Influence of the beam spot size on ablation rates in pulsed-laser processing

Abstract

Ablation rates in pulsed-laser processing depend heavily on the laser beam spot size. This has been observed for the first time for a number of different materials. Detailed investigations on this effect, performed by means of XeCl excimer-laser radiation and the example of LiNbO3, are reported in this letter. With this material, the ablation rate at constant fluence saturates at laser beam spot sizes of 2w≳80 μm and increases by about a factor of 3 when 2w is decreased to 24 μm. The effect is interpreted as being due to changes in the material transport which depend on the size of the region being processed.