Extending the capabilities of vectorial ptychography to circular-polarizing materials such as cholesteric liquid crystals

TL;DR

This paper enhances vectorial ptychography for circular-polarizing materials by introducing elliptical polarization measurements, enabling accurate characterization of cholesteric liquid crystals' polarization properties through theoretical, numerical, and experimental validation.

Contribution

It proposes a novel measurement approach using elliptical polarizations to address unicity issues in vectorial ptychography for circular-polarizing materials.

Findings

Improved measurement approach effectively distinguishes circular polarizer types.

Numerical simulations and experiments confirm the method's accuracy.

Technique can determine handedness of cholesteric liquid crystals.

Abstract

The problem of imaging materials with circular polarization properties is discussed within the framework of vectorial ptychography. We demonstrate, both theoretically and numerically, that using linear polarizations to investigate such materials compromises the unicity of the solution provided by this computational method. To overcome this limitation, an improved measurement approach is proposed, which involves specific combinations of elliptical polarizations. The effectiveness of this strategy is demonstrated by numerical simulations and experimental measurements on cholesteric liquid crystals films, which possess unique polarization properties. With the help of Pauli matrices algebra, our results highlight the technique's ability to discern between different types of circular polarizers, uniform vs. non-uniform, and determine their handedness.