Design of focal beam shaping system through irradiance and phase control

Meijie Li, Youri Meuret, Michael Vervaeke, Hugo Thienpont, Fabian Duerr

Research output: Chapter in Book/Report/Conference proceedingConference paper

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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 flat-top. The shaping quality depends strongly on a dimensionless parameter 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,3 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.
Original languageEnglish
Title of host publicationOptical Modelling and Design IV
PublisherSPIE
Number of pages8
Volume9889
ISBN (Print)978-1-5106-0134-5
DOIs
Publication statusPublished - 27 Apr 2016
EventConference on Optical Modelling and Design IV - Brussels, Belgium
Duration: 5 Apr 20167 Apr 2016

Conference

ConferenceConference on Optical Modelling and Design IV
Country/TerritoryBelgium
CityBrussels
Period5/04/167/04/16

Keywords

  • FLATTOP BEAM
  • LASER
  • SURFACES
  • WAVE

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