照明倾斜对显微成像系统测量精度的影响

Effect of Illumination Tilt on Measurement Accuracy of Microscopic Imaging System

显微成像系统被广泛应用于对准检测系统中,照明光束倾斜和物方离焦耦合会造成图像位置偏移,进而导致对准精度下降。通过仿真分析,确定了照明光束倾斜与离焦对准偏差的关系,当照明倾斜角度较小时,可通过倾斜物面补偿照明光束倾斜造成的离焦对准偏差,而当照明倾角较大时,需调节同轴照明光路自身的倾斜和偏心,减小系统误差。据此,优化了科勒照明的系统结构,使照明光路倾斜和偏心的调节有效解耦,降低系统集成难度,减小系统离焦对准偏差。

The microscopic imaging system is widely used in alignment detection system.The coupling of illumination beam tilt and object defocus will cause image position deviation,which will lead to the decrease of the alignment accuracy.In this paper,the relationship between illumination beam tilt and the alignment deviation by defocus is discussed through simulation analysis.When the illumination tilt angle is small,the alignment deviation by defocus can be compensated by tilting the object plane or the optical axis.When the off-axis angle of the main illumination light is significant,it is necessary to adjust the tilt and eccentricity of the coaxial illumination light path to reduce the system error.According to this,the system structure of Kohler lighting is optimized to effectively decouple the adjustment of the tilt and eccentricity of the illumination light path,and reduce the difficulty of system integration,and then reduce the alignment deviation by defocus.