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Proceedings Paper

NC-controlled production of smooth 3D surfaces in brittle materials with 193-nm excimer laser
Author(s): Hans Kurt Toenshoff; Christoph Graumann; Hanno Hesener; Marcus Rinke
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Paper Abstract

Micromachining performed by Excimer Lasers in conjunction with NC-controlled machines offer flexible production possibilities for 3-D-surfaces. Due to the limitations of conventional micromachining technology for brittle transparent materials in the micro range, a new laser machining beam guiding and data handling system was designed and built. The data handling starts with the mathematical description of the surface shape to be machined. The contour can be derived from a mathematical function or individual xyz-data point information from any CAD-program. A pre-processor calculates the nc-data for laser triggering, xyz-motion and the nc-mask control. Each laser pulse leads to a material removal, defined by the illuminated surface on the work piece as well as the energy density. The principal of superposition of pulses allows the creation of the desired contour. The chosen ablation strategy determines the surface roughness and the process speed. To achieve best results, it has to be carefully adjusted for a specific material. This technique does not require prefabricated tools such as semiconductor masks. This is a sufficient method for structuring grooves in ceramics, diamonds or glass as well as aspherical transparent optical surfaces or micro lens arrays. The excellent absorption of 193 nm compared to 248 nm or larger wavelengths leads to damage free structuring of most brittle materials. The optimized surface ablation process requires spot sizes and energy densities on the work piece which can not be realized with a mirror based beam guidance system. To eliminate these restrictions, a new mirror free machining concept with a gas flushed beam guiding system mounted on a granite vibration reduction table with air bearing positioning system was build. This paper describes the potential of 193 nm treatment of 3-D micro surfaces with a process optimized machine and data handling system.

Paper Details

Date Published: 31 August 1998
PDF: 11 pages
Proc. SPIE 3511, Micromachining and Microfabrication Process Technology IV, (31 August 1998); doi: 10.1117/12.324312
Show Author Affiliations
Hans Kurt Toenshoff, Laser Zentrum Hannover e.V. (Germany)
Christoph Graumann, Laser Zentrum Hannover e.V. (Germany)
Hanno Hesener, Laser Zentrum Hannover e.V. (Germany)
Marcus Rinke, Laser Zentrum Hannover e.V. (Germany)

Published in SPIE Proceedings Vol. 3511:
Micromachining and Microfabrication Process Technology IV
James H. Smith, Editor(s)

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