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Proceedings Paper

Photoacoustic energy conversion efficiency for a simplified absorber model
Author(s): Pingyu Liu
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Paper Abstract

Electromagnetic energy that is carried by light is converted to thermodynamic and mechanical forms of energy, i.e., heat and kinetic energy, when light interacts with tissue. The conversion efficiency from the absorbed radiative energy by an object into the kinetic energy is an important issue in the study of laser-tissue interactions, because the kinetic energy is the source of acoustic signals. Based on the first law of thermodynamics and some simplified assumptions, an expression for the conversion efficiency of optical to kinetic energy has been derived for an isolated, uniformly absorbing sphere. If there is no phase transition, the rule of thumb is that the converted kinetic energy is proportional to the square of the total absorbed radiative energy per unit time, and the square of the linear thermal expansion coefficient; and, it is inversely proportional to the product of the density, radius and the square of the specific heat of the sphere. This result will be used to optimize a design for photo-acoustic measurement of the optical absorption properties of phantoms and biological tissues in vivo.

Paper Details

Date Published: 17 August 1994
PDF: 4 pages
Proc. SPIE 2134, Laser-Tissue Interaction V; and Ultraviolet Radiation Hazards, (17 August 1994); doi: 10.1117/12.182922
Show Author Affiliations
Pingyu Liu, Indiana Univ. School of Medicine (United States)

Published in SPIE Proceedings Vol. 2134:
Laser-Tissue Interaction V; and Ultraviolet Radiation Hazards
Steven L. Jacques; David H. Sliney; Michael Belkin M.D., Editor(s)

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