Diffusion studies in transparent liquid mediums utilizing polarization imaging

Abstract

Diffusion process occurs in many areas of physical, chemical and biological sciences. The imaging/monitoring of this transfer process and the measurement of diffusion coefficient are of utmost importance, in these areas of research. Usually interferometric methods are used for this. Even though very accurate, they require controlled environments (especially to be isolated from external noise) and should adhere to stringent optical considerations. Single-beam optical techniques are more suitable in noisy environments. A ray passing through a non-uniform refractive index distribution deflects towards region of higher refractive index. A diffusing medium has such a non-uniform refractive index distribution. If this deflection can be measured somehow, it can be used to find the refractive index gradient and hence the refractive index distribution inside the medium. Here a method is proposed to measure these deflections and hence the diffusion coefficient using active optical elements, by converting the incident light into a spatially varying polarization pattern. The method is demonstrated using optical simulations.