Fig. 1. Energy accumulation model of femtosecond laser multi-pulse processing

Fig. 2. The variable defocus amount model for femtosecond laser processing

Fig. 3. Temperature variation curves of electrons and lattices under variable energy and variable pulse width

Fig. 4. Ablation crater depth and radius simulation results

Fig. 5. Schematic diagram of femtosecond laser processing system

Fig. 6. Femtosecond laser surface machining schematic and surface morphology microstructure

Fig. 7. The ratio of effective light intensity I_i to peak energy I₀ with tilt angle curve

Fig. 8. Schematic diagram of the energy distribution of the laser spot acting on an oblique surface

Fig. 9. Detection diagram of single-pulse slope ablation pits with variable pulse width

Fig. 10. Multi-pulse slope ablation pit detection diagram

Fig. 11. Ablation crater left side profile shape change diagram

Fig. 12. The microstructure of the pit surface ablated by the variable pulse（the magnification scale is 5 μm）