Fig. 1. Laser scanning path diagram

Fig. 2. Microhole images of different pulse energy densities, ×50. (a) 0.28 J/cm²; (b) 0.52 J/cm²; (c) 0.68 J/cm²; (d) 0.79 J/cm²; (e) 1.59 J/cm²; (f) 2.39 J/cm²; (g) 3.18 J/cm²; (h) 4.77 J/cm²; (i) 6.37 J/cm²

Fig. 3. Experimental results. (a) SEM of grooves; (b) a partial enlargement of Fig. (a); (c) SEM of microholes; (d) a partial enlargement of Fig. (c)

Fig. 4. Microhole images of different repeat scan times, ×50. (a) 1 time; (b) 5 times; (c) 10 times; (d) 15 times; (e) 20 times;

Fig. 5. Unilateral microhole images at different scanning speeds, ×100. (a) 1400 mm/s; (b) 1200 mm/s; (c) 1000 mm/s; (d) 800 mm/s

Fig. 6. Surface maximum temperature curves of different pulse energy densities

Fig. 7. Simulation of temperature field in a pulse cycle. (a) 80 μs; (b) 81 μs; (c) 83 μs; (d) 84 μs

Fig. 8. Schematic of microhole evolution process

Fig. 9. Relationship between maximum temperature at edge of groove and number of effective pulses per unit area