Interferometric measurement of temporal behavior of linear birefringence with extended range

A heterodyne interferometer is developed to measure the static and temporal behaviors of birefringence of a liquid crystal variable retarder. The interferometer is designed based on the analysis of the polarization state of a coherent wave. Since the optical components of the interferometer are fixed without any adjustment, the phase retardation and the azimuthal angle of a liquid crystal variable retarder is measured independently in real time, where the environmental perturbations and common mode noises can be reduced. From the analysis and experimental demonstrations, the phase retardation can be determined in the [0, 4π] range. Meanwhile, the orientational variation of the azimuthal angle of the optic axis is found.