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Ultrashort Pulsed Laser Processing at 1 Kilowatt Using a Flexible Multi Beam Approach

Periodic Reporting for period 3 - MultiFlex (Ultrashort Pulsed Laser Processing at 1 Kilowatt Using a Flexible Multi Beam Approach)

Reporting period: 2022-07-01 to 2023-06-30

Ultrafast lasers can do something very unique: They ablate material of almost any kind without thermal load of the adjacent material. Their cuts are smooth and melt-free, even on a micron scale. This makes ultrafast lasers very interesting for many industry branches such as tool making, where hard materials must be processed very precisely. Such precise processes take time. Too much time for an efficient use of this technology for many industrial applications.
The MultiFlex project will overcome this obstacle and pave the way for a widespread, cost-effective application of ultrafast lasers in industrial manufacturing.
In the MultiFlex project, a consortium of six partners from industry and research is doing the next step in the development of the ultrafast laser process technology to make material processing with ultrafast lasers up to a hundred times faster.

The basic idea behind MultiFlex is to setup a high power “USP laser-dot-matrix-printer”, which consists of a newly developed high power ultrashort pulsed laser with an output power of more than 1 kilowatt and a flexible multi beam optics concept.
In MultiFlex a highly stable high power laser with average power of more than 1 kilowatt and a pulse duration below 1 ps will be developed as pulse durations in the femtosecond range enable higher process efficiency, better quality and broader process windows. Special emphasis will be given to flexibility in pulse shaping, power stability and pulse modulation capability at high pulse energies.
The optical system converts the single laser beam into a pattern of 64 beamlets, where each single beamlet can be turned on and off separately. The resulting pattern can be directed onto the workpiece with a fast scanner. By enabling the flexible switching of the separated single beams and a control system for compensating field distortions, arbitrary surface structures can be generated with highest precision and throughput. The complex system will be accomplished by an industry grade control unit.
The “USP laser-dot-matrix-printer” developed within MultiFlex will be evaluated on several demonstrator parts as well as in two industrial use cases provided by associated industrial partners.
At the beginning of the MultiFlex project the requirements of all core components were defined.
Based in the demands for fabricating the desired structures the requirements on system components like, machine, laser source and optical system were defined.
Different concepts and configurations to build up an ultrafast laser with 1 kW average output power have been investigated. Based on considerations about expectable performance, stability and risk in the development one approach was selected. The amplifier setup was tested and in laboratory already 1.2 kW have been achieved. The flexible laser control option (“Femtotrig”) has been validated for the needed parameter set. A prototype laser with 640 W average output power was realized and the Femtotrig option was included.
Regarding the optical system, a new design approach was developed.
The multi-channel modulators as key elements for dynamic switching of the multibeam pattern has been designed, manufactured and integrated into the final optical system. Optical components like the DOE, prism arrays and imaging lenses have been designed, manufactured and tested.
A FPGA based control unit and a software plattform has been realized to sychronize and control all 64 beamlets in dependence on the galvanometer position and the ablation pattern.
The parameters for the process and machine monitoring have been specified, sensors have been selected and a prototype version for the data acquisition system including a software solution was developed.
A Multiflex machine concept integrating all components has been developed, manufactured, tested and handed over to the application center at Fraunhofer ILT.
The Multiflex consortium participated in more than 50 international events to promote the progress of the new flexible multi-beam laser structuring technology. Fraunhofer ILT also hosted the "Ultrakurzpuls Workshop2023" with more than 150 international industrial customers in Aachen. Here, the MultiFlex consortium presented the final state of the machine and announced the "Joint application lab", which allows partners to perform feasibility studies on this unique prototype laser processing machine.
The MultiFlex project aimed for a completely new dimension in ultrafast laser processing. By efficiently using twenty times higher laser power compared to conventional processes, a 20 times faster control system, the current process demonstrations reveal an increased productivity by a factor of 30 for all tested use cases.
With the developed technology opening up a new dimension of disruptive flexible multi-beam processing, large area applications get feasible.
Ultrafast laser processing and surface structuring has numerous potential fields of application. The focus of MultiFlex is in the field of structuring tools and molds, but the planned developments can be used for scanner-based laser processing in general, which is 80% of laser based materials processing. Therefore, the impact of these developments are expected to be significant. The developments of this project help to strengthening industrial manufacturing based on ultrashort pulse lasers and to extend its field of applications.
MultiFlex delivers an enabling technology for the European industry in the field of mass production of functional and design surfaces in several fields, e.g. Automotive, Lighting, Consumer and Luxury Goods, Lightweight Construction and Filter Systems.
This helps to bring the advantages of ultrafast laser processing to a broader application and helps to replace environmental problematic technologies like chemical etching.
Due to the significant increase new field of applications like surface functionalization of large parts like ship hulls, wings or wind turbine blades get thinkable, helping to increase energy efficiency and reduce CO2 emission.
The realized average power of 650 W is approximately 200-300% increase compared to commercially available 200-300 W USP-Laser systems.
The the groundbreaking new approach of the individually switchable multi-beam optics has been completed. First demonstration videos of an ablation process of the Multiflex Logo with a fully flexible beam pattern has been published.
A completely new FPGA-based system to control the single beams in dependence on the current beam position has been developed. The system enables arbitrary processing strategies, higher accuracy, and easier usability. Multi-channel AOM as a device to switch multiple beamlets has been developed. To withstand high peak intensities and powers quartz as new material for these devices was used.
An FPGA-based system for acquiring sensor data was developed and realized, correlating sensor data with processing result using different algorithm helping to understand the processes and keep track on the status of key components of the overall system.
The overall on of a kind Multiflex processing machine has been realized and transferred to ILT for the purpose of a “Joint application Lab” to demonstrate different use cases and feasibility studies by end of 2023.
Due to the flexibility in accessing processing parameters, Multiflex technology represents a unique hardware platform to develop future AI algorithms for multidimensional processing strategy development.
Sketch of the MultiFlex optical system.
Multibeam Structuring Demonstration
Thermal multibeam management simulation
Machine at ILT
Tasks within MultiFlex.
Concept of MultiFlex solution.
Live Demonstration Multibeam Machine
Tailormade Multibeam Optics