AUSTRALIAN OPTICAL SOCIETY
Submission for Poster Presentation
UV LASER CLEANING – THE IMPACT OF LASER BEAM GEOMETRY AND SCANNING ON THE REMOVAL OF ALUMINA PARTICLES FROM GLASS SLIDES
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Alanna FERNANDES and Deb KANE
Dept of Physics, Macquarie University, North Ryde, NSW 2109, Australia.
Tel: +61-2-9850-6370; Fax: +61-2-9850-8115; E-mail:
Sub-micron particles on surfaces can be a hindrance in optical industries. Standard cleaning methods are not always able to remove these contaminants, and may also cause substrate damage or leave solvent residues. An alternative technique is to use direct irradiation of short-pulsed ultraviolet lasers. This has demonstrated the efficient removal of sub-micron particles without causing damage to the substrate.
Kumar et al [1] and Vereecke et al [2] have utilised a thin ‘line’ beam and scanned it over a substrate. They reported that it removed particles more efficiently than a wider beam. It was proposed that this reduced width and continuous scanning of the laser beam caused the particles to roll off [2]. This has not been further investigated to our knowledge.
In this study, the effects of laser scanning and beam dimensions on the removal of non-spherical alumina particles from glass slides were examined. A surface was scanned with a line beam both continuously and in discrete static steps. Similar cleaning efficiencies were observed in each case, indicating no dependence on the beam scanning at low speeds. Further results of cleaning efficiencies at higher scan rates will be presented, where the deposited energy per unit area is the same. Removal of non-spherical and spherical particles will also be discussed.
References:
[1] D. Kumar, A. Ata, U. Mahajan & R.K. Singh, ‘Role of Line-Beam on the Removal of Particulate Contaminations from Solid Surfaces by Pulsed Laser’, Journal of Electronic Materials, 27 (10), 1998;
[2] G. Vereecke, E. Rohr & M.M. Heyns, ‘Influence of Beam Incidence Angle on Dry Laser Cleaning of Surface Particles’, Applied Surface Science, 157, 2000.