@article{jacques87b, author = {S. L. Jacques and C. A. Alter and S. A. Prahl}, title = {Angular Dependence of {HeNe} Laser Light Scattering by Human Dermis}, journal = {Lasers Life Sci.}, year = {1987}, volume = {1}, pages = {309--333}, abstract = {A goniometric apparatus is presented for measuring angular dependence of scattering of a HeNe laser beam by \textit{in vitro} human dermis samples of various thicknesses, hydrated to an 85 percent water content. Measurements of the transmitted and reflected light as a function of angle are presented for tissue thicknesses of 20--650\,$\mu$m. Extrapolation of these angular scattering patters to the limit of an incremental tissue thickness specifies the scattering phase function appropriate for use in the radiative transport equation. The scattering phase function is composed of a forward-directed scattering component (90 percent contribution) characterized as a Henyey-Greenstein function with $g_{HG}=0.91$, and an additional isotropic component (10 percent contribution, $b=0.10$). The net value for the average cosine of the scattering phase function, $g=(1-b)g_{HG}$ is 0.82, which corresponds to an average deflection angle of 35$^\circ$ for a scattering event. The on-axis attenuation of the collimated HeNe laser beam indicates a total attenuation constant of 190\,cm$^{-1}$ , composed of an absorption coefficient of 2.7\,cm$^{-1}$ and a scattering coefficient of 187\,cm$^{-1}$.}, }