Birefringent Properties of 3D-Printed Polymers Birefringence describes the optical properties of optically anisotropic or chiral materials. As linear birefringence is a measure of anisotropy in the structure of a glass or a polymer, stress induced in glasses or polymers can be measured by stress birefringence. Interestingly, this effect can also be found in 3D-printed materials, such as fused filament fabrication (FFF)- or stereolithography (SLA)-printed objects, for some materials or material blends. Here, we report birefringence measurements on 3D-printed translucent objects, performed using a microscope with crossed polarizers as well as large-scale crossed polarizers, and show visual differences between macroscopic and microscopic effects. 156 1 3 3 MDPI application/pdf