Dynamics of tissue optics during laser heating of turbid media

Wei Chiang Lin, Massoud Motamedi, Ashley J. Welch

Research output: Contribution to journalArticle

51 Scopus citations

Abstract

The dynamics of the optical behavior of tissue during the photothermal interaction of laser radiation with tissue could significantly affect the optimization of light doses for effective and safe applications of lasers in medicine. Characterization of the dynamics of tissue optics during laser heating was performed by means of simultaneous measurements of the total transmittance, diffuse reflectance, and surface temperature of fresh and thermally coagulated human skin and canine aorta during long-pulsed Nd:YAG laser heating with a double integrating-sphere system and an infrared camera. Thermally induced changes in the optical properties of tissue caused a decrease in the total transmittance and an increase in the diffuse reflectance of both fresh and precoagulated skin and aorta samples. For fresh tissue, these changes were primarily reversible until photocoagulation occurred, then both the reversible, as well as the irreversible, changes were observed. However, for precoagulated tissue the reversible changes in the optical properties were dominant, whereas the irreversible changes were insignificant. Results from this study indicate the existence of the nonlinear behavior in the optics of turbid biological media during pulsed laser heating. Possible mechanisms responsible for this nonlinear optical behavior are discussed.

Original languageEnglish (US)
Pages (from-to)3413-3420
Number of pages8
JournalApplied Optics
Volume35
Issue number19
DOIs
StatePublished - Jul 1 1996

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Keywords

  • Diffuse reflectance
  • Laser heating
  • Pulsed laser
  • Reversible optical behavior
  • Tissue coagulation
  • Tissue optics
  • Total transmittance

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Engineering (miscellaneous)
  • Electrical and Electronic Engineering

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