Precise weight measurements of stainless steel, PZT and PMMA samples were performed after groove machining with femtosecond laser pulses (150 fs, 800 nm, 5 kHz) to determine volume ablation rates and ablation threshold with good accuracy. Weighing clearly enables faster determination of such phenomenological parameters without any methodological issue compared to other methods. Comparisons of the three types of materials reveal similar monotonous trends depending on peak fluences from 0.2 to 15 J/cm². The metallic target exhibits both the lowest volume ablation rate under the highest irradiation conditions with almost 400 µm³/pulse and the lowest ablation threshold with 0.13 J/cm². Ceramic PZT reaches 3.10³ µm³/pulse with a threshold fluence of 0.26 J/cm² while polymer PMMA attains 10⁴ µm³/pulse for a 0.76 J/cm² threshold. Pros and cons of this method are also deduced from complementary results obtained on microscopic and confocal characterizations.

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We demonstrate operation of a simple and reliable water-cooled femtosecond laser running at 10 kHz suitable for industrial micromachining applications. A laser geometry involving only a regenerative amplifier and delivering 3.5 W average power 60-fs pulses is compared to a more conventional architecture using an additional multi-pass amplifier. Both laser systems require a moderate pumping laser of ~30 W average power and deliver high-quality beams (M2<1.2).

Résumé : Une nouvelle technique kilohertz de mesure de temps de vol picoseconde sur un large domaine spectral (ISO nm) est détaillée. Le dispositif se compose d'un laser femtoseconde avec amplification à dérive de fréquence et d'une caméra à balayage de fente monocoup couplé a un polychromateur. Un continuum de lumière blanche est généré dans de l'eau de manière à obtenir une source 450-750 nm la plus intense. Les images obtenues permettent une analyse spectrale et temporelle simultanée dont la résolution en temps de vol est inférieure à 5 mm pour un temps d'intégration inférieur à 60 secondes.