Monday, 11 October 2004 - 4:45 PM

This presentation is part of : Femtosecond Laser Micro/nano-machining I

Blackening of metal surfaces by femto-second laser machining

Neha Singh1, Dennis R. Alexander1, John Schiffern2, and David W. Doerr1. (1) Dept. of Electrical Engineering and Center for Electro-Optics (University of Nebraska-Lincoln), University of Nebraska, Center for Electro-Optics, 209N. WSEC, Lincoln, NE 68588-0511, (2) Center for Electro-Optics, University of Nebraska-Lincoln, 248 WSEC, Box 880511, Lincoln, NE 68588-0511

Metal surfaces like aluminum and gold turn black in color upon laser ablation. A Ti:Sapphire Femto-Second laser is used for machining the metal surface at a high fluence in air and vacuum. The blackening of surface is due to surface roughness and formation of micro- and nano- sized surface structures. Reflectance measurements are made using ellipsometry and integrating sphere and the surface is found to have a very low reflectance in the UV-VIS and also in the IR spectrum. The EDX, XPS and AES techniques are used to analyze the surface material properties. A study of how the laser machining parameters affects the reflectance values over a broad spectral range is conducted. An attempt is made to understand the role of shape, size, and material properties of the micro- and nano- sized surface structures in the absorption and scattering of light.

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