摘要
普通透镜受焦深和焦斑尺寸间制约关系的影响,分辨率与焦深难以协同提升,贝塞尔光束这类无衍射光束虽然在一定程度上解决了焦深与焦斑尺寸的矛盾,但是在焦深范围内的强度不均匀。针对上述问题,本文提出了一种基于空间光调制器的长焦深光束生成方法,其核心思路是在普通透镜聚焦相位的基础上叠加焦点偏移相位来构建沿光轴的多焦点分布,通过动态调整焦点之间的间距抵消能量分散引发的波动,从而避免焦深范围内光强不均匀的问题,同时需要抑制多焦点叠加导致的光斑展宽避免分辨率下降。仿真结果证明,设计的光针焦深为同等数值孔径下普通透镜的12.5倍,聚焦光斑尺寸接近衍射极限,并在实验上利用空间光调制器验证了仿真的正确性。这种长焦深光束的设计在颗粒操控、高密度光数据存储、激光加工、生物成像等领域都有重要应用前景。
Conventional lenses are constrained by the trade-off between depth of focus(DOF)and focal spot size,making it challenging to simultaneously improve resolution and DOF.Non-diffracting beams such as Bessel beams alleviate this trade-off to a certain extent but suffer from non-uniform intensity within the DOF.To address these issues,a method for generating a long-depth-of-focus(LDOF)beam based on a spatial light modulator(SLM)is proposed.The core idea involves superimposing a focus-shifting phase term onto the focusing phase of a conventional lens to construct a multi-focus distribution along the optical axis.Dynamic adjustment of the spacing between adjacent foci counteracts intensity fluctuations caused by energy spreading among the foci,thus avoiding non-uniform intensity within the DOF.Additionally,it is necessary to suppress focal spot broadening induced by multi-focus superposition to prevent resolution degradation.Simulation results demonstrate that the DOF of the designed optical needle is 12.5 times that of a conventional lens with the same numerical aperture(NA),and the focal spot size approaches the diffraction limit.Experimental validation using an SLM confirms the validity of the simulations.This LDOF beam design shows strong potential in fields such as particle manipulation,high-density optical data storage,laser processing,and bioimaging.
作者
李武胜
谭毅
王腾
肖冠张翱
汤东亮
Li Wusheng;Tan Yi;Wang Teng;Xiao Guanzhangao;Tang Dongliang(School of Physics and Electronics,Hunan University,Changsha,Hunan 410082,China)
出处
《光电工程》
北大核心
2025年第12期264-275,共12页
Opto-Electronic Engineering
基金
国家自然科学基金资助项目(62275077)。
关键词
空间光调制器
长焦深
衍射极限
spatial light modulator
long depth of focus
diffraction limit
