title: Monte Carlo simulation of light reflection from cosmetic powder particles near the human skin surface.
abstract: The reflection and scattering properties of light incident on human skin covered with powder particles have been investigated. A three-layer skin structure with a pigmented area is modeled, and the propagation of light in the skin's layers and in a layer of particles near the skin's surface is simulated using the Monte Carlo method. Assuming that only single scattering of light occurs in the powder layer, the simulation results show that the reflection spectra of light from the skin change with the size of powder particles. The color difference between normal and discolored skin is found to decrease considerably when powder particles with a diameter of approximately 0.25 μm are present near the skin's surface. The effects of the medium surrounding the particles, and the influence of the distribution of particle size (polydispersity), are also examined. It is shown that a surrounding medium with a refractive index close to that of the skin substantially suppresses the extreme spectral changes caused by the powder particles covering the skin surface.
authors.affiliation: Department of Systems Design and Informatics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka 820-8502, Japan. okamoto@ces.kyutech.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Okamoto
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kumagawa
authors.forename: Masafumi
authors.initials: M
authors.lastname: Motoda
authors.forename: Takanori
authors.initials: T
authors.lastname: Igarashi
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nakao
mesh_terms: D003358:Cosmetics; D004817:Epidermis; D006801:Humans; D008027:Light; D009010:Monte Carlo Method; D010316:Particle Size; D011208:Powders; D012867:Skin
chemical_list: D003358:Cosmetics; D011208:Powders