Digital full-field photoelasticity of tempered architectural glass: A review

The standard tempering process for architectural flat glass creates minor fluctuations in the lateral stress distribution resulting in birefringence and undesired optical iridescence, also known as anisotropy effects, in modern glass applications. Recent advances in full-field digital photoelasticity have made it possible to measure retardation in glass panes in-line at the end of the furnace and evaluate the optical quality of tempered glass on the square-meter scale. Depending on the application, various techniques can be used to analyze stresses or measure retardation levels ranging from zero to about 1000 nm. A brief introduction to the creation of stress differences and their effect on the optical anisotropy effects of facade glazing is given to illustrate the benefits of these novel techniques. The purpose of this paper is to provide a general overview of the different full-field methods for measuring retardations in tempered glass and their current state of development and usage. Finally, a comparison based on recent literature is presented.