Ablation efficiency in MHz burst-mode ultrashort-pulse laser percussion drilling of thin metal foils

Gregorčič, Peter (avtor), Ahmed, Rida (avtor), Förster, Daniel (avtor)

The increasing average power of ultrashort-pulse lasers requires efficient use of the available pulse energy, and MHz burst operation offers one route by distributing this energy among temporally separated sub-pulses. However, systematic understanding of how ablation efficiency evolves with the number of pulses per burst, N$_{p}$, during percussion drilling of thin metal foils remains limited. Therefore, we investigate how the maximum depth-based ablation efficiency, η$_{max}$, evolves with N$_{p}$ up to 40 during MHz burst-mode percussion drilling of 50-µm-thick metal foils using 300-fs, 1030-nm laser pulses. Measurements for stainless steel (SS) and Ti are compared with those for Al and Cu, with thermal diffusivities approximately one order of magnitude higher. We separate η$_{max}$ into two contributions: the optimum sub-pulse fluence, F▫$_{b}^{opt}$▫, and the average ablation depth per sub-pulse, Δd$_{b}$. A simple theoretical model describes how residual heat accumulation affects F▫$_{b}^{opt}$▫, while the logarithmic ablation-depth law is extended phenomenologically to describe deviations from additive depth scaling. For SS and Ti, F▫$_{b}^{opt}$▫ decreases with N$_{p}$, in agreement with the baseline predicted by the model, while moderately super-additive depth scaling produces a strong initial increase in η$_{max}$; at higher N$_{p}$, η$_{max}$ reaches more than 470% above the single-pulse value. Al and Cu deviate from this baseline through an initial increase in F▫$_{b}^{opt}$▫ and pronounced odd-even modulation of Δd$_{b}$ and η$_{max}$. These departures are consistent with additional plume-mediated attenuation and re-deposition reported in the literature. At larger N$_{p}$, the decrease in Δd$_{b}$ and increasingly melt-dominated morphology coincide with diminishing further gains in η$_{max}$, consistent with melt redistribution and plume-mediated attenuation.

• Jezik: Angleški jezik
• Ključne besede: laser drilling, laser machining, MHz burst mode, ablation efficiency, ultrashort laser pulses
• Vrsta gradiva: Članek v reviji
• Tipologija: 1.01 - Izvirni znanstveni članek
• Organizacija: FS - Fakulteta za strojništvo
• Status publikacije: Objavljeno
• Različica publikacije: Objavljena publikacija
• Leto izida: 2026
• Št. strani: 19 str.
• Številčenje: Vol. 358, art. 119552
• PID: 20.500.12556/RUL-190344
• UDK: 621.9.048
• ISSN pri članku: 0924-0136
• DOI: 10.1016/j.jmatprotec.2026.119552
• COBISS.SI-ID: 302430211
• Datum objave v RUL: 26.10.2026

Gradivo je del revije

• Naslov: Journal of materials processing technology
• Skrajšan naslov: J. mater. process. technol.
• Založnik: Elsevier
• ISSN: 0924-0136
• COBISS.SI-ID: 30105600

Licence

• Licenca: CC BY 4.0, Creative Commons Priznanje avtorstva 4.0 Mednarodna
• Povezava: http://creativecommons.org/licenses/by/4.0/deed.sl
• Opis: To je standardna licenca Creative Commons, ki daje uporabnikom največ možnosti za nadaljnjo uporabo dela, pri čemer morajo navesti avtorja.

Sekundarni jezik

• Jezik: Slovenski jezik
• Ključne besede: lasersko vrtanje, laserska obdelava, laserski bliski v nizu, učinkovitost ablacije, ultrakratki laserski bliski