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Proceedings Paper

Influence of pulse duration on erbium and holmium laser ablation under water
Author(s): Michael Ith; Martin Frenz; Hans Surya Pratisto; Heinz P. Weber; Hans Joerg Altermatt; Hans U. Staeubli; Thomas Asshauer; Guy P. Delacretaz; Rene-Paul Salathe; Bruno E. Gerber
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Paper Abstract

Erbium and Holmium lasers are ideally suited for cutting and drilling biological tissue. This is due to the fact that their wavelengths (Er:YSGG at 2.79 micrometers and Ho:YAG at 2.12 micrometers ) are strongly absorbed in water which is present in all tissues. Combined with an optical fiber these lasers seem to be optimal instruments for endoscopic and/or minimal invasive applications in surgery. In this study we focused our interest on cutting of human meniscus in the knee where, besides a very limited operation field, the standard arthroscopic treatment is performed in a liquid, highly absorbing environment. The bubble formation process, therefore, has to be well understood because it mainly determines relevant aspects of tissue ablation. The influence of the laser parameters in general and the influence of pulse duration in particular are determined in this paper for two different laser wavelengths. The goal was to determine the optimum laser parameters in view of a high ablation efficiency, a high precision and a minimal destruction of the adjacent tissue. To determine the optimum pulse duration for ablating tissue under water and to obtain a better understanding of the channel formation process, transmission and pressure measurements together with video flash photography were performed. Additionally, we determined experimentally the ratio between initial laser pulse energy and energy available for tissue treatment under water. To prove the results obtained, cuts in human meniscus were performed, sectioned and evaluated. The comparison between the results obtained with the Erbium and Holmium laser revealed a strong influence of the absorption coefficients on the tissue effects, especially on the ablation efficiency and on the zone of thermally and mechanically damaged tissue.

Paper Details

Date Published: 18 January 1995
PDF: 9 pages
Proc. SPIE 2323, Laser Interaction with Hard and Soft Tissue II, (18 January 1995); doi: 10.1117/12.199190
Show Author Affiliations
Michael Ith, Univ. Bern (Switzerland)
Martin Frenz, Univ. Bern (United States)
Hans Surya Pratisto, Univ. Bern (United States)
Heinz P. Weber, Univ. Bern (Switzerland)
Hans Joerg Altermatt, Univ. Bern (Switzerland)
Hans U. Staeubli, Tiefenauspital Bern (Switzerland)
Thomas Asshauer, Ecole Polytechnique Federale de Lausanne (Switzerland)
Guy P. Delacretaz, Ecole Polytechnique Federale de Lausanne (Switzerland)
Rene-Paul Salathe, Ecole Polytechnique Federale de Lausanne (Switzerland)
Bruno E. Gerber, Hopital Pourtales (Switzerland)

Published in SPIE Proceedings Vol. 2323:
Laser Interaction with Hard and Soft Tissue II
Hans Joerg Albrecht; Guy P. Delacretaz; Thomas H. Meier; Rudolf W. Steiner; Lars Othar Svaasand; Martin J. C. van Gemert, Editor(s)

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