Focusing properties of elliptical mirror with an aperture angle greater than π

Jian Liu; Min Ai; He Zhang; Jiubin Tan

doi:10.1117/1.OE.53.6.061606

2 December 2013 Focusing properties of elliptical mirror with an aperture angle greater than π

Jian Liu, Min Ai, He Zhang, Jiubin Tan

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Optical Engineering, Vol. 53, Issue 6, 061606 (December 2013). https://doi.org/10.1117/1.OE.53.6.061606

Abstract

An analytical apodization function of an elliptical mirror with an aperture angle greater than π is derived for the analysis of the focusing properties. The distribution of electric field intensity near the focal region is given using vectorial Debye theory. Simulation results indicate that a bone-shaped focal spot is formed under linearly polarized illumination, and a tight-circularly symmetric spot is generated under radially polarized illumination. The change in eccentricity causes such a change in the focusing pattern under radially polarized illumination, that a greater eccentricity causes a spot tighter in transverse direction but wider in axial direction. Under radially polarized illumination, the transverse and axial full-width-at-half-maximum will be 0.382λ and 0.757λ , respectively, and the conversion efficiency of the longitudinal component can go beyond 99%, when the semi-aperture angle is 2π/3 and the eccentricity is 0.6. It can, therefore, be concluded that the tight focusing pattern with strong and pure longitudinal field can be achieved under radially polarized illumination for particle acceleration, optical tweezers, and high-resolution scanning microscopy.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Jian Liu, Min Ai, He Zhang, and Jiubin Tan "Focusing properties of elliptical mirror with an aperture angle greater than π," Optical Engineering 53(6), 061606 (2 December 2013). https://doi.org/10.1117/1.OE.53.6.061606

Published: 2 December 2013

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