Femtosecond laser volume ablation rate and threshold measurements by differential weighing

Abstract

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.