Abstract

We present an autofocus technique that combines focusing technology by using a double wedge splitter and computer image processing technology in order to achieve high-precision focusing. The focusing technique we propose uses a cooperation target (a ring object) as an imaging object. The ring image is divided into two half-ring images by using a double wedge splitter, which extracts their edge information for curve fitting to obtain the center of curvature of the two half rings so we can calculate the deviation distance between the two half-ring images. The control system uses the deviation distance as feedback, and the real-time closed loop adjusts the relative position of the secondary imaging system and the double wedge splitter so that the deviation distance is the smallest and the defocusing amount is also the smallest. In this paper, we propose the optical system model, analyze the algorithm flow in detail, and verify the feasibility of the focusing method by experiments. The results show that this focusing method has the advantages of high focusing accuracy and easy operation. The defocusing amount of this technology is within 10 µm.

© 2020 Optical Society of America

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