Analytical modeling for the optical properties of the skin with in vitro and in vivo applications.

Analytical modeling that interrelates the optical properties of multilayered structures is applied to the skin. The mathematical approach is based on relations of diffuse reflectance and transmittance of a multilayered system and the diffuse reflectance and transmittance of each component layer. The formula can also be derived from the Kubelka-Munk theory of radiation transfer. Using both collimated and diffuse incident irradiance, the applicability of the model to human epidermis over the UV and visible region has been verified. The model has been applied to calculate to absorption and scattering coefficients of human epidermis in vitro, and to estimate the epidermal transmittance under simulated in vivo condition.