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Proceedings Paper

Longitudinal vibration response of a curved fiber used for laser ultrasound surgical therapy (LUST)
Author(s): Kai Desinger; J. Pankau; S. N. Makarov; M. Ochmann; Thomas Stein; Juergen Helfmann; Gerhard J. Mueller
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Paper Abstract

A theoretical study of the longitudinal vibration response of a bent fiber used as an active element of a medical applicator for laser ultrasound surgical therapy (LUST) is presented. An important problem concerns taking into account fiber bending which may appear due to applications in endoscopy. NIR laser radiation and low frequency ultrasound (20 - 50 kHz) with amplitudes of up to 100 micrometers can be transmitted by silica glass fibers. The fiber cross- section is much smaller than the longitudinal wavelength. Wave propagation in the bent fiber is described by the governing second-order equations of motion which neglect the flexure effect. In contest to numerous works on bent rods, the case of an arbitrary continuous curvative distribution along the fiber is investigated. A simple analytical formula for the transfer function (the ratio of displacements at the working end of the fiber divided by those at the driven end) is obtained. The transfer function depends on frequency, fiber length, output impedance, loss factor, and the mean- square curvative of the fiber. The behavior of this function is investigated applied to some fibers whose lengths are of the order 1 m. If the displacement at the driven end of the fiber is known, the acoustical power output of the applicator can be found from the known values of the tissue impedance and the transfer function.

Paper Details

Date Published: 18 April 1997
PDF: 10 pages
Proc. SPIE 2977, Specialty Fiber Optics for Biomedical and Industrial Applications, (18 April 1997); doi: 10.1117/12.271018
Show Author Affiliations
Kai Desinger, Laser- und Medizin-Technologie gGmbH Berlin (Germany)
J. Pankau, Laser- und Medizin-Technologie gGmbH Berlin (Germany)
S. N. Makarov, St. Petersburg State Univ. (Russia)
M. Ochmann, Technische Fachhochschule Berlin (Germany)
Thomas Stein, Institut fuer Medizinische/Technische Physik und Lasermedizin/Freie Univ. Berlin (Germany)
Juergen Helfmann, Institut fuer Medizinische/Technische Physik und Lasermedizin/Freie Univ. Berlin (Germany)
Gerhard J. Mueller, Laser- und Medizin-Technologie gGmbH Berlin (Germany)
Institut fur Medizinische/Technische Physik und Lasermedizin/Freie Univ. Berlin (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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