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Proceedings Paper

Laser surgery at the micrometer scale: possibilities and limitations
Author(s): Klaus Rink; Guy P. Delacretaz; Rene-Paul Salathe; Alfred Senn; Dorotha Nocera; Marc Germond
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Paper Abstract

For a few years promising techniques have been worked out for microsurgery of cells and organelles by laser micro-cutting and micro-drilling. In this paper the specific requirements for controlled and safe laser surgery at this scale are addressed. Laser micro-drilling is investigated for various interaction parameters. For this a Nd:YAG laser ((lambda) equals 1064 nm) in Q-switched (7 ns) mode and a cw diode laser ((lambda) equals 1.48 micrometers ) in pulsed mode are used. The lasers are coupled to an inverted microscope and focused through the microscope objective (40X and 45X) in a spot of 1 to 3 micrometers in diameter. Ablation of biological targets (mouse zygotes zona pellucida) is compared with ablation of model targets (ink films), all in liquid environment. Possible generation of acoustical transients and cavitation bubbles is monitored with a PVDF pressure transducer and by time resolved video flash photography. The results show that, for the pulse durations investigated, a large absorption coefficient is a necessary condition for controlled micro-drilling. In liquid environment, short pulse lasers in combination with a low light absorption coefficient of the target induce unacceptable mechanical effects related to the generation of a cavitation bubble. These effects are due to a too high energy threshold for ablation in these processes. Video images of the drilled holes reveal walls of regular shape with small surrounding damage immediately after laser irradiation, which are completely destroyed at the bubble collapse. By contrast, with the 1.48 micrometers laser diode, which is strongly absorbed by the target, reproducible micro-drillings without mechanical effects are performed.

Paper Details

Date Published: 18 January 1995
PDF: 11 pages
Proc. SPIE 2323, Laser Interaction with Hard and Soft Tissue II, (18 January 1995); doi: 10.1117/12.199204
Show Author Affiliations
Klaus Rink, Ecole Polytechnique Federale de Lausanne (Switzerland)
Guy P. Delacretaz, Ecole Polytechnique Federale de Lausanne (Switzerland)
Rene-Paul Salathe, Ecole Polytechnique Federale de Lausanne (Switzerland)
Alfred Senn, Ctr. Hospitalier Univ. Vaudois (Switzerland)
Dorotha Nocera, Ctr. Hospitalier Univ. Vaudois (Switzerland)
Marc Germond, Ctr. Hospitalier Univ. Vaudois (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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