Optical measurements of the twist constant and angle in nematic liquid crystal cells.

We present a reliable optical method for measuring the twist elastic constant and for assessing the total twist angle in a standard nematic twist cell. The method relies on the use of a non-standard configuration of crossed polarisers and a twist cell, which allows us to measure accurately the twist-cell parameters by reducing the degeneracy between them. Grid patching and an efficient beam propagation method are utilised in the numerical models used for fitting the experimental data.

Characterization of optically thin cells and experimental liquid crystals.

The current development of new liquid crystal devices often requires the use of thin cells and new experimental materials. Characterizing these devices and materials with optical methods can be challenging if (1) the total phase lag is small ("thin cells") or (2) the liquid crystal optical and dielectric properties are only partially known. We explore the limitations of these two challenges for efficient characterization and assessment of new, to the best of our knowledge, liquid crystal devices.

Nanoparticle-Induced Property Changes in Nematic Liquid Crystals.

Doping liquid crystals with nanoparticles is a widely accepted method to enhance liquid crystal's intrinsic properties. In this study, a quick and reliable method to characterise such colloidal suspensions using an optical multi-parameter analyser, a cross-polarised intensity measurement-based device, is presented. Suspensions characterised in this work are either plasmonic (azo-thiol gold AzoGNPs) or ferroelectric SnPS (SPS) nanoparticles in nematic liquid crystals.