Finiate Element Calculation Of Refractive Index In Optical Glass Undergoing Viscous Relaxation And Analysis Of The Efefcts Of Cooling Rate And Material Properties

In this research, a methodology based on a numerical simulation model is presented to predict refractive index change introduced to two low Tg optical glasses, namely, P-SK57 and P-LASF47, by cooling. To model the structural relaxation behaviour of the glass around glass transition temperature, the Tool-Narayanaswamy-Moynihan (TNM) model is used. In addition, the fictive temperature of the glass samples during cooling is discussed. The effect of cooling rate on the fictive temperature of the glass samples is also presented. The study demonstrated that finite element method is capable of predicting refractive index of optical glass undergoing viscous relaxation.