一种微米级高度台阶镜面条纹反射的三维测量系统

提出了一种检测微米级高度衍射台阶结构的条纹反射三维检测方法.对条纹反射光路的理论分析表明,合理选择入射光线角度和液晶屏放置角度以及液晶屏像素尺寸等系统参数,条纹反射系统能够分辨微米乃至亚微米级的镜面台阶.实际构建了一套微米级台阶镜面条纹反射测量实验装置;采用四步相移法进行条纹相位解算,运用移动屏幕方法确定反射光线方程,结合三角交汇原理,对待测台阶镜面进行三维重构.实际测量了名义值为5μm和10μm的台阶镜面,测量结果不确定度在0.5μm内,和商业仪器测量结果的偏差<0.5μm,证明了设计方法的可行性.本文结果对于包含衍射台阶结构的光学元件三维测量研究具有一定的借鉴意义.

A Specular Stepped Surface Profile Measurement System Based on Fringe Reflection Principle with Micrometer-level Height Resolution

A fringe reflection three dimensional(3D)profile measurement system is proposed for micrometer-level height stepped mirrors.A systematic theoretical analysis of fringe reflection ray path is conducted,showing that by proper selection of the structure parameters including the ray incident angle,the Liquid Crystal Display(LCD)screen orientation angle and the LCD screen pixel size,the fringe reflection system can resolve micron and even sub-micron level stepped mirrors.A micrometer-level resolution fringe reflection measurement setup for stepped mirrors is constructed,which calculates the fringe phase using the four-step phase shift method,determines the reflected light equation using the moving screen method and reconstructs the 3D shape based on triangulation method.A stepped mirror sample with 5μm and 10μm steps is finally measured.The measurement uncertainty is within 0.5μm and the discrepancy with the commercial system result is less than 0.5μm,which proves the feasibility of the designing method.The result of this paper can be of great reference to the 3D reconstruction study of specular surfaces with diffractive structures.