Fig. 1. Schematic diagram of femtosecond laser processing system

Fig. 2. Flow chart of grinding teeth by femtosecond laser. (a) Caries are soaked in acetone solution for 6 h; (b) rinsing with anhydrous ethanol; (c) grinding of cavities by femtosecond laser; (d) observation by laser confocal microscope

Fig. 3. Effect of scanning speed on hole depth. (a) Line roughness curves at different scanning speeds; (b) three-dimensional morphology of hole at scanning speed of 9 mm/s; (c) three-dimensional morphology of hole at scanning speed of 2 mm/s

Fig. 4. Effect of scanning number on drilling depth. (a) Line roughness curves under different scanning numbers; (b) three-dimensional morphology of hole when scanning number is 1; (c) three-dimensional morphology of hole when scanning number is 8

Fig. 5. Effect of scanning power on drilling depth. (a) Line roughness curves at different scanning powers; (b) three-dimensional morphology of hole when scanning power is 100 mW; (c) three-dimensional morphology of hole when scanning power is 800 mW

Fig. 6. Effects of different machining parameters on bottom roughness of micro-pores. (a) Effect of scanning speed on bottom roughness of micro-pores; (b) effect of scanning number on bottom roughness of micro-pores; (c) effect of scanning power on bottom roughness of micro-pores