Open AccessA comparative study on reflection of nanosecond Nd-YAG laser pulses in ablation of metals in air and in vacuum
Author(s) -
Olena Benavides,
L. de la Cruz-May,
Aaron Flores
Publication year - 2013
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.21.013068
Subject(s) - materials science , optics , plasma , ablation , fluence , laser , drop (telecommunication) , nanosecond , laser ablation , aluminium , absorption (acoustics) , reflectivity , composite material , telecommunications , physics , quantum mechanics , computer science , engineering , aerospace engineering
A comparative study on reflection of nanosecond Nd-YAG laser pulses in ablation of aluminum in air and in vacuum under the same other experimental conditions is performed. We find that, hemispherical total reflectivity of aluminum undergoes a sharp drop at the plasma formation threshold both in the air and in vacuum. The initial large value (0.8) of aluminum reflectivity decreases to a level of about 0.14 and 0.24 for ablation in the air and in vacuum, respectively. These decreased reflectivity values remain virtually unchanged with further increasing laser fluence. The reflectivity drop in the air is observed to be sharper than in vacuum. Our study indicates that the reflectivity drop is predominantly caused by absorption of the laser light in plasma. Nano/micro-structural defects present on practical sample surfaces play the important role in the plasma formation, especially for the ablation in the air, where the plasma formation threshold is found to be by a factor of 3 smaller than in vacuum.