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Proceedings Paper

Flat-top beam for laser-stimulated pain
Author(s): Ryan McCaughey; Valerie Nadeau; Mark Dickinson
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Paper Abstract

One of the main problems during laser stimulation in human pain research is the risk of tissue damage caused by excessive heating of the skin. This risk has been reduced by using a laser beam with a flattop (or superGaussian) intensity profile, instead of the conventional Gaussian beam. A finite difference approximation to the heat conduction equation has been applied to model the temperature distribution in skin as a result of irradiation by flattop and Gaussian profile CO2 laser beams. The model predicts that a 15 mm diameter, 15 W, 100 ms CO2 laser pulse with an order 6 superGaussian profile produces a maximum temperature 6 oC less than a Gaussian beam with the same energy density. A superGaussian profile was created by passing a Gaussian beam through a pair of zinc selenide aspheric lenses which refract the more intense central region of the beam towards the less intense periphery. The profiles of the lenses were determined by geometrical optics. In human pain trials the superGaussian beam required more power than the Gaussian beam to reach sensory and pain thresholds.

Paper Details

Date Published: 14 April 2005
PDF: 10 pages
Proc. SPIE 5698, Thermal Treatment of Tissue: Energy Delivery and Assessment III, (14 April 2005); doi: 10.1117/12.587577
Show Author Affiliations
Ryan McCaughey, Univ. of Manchester (United Kingdom)
Valerie Nadeau, Univ. of Manchester (United Kingdom)
Mark Dickinson, Univ. of Manchester (United Kingdom)

Published in SPIE Proceedings Vol. 5698:
Thermal Treatment of Tissue: Energy Delivery and Assessment III
Thomas P. Ryan, Editor(s)

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