Use diffusion theory to estimate light penetration in biological tissues. A 10-mW isotropic point source is buried in an infinite turbid medium. Assume that the absorption coefficient is 0:1 cm-1, the scattering coefficient of a 5-cm thick tissue is 100 cm-1, the scattering anisotropy is 0.9, and the wavelength of light is 0:5 mm. Calculate the light fluence rate 5 cm from the source.