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Title

Focusing of doughnut laser beams by a high numerical-aperture objective in free space

Author(s)

Gan, Xiaosong;  Ganic, Djenan;  Gu, Min

Abstract

We report on, in this letter, a phenomenon that the central zerointensity point of a doughnut beam, caused by phase singularity, disappears in the focus, when such a beam is focused by a high numerical-aperture objective in free space. In addition, the focal shape of the doughnut beam of a given topological charge exhibits the increased ring intensity in the direction orthogonal to the incident polarization state and an elongation in the polarization direction. These phenomena are caused by the effect of depolarization, associated with a high numerical-aperture objective, and become pronounced by the use of a central obstruction in the objective aperture.

Publication type

Journal article

Research centre

Swinburne University of Technology. School of Biophysical Science and Electrical Engineering

Source

Optics Express, Vol. 11, no. 21 (Oct. 2003), pp. 2747-2752

Publication year

2003

Publisher

Optical Society of America

ISSN

1094-4087

Publisher URL

http://www.opticsexpress.org/abstract.cfm?id=77667

Copyright

Copyright © 2003 Optical Society of America. Published version of the paper reproduced here in accordance with the copyright policy of the publisher. This paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsexpress.org/abstract.cfm?id=77667. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

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