摘要
针对基于SMT技术生产的PCB板产品的三维缺陷检测问题,设计了一款高分辨率、高远心度及低畸变的双光路双远心光学系统。它通过远心投影物镜经共光路物镜将DMD数字条纹均匀投影至待测物面,同时经由共光路物镜和成像物镜收集物面反射条纹光至CMOS接收面。使用ZEMAX光学软件分别对三部分镜组进行优化设计,分析了系统的像差和调制传递函数。设计结果表明:共光路物镜部分采用长工作距离、大视场角及物方远心结构,空间频率50lp/mm处,各视场的MTF接近衍射极限;投影光路畸变小于0.1%,在投影面上全视场范围MTF在6lp/mm处大于0.8且条纹周期均匀;成像光路畸变小于0.05%,在全视场范围MTF在80lp/mm处大于0.3。仿真成像结果表明,在离焦量为+/-6mm时仍能达到景深范围内分辨率要求,能有效提高3D AOI检测质量。且双光路双远心系统所用材料基本为普通玻璃且重复率较高,利于加工和节省成本。
According to the 3D Automatic Optical Inspection(AOI)of print circuit boards(PCB)produced by surface mounted technology(SMT),the design of a bi-telecentric optical system with high resolution,high telecentricity and low distortion was introduced.The fringes produced by digital micro-mirror device(DMD)are projected uniformly onto the object plane by telecentric projection lens and common-path lens.Concurrently,the reflected fringes are collected to CMOS by common-path and imaging lens.The three parts of the system designed and optimized respectively by ZEMAX and their aberration and MTF were analyzed.The design result shows that the common-path lens have long work distance,large field of view(FOV)and object telecentic structure,the MTF of each FOV approaches the diffraction limit at50 lp/mm.The distortion of projection path is less than 0.1%,its MTF at 6 lp/mm is more than 0.8 in the whole FOV and the fringe period is uniform.The distortion of imaging path is less than 1%,its MTF is more than 0.3 at 80 lp/mm in the whole FOV and the reflected fringes remain clear within a depth of focus of+/-6 mm.The optical system can effectively improve the test quality of 3 DAOI.Besides,ordinary material was used in the system in order to facilitate machining and cut costs.
作者
韦晓孝
李雪宸
万新军
张薇
WEI Xiaoxiao;LI Xuechen;WAN Xinjun;ZHANG Wei(School of Optical-Electrical Information and Computer Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China)
出处
《光学技术》
CAS
CSCD
北大核心
2020年第1期14-19,共6页
Optical Technique
基金
上海市科技创新行动计划项目(19511104600).
关键词
应用光学
光学设计
双光路结构
双远心镜头
高分辨率
投影
applied optics
optical design
two-path configuration
bi-telecentric lens
high resolution
projection
