Light Scattering 1—The Physics of Light Scattering

Abstract

The function of particles in many paints, plastics, and paper applications is to interact with light—either through absorption or scattering. In this chapter, we focus on light scattering. There are three ways by which individual particles scatter light—reflection, refraction, and diffraction. The relative importance of the three mechanisms of light scattering is determined by particle size, and the overall efficiency of light scattering is determined by four factors: the refractive indices of the particle and the surrounding matrix, the size of the particle and the wavelength of light to be scattered. While scattering from an isolated particle is well understood based on theoretical principles, the scattering strengths of particles within groups are more complex. This is because particles close to one another interfere with one another’s ability to scatter light, a phenomenon known as “dependent light scattering”. This reduces the scattering strength of particles in many real-life applications.