[1] A E SIGEMAN. Unstable optical resonators for laser application. Proceeding of IEEE, 53, 277-287(1965).

[2] Jingrun LI, Mudi XIONG, Zengbao ZHANG. Optical cavity self-collimation research method based on image processing. High Power Laser and Particle Beams, 32, 051002(2020).

[3] Mudi XIONG, Sinan JIA, Zengbao ZHANG et al. Three-point collimation technology of COIL resonator. High Power Laser and Particle Beams, 19, 1812-1816(2007).

[6] LÜ Fengnian, Daizhong LIU, Renfang XU et al. Performance of image processing in automatic alignment system. Optical Technique, 31, 335-337(2005).

[7] Ruihua XU, Junhua HE, Wei WANG et al. Automatic alignment algorithm of high-power laser beam. Acta Photonica Sinica, 44, 0214002(2015).

[8] Hong LI, Jianqiang ZHU, Qiang LIN et al. Laser beam fast automatic alignment system for high power laser facility. Acta Photonica Sinica, 44, 1014002(2017).

[9] Peiying ZENG, Baoqiang ZHU, Jianqiang ZHU. Alignment image optimization based on ant colony algorithm. Laser & Optoelectronics Progress, 59, 1011001(2022).

[10] C TOMASI, R MANDUCHI. Bilateral filtering for gray and color images. ICCV, 839-846(1998).

[11] N OSTU. A threshold selection method from gray-level histograms. IEEE Transactions on Systems, Man, and Cybernetics, 9, 62-66(1979).

[12] Sumin YIN, Jingping ZHU, Zusheng WANG et al. Research on image segmentation method based on top-hat transformation and Otsu. Science Technology and Engineering, 14, 60-64(2014).

[13] Changgao ZHAO, Lei ZHANG, Fengbo WU. Application of improved median filtering algorithm to image denoising. Journal of Applied Optics, 32, 678-682(2011).

[14] H RADIM, J FLUSSER. Numerically stable direct least squares fitting of ellipses(1998).

[15] Yan XU, Weifeng AN. Visual SLAM based on the improved RANSAC algorithm. Journal of Tianjing University(Science and Technology), 53, 1069-1076(2020).