Periodic Reporting for period 2 - MULTIPOINT (Multibeam Femtosecond Laser System for High Throughput Micro-drilling of HLFC Structures) Reporting period: 2020-07-01 to 2023-03-31 Summary of the context and overall objectives of the project In recent years, there has been extensive research focused on the advancement of ultra-short pulse lasers and their application across various industrial sectors. Specifically, femtosecond lasers, with pulse durations ranging from 10-15 to 10-13 seconds, have become indispensable tools for micro-structuring, cutting, and micro-drilling applications. These lasers exhibit exceptional characteristics, including high machining quality and precision at the micrometer scale. Such qualities are primarily attributed to two key factors: the minimal thermal impact zone resulting from the interaction of femtosecond pulses with the material, causing instantaneous ablation of the surface layers, and the utilization of laser beams with spot diameters below 0.7 mm x mrad (M2 < 2). Despite the extraordinary quality and precision offered by these laser systems, their productivity is still constrained by the current performance of ultrashort laser sources. Although significant progress has been made in recent years, there is a need to further enhance the technology by increasing the average power of femtosecond sources to ensure productivity gains, while simultaneously optimizing beam delivery to maximize material removal per unit of energy supplied.Addressing these challenges, the MULTIPOINT project has undertaken three pivotal objectives. Firstly, the development of kilowatt-level femtosecond laser sources has been pursued to significantly increase the average power output. Secondly, a multibeam generation system has been devised to optimize the energy balance per beam, thereby maximizing the efficiency of material removal. Lastly, a suitable laser system prototype has been designed and implemented to enable the application of micro-drilling to large surfaces.Despite MULTIPOINT being just a project under the "research and innovation action" category, the obtained results are highly aligned with these objectives. Specifically, it has been demonstrated that the development of a femtosecond laser with a real output power of approximately 700 W, equipped with a customized multi-beam system for micro-drilling applications, is capable of increasing production rates to levels close to those of more conventional but less precise technologies. Furthermore, a compromise between productivity and quality can be achieved by defining laser processes that strike a desired balance between fusion-based processes (lower quality) and ablation-based processes (higher quality). Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far This document reports the work performed from M19 to M51. During this period, all work packages of the project have been active except for work package 1, the objectives and conclusions of which were described in the previous periodic report. Within the project, 7 key exploitable results have been defined in relation to the previously described project objectives. They are briefly described below:- Ultrashort multibeam laser processing system for high throughput in micro-drilling and microtexturing tasks of large areas: This primarily involves know-how obtained regarding the construction of machines and prototypes containing high-power femtosecond lasers and multibeam delivery systems.- Multibeam percussion drilling for producing Ti panels for HLFC structures: This is a drilling process developed for optimized quality and productivity with multibeam and high-power lasers.- High power femtosecond laser source: A femtosecond laser source has been developed, amplified to slightly over one kilowatt of average power. To improve robustness and quality, the actual power used is, however, in the range of 700 W.- Multibeam unit generator for ultrashort pulses at high average power: Two stages of multibeam generation have been developed. One is based on polarizing optics, and the other is based on DOE (diffractive optical element). With this strategy, virtually any type of laser beam division can be achieved at the laser head output.- Multibeam scanner: A galvanometric mirror scanner with a large aperture capable of accepting a multibeam.- Beam delivery Bridge Module: This is the main structure of the machine that accommodates the laser, the optical path, the axes, and the heads. The design undertaken in the project and the development of the structure itself are exploitable results applicable to future similar configurations. However, the main exploitable result in this area is the obtained know-how, applicable to future machine and prototype developments.- Complete system design: This primarily consists of an exploitable result that may include the current design of the MULTIPOINT prototype, as well as applicable know-how for other similar prototypes..The dissemination of all these results has been extensive and aimed at the scientific community, potential industrial users, and a general audience. Actions carried out, among others, include the development of publications for scientific journals, participation in conferences, organization of workshops, webinars, etc. More details on this aspect can be found in the deliverables of work package 7. Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far) The considered MULTIPOINT solution presents a highly innovative laser workstation development, which stands as a unique offering in Europe. By combining precise micromachining using ultrafast pulses, the advancement of a parallel processing laser system for optimized energy balance, and a high-rate laser drilling system for extensive surfaces, this solution pushes the boundaries of laser technology. Importantly, the knowledge and photonics technology developed within the MULTIPOINT project pave the way for scaling up ultrashort laser machining to an industrial level across diverse applications. Anticipated impacts stemming from these advancements span three key areas:- High power femtosecond system and beam delivery: The project has successfully demonstrated that increasing the average power of the laser source directly enhances productivity in drilling processes. Notably, it has been shown that production rates comparable to those achieved with existing laser techniques can be attained while simultaneously improving overall quality.- Environmental and economic impact: The expected impact of implementing Hybrid Laminar Flow Control (HLFC) technology on the environment and the economy has been confirmed through extensive aerodynamic tests and test flights. In this context, MULTIPOINT introduces a novel laser technology capable of minimizing post-processing steps such as polishing and chemical etching, which are traditionally required for panels following micro-drilling with conventional laser techniques. As a result, this breakthrough will lead to reduced part rejection rates and decreased effort in manufacturing processes.- Other anticipated impacts: The developed technology brings forth additional functionalities and features. Notably, the same tool, with minimal modifications, can be utilized for large-scale micro-texturing and micromachining applications. Furthermore, the capability to perform micro-drilling on non-metallic materials like composites and polymers expands the potential reach of this technology. This establishes a clear advantage for the newly developed technology compared to existing alternatives. However, further research efforts are necessary to enhance the robustness and achieve greater miniaturization of the elements, particularly focusing on the laser source itself. multipoint.jpg
