Effects of Polarization State and Effective Numerical Aperture on the Resolution in Confocal Total Internal Reflection Microscopy

In order to study the effects of polarization state and effective numerical aperture on the focal fullwidth at halfmaximum (FWHM) and evanescent depth in confocal total internal reflection Microscopy (CTIRM), according to the RichardWolf theory, the intensity distribution in the interface is calculated and discussed with linearly, circularly, radially and azimuthally polarized beams, respectively. Meanwhile, the numerical calculations of FWHM and depth are researched for three different effective numerical apertures (1.33~1.45, 1~1.45 and 1~1.12, respectively). The results indicate that the FWHM of radially polarized beam is 144 nm, breaking through the limitation of diffraction, which is also better than 330 nm of linearly and 360 nm of circularly polarized ones, by using 532 nm incident wave and 1.33~1.45 aperture. The sharper focuscan be got with the larger and thinner aperture. Also the smaller depth of transmission can be got with the larger difference of squares of upper and lower limits, for which 140 nm is the shallowest depth with 1~1.45 aperture. Compared to other polarizations, radially polarized beam is the most suitable choice for CTIRM. And by optimizing the 收稿日期:2013-09-09;收到修改稿日期:2013-10-18; 网络出版日期 : 2013-12-14 基金项目:中国科学院苏州生物医学工程技术研究所“一三五”规划重大突破项目(Y052031205)、苏州市应用基础研究 计划(SYG201128) 作者简介:魏通达(1986—),男,博士研究生,主要从事光学显微成像方面的研究。E-mail:weitd@sibet.ac.cn 导师简介 : 唐玉国(1967—),男,博士,研究员,博士生导师,主要从事医用光学、医用光学工程、光谱学及光谱分析仪器等 方面的研究。E-mail: tangyg@sibet.ac.cn 51, 011102(2014) 激光与光电子学进展 www.opticsjournal.net 011102effective numerical aperture, high horizontal resolutions and low axial fluorescent noise near the sample surfacecan be obtained simultaneously.