Formation of Porous Structure with Subspot Size under the Irradiation of Picosecond Laser Pulses

Figure 6

SEM images of an array of craters ablated on the surface of stainless steel 304 with fluence 0.8 J/cm² and pulse number of 100 (a), 200 (c), 500 (e), and 1000 (g) and fluence 1.6 J/cm² and pulse number of 100 (b), 200 (d), 500 (f), and 1000 (h), respectively.

(a)

(b)

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(h)