High Load-Induced Birefringence of PMMA Investigated in VIS/NIR Spectral Range

In the paper, we present the results of an investigation of polymethylmetacrylate’s birefringence induced due to applying high-load. The stress-induced birefringence of the polymethylmetacrylate samples was experimentally investigated by an apparatus combining an in-house made plane polariscope with a machine for fatigue testing of materials. A halogen lamp was used as the source of white light. The polariscope’s basis was formed by two sets of plane polarizers, one designed for visible (470-750) nm and another one for near-infrared (900-1800) nm spectral range, respectively. The investigated sample was placed between the polarizers and light that passed through the polariscope was collected by an optical fiber connected to an appropriate optical spectral analyzer. The spectra of transmitted light were measured as a function of load and their analysis provided information on the load-induced birefringence of the investigated polymethylmetacrylate samples.