三维形貌测量中自动调焦系统的设计

Design of an automatic focusing system for 3-D topography measurement

在相移干涉显微镜中增加了自动调焦系统,使其快速获取高清晰干涉图像,提高了三维形貌的测量速度和测量精度。调焦系统采用图像自动调焦方法,分别以图像标准差函数和图像最大熵函数作为粗调函数和精调函数。实验表明本系统自动调焦范围扩大到150m,自动调焦精度为0.3m,调焦时间为4-8s。

The measuring speed and measuring accuracy are improved through adding an automatic focusing system to the phase-shifting interference microscope, by which interference images with high definition are quickly obtained. An automatic focusing method for image is adopted in the focusing system. Image standard difference function and maximum entropy function have been used as coarse adjustment function and fine adjustment function, respectively. The experiments show that the automatic focusing range of the system has been enlarged to +/-150靘, automatic focusing accuracy +/-0.3靘 and focusing time 4-8 seconds.