Fig. 1. Schematic diagram of the laser irradiation system.

Fig. 2. LCM images of the hole drilled by the fs laser with different defocused irradiation times. (a) 0 min; (b) 15 min; (c) 30 min.

Fig. 3. (Color online) Holes geometry as a function of defocused irradiation time at average laser power of 6 mW: (a) the LCM images; (b) the depth; (c) the width (diameter).

Fig. 4. SEM images with (15 min) and without the defocused irradiation at various pulse numbers.

Fig. 5. SEM images of LIPSS on the stainless alloy surface following 20 laser pulse ablations at a fluence of 3 μJ with different defocused irradiation times: (a) 0 min; (b) partial enlarged view of (a); (c) 15 min; (d) partial enlarged view of (d); (e) 30 min; (f) partial enlarged view of (e).

Fig. 6. LCM images of the microchannels fabricated (c) with and (b) without defocused irradiation.