Design and Characterization of Precise Laser-Based Autofocusing Microscope with Reduced Geometrical Fluctuations

Abstract

The present study proposes a laser-based microscope system in which a precise autofocusing capability is achieved using a position feedback signal based on the distance L between the geometrical center (Xc, Yc) of the image captured by the CCD sensor and the centroid (xcentroid, ycentroid) of the image. The experimental results show that the proposed system has a positioning accuracy of 2.2 μm given a working range of ±200 μm. The autofocusing performance of the proposed system is thus better than that of a conventional centroid-based system, which typically achieves a positioning accuracy of around 5.2 μm.