Microlens laser beam homogenizer - From theory to application

Zimmermann M, Lindlein N, Völkl R, Weible K (2007)

Publication Status: Published

Publication Type: Conference contribution, Conference Contribution

Publication year: 2007

Book Volume: 6663

Article Number: 666302

Event location: San Diego, CA US

ISBN: 9780819468116

DOI: 10.1117/12.731391

Abstract

Many applications in laser manufacturing like semiconductor lithography, micro-machining, micro-structuring or material-analysis require a homogeneous intensity distribution of the laser beam over its complete profile. Refractive and diffractive beam homogenizer solutions have been developed for this challenge, but their applicability strongly depends on the physics of the individual laser beam. This paper investigates the influence of laser beam properties like spatial coherence for microlens beam homogenizers. Diffraction at the small lens apertures and interference effects of periodic arrays are explained by using diffraction theory. Different microlens beam homogenizer configurations are presented. Design considerations that might be helpful for the layout of a specific microlens beam homogenizer system are discussed. It is shown that, among other factors, the Fresnel number is the most important quantity to characterize the influence of diffraction effects on microlens laser beam homogenizers. The influence of the spatial partial coherence will be explained for the example of a Fly's eye condenser. For cw laser sources, the influence of a rotating diffuser plate on grating interference and speckles effects is investigated. Finally, the theory will be compared to some practical examples in planar laser measurement techniques, in combustion diagnostics and micromachining with Excimer lasers.

Authors with CRIS profile

Norbert Lindlein Lehrstuhl für Experimentalphysik

Involved external institutions

Bayerisches Laserzentrum gemeinnützige Forschungsgesellschaft mbH (BLZ) DE Germany (DE)

How to cite

APA:

Zimmermann, M., Lindlein, N., Völkl, R., & Weible, K. (2007). Microlens laser beam homogenizer - From theory to application. In Proceedings of the Laser Beam Shaping VIII. San Diego, CA, US.

MLA:

Zimmermann, Maik, et al. "Microlens laser beam homogenizer - From theory to application." Proceedings of the Laser Beam Shaping VIII, San Diego, CA 2007.

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