Absolute measurement of absorption and scattering coefficients spectra of a multiply scattering medium

Sergio Fantini; Maria-Angela Franceschini; Joshua B. Fishkin; Enrico Gratton

doi:10.1117/12.180732

28 July 1994 Absolute measurement of absorption and scattering coefficients spectra of a multiply scattering medium

Sergio Fantini, Maria-Angela Franceschini, Joshua B. Fishkin, Enrico Gratton

Proceedings Volume 2131, Biomedical Fiber Optic Instrumentation; (1994) https://doi.org/10.1117/12.180732
Event: OE/LASE '94, 1994, Los Angeles, CA, United States

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.

Citation Download Citation

Sergio Fantini, Maria-Angela Franceschini, Joshua B. Fishkin, and Enrico Gratton "Absolute measurement of absorption and scattering coefficients spectra of a multiply scattering medium", Proc. SPIE 2131, Biomedical Fiber Optic Instrumentation, (28 July 1994); https://doi.org/10.1117/12.180732

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