应用光栅刻线与CCD测量运动位移的研究

Method for getting movement displacement using standard reticle and CCD

将计量光栅作为标准刻线,应用到对微细物体高精度定位的工作台上,并提出了一种新的直接获取运动位移的方法。调整光路使CCD获取清晰的光栅图像;对图像进行分析处理,计算出栅距与像素之间的映射关系;再对工作台移动前后的光栅图像进行对比,采用基于X-Y图的相位差比率算法获取像素位置差;从而计算出工作台的实际运行位移。实验结果表明,该方法能简单快速地实现微电子加工领域亚像素级的测量。

A new method is put forward to get movement displacement directly when standard reticle of grating is applied to driven worktable whose object is very small for high precise orientation. Firstly, adjust the optical path until grating reticle image can be collected clearly by CCD. Then, analyzing and processing the grating reticle image collected by CCD, we can accurately calculate the mapping coefficient from grid size to pixels. Compare the fore-and-aft two grating reticle images before and after moving the worktable. Adopting phase difference ratio arithmetic based on X-Y graph, we can figure out the phase difference of the two images. The displacement of the worktable can be further calculated by the mapping coefficient. The experiment result shows that this method can easily and quickly implement sub-pixel measurement in micro-electronics manufacture.