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arXiv · 2607.17919

Femtosecond-to-millisecond holographic imaging of laser ablation dynamics

Shotaro Kawano·Keiichiro Toda·Miu Tamamitsu·Haruyuki Sakurai·Kuniaki Konishi·Takuro Ideguchi
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Abstract

Femtosecond laser ablation redistributes optically deposited energy across electronic, structural, mechanical, and thermal degrees of freedom over timescales from femtoseconds to milliseconds. However, these coupled processes are usually measured in separate temporal ranges and through different observables, limiting quantitative comparison between early transient dynamics, residual heating, and final morphology. Here we introduce pump-probe holographic imaging that reconstructs amplitude- and phase-resolved optical fields across this full temporal range under matched imaging conditions. Applied to deep-ultraviolet femtosecond ablation of BK7 glass, the method captures the transition from early excitation and removal-stage dynamics to residual substrate heating and permanent modification. Differential phase analysis isolates sub-nanosecond evolution of the transient ablating layer and microsecond residual heating after material removal. Above the ablation threshold, crater depth increases with fluence, whereas the residual thermal signal saturates, indicating that additional absorbed energy is preferentially partitioned into material removal and ablation-related processes rather than retained as substrate heat. These results identify fluence-dependent energy partitioning as a dynamical basis of low-heat-affected femtosecond processing and establish holographic imaging as a route to tracking laser-driven nonequilibrium material transformations.

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Shotaro Kawano, Keiichiro Toda, Miu Tamamitsu, Haruyuki Sakurai, Kuniaki Konishi, Takuro Ideguchi. 2026-07-20. Femtosecond-to-millisecond holographic imaging of laser ablation dynamics. https://arxiv.org/abs/2607.17919

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