Fig. 1. Principle diagram of laser cleaning

Fig. 2. Finite element model and meshing of laser cleaned samples

Fig. 3. Surface temperature field distributions of acrylic polyurethane paint layer at different scanning moments. (a) t=0.002 s; (b) t=0.003 s; (c) t=0.004 s; (d) t=0.048 s

Fig. 4. Temperature field distributions in depth direction

Fig. 5. Temperature field distributions at different scanning speeds. (a) Scanning speed of 2500 mm/s and spot overlapping of 50%; (b) scanning speed of 5000 mm/s and spot overlapping of 0

Fig. 6. Maximum surface temperature curves of paint layer and substrate at different scanning speeds

Fig. 7. Maximum surface temperature curves of paint layer and substrate at different laser energy densities

Fig. 8. Surface temperature field distributions at laser energy density of 25 J/cm². (a) Paint layer; (b) substrate

Fig. 9. Cleaning depths at different energy densities. (a) 5 J/cm²; (b) 15 J/cm²; (c) 25 J/cm²; (d) 40 J/cm²

Fig. 10. Three-dimensional surface topographies of aluminum alloy substrate after cleaning by laser with different energy densities. (a) 15 J/cm²; (b) 25 J/cm²; (c) 40 J/cm²; (d) 50 J/cm²

Fig. 11. SEM images of aluminum alloy substrate after cleaning by laser with different energy densities. (a) 5 J/cm²; (b) 15 J/cm²; (c) 25 J/cm²; (d) 40 J/cm²