[1] Lee C H, Wang J. Noninterferometric differential confocal microscopy with 2-nm depth resolution. Opt. Commun., 1997, 135(4～6):233～237

[2] Tsai C W, Lee C H, Wang J. Deconvolution of local surface response from tomography in nanometer profilometry with a dual-scan method. Opt. Lett., 1999, 24(23):1732～1734

[3] Welford W T. Use of annular apertures to increase focal depth. J. Opt. Soc. Am., 1960, 50(8):749～753

[4] Yang Lisong, Wang Guiying. Surface profilometry with fiber optical confocal scanning microscope. Measurement Science and Technology, 2000, 11(12):1786～1791

[5] Deng X Q, Wang G, Xu Z. Optical pupil filter for improving optical sectioning property in confocal microscope. Proc. SPIE, 1999, 3863:322～326

[6] Corral M M, Andres P, Castaneda J O et al.. Tunable axial superresolution by annular binary filters, application to confocal microscopy. Opt. Commun., 1995, 119(5,6):491～498

[7] Ding Zhihua, Wang Guiying, Gu Min et al.. Superresolution with an apodization film in a confocal setup. Appl. Opt., 1997, 36(1):360～363