Volume 101, Number 5, March 2013
|Number of page(s)||6|
|Section||Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics|
|Published online||20 March 2013|
Dark zone in the centre of the Arago-Poisson diffraction spot of a helical laser beam
1 URU 435 LPL, Université Rennes 1 - 35042 Rennes Cedex, France, EU
2 UMR CNRS 6164 IETR, Université Rennes 1 - 35042 Rennes Cedex, France, EU
3 UPR CNRS 3321 LAC, B 505, Campus d'Orsay - 91405 Orsay Cedex, France, EU
4 UMR CNRS 6251 IPR, Université Rennes 1 - 35042 Rennes Cedex, France, EU
Received: 29 November 2012
Accepted: 19 February 2013
We report on the diffraction of non-zero Laguerre Gaussian laser beams by an opaque disk. We observe a tiny circular dark zone at the centre of the usual Arago-Poisson diffraction bright spot. For such non-diffracting dark hollow beams, we have measured diameters as small as 20 μm on distances of the order of ten metres, without focalization. Diameters depend on the diffracting object size and on the topological charge of the input Laguerre Gaussian beam. These results are in good agreement with theoretical considerations. Potential applications are then discussed.
PACS: 42.25.Fx – Diffraction and scattering / 42.50.Tx – Optical angular momentum and its quantum aspects / 42.87.Bg – Phase shifting interferometry
© EPLA, 2013
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