Measurement of Diffusion Coefficient of Liquids by Using an Asymmetric Liquid-Core Cylindrical Lens: Observing the Diffusion Process Directly

We report a method for measuring diffusion coefficient D of liquids by using an aplanatic and asymmetric cylinder lens with a liquid core, which is designed as both a diffusion pool and the main imaging element. The precision is better than 10^?4 RIU in measuring refractive index. The D values of ethylene glycol (EG) in water are measured for various EG concentrations at 25°C, and D_inf=1.043×10^?5 cm²/s under the condition of infinite dilution is obtained. The method is characterized by observing the diffusion process directly, faster measurement and obtaining the D value under the condition of infinite dilution.