基于响应函数的大口径衍射元件光场调制分析  

Analysis of Light Field Modulation by Large-Aperture Diffractive Element Based on Response Function

作　　者：刘盾 石恒 汪利华[1] 高国涵 范斌[1] Liu Dun;Shi Heng;Wang Lihua;Gao Guohan;Fan Bin(Institute of Optics and Electronics,Chinese Academy of Sciences,Chengdu 610209,Sichuan,China)

机构地区：[1]中国科学院光电技术研究所,四川成都610209

出　　处：《光学学报》2023年第7期1-9,共9页Acta Optica Sinica

基　　金：国家自然科学基金(61905254,62075220);“西部之光”人才培养计划。

摘　　要：针对大口径衍射光学元件快速高精度分析难题,提出了基于响应函数的光场调制分析方法。首先,将衍射元件表面的微结构分解成多个台阶结构;然后,使用严格矢量理论方法计算台阶对入射光场的调制作用,并转化成阶跃响应函数;最后,利用相干合成原理将每个台阶的阶跃响应函数合成为微结构对入射光场的响应。分析了微结构最小线宽、响应函数作用范围和台阶定位误差等对计算精度的影响,并利用所提方法计算了不同口径衍射透镜的近场及远场分布。结果表明,即使存在25 nm的台阶定位误差,透镜远场的最大光强和衍射效率与严格矢量理论计算结果的差异仍然小于2%,同时计算效率提升了至少3个数量级,可见,所提方法可兼顾大口径衍射元件分析的精度与速度。Objective Compared with the traditional optical elements,diffractive optical elements(DOEs)have many advantages,such as light weight,flexible design,and unique dispersion.Greatly promoting the miniaturization and lightweight of optical systems,DOEs are widely used in laser communication,laser radar,space imaging,high-precision optical testing,and other fields.The high-precision analysis of light field modulation by DOEs is a key point in the application of DOEs.However,most optical design software calculates the deflection of light by DOEs with the grating equation model,ignoring the physical structure of DOEs.The quantitative analysis of the comprehensive performance of the system has defects,especially the analysis of energy utilization,stray light,and other performance.The thin element approximation(TEA)model based on the scalar diffraction theory is widely employed to quantitatively analyze the complex-amplitude transmittance,diffraction efficiency,and other properties of DOEs.When the microstructure size of a DOE is larger than 10 times the wavelength,the TEA model can obtain comparatively accurate results.However,the error increases rapidly as the microstructure size gradually approaches the order of magnitude of wavelength.The vector diffraction theory using mathematical tools to strictly solve Maxwell equations is a perfect solution for high-precision analysis of DOEs.Unfortunately,strict vector diffraction calculation involves a large amount of data and is thus generally applicable to smallsize elements only.When the diffraction phenomenon of the microstructures is analyzed by the strict vector diffraction theory,violent oscillation of the light field is only observed at the positions with abrupt changes in height.Due to this phenomenon,the paper equates the effect of step microstructures on light wave modulation with step response functions and synthesizes the modulation effect of the DOE as the coherent superposition of multiple step response functions(STEPRFs).When the incident light wave and the step

关 键 词：衍射 光学元件 光场调制 响应函数 矢量衍射理论 

分 类 号：O439[机械工程—光学工程]