[1] Gao Sitian. Research for metrological atomic force microscope [D]. Tianjin: Tianjin University, 2007.

[2] Hignette O, Woch J, Gotti L. Large-bandwidth deep-UV microscope for CD metrology[C]//Microlithography'90, Intern-atonal national Society for Optics and Photonics, 1990: 79-90.

[3] Bodermann B, Buhr E, Ehret G, et al. Optical metrology of micro-and nanostructures at PTB: status and future developments[C]//Ninth International Symposium on Laser Metrology, International Society for Optics and Photonics, 2008: 71550V-71550V-12.

[4] Ehret G, Pilarski F, Bergmann D, et al. A new high-aperture 193 nm microscope for the traceable dimensional characterization of micro-and nanostructures[J]. Measurement Science and Technology, 2009, 20(8): 084010.

[5] Attota R, Silver R. Nanometrology using a through-focus scanning optical microscopy method[J]. Measurement Science and Technology, 2011, 22(2): 024002.

[6] Ehret G, Bodermann B, Mirandé W. Quantitative linewidth measurement down to 100 nm by means of optical dark-field microscopy and rigorous model-based evaluation[J]. Measurement Science and Technology, 2007, 18(2): 430.

[7] Groen F C A, Young I T, Ligthart G. A comparison of different focus functions for use in autofocus algorithms[J]. Cytometry, 1985, 6(2): 81-91.

[8] Zheng Yuanyuan, Jiang Wei. Research on a new auto-focusing algorithm[J]. Optical Technique，2011， 37(4): 471-474. (in Chinese)

[9] Liqi. Research for digital auto-focus technology and implementation method[D]. Hangzhou: Zhejiang University, 2004. (in Chinese)

[10] Pu Li, Jin Weiqi, Liu Yushu. Super-resolution algorithm based on post wavelet treatment[J]. Infrared and Laser Engineering, 2008, 37(1): 173-176. (in Chinese)

[11] Wang Yiwen, Liu Xianli, Xie Hui. A wavelet-based focus measure and 3-D autofocusing for microscope images[J].Optics and Precision Engineering, 2006, 14(6): 1063-1069. (in Chinese)