Zeit- und ortsaufgelöste Untersuchungen dynamischer Prozesse bei der Femtosekunden- und Piktosekundenlaser-Materie-Wechselwirkung

• Antragsteller: Dr. Ernst Wolfgang Kreutz
• Fachliche Zuordnung: Produktionsautomatisierung und Montagetechnik
• Förderung: Förderung von 2004 bis 2011
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 5431482

• Erstellungsjahr: 2009

Zusammenfassung der Projektergebnisse

This work contributes to the understanding of the ultrafast melting and ablation of solids irradiated at large laser intensities. Fundamental aspects of the ultrafast laser ablation of pure metals (Au, Al, Cu, Fe, W), such as laser-matter interaction, plasma formation, evaporation and melt dynamics have been matter of research. Melting of technical borosilicate glass by high-repetition rate ultrafast laser radiation have been studied as well. Novel experimental techniques and tools have been developed and applied in order to enable investigations of laser induced transient phenomena on different time scales. Pump-probe imaging technique has been adopted featuring an extended temporal detection limit of approx. 2 microseconds and preserving a temporal resolution in the sub-picosecond range. A novel quantitative optical phase microscopy technique (TQPm) has been developed for time-resolved investigations of transient refractive index and morphology changes. For laser ablation of metals at large irradiation intensities, the temporal and spatial profiles of the adopted laser radiation have been examined. The heating effect of the radiation pedestals caused by amplified spontaneous emission has been estimated numerically resulting in a temperature increase by several hundreds of Kelvin, depending on material properties. Time-resolved shadowgraphy and quantitative measurements of the ablated volume in metals have been performed in different ambient conditions. In the adopted delay range, the observed ablation phenomena can be classified by at least four characteristic time regions, featuring the ejection of plasma and highly pressurized vapor, material vapor due to nucleation effects, liquid melt jets, and resolidification, respectively. Based on the experimental results of this work, a qualitative description for ablation of metals at large intensities is given, and important differences to the ablation at near-threshold intensities are specified. Particularly, phenomena concerned with overheating of material, e.g. phase explosion and “boiling crisis”, are assumed as the prevailing mechanisms of ablation. Melting of technical borosilicate glass by high-repetition rate ultrafast laser radiation has been studied dynamically by means of TQPm. The obtained results exhibit transient modifications of the refractive index which reflects either the ionization process or the material densification.

Projektbezogene Publikationen (Auswahl)

• Diagnostics of laser-induced melting of matter by ultra-fast metrology, I. Miyamoto. J. Laser Micro/Nanoeng. 1, 264 (2006)
  A. Horn, I. Mingareev
  
• Observation of melt ejection in metals up to 1 µs after femtosecond laser irradiation by a novel pump-probe photography setup. Proc. SPIE 6261, 62610A-1 (2006)
  I. Mingareev, A. Horn, E.W. Kreutz
  
• Investigations on melting and welding of glass with ultra-short pulsed laser radiation. Proc. LPM’07, Vienna (2007)
  A. Horn, I. Mingareev, I. Miyamoto
  
• Dynamical detection of optical phase changes during micro-welding of glass with ultra-short laser radiation. Meas. Sci. Technol. 19 015302 (2008)
  A. Horn, I. Mingareev, J. Gottmann, A. Werth, U. Brenk
  
• Investigations of the ultrafast laser induced melt dynamics by means of transient quantitative phase microscopy (TQPm). Proc. SPIE, Vol. 7005, 70050P (2008)
  I. Mingareev, A. Horn
  
• Investigations on melting and welding of glass by ultrashort laser radiation. J. Laser Micro/Nanoeng., Vol. 3, No. 2, 114 (2008)
  A. Horn, I. Mingareev, A. Werth
  
• Investigations on ultrafast welding of glass-glass and glass-silicon. Appl. Phys.s A, Vol. 93, No. 1, 171 (2008)
  A. Horn, I. Mingareev, A. Werth, M. Kachel, U. Brenk
  
• Non-interferometric transient quantitative phase microscopy for ultrafast engineering. Appl. Phys. A, Vol. 93, No. 1, 165 (2008)
  A. Horn, I. Mingareev, A. Werth, M. Kachel, U. Brenk
  
• Novel fusion welding technology of glass using ultrashort pulse lasers. Proc. ICALEO’08 (2008)
  I. Miyamoto, A. Horn, J. Gottmann, D. Wortmann, I. Mingareev, F. Yoshino, M. Schmidt, P. Bechtold, Y. Okamoto, Y. Uno, T. Herrmann
  
• Time-resolved investigations of plasma and melt ejections in metals by pump-probe shadowgraphy. Appl. Phys. A, Vol. 92, No. 4, 917 (2008)
  I. Mingareev, A. Horn
  
• Melt dynamics of aluminum irradiated with ultrafast laser radiation at large intensities. J. Appl. Phys. 106, 013513 (2009)
  I. Mingareev, A. Horn