The effect of target temperature on the deterioration of metal surfaces under pulsed laser irradiation

The effects of pulsed laser irradiation on preheated solid metal surfaces have been studied. The surface of low-melting point metals In and Bi.is irradiated by KrF excimer laser pulses of fluences below 400 mJrcm2. Evaluation of the optical microscopic pictures of the processed metal surfaces reveals that the characteristic lateral dimension of laser-induced surface structures increases as the melting point is approached. The results are explained in terms of the lifetime of the melt pool, obtained by numerical temperature calculations. Close to the melting point, the increased lifetime of the molten phase allows ample time for smoothing of the surface before its resolidification. q2000 Elsevier Science B.V. All rights reserved