Highly dynamic positioning of individual laser beams in a multi-beam system for laser surface processing

Hofmann, Oskar; Chemerenko, Olga; Finger, Johannes; Eifel, Stephan; Stollenwerk, Jochen; Loosen, Peter

doi:10.1016/j.procir.2020.09.123

Cited by 4 publications

(3 citation statements)

References 3 publications

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“…Beam delivery systems that address this problem are those that solve the parallelization of laser material processes. These systems [52][53][54][55][56][57] consist of multiple active scan systems (or even phase modulators) and/or passive elements (such as diffractive beam splitters/shapers) that are then superimposed to generate the desired effect, such as a parallelized scanning or drilling process, 25,52,53 or scanning with beam shaping. 54,55,57 This superposition is necessary because there is currently no single technology or element that can provide the required functionality in one package.…”

Section: Discussionmentioning

confidence: 99%

Feasibility assessment of parallelized helical drilling

2023

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With the average power of commercial ultrafast lasers reaching the kW-level, process parallelization is required to avoid detrimental quality issues, such as caused by heat accumulation. This is especially relevant in the case of helical drilling, as the processing strategy is only employed when precise geometry, high-quality surface finish, tight tolerances, and high reproducibility are a priority. We illustrate that parallelization by means of a multipass process is conceptually attractive for pulsed drilling processes, but also challenging due to limitations imposed by the properties of appropriate beam-steering devices. While paraxial beam propagation methods applied to the suggested setup predict no aberrations, deviations from the idealized solution are a concern. Our experimental proof-of-principle investigations show that parallelization by means of a deflector preceding the helical drilling optics is possible while ensuring nearly identical processing parameters for all parallelly processed boreholes.

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Section: Discussionmentioning

confidence: 99%

Feasibility assessment of parallelized helical drilling

2023

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“…2 To meet the productivity requirements, the laser can be combined with a multibeam scanner. 3 During the production of FMMs, it is important to avoid distortions or discoloration due to heat accumulation. 4 Therefore, process parameters and processing strategies that avoid such problems are sought.…”

Section: Introductionmentioning

confidence: 99%

“…The main reason for resorting to USP lasers is their ability to insert a lot of energy into the material without too much heating, which would destroy such thin foils 2 . To meet the productivity requirements, the laser can be combined with a multibeam scanner 3 . During the production of FMMs, it is important to avoid distortions or discoloration due to heat accumulation 4 .…”

Section: Introductionmentioning

confidence: 99%

Multiscale model for ultrashort pulsed parallel laser structuring—part II. The macroscale model

et al. 2022

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The increasing pixel density in displays demands high quality in the production of fine metal masks (FMMs). The production process of FMMs boils down to structuring tiny holes in thin metal sheets or foils. The manufacturing requirements of FMMs are high precision in terms of the hole geometry to let enough light escape from each diode and high productivity to produce the required amount. To achieve both objectives, high power ultrashort pulse (USP) lasers can be utilized. Because USP lasers fall short of the productivity requirements, they are combined with multibeam scanners. During production, the multibeam scanners deposit a lot of heat in the metal foil, which can ultimately yield temperature-induced distortions. To understand and finally avoid such distortions, a process simulation is sought. In a preceding study, the structuring of a single hole (the microscale) was investigated, but due to the large differences in the time and spatial scales involved, it was not feasible to simulate the production of the whole part (the macroscale). Within this treatise, a multiscale approach that takes into account the necessary information from the microscale to describe temperature-induced distortions on the macroscale is described. This approach targets laser ablation processes with pulse durations ranging from picoseconds up to nanoseconds provided the ablation is not melt-driven. First, a representative volume element (RVE) is generated from the results of the microscale model. Then, this RVE is utilized in the thermo-elastic structural mechanics simulation on the macroscale. The multiscale model is validated numerically against a hole-resolved computation, which shows good agreement. Naturally, the simulation is highly dependent on the microscale model, which in turn depends on the material properties. To handle material changes well, an experimental calibration has to be performed. This calibration is not part of this treatise, but it will be described in a future publication. In addition to the calibration process, the validation with experiments will be conducted in future research. Additionally, the authors envision the automation of the whole process, resulting in a first-time-right approach for the development of FMMs. Finally, the procedure might be extended to the requirements of other filtration purposes.

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