Laser Diode Micro-Optics Enhance Cutting

Although a high-power diode laser operates at a relatively modest brilliance, optimized micro-optics make it well-suited for the rapid and precise cutting of 6-mm-thick stainless steel.

That's the conclusion of Brilamet, a research project carried out by Lissotschenko Mikrooptik GmbH (Limo) and the Laser Center at the Münster University of Applied Sciences (LFM) under the German Federal Ministry of Education and Research's Optical Technologies in Innovative Small- and Medium-Sized Enterprises program. The project names stands for brilliant high-power diode lasers for metal processing.

High-power diode lasers are suitable for the industrial-strength precision cutting of thick metal sheets, a recent study found. Courtesy of Limo/Markus Steur Fotografie.

"The key ingredient here is not only the asymmetrical laser beam geometry but also the model for predicting machining results, which was developed during the project," said Dr. Jens Meinschien, vice president of innovations management at Limo. "By making further laser beam-shaping adjustments, cutting speeds of 2.5 m per minute can even be achieved with 4-kW diode lasers."

The project initially used a 2.5-kW high-power diode laser (HPDL) coupled to industrial computer-numerical-control machining equipment. Micro-optics were used to optically connect the HPDL beam source modules. Through an optical fiber, the HPDL beam was then guided to the cutting head.

LFM and Limo employed the Design of Experiments methodology to optimize the cutting process by experimenting with different nozzle geometries and diameters. As the project progressed, the experiments were expanded to include a 4-kW HPDL beam source, which likewise consisted of two laser units coupled together.

"We now know how to improve the components and, most importantly, the beam-shaping systems for kilowatt beam sources using an adapted optical, mechanical and thermal design," Meinschien said.

Limo is pursuing additional laser-cutting research as part of the European Union's Lashare Nexcut subproject. The company develops, manufactures, and sells micro-optics and laser systems.