摘要
影栅云纹是物体离面变形和表面形貌测量常用的一种比较简单的方法,用单纯的影栅云纹法即便在最好的光学系统配置情况下测量精度也只有1～100 μm左右,在影栅云纹测试方法中引进相移技术是提高测量精度的主要手段.采用液晶投影仪和数字图像处理技术实现数字影栅云纹测量的准确数字相移,避免了在影栅云纹法中使用结构比较复杂或特制的相移机构.由计算机产生相移条纹图经液晶显示投影,应用实时图像灰度算术相减技术得到数字相移影栅云纹条纹图.该方法具有'基准栅'的栅距和相移步长实时可调,配置高速图像采集系统和图像后处理软件,可将相移技术引入动态测量中,从而提高动态测量的精度的优点.最后的悬臂梁实验结果证实了该方法的有效性.
Shadow moiré is one of the simple optical techniques for topography and out-of-plane displacement measurement. The sensitivity of this procedure is in the range of 1～100μm in best cases. Introduction of a phaseshifting procedure may further give a better resolution. A new digital shadow moiré method with digital phase-shifting based on liquid crystal display （LCD） projector is presented. One of four computer-generated phase-shifting fringe patterns, with using LCD projector, is projected on the surface of object to be tested while all fringe patterns are projected on a plate for generating phase-shifting moiré fringes. The projected fringe patterns are captured in real time by a charge coupled device （CCD） camera. This new method provides many advantages in performing topography and out-of-plane displacement measurement. First, the spatial line pitch and phase step are readily adjusted to suit the measurement precision. Second, the measuring speed is relatively fast and suit for dynamic testing because the digital phase shifting is no time-consuming comparing with other phase-shifting techniques. The experimental result on a cantilever beam well demonstrates the validity of the new method.
出处
《光学学报》
EI
CAS
CSCD
北大核心
2005年第8期1057-1061,共5页
Acta Optica Sinica
基金
国家自然科学基金(10072017)
国家863计划(2002AA404140)资助课题。
关键词
光学测量
数字影栅云纹
数字相移
液晶投影仪
平滑滤波
optical measurement
digital shadow moiré
digital phase-shifting
LCD projector
smooth filtering
