Milky translucent haze of a large-scale topological defect array in nematic liquid crystal

A large two-dimensional (2D) topological defect array in nematic liquid crystal (NLC) shows a translucent watery hazy texture. The haze is a composition of three optical phenomena: scatter-ing of light, lens imaging and diffraction. The scattering of light causes the milky haze. Vertically aligned NLC cells with pixel electrodes were fabricated to produce the crowded irregular defects. The key parameters are the electrode shape (pad or annulus), the array structure (square or hexagonal) and the pixel size (from 15 mu m x 15 mu m to 200 mu m x 200 mu m). Location and topological charge of the defects are identified under a polarised optical microscope. 2D Fourier transform of the defect distribution gives the spatial frequency spectrum, which is the diffraction pattern of light through the defects. Large pad electrodes produce ordered defects and significant diffraction. Crowded irregular defects render the milky translucent haze and a continuous spatial spectrum. The traditional haze measurement is not able to distinguish the scattered and diffracted light. The spatial spectrum can accurately describe the appearance perceived by the viewers. Small annulus electrodes in a hexagonal array produce the messiest defects, the haziest texture and the most comfortable visual experience among the others.

Automated summary

A large 2D topological defect array in a nematic liquid crystal exhibits a translucent watery hazy texture, which is a combination of light scattering, lens imaging, and diffraction. The traditional haze measurement is unable to distinguish between scattered and diffracted light, while the spatial spectrum accurately describes the perceived appearance. Small annulus electrodes in a hexagonal array produce the messiest defects, haziest texture, and most comfortable visual experience among the others.