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Proceedings Paper

Design of focal beam shaping system through irradiance and phase control
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Paper Abstract

Focal beam shaping (FBS), or laser beam shaping at focus, is required in many laser applications. The most common approach is to use a phase element and a Fourier transform lens to generate at the focal plane of the lens the desired irradiance pattern, usually a at-top. The shaping quality depends strongly on a dimensionless parameter β. In case of long focal length and/or small focal spot, the input laser beam should be sufficiently large in order to get a large β value for a satisfying shaping quality. Therefore additional beam expansions might be needed. In this work, we propose a different approach with two plano-aspheric lenses that allows to control both irradiance and phase at focus. The two lenses are designed by an extended ray mapping technique combined with a rigorous backward wave propagation method, so that diffraction effects around laser focus can be implemented in a reliable way. With the developed approach, the shaping quality is guaranteed without the possible need for extra beam expanders, which makes the system more compact. The advantage of our design approach is demonstrated in direct comparison with the conventional Fourier approach for the same design example to transform a Gaussian beam to have a circular flat-top irradiance pattern.

Paper Details

Date Published: 27 April 2016
PDF: 8 pages
Proc. SPIE 9889, Optical Modelling and Design IV, 988910 (27 April 2016); doi: 10.1117/12.2227899
Show Author Affiliations
Meijie Li, Vrije Univ. Brussel (Belgium)
Youri Meuret, Vrije Univ. Brussel (Belgium)
KU Leuven (Belgium)
Michael Vervaeke, Vrije Univ. Brussel (Belgium)
Hugo Thienpont, Vrije Univ. Brussel (Belgium)
Fabian Duerr, Vrije Univ. Brussel (Belgium)

Published in SPIE Proceedings Vol. 9889:
Optical Modelling and Design IV
Frank Wyrowski; John T. Sheridan; Youri Meuret, Editor(s)

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