Rofin (Germany)

Beam delivery fibers have been used widely for transporting the optical beams from the laser to the subject of irradiation in a variety of markets including industrial, medical and defense applications. Standard beam delivery fibers range from 50 to 1500 μm core diameter and are used to guide CW or pulsed laser light, generated by solid state, fiber or diode lasers. Here, we introduce a novel fiber technology capable of simultaneously controlling the beam profile and the angular divergence of single-mode (SM) and multi-mode (MM) beams using a single-optical fiber. Results of beam transformation from a SM to a MM beam with flat-top intensity profile are presented in the case of a controlled BPP at 3.8 mm*mrad. The scaling capabilities of this flat-top fiber design to achieve a range of BPP values while ensuring a flat-top beam profile are discussed. In addition, we demonstrate, for the first time to the best of our knowledge, the homogenizer capabilities of this novel technology, able to transform random MM beams into uniform flat-top beam profiles with very limited impact on the beam brightness. This study is concluded with a discussion on the scalability of this fiber technology to fit from 50 up to 1500 μm core fibers and its potential for a broader range of applications.

We have demonstrated a linearly polarized cw all-in-fiber oscillator providing 1 kW of output power and a polarization extinction ratio (PER) of up to 21.7 dB. The design of the laser oscillator is simple and consists of an Ytterbium-doped polarization maintaining large mode area (PLMA) fiber and suitable fiber Bragg gratings (FBG) in matching PLMA fibers. The oscillator has nearly diffraction-limited beam quality (M² < 1.2). Pump power is delivered via a high power 6+1:1 pump coupler. The slope efficiency of the laser is 75 %. The electro/optical efficiency of the complete laser system is ~30 % and hence in the range of Rofin's cw non-polarized fiber lasers. Choosing an adequate bending diameter for the Yb-doped PLMA fiber, one polarization mode as well as higher order modes are sufficiently supressed1. Resulting in a compact and robust linearly polarized high power single mode laser without external polarizing components. Linearly polarized lasers are well established for one dimensional cutting or welding applications. Using beam shaping optics radially polarized laser light can be generated to be independent from the angle of incident to the processing surface. Furthermore, high power linearly polarized laser light is fundamental for nonlinear frequency conversion of nonlinear materials.

The laser as an industrial tool is an essential part of today's solar cell production. Due to the on-going efforts in the solar industry, to increase the cell efficiency, more and more laser-based processes, which have been discussed and tested at lab-scale for many years, are now being implemented in mass production lines. In order to cope with throughput requirements, standard laser concepts have to be improved continuously with respect to available average power levels, repetition rates or beam profile. Some of the laser concepts, that showed high potential in the past couple of years, will be substituted by other, more economic laser types. Furthermore, requirements for processing with less-heat affected zones fuel the development of industry-ready ultra short pulsed lasers with pulse widths even below the picosecond range. In 2011, the German Ministry of Education and Research (BMBF) had launched the program "PV-Innovation Alliance", with the aim to support the rapid transfer of high-efficiency processes out of development departments and research institutes into solar cell production lines. Here, lasers play an important role as production tools, allowing the fast implementation of high-performance solar cell concepts. We will report on the results achieved within the joint project FUTUREFAB, where efficiency optimization, throughput enhancement and cost reduction are the main goals. Here, the presentation will focus on laser processes like selective emitter doping and ablation of dielectric layers. An indispensable part of the efforts towards cost reduction in solar cell production is the improvement of wafer handling and throughput capabilities of the laser processing system. Therefore, the presentation will also elaborate on new developments in the design of complete production machines.

Abstract Interconnection of crystalline solar cells to modules is a critical step in photovoltaic module production. The typical tabbing and stringing process requires complex handling of delicate solar cells as well as a reliable but gentle joining process. Things become even more complicated as there is a trend to cell thicknesses way below 200 μm together with steadily rising production rates.

Abstract Nachdem in den letzten Jahren viele verschiedene Konzepte für Hochleistungslaser in der Materialbearbeitung getestet und eingeführt wurden, kommt es immer häufiger zu der Situation, dass mehrere technische Lösungsansätze zur Verfügung stehen. Anwender sind in diesem Zusammenhang oft unsicher, welche der Technologien für ihren Einsatz die optimale ist. Auch die Anwendungsbreite hat sich inzwischen vom klassischen Schneiden und Schweißen entsprechend erweitert, die Zahl der Freiheitsgrade einer geplanten Installation nimmt entsprechend zu. In diesem Beitrag soll aufgezeigt werden, mit welchen grundsätzlichen Faktoren man sich dabei auseinandersetzen kann oder sogar muss.

Abstract Mehrere Marktexperten rechnen im Krisenjahr 2009 mit Umsatzeinbrüchen von bis zu 40 Prozent in der Lasermaterialbearbeitungsbranche. Francisco Velasco und Andreas Tho� sprachen mit drei führenden Managern aus der Laserindustrie über Chancen und Strategien in der Krise.

Abstract For more than 30 years lasers are used for industrial production with high success. Modern efficient production would not be imaginable without lasers and laser processes. Since the beginning days CO2 lasers were dominating the market of continuous cutting and welding applications (referred here as “Macro” applications) because of their high power and electrical efficiency, reliability and cost efficiency.

Abstract Rofin‐Sinar war eine der ersten deutschen Laserfirmen, die den Schritt an die Börse gewagt haben. Der Erfolg hat ihnen recht gegeben. Das Unternehmen konnte sowohl den Umsatz als auch den Börsenkurs vervielfachen. Andreas Thoß sprach für das Laser Technik Journal mit dem CEO von RSTI Günther Braun.

Laser systems for industrial materials processing are today's state-of-theart technology driving innovation and productivity. For the automotive and aerospace industries, laser systems represent the very latest production methods and provide new solutions in micro and macro applications. Although growth in the overall machining sector has been stagnant in recent years, the laser industry has experienced continuous growth. Rofin-Sinar Inc. is one of the most successful companies within the industry and has head quarters in Hamburg, Germany, and Plymouth (MI), USA. Andreas Thoß interviewed Peter Wirth of Rofin-Sinar Technologies Inc.

The National German research project "MDS", which stands for the German equivalent of "Modular Diode Laser Beam Tools", is now in its fifth year. The aim of the project is the development of new diode laser technology as well as novel applications, especially taylored to the special features of high power diode lasers. The project has a strong vertical structure: All necessary technologies for a successful performance of the project, i.e. chip-technology, laser-system-technology and applications are represented in the project. The aspect of laser systems can be divided into two fields: one is of course improving the beam quality and power, i.e. brilliance of conventional diode laser systems; this can be reached by further development of the semiconductors the other is using the individual bars and assembling them in a special way, which is adapted to the application. That's what is meant by the word "modular". This paper will mainly focus on the special systems and their applications and illuminate the actual status as well as the hurdles, which had to be overcome during the project.