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Proceedings Paper

Multi-focus beam shaping of high power multimode lasers
Author(s): Alexander Laskin; Joerg Volpp; Vadim Laskin; Aleksei Ostrun
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Paper Abstract

Beam shaping of powerful multimode fiber lasers, fiber-coupled solid-state and diode lasers is of great importance for improvements of industrial laser applications. Welding, cladding with millimetre scale working spots benefit from “inverseGauss” intensity profiles; performance of thick metal sheet cutting, deep penetration welding can be enhanced when distributing the laser energy along the optical axis as more efficient usage of laser energy, higher edge quality and reduction of the heat affected zone can be achieved. Building of beam shaping optics for multimode lasers encounters physical limitations due to the low beam spatial coherence of multimode fiber-coupled lasers resulting in big Beam Parameter Products (BPP) or M² values. The laser radiation emerging from a multimode fiber presents a mixture of wavefronts. The fiber end can be considered as a light source which optical properties are intermediate between a Lambertian source and a single mode laser beam. Imaging of the fiber end, using a collimator and a focusing objective, is a robust and widely used beam delivery approach. Beam shaping solutions are suggested in form of optics combining fiber end imaging and geometrical separation of focused spots either perpendicular to or along the optical axis. Thus, energy of high power lasers is distributed among multiple foci. In order to provide reliable operation with multi-kW lasers and avoid damages the optics are designed as refractive elements with smooth optical surfaces. The paper presents descriptions of multi-focus optics as well as examples of intensity profile measurements of beam caustics and application results.

Paper Details

Date Published: 25 August 2017
PDF: 10 pages
Proc. SPIE 10347, Optical Trapping and Optical Micromanipulation XIV, 103470N (25 August 2017); doi: 10.1117/12.2273494
Show Author Affiliations
Alexander Laskin, AdlOptica GmbH (Germany)
Joerg Volpp, Bremer Institut für angewandte Strahltechnik GmbH (Germany)
Vadim Laskin, AdlOptica GmbH (Germany)
Aleksei Ostrun, St. Petersburg National Research Univ. of Information Technologies (Russian Federation)


Published in SPIE Proceedings Vol. 10347:
Optical Trapping and Optical Micromanipulation XIV
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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