Tuesday, 27 June at 1pm
Duration: 1.5 - 2 hours
Speaker: Christian Hagenlocher, University of Stuttgart

The intensity distribution of a laser beam determines the energy input into the material and consequently influences all other process characteristics during laser material processing. Thus, it has a decisive influence on the stability of the process itself and on the quality of the resulting welds. Spatial beam oscillation allows for an adjustment of the local energy input during welding. This is applied to develop process strategies to stabilize the capillary and to adjust the solidification during laser welding. It provides the possibility to create specific micro structures, which are beneficial to avoid hot crack formation or enhance the mechanical strength of the weld seam.

Latest beam sources and beam shaping technologies allow for the variation of the intensity distribution. Stabilization of welding and cutting processes has recently been demonstrated for example by using multi-core beam guiding fibers, diffractive optical elements (DOE), superposition of multiple laser beams, or fast spatial oscillation of the laser beam by means of scanner optics. The latest beam shaping technology of coherent beam combining enables the flexible generation of a large variety of intensity distributions as well as their dynamic modulation at frequencies of several MHz.

High speed X-ray imaging captures the effect of static and dynamic beam shaping on the keyhole shape and its change during laser beam welding. The results show, that specific beam shaping strategies lead to a stabilization of the keyhole, which coincides with a reduction of spatter and pore formation. In addition, the geometry of the keyhole determines the characteristics of the fluid flow. In particular, the flexible capabilities of coherent beam combining provide the opportunity to directly shape the capillary into specific geometries that significantly affect the directions and velocities of local melt flows in the melt pool. This allowed for the development of beam shaping strategies in order to optimize the melt flow, which enhance the process efficiency and hinder the formation of hot cracks.

Wednesday, 28 June at 1pm
Speaker: Peter O'Brien, Tyndall National Institute
Registration for this course is closed as the maximum number of registrants has been reached.

The training course will provide an overview of the development of advanced photonic-electronic packaging technologies and their transition to Pilot-scale production. The course will cover the many aspects of advanced packaging, including design requirements, the importance of packaging design rules, the use of advanced packaging equipment, fibre and micro-optical packaging, flip-chip and transfer-print integration processes, interposer development for co-packaging of optical and electronic components, and thermal packaging requirements. The future of photonic-electric packaging and the potential for continued innovation in the field will also be discussed. Finally, the course will present the challenges and opportunities in transitioning from research to pilot-scale manufacturing, highlighting the importance of collaboration between academic institutions and industry partners to build the complete ecosystem and in training the future workforce.

Thursday, 29 June at 9am
Duration: 1.5 - 2 hours
Speaker: Ulrike Fuchs, Asphericon

The main emphasis will be on beam shaping for single-mode laser sources. Every topic is not only discussed in physical theory, but also always supported with real examples and measurements. The applications range from examples from microscopy to materials processing with ultrashort laser pulses.

1. An overview on different approaches to beam shaping: truncation, field mapping and beam homogenizers, will be given.

2. The field mapping approach will be discussed in detail for beam shaping in the focal plane, discussing scaling, diffraction effects, and physical limitations for the achievable shapes and dimensions. This is followed by the presentation of different variants of the implementation, such as refractive and diffractive phase elemnts, deformable mirrors and spatial light modulators. The respective field of application as well as the given limitations are also discussed. Analysis of the alignment sensitivity for such elements will be shown.

3. The field mapping approach will then be extended to the generation of collimated output beams with flat-top distributions. Additionally, to looking into scaling behavior, diffraction effects and physical limitations of different versions, employing relay optics and imaging approaches will be discussed. Latter is especially important when the location of beam shaping is different from the place the shaped distribution is needed. Analysis of the alignment sensitivity for such beam shaping elements will be shown. As another special feature, the use of fiber-coupled sources is also shown for these beam shaping optics and the challenges involved are explained

4. As soon as coherent laser sources are used, an additional modulation of the intensity profiles occurs due to the occurrence of speckle. This is shown by examples and possible solutions are discussed.

5. Laser beam shaping employing axicons to create (localized) Bessel beams and ring beams of variable shapes and sizes.

Target Audience: Physicists and application engineers who want to better understand what can be achieved with laser beam shaping and when which approach is best suited.

Benefits/course outcome: The major benefit is a deeper understanding of the underlying principles of laser beam shaping. This will not only help choosing the right approach for an application, but also help to identify and avoid sources of error more quickly in practice.

Thursday, 29 June at 1pm
Speaker: Markus Kogel-Hollacher, Precitec

It is a well-known paradigm of modern production strategy to gain product quality by safely controlled technologies rather than by post-process treatment of faulty products. Mastering any sophisticated process technology necessarily relies on more or less sophisticated on-line monitoring or closed loop control means. Fortunately, the remotely observable phenomena during laser material processing create no problem to that requirement.

Next to the applied sensor technology and the intuitive usability of system software, next to the complexity of the data processing and the integration into production lines, the basis for reliable on-line process monitoring systems are significant indicators which instantaneously display the status of the interaction zone and/or neighbouring areas.

This course will explain the state-of-the-art in quality assurance technologies for laser processes and will provide examples of successful industrial solutions with the ultimate goal to reduce the subjective human impact on the resulting product quality.