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Polishing of illumination optics with CO2 laser radiation

 
: Richmann, A.; Willenborg, E.; Wissenbach, K.

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Fulltext (PDF; )

DGaO-Proceedings. Online journal (2012), Paper B21, 2 pp.
http://www.dgao-proceedings.de/home/home_d.php
ISSN: 1614-8436
Deutsche Gesellschaft für Angewandte Optik (DGaO Jahrestagung) <113, 2012, Eindhoven>
English
Conference Paper, Electronic Publication
Fraunhofer ILT ()
Fertigung optischer Systeme; Beleuchtung; Lasermaterialbearbeitung

Abstract
Polishing of illumination optics with CO2 laser radiation - Polishing of optical components with CO2 laser radiation is a current research topic at the Fraunhofer ILT. The laser radiation is guided on the surface of the glass and due to the high absorption of the laser radiation in the material the temperature rises. The viscosity is lowered and the glass can flow. Due to the surface tension the surface is smoothened. With this polishing technique the micro roughness can be efficiently reduced in the sub-nanometer regime while the form deviation is below 1 µm for a 25 mm diameter lenses. This form deviation is sufficient for lightning applications. The micro roughness of the laser polished optics is very low so that e.g. the transmission of the optics can be increased. The processing time is with less than 10 s for a whole lens of 25 mm diameter very short compared to conventional techniques. This process is suitable for different glass materials e.g. BK7 and Floatglass. To prevent thermal damage while polishing the glass is preheated to the glass transition temperature. The glass can be annealed after to reduce thermal tensions but this is not always necessary.

: http://publica.fraunhofer.de/documents/N-215975.html