Examination of flow birefringence induced by the shear components along the optical axis using a parallel-plate-type rheometer.

In this study, the concept of rheo-optics was applied to explore the flow birefringence induced by the stress components along the camera's optical axis since it is often overlooked in the traditional theories of photoelastic flow measurement. A novel aspect of this research is that it involved conducting polarization measurements on simple shear flows, specifically from a perspective in which a shear-velocity gradient exists along the camera's optical axis. A parallel-plate-type rheometer and a polarization camera are employed for these systematic measurements.