Characterizing liquid turbid media by frequency-domain photon-migration spectroscopy.
We present a wavelength-tunable frequency-domain instrument for the characterization of liquid turbid media. The instrument employs a tunable titanium-sapphire laser modulated by an acousto-optic modulator. The absorption and reduced scattering coefficient of Intralipid(R) 20%, diluted to concentrations of 0.94 to 4.00%, are measured over the wavelength range 710 to 850 nm at 10-nm intervals. The standard measurement errors for the absorption and reduced scattering coefficients are 1 and 2.5%, respectively. Extrapolation to 0% Intralipid(R) concentration gives an absorption coefficient that closely follows that of water, overestimating the absorption of pure water by less than 10%. The reduced scattering coefficient is compared at 750 nm with published results and is found consistent within the experimental error. We compare the reduced scattering coefficient to an estimate based on Mie theory and find the reduced scattering coefficient underestimated the Mie theory result by about 9%.
Cletus
Biju
B
The University of Waikato, Hillcrest Road, Hamilton, Waikato 3210, New Zealand. biju@waikato.ac.nz
Künnemeyer
Rainer
R
Martinsen
Paul
P
McGlone
Andrew
A
Jordan
Robert
R
D000465:Algorithms; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007834:Lasers; D009391:Nephelometry and Turbidimetry / Q000295:instrumentation* / Q000379:methods; D017785:Photons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity