supported by the National Natural Science Foundation of China (Nos. 11474097, 11274116, 11104178, 44108280, and 51132004);the National Special Science Research Program of China (No. 2011CB808105)
This Letter reports the formation of periodic surface structures on Ni–Fe film irradiated by a single femtosecond laser pulse. A concave lens with a focus length of-150 mm is placed in front of an objective(100×, N...