In-situ measurements of residual heating during pulse-on-demand femtosecond laser surface microprocessing

Petelin, Jaka (author), Marš, Matevž (author), Mur, Jaka (author), Petkovšek, Rok (author)

Femtosecond laser processing offers highly precise structuring with minimal residual heating of materials. However, at high average powers and pulse repetition rates, heating can limit process efficiency. The pulse-on-demand laser operation regime has proven to be an optimal solution for achieving high throughput and quality in laser microstructuring, independent of the scanner’s capabilities. Here, we present in situ measurements of residual heating during femtosecond laser microstructuring. By combining experimental observations with simulations, we investigate residual heat retention in various target materials and its associated effects. A high-speed thermal camera was employed for direct process monitoring, providing spatially and temporally resolved measurements of surface temperatures during laser microstructuring. The results were quantified using finite element–based numerical simulations of the material’s transient thermal response, enabling us to assess the conversion of laser power into unwanted residual heating. Surface topography measurements further contextualize the temperature data within the framework of microprocessing performance. We compare the effects of the pulse-on-demand regime with those observed in quasi-stationary cases, addressing both scanner acceleration compensation and advanced surface shaping achieved through laser repetition rate modulation algorithms. The pulse-on-demand regime’s ability to compensate for irregular scanner movements enables faster and more precise femtosecond laser processing of brittle and heat-sensitive materials.

• Language: English
• Keywords: femtosecond laser, laser microstructuring, pulse-on-demand, thermal imaging
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 8 str.
• Numbering: Vol. 190, art. 113201
• PID: 20.500.12556/RUL-169328
• UDC: 621.375.826
• ISSN on article: 0030-3992
• DOI: 10.1016/j.optlastec.2025.113201
• COBISS.SI-ID: 236944643
• Publication date in RUL: 23.05.2025

Record is a part of a journal

• Title: Optics and laser technology
• Shortened title: Opt. Laser Technol.
• Publisher: Elsevier
• ISSN: 0030-3992
• COBISS.SI-ID: 26072576

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Projects

• Funder: EC - European Commission
• Funding programme: NextGenerationEU
• Acronym: GREENTECH

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P2-0270
• Name: Proizvodni sistemi, laserske tehnologije in spajanje materialov