Locate transmission axis of a polarizer by one-shot spatial modulation of a q-plate: Principle, configuration and analysis

Transmission axis of a linear polarizer was generally measured by conventional rotation-Malus approach, which inevitably required mechanical motions, ultra-stable illumination and additional high-accuracy polarizer for calibration. Researchers have been studying how to locate the transmission axis of a polarizer conveniently, directly and accurately. Our group focuses on solving the problem by spatial solution via a nano-fabricated vortex retarder. This work introduces the fundamental measurement principle, the home-developed practical configuration and detailed analysis. Compared with conventional rotation-Malus approach, our approach shows superiorities in no mechanical motion, extremely compact configuration and one-shot measurement. We layout our work as follows: i) it is the circularly-polarized component that functions for the measurement; ii) how to achieve a more practical measurement: a mixed-mode polarized light, which contains a circular-polarization component, can work for the measurement; iii) an experimental system is developed for verification; iv) we specifically analyze how the mixed polarization effect influences the measurement.