## Reduced scattering coefficient## µ
| ECE532 Biomedical Optics ©1998 Steven L. Jacques, Scott A. Prahl Oregon Graduate Institute |

The **reduced scattering coefficient** is a lumped property incorporating the **scattering coefficient µ _{s}** and the

The purpose of µ_{s}' is to describe the diffusion of photons in a random walk of step size of 1/µ_{s}' [cm] where each step involves isotropic scattering. Such a description is equivalent to description of photon movement using many small steps 1/µ_{s} that each involve only a partial deflection angle if there are many scattering events before an absorption event, i.e., µ_{a} << µ_{s}'. This situation of scattering-dominated light transport is called the diffusion regime and µ_{s}'is useful in the diffusion regime which is commonly encountered when treating how visible and near-infrared light propagates through biological tissues.

The following figure shows the equivalence of taking 10 smaller steps of "mean free path" mfp = 1/µ_{s} with anisotropic deflection angles and one big step with a "reduced mean free path" mfp' = 1/µ_{s}'.

The following figure shows how many such big steps involving isotropic scattering are equivalent to many small anisotropic steps:

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