Refractive index retrieval from transmittance measurements

This study focuses on the development of an analytical method for simultaneous retrieval of the refractive index and the concentration of particles by measuring suspensions in industrial applications. The proposed method is based on the wavelength-matching method, where the idea is to find the maximum value of light transmittance of the suspension by scanning the irradiation wavelength. The samples were calcium fluoride (CaF2) powders manufactured by different global producers. The wavelength-matching method is suggested to be a relatively easy, economic and fast modality to retrieve the refractive index of particles. The wavelength-matching method is also considered to be independent on particle size and morphology. The refractive index is of high importance, for instance, if the opacity of products, such as paper or sunscreens, is sought to be increased for product quality improvement.