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Proceedings Paper

Absolute measurement of absorption and scattering coefficients spectra of a multiply scattering medium
Author(s): Sergio Fantini; Maria-Angela Franceschini; Joshua B. Fishkin; Enrico Gratton
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Paper Abstract

On the basis of the diffusion theory model, frequency-domain spectroscopy allows for a quantitative determination of the absorption ((mu) a) and scattering ((mu) s') coefficient spectra of a homogeneous multiple scattering medium. We performed measurements using an intensity modulated light emitting diode (LED) as the light source. The LED's spectral distribution permits the study of a spectral region extending for about 80 nm. Data sets (phase shift and average intensity) at two different source-detector distances are acquired: the absorption and scattering coefficient spectra of the medium are then calculated from analytical expressions for (mu) a and (mu) s'. Methylene blue (peak absorption wavelength 656 nm) is used as a test absorbing material. The methylene blue is dissolved in an aqueous Liposyn solution which serves as the multiple scattering medium. The relative amounts of absorber and scatterer are chosen such that the values of (mu) a and (mu) s' match typical values in tissues. The results obtained for (mu) a((lambda) ) with this LED based technique are in quantitative agreement with those obtained with a standard spectrophotometer in a nonscattering regime.

Paper Details

Date Published: 28 July 1994
PDF: 9 pages
Proc. SPIE 2131, Biomedical Fiber Optic Instrumentation, (28 July 1994);
Show Author Affiliations
Sergio Fantini, Univ. of Illinois/Urbana-Champaign (United States)
Maria-Angela Franceschini, Univ. of Illinois/Urbana-Champaign (United States)
Joshua B. Fishkin, Univ. of Illinois/Urbana-Champaign (United States)
Enrico Gratton, Univ. of Illinois/Urbana-Champaign (United States)

Published in SPIE Proceedings Vol. 2131:
Biomedical Fiber Optic Instrumentation
James A. Harrington; David M. Harris; Abraham Katzir; Fred P. Milanovich, Editor(s)

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