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Proceedings Paper

High-power laser waveguide with a circulating liquid core for IR applications
Author(s): Sandra Klein; Joerg Meister; Stefan Diemer; Roland Jung; Werner Fuss; Peter Hering
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Paper Abstract

Due to the high absorption coefficient of water in biological tissues at 3 micrometer, the Er:YAG (2.94 micrometer) and the Er:YSGG laser (2.79 micrometer) are very effective tools for medical applications. A widespread use of these lasers is prevented by the lack of a lightguide which satisfies the demands of medical practice, e.g. flexibility, low bending radius and unbreakability. If teflon (FEP) tubes filled with carbontetrachloride (CCl4) are used for high laser energies, absorbing and scattering particles in the liquid core are responsible for the decreasing transmission and damaging of the lightguide. A system was developed therefore to purify the liquid continuously even during laser irradiation. Two concentric FEP tubes are used to realize a circulation system. Different inner diameters of cladding tubes (1.6 mm and 0.5 mm) were tested with an Er:YAG and a Ho:YAG laser. A theoretical model of the different intrinsic attenuation losses in those lightguides was developed, which is in good agreement with the experimental results. Distal energy densities of 88 J/cm2 (Er:YAG) up to 220 J/cm2 (Ho:YAG) could be achieved with the small cladding tubes. These values were only limited by the output power of our laser devices. This waveguide setup has a better flexibility than those with a solid core. Due to the high numerical aperture (NA equals 0.54) the bending losses are negligible down to a bending radius of 15 mm. The high flexibility and transmittable power of the presented circulation system is particularly attractive for medical laser treatments.

Paper Details

Date Published: 18 April 1997
PDF: 9 pages
Proc. SPIE 2977, Specialty Fiber Optics for Biomedical and Industrial Applications, (18 April 1997); doi: 10.1117/12.271020
Show Author Affiliations
Sandra Klein, Institut fuer Lasermedizin/Heinrich-Heine-Univ. Duesseldorf (Germany)
Joerg Meister, Institut fuer Lasermedizin/Heinrich-Heine-Univ. Duesseldorf (Germany)
Stefan Diemer, Institut fuer Lasermedizin/Heinrich-Heine-Univ. Duesseldorf (Germany)
Roland Jung, Institut fuer Lasermedizin/Heinrich-Heine-Univ. Duesseldorf (Germany)
Werner Fuss, Institut fuer Lasermedizin/Heinrich-Heine Univ. and Max-Planck-Institut fuer Quantenoptik (Germany)
Peter Hering, Institut fuer Lasermedizin/Heinrich-Heine Univ. and Max-Planck-Institut fuer Quantenoptik (Germany)

Published in SPIE Proceedings Vol. 2977:
Specialty Fiber Optics for Biomedical and Industrial Applications
Abraham Katzir; James A. Harrington, Editor(s)

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