A dual thickness spatial system for determining optical coefficients from scattering media

A new method for determining the optical absorption coefficient from scattering media is presented. The system measures the transmitted spatial intensity distribution from two samples of different thicknesses. The first moments of the distributions are calculated and used to determine the corresponding pair of optical coefficients. The system is robust to noise and does not require calibration. Error analysis shows that limiting factors are errors in assumed values of the anisotropy factor and refractive index of the medium. The system is tested experimentally on aqueous samples with added dye and polystyrene scattering spheres and is found to determine the absorption coefficient to an accuracy of 12–14%.