机器视觉光学系统的复消色差设计

Apochromatic Design of Machine Vision Optical System

根据机器视觉物镜对复消色差和高分辨率的要求,将光学系统分成四个光组,对每组初始结构分别进行优化后再组合,得到透镜组的初始结构。利用Buchdahl色散矢量分析方法对部分玻璃材料进行针对性替换,通过多次优化得到符合光学性能要求的复消色差机器视觉光学系统。系统的焦距为60 mm,半视场角为11°,F数为5.45,像方视场可匹配1″大靶面CMOS相机,且各视场的调制传递函数值在200 lp/mm处均大于0.2。系统在0.707孔径处的残余色差为0.01665μm,满足系统的色差容限。系统的二级光谱为0.08385μm,基本实现了光学系统的复消色差。实验结果表明,Buchdahl色散矢量分析方法在分组设计和透镜系统的整体优化过程中,可为光学玻璃的选择及系统整体优化提供较大的便利。

The optical system is divided into four segments in this study,according to the apochromatic and high-resolution requirements of the machine vision lens,and the initial structure of each segment is optimised independently before being merged to obtain the initial structure of the lens segment.The Buchdahl dispersion vector analysis method is employed to perform targeted replacement of some glass materials,and multiple optimisations are applied to provide an apochromatic machine vision optical system that fulfils the criteria of optical performance.The focal length of the system is 60 mm,the half field of view is 11°and the F-number is 5.45.The image field can match a 1″large target CMOS camera,and each field of view has a modulation transfer function value of 200 lp/mm.At an aperture of 0.707,the system’s residual chromatic aberration is 0.01665μm,which is within the system’s chromatic aberration tolerance.The secondary spectrum of the system is 0.08385μm,indicating that the optical system is apochromatic.The Buchdahl dispersion vector is shown to be effective in the experiments.In the process of grouping design and overall optimisation of the lens system,the analysis method can provide greater convenience for the selection of optical glass and the overall optimisation of the system.