Photoelastic stress patterns in acrylic spectacle lenses, seen under polarised light. The plastic that the lenses are made from is displaying coloured interference fringe patterns. Areas of similar colour correspond to regions of similar stress. From these patterns, the direction and magnitude of the stresses can be calculated. This principle is used in photoelastic studies that use plastic models to study stresses in real-life objects.
Model release not required. Property release not required.