DOI: 10.17586/1023-5086-2020-87-04-44-51

High-precision autofocus using double wedge splitter

He, Wenjun, Huang, Bingkun, Jing Wenbo, Weng, Yue, Yu, Hongyang

Publication in Journal of Optical Technology

For Russian citation (Opticheskii Zhurnal):

Yue Weng, Wenbo Jing, Bingkun Huang, Hongyang Yu, Wenjun He High-precision autofocus using double wedge splitter (Высокоточная автофокусировка с использованием двойного клиновидного светоделителя) [на англ. яз.] // Оптический журнал. 2020. Т. 87. № 4. С. 44–51. http://doi.org/10.17586/1023-5086-2020-87-04-44-51

Yue Weng, Wenbo Jing, Bingkun Huang, Hongyang Yu, Wenjun He High-precision autofocus using double wedge splitter (Высокоточная автофокусировка с использованием двойного клиновидного светоделителя) [in English] // Opticheskii Zhurnal. 2020. V. 87. № 4. P. 44–51. http://doi.org/10.17586/1023-5086-2020-87-04-44-51

For citation (Journal of Optical Technology):

Yue Weng, Wenbo Jing, Bingkun Huang, Hongyang Yu, and Wenjun He, "High-precision autofocus using a double wedge splitter," Journal of Optical Technology. 87(4), 224-229 (2020). https://doi.org/10.1364/JOT.87.000224

Abstract:

We present an autofocus technique that combines focusing technology by using double wedge splitter and computer image processing technology in order to achieve high-precision focusing. The focusing technique we proposed uses a cooperation target (a ring object) as an imaging object. The ring image is divided into two half-ring images by using double wedge splitter, and extract 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 closed-loop real-time 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 now. In this paper, we propose the optical system model, analyze the algorithm flow in details, and verify the feasibility of the focusing method by experiments. The results show that this focusing method has the advantages of high focusing accuracy, easy operation. And the defocusing amount of this technology is within 10 μm.

Keywords:

autofocus, double wedge splitter image, computer aided alignment, high precision

Acknowledgements:

This work was supported by Jilin Province Science and Technology Development Plan Project (No.20160204009GX, No.20170204014GX) and Ministry of Science and Technology Project (2018YFB1107600).

OCIS codes: 260.5950, 120.0120, 080.0080

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