Elliptically polarized light photoelasticity based on LCD

Abstract

We propose a three-wavelength elliptically polarized light photoelasticity method for high efficiency and low-cost stress measurement. By illuminating the sample with two different forms of elliptically polarized light for each wavelength sources, twelve images are acquired. From these images, phase delay and the principal internal stress difference are precisely computed using developed algorithms. Our proposed method based on an LCD panel has the unrivalled advantage that elliptically polarized light can be automatically adjusted, which reduces the mechanical rotation of the system, in contrast to the traditional six-step phase-shifting photoelasticity method, which requires manual rotation for circularly polarized light. In addition, the system has the potential to theoretically expand the area of illumination infinitely, thereby expanding the measurement area. The viability of the suggested methods is confirmed with numerical simulation and stress measurement.