Underwater and water-assisted laser processing: Part 2 - Etching, cutting and rarely used methods

In the second part of the article, the subtractive processes-laser etching and cutting-in the presence of liquid water will be reviewed; but the rarely used methods of water assisted/underwater laser processing, such as welding, silicon wafer breaking, surface modification of polymers, pulsed laser deposition, particle formation and water mask defined microstructures fabrication, will also be described. Etching and cutting under water provide better tolerances and smaller heat-affected zone widths and avoid the re-deposition of debris. Irradiation under water results in increased wetting of fluoropolymers, and laser ablation in water vapor provides deposition of highly crystalline hydroxyapatite coatings. Laser irradiation of solid targets in water has been used to fabricate Ag, Au, Ni, Cu and carbon nanoparticles. The results of an original study on the formation of free-standing high aspect ratio Pb(ZrxTi1-x)O-3 microplates fabricated by laser irradiation of Pb(ZrxTi1-x)O-3 ceramics in water are also reported. The platelets were up to 60 pm in diameter and 50-160 nm in thickness. The use of neutral liquids other than water and some medical applications of underwater/water-assisted laser light driven processes will also be briefly reviewed. (C) 2002 Published by Elsevier Science Ltd.