Photoelastic Tensor Elements of Optical Glasses: Dispersion and Relation to Structure

Abstract

Photoelasticity refers to the change in index of refraction of a material due to applied stress or strain, and in glass, results in birefringence. Understanding and controlling this effect is an important aspect in the design and technological application of glass. Further complicating the issue is that photoelasticity shows a complicated dispersive behaviour, which has been very little studied. In this thesis, the dispersion of the photoelastic response of a set of CDGM commercial glasses was investigated using a modified acousto-optic technique. Electron microprobe analysis paired with Raman and solid-state nuclear magnetic resonance spectroscopy proved the importance of verifying the compositional discrepancies that may occur when acquiring samples from commercial suppliers. The structural insight provided by these techniques was used to understand trends in the photoelastic data. This understanding was contextualized based on the calculated parameters of the bond polarizability model for the first time for these glasses.