Optical properties of bovine muscle tissue in vitro; a comparison of methods

We measured the optical properties of muscular tissue using several methods. Collimated transmission measurements of thin slabs showed spatial anisotropy of the scattering processes. Surface roughness of the sample disables the calculation of the extinction coefficient from these measurements. From angular intensity measurements we found a scattering asymmetry parameter g = 0.96. In fresh samples the optical diffusion constant D depends on the orientation with respect to the longitudinal direction of the muscular cells. From the D values we calculated s' perpendicular to the longitudinal direction as 0.19 mm(-1) (at 543 nm), 0.39 mm(-1) (at 594 nm) and 0.59 mm(-1) (at 632 nm). The values for D which we measured from samples that were frozen and thawed did not show dependence on orientation. From spectral dependent reflectance measurements we found an oxygenation degree of 0.61 and a reduced scattering coefficient s' = 0.85 mm(-1) around 560 nm

Determination of Kubelka-Munk scattering and absorption coefficients by diffuse illumination

The Kubelka-Munk theory, although it provides an equation that relates the reflection of a sample under diffuse illumination to certain of its properties, does not take boundary reflectance into account. Boundary reflection is always present because there is always a difference between the refractive indices of the sample and of the surrounding medium. We describe how a half-sphere is used to achieve diffuse illumination, and we present and exemplify equations that correct for boundary reflection with measurements of four composite restorative dental materials. The refractive index of the sample is measured with a matching technique that employs a glycerol-water mixture. Edge loss errors are estimated. (C) 1999 Optical Society of America

Reduced light-scattering properties for mixtures off spherical particles: a simple approximation derived from Mie calculations

The reduced scattering cross section per unit of volume SIGMA(s)' = SIGMA(s)(1 - g) is an important parameter to describe light propagation in media with scattering and absorption. Mie calculations of the asymmetry factor g for nonabsorbing spheres and Q(sca), the ratio of the scattering cross section SIGMA(s) and the particle cross section, show that Q(sca)(1 - g) = 3.28x0.37 (m - 1)2.09 is true to within a few percent, when the Mie parameters for relative refractive index m and size x are in the ranges of 1 <m less-than-or-equal-to 1.1 and 5 <x <50, respectively. A ratio of reduced scattering cross sections for radiation at two wavelengths is also independent of the size within the range mentioned, even for mixtures of different size spheres. The results seem promising for biomedical applications

REDUCED LIGHT-SCATTERING PROPERTIES FOR MIXTURES OF SPHERICAL-PARTICLES - A SIMPLE APPROXIMATION DERIVED FROM MIE CALCULATIONS

The reduced scattering cross section per unit of volume SIGMA(s)' = SIGMA(s)(1 - g) is an important parameter to describe light propagation in media with scattering and absorption. Mie calculations of the asymmetry factor g for nonabsorbing spheres and Q(sca), the ratio of the scattering cross section SIGMA(s) and the particle cross section, show that Q(sca)(1 - g) = 3.28x0.37 (m - 1)2.09 is true to within a few percent, when the Mie parameters for relative refractive index m and size x are in the ranges of 1 <m less-than-or-equal-to 1.1 and 5 <x <50, respectively. A ratio of reduced scattering cross sections for radiation at two wavelengths is also independent of the size within the range mentioned, even for mixtures of different size spheres. The results seem promising for biomedical applications