LASER-ASSISTED SURFACE MODIFICATION OF THIN CHROMIUM FILMS

The objective is to investigate a process by which micrometer scale to pographical changes are produced on thin chromium films using a pulsed Nd:YLF laser. The surface of chromium films is altered through laser- induced solid-liquid phase transformation and fluid flow. Experimental parametric studies are conducted to correlate the laser parameters wi th the topography of the laser irradiated surfaces. Experimental and a nalytical work is also performed to study the transport phenomena invo lved in the process. A numerical finite-element analysis is used to si mulate the transient field variables. A nanosecond-time-resolution, fa st photography system is constructed to capture the phase change and t he fluid flow occurring at the target surface. The experimental and th e numerical studies showed that the surface topography change was caus ed by the laser-induced surface-tension-driven flow, and the recoil pr essure due to surface evaporation had negligible effect on the topogra phy variation. (C) 1998 Society of Photo-Optical Instrumentation Engin eers. [S0091-3286(98)03303-0].