Precise calibration of liquid crystal variable retarder for various incident angles

This study investigates the reduction in polarization measurement accuracy caused by varying incident angles in a liquid crystal variable retarder (LCVR). The phase delay characteristics of the LCVR were examined, with particular emphasis on the influence of different two-dimensional incident angles on phase delay behavior. Building upon the calibration of phase delay under normal incidence, a phase delay calibration model was developed to account for variations in incident angle and driving voltage. A mathematical relationship was established between phase delay and the azimuth angle (α) and pitch angle (β). Experimental validation was conducted under three conditions: α = 20°, β = 0°; α = 0°, β = 20°; and an arbitrary angle where α = 5°, β = 15°. The results demonstrated that the maximum average deviation between theoretical predictions and experimental measurements did not exceed 0.059 rad. The proposed calibration method proved to be both accurate and practical. This approach offers robust support for LCVR parameter calibration and performance optimization in optical systems, particularly in polarization imaging applications.