam shaping method based on combined gratings:external blazed grating(EBG)and internal gradient grating(IGG).The EBG can diffract the beam into different orders,and with the help of an aperture,we can obtain the expected shape with a steep edge.The IGG can change the energy distribution in the inner region of the geometric shape and improve the uniformity by using either gradual binary grating(IGBG,internal graded binary grating)or graded orthogonal grating(IGOG,internal gradient orthogonal grating).We hope that this method will be useful in laser processing where high uniformity of flat-topped beams is required.Methods A pure phase parallel nematic liquid crystal device is used in this study.Among them,the external grating uses a blazed grating,which can divide the incident Gaussian beam into zero and nonzero diffraction orders,and use an aperture to block the nonzero-order beam to obtain the zero-order beam with desired shape.The internal grating uses gradual binary grating or graded orthogonal grating,which can improve energy distribution in t

关 键 词：光束传输 渐变二元光栅 渐变正交光栅 激光加工 

分 类 号：O436.1[机械工程—光学工程]