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Poster Hall B0 European Conferences on Biomedical Optics (ECBO) > Diffuse Optical Spectroscopy and Imaging > Lunch Break and Poster Session - Monday
12:45-14:15 h | Hall B0 Hall B0, ICM
Subjects: Biophotonics and Medical Engineering
The optical appearance of materials plays a big role for many products of our daily life like cosmetics, food or paints. In case of sunscreen design of the optical properties is even crucial for its performance. Here, high light transmission in the visible spectrum is desirable to not alter the skin appearance but filtering of UV light and hence low transmission in the UV range is essential to protect the skin from destructing UV radiation. Due to the thin film (micrometer thickness) of sunscreen typically applied to the skin, filtering of UV radiation has to be very effective. This is achieved by a complex formulation, i.e. different UV-absorbers and scattering particles dispersed in an oily or aqueous medium. The combination of absorption and scattering leads to a complex interplay of both effects. Additionally, due to the typically high content of scattering particles so-called dependent scattering may arise leading to higher light transmission compared to independent scattering. Therefore, too much scattering particles are disadvantageous. In this study Monte-Carlo (MC) simulations are realized to calculate the diffusely transmitted light through such absorbing and scattering materials. Calculations are carried out firstly for simple polymer-water dispersions in the visible range to validate the results with experiments. Results show clear influences of e.g. particle size, particle interaction type or absorber concentration and indicate optimal concentrations ranges for scattering particles. By adaptation of the simulation parameters like wavelength or sample constitution the efficiency of different sunscreen formulations can be calculated easily and hence the formulation optimized.