[1] [1] Chen Z H, Wang Y, Jiang Y, et al. Grating coupler on single-crystal lithium niobate thin film[J]. Optical Materials, 2017, 72: 136-139.

[2] [2] Wu Hua, Han Mingfu, Guo Xia. Broadband high-efficiency grating coupler based on the tailored artificial equivalent refractive index [J]. Acta Optica Sinica, 2014, 34(11): 52-57. (in Chinese)

[3] [3] Yang Biao, Li Zhiyong, Xiao Xia, et al. The progress of silicon-based grating couplers[J]. Acta Physica Sinica, 2013, 62(18): 254-260. (in Chinese)

[4] [4] Dai M, Ma L L, Xu Y L, et al. Highly efficient and perfectly vertical chip-to-fiber dual-layer grating coupler[J]. Optics Express, 2015, 23(2): 1691-1698.

[5] [5] Bolten J, Hofrichter J, Moll N, et al. CMOS compatible cost-efficient fabrication of SOI grating couplers[J]. Microelectronic Engineering, 2009, 86(4): 1114-1116.

[6] [6] Taillaert S, Laere F V, Ayre M, et al. Grating couplers for coupling between optical fibers and nanophotonic waveguides[J]. Japanese Journal of Applied Physics, 2006, 45(45): 6071-6077.

[7] [7] Li Lichun, Yu Qifeng, Lei Zhihui, et al. High-accuracy measurement of rotation angle based on image[J]. Acta Optica Sinica, 2005, 25(4):491-496. (in Chinese)

[8] [8] Hu Wenchuan, Qiu Zurong, Zhang Guoxiong. Measurement of large-scale space angle formed by non-uniplanar lines[J]. Optics and Precision Engineering, 2012, 20(7): 1427-1433. (in Chinese)

[9] [9] Zhang Wancheng, Ye Zequn. A design of visual identifi- cation technology for accurate winding of optical fiber[J]. Electronics Process Technology, 2015, 36(3): 172-174, 178. (in Chinese)

[10] [10] Fang Qimeng, Feng Di, Yu Wenhai, et al. Positioning method based on image processing for pigtail of polarization maintaining fiber[J]. Optoelectronic Technology, 2018, 38(2): 83-88. (in Chinese)

[11] [11] Sun Wei, Zhang Xiaorui, Tang Hhuiqiang, et al. Lane coordination detection based Hough transformation and least square fitting[J]. Opto-Electronic Engineering, 2011, 38(10): 13-19. (in Chinese)

[12] [12] Huang Zhuo, Chen Fengdong, Liu Guodong, et al. Dark field image registration based on connection vector feature matching method[J]. Infrared and Laser Engineering, 2018, 47(11): 1126005. (in Chinese)

[13] [13] Kumar B K S. Image fusion based on pixel significance using cross bilateral filter[J]. Signal Image and Video Processing, 2015, 9(5): 1193-1204.

[14] [14] Wang Linhua, Yuan Minghui, Huang Hui, et al. Recognition of edge object of human body in THz security inspection system[J]. Infrared and Laser Engineering, 2017, 46(11): 1125002. (in Chinese)

[15] [15] Gao J W, Xie H T, Zuo L, et al. A robust pointer meter reading recognition method for substation inspection robot[C]//2017 International Conference on Robotics and Automation Sciences, 2017: 43-47.

[16] [16] Sun Fengjie, Guo Fengshun, Fan Jieqing, et al. Studies of the recognition of pointer angle of dial based on image processing[J]. Proceedings of the CSEE, 2005, 25(16): 73-78. (in Chinese)

[17] [17] Zhang T Y, Suen C Y. A fast parallel algorithm for thinning digital patterns[J]. Communications of the ACM, 1984, 27(3): 236-239.

[18] [18] Zhang Cun， Lei Junfneg， Guo Yong, et al. The real-time measurement of the rotation angle[J]. Opto-Electronic Engineering, 2016, 43(3): 16-22. (in Chinese)

[19] [19] Liu Bin, Wang Jianping, Li Xiaofeng. Perspective projection error in visual inspection of the LAM OST focal plane[J]. Machinery & Electronics, 2010(5): 11-14.

[20] [20] Meng Libo, Jin Guanchang, Yao Xuefeng. Errors caused by misalignment of the optical camera axis and the object surface in the DSCM[J]. Journal of Tsinghua University(Science and Technology), 2006(11): 1930-1932, 1936. (in Chinese)