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Axial two focus zone plate under tight foucsing conditions

Authors Ji, Shengzhe
Zhu, Linwei
Sun, Meiyu
Wang, Lili
Li, Zhigang View this author's profile
Issue Date 2015
Source Guangxue Xuebao/Acta Optica Sinica , v. 35, (3), March 2015, article number 0305003
Summary An analytic formula of the radius of a zone plate is deduced by the vector diffraction theory under the tight-focusing conditions. Based on the binary phase zone plate designed by the formula, axial two focuses can be created in the focusing area of a high numerical aperture (NA) objective lens. Because the formula of the radius of the zone plate is related to the axial shifting distance of the two focuses, it is possible to design a set of zone plates with different axial shifting distances for generating tunable axial two focuses. For a high NA objective illuminated by a radial polarized Bessel-Gaussian light, the field distributions of the objective modulated by the binary zone plate with different axial shifting distances are simulated. It is shown that axial tunable two focuses can be realized successfully. In addition, using the zone plate with suitable axial distance, some special focusing fields, such as "optical bubble" and "optical needle" can also be realized under the tightfocusing condition. Hence, such binary zone plates could be utilized for optical trapping and manipulation of particles. ©, 2015, Chinese Optical Society. All right reserved.
ISSN 02532239
Language English
Format Article
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