Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5366834 | Applied Surface Science | 2009 | 5 Pages |
In this paper the surface topography of titanium samples irradiated by femtosecond laser pulses is described. When the fluence is about 0.5Â J/cm2 periodic ripples with a period of about 700Â nm are formed. For fluences between 0.5 and 2Â J/cm2, a microcolumnar surface texture develops in the center of the irradiated spots and ripples are formed in the periphery of the spots. When experiments are performed with a non-stationary sample, the microcolumns exhibit ripples similar to those observed when the radiation fluence is about 0.5Â J/cm2 and in the outer regions of the irradiated areas for fluences between 0.5 and 2Â J/cm2. Since the energy distribution in the transverse cross-section of the laser beam is Gaussian, we conclude that the ripples form when the microcolumns are subjected to fluences near the melting threshold of the material at the trailing edge of the moving laser beam.