  We formulate a quantitative description of backscattered linearly polarized
light using an extended photon diffusion formalism taking explicitly into
account the scattering anisotropy parameter g of the medium. From diffusing
wave spectroscopy measurements the characteristic depolarization length for
linearly polarized light is deduced. We investigate the dependance of this
length on the scattering anisotropy parameter g spanning an extended range from
-1 (backscattering) to 1 (forward scattering). Good agreement is found with
Monte Carlo simulations of multiply scattered light.
