[2] CAO Yongpeng, XIN Chunhui, PAN Qingsong. Study on auto-focusing searching algorithm applied to integrated camera[J]. Journal of Applied Optics,2018, 39(4): 483-490.

[3] Erasmus S J, Smith K C A. An automatic focusing and astigmatism correction system for the SEM and CTEM[J]. Journal of Microscopy, 1982, 127(2): 185-199.

[6] YU X, YU R, YANG J, et al. A Robotic Auto-Focus System based on Deep Reinforcement Learning[C]//2018 15th International Conference on Control, Automation, Robotics and Vision (ICARCV), IEEE, 2018: 204-209.

[7] CHEN R, Van Beek P. Improving the accuracy and low-light performance of contrast-based autofocus using supervised machine learning[J]. Pattern Recognition Letters, 2015, 56: 30-37.

[8] ZHANG Y, LIU L, GONG W, et al. Autofocus system and evaluation methodologies: a literature review[J]. Sens. Mater., 2018, 30(5): 1165-1174.

[11] SHA X, LI W, LV X, et al. Research on auto-focusing technology for micro vision system[J]. Optik,2017, 142: 226-233.