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Optical Engineering • Open Access

Focusing properties of elliptical mirror with an aperture angle greater than π
Author(s): Jian Liu; Min Ai; He Zhang; Jiubin Tan

Paper 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 /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.

Paper Details

Date Published: 2 December 2013
PDF: 7 pages
Opt. Eng. 53(6) 061606 doi: 10.1117/1.OE.53.6.061606
Published in: Optical Engineering Volume 53, Issue 6
Show Author Affiliations
Jian Liu, Harbin Institute of Technology (China)
Min Ai, Harbin Institute of Technology (China)
He Zhang, Harbin Institute of Technology (China)
Jiubin Tan, Harbin Institute of Technology (China)


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