基于线阵CCD的多表面焦点偏移测量

摘要

Focus drift has a significant effect during long time live cell observations in microscopy imaging,so autofo-cusing is one of the most effective techniques to solve this problem.Active focus drift measurement using surface re-flected signal is the key of auto-focusing,however,there is still a question to precisely measure the drift when multi-surface reflection exists.A measurement method of the focus drift for multi-surface reflection was proposed.The reflec-ted spots were imaged by a linear array CCD,and the spots reflected from different surfaces can be easily separated on the linear array CCD.The weighted centroid method is used to accurately measure the drifts of the spots in defined window.The measurement precisions of the method are 106 nm and 1 1 1 nm under the condition of sample drying and wetting,respectively.%在显微成像过程中,焦点偏移对长时间的活细胞观测等应用有很大影响,自动对焦技术是解决该问题最有效的技术手段之一.反射式的主动式表面偏移测量是显微镜实现自动对焦的关键,但是在存在多个表面反射的情况下如何进行准确的焦点偏移测量仍是需要解决的一个问题.本文提出了一种针对多表面反射的焦点偏移测量方法,该方法采用线阵CCD对反射光斑进行成像,不同表面反射回来的光斑在线阵CCD上可以很好的区分,通过窗口加权质心法够精确地测量所需要的表面反射光斑在CCD上的位移,从而精确测定焦点偏移,在样品干燥和样品湿润的情况下测量精度分别达到106 nm和111 nm.