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Proceedings Paper

Comparison of fly's eye condensers based on regular, chirped, and stochastic tandem microlens arrays
Author(s): Frank C. Wippermann; Peter Dannberg; Andreas Bräuer
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Paper Abstract

Fly's eye condensers are commonly used for the beam shaping of an arbitrary input intensity distribution into a top hat. The setup usually consists of a Fourier lens and two identical regular microlens arrays - often referred to as tandem lens array - where the second one is placed in the focal plane of the first microlenses. The output intensity distribution is modulated by equidistantly located sharp intensity peaks due to the periodic structure of the regular arrays. In a chirped array, the inflexibility of a regular structure has been overcome. Hence, an array can be formed which is non-periodic and consequently the equidistantly located intensity peaks can be suppressed. A far field speckle pattern results with more densely and irregularly located intensity peaks leading to an improved homogeneity of the intensity distribution. Additionally, a stochastic array which features a nonperiodic layout can be used in order to avoid the equidistantly located intensity peaks. Again, a far field speckle pattern results with more densely and irregularly located intensity peaks leading to an improved homogeneity of the intensity distribution. We compare fly's eye condensers based on regular, chirped and stochastic tandem microlens arrays in terms of achievable intensity homogenization, design and fabrication methods and their advantages and disadvantages in their applications.

Paper Details

Date Published: 19 February 2009
PDF: 10 pages
Proc. SPIE 7194, Laser Resonators and Beam Control XI, 719404 (19 February 2009); doi: 10.1117/12.822737
Show Author Affiliations
Frank C. Wippermann, Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)
Peter Dannberg, Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)
Andreas Bräuer, Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)


Published in SPIE Proceedings Vol. 7194:
Laser Resonators and Beam Control XI
Alexis V. Kudryashov; Alan H. Paxton; Vladimir S. Ilchenko; Lutz Aschke, Editor(s)

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