Phase-resolved structure of a disclination in a liquid-crystal θ-cell

An experimental testing of a disclination structure in a liquid crystal was performed. The origin of a disclination is a conflict between opposite-sign twist in a planar 90° twist-cell or a θ-cell. A theoretical analysis has shown a topological defect with the charge 1/2 (π variation in the azimuth angle of a twist along a close loop around the disclination). In the experiment we have tested a disclination zone by plane-wave linearly polarized light. The presence of the Mauguin lines was revealed in a numerical modeling and direct experiment. To resolve the structure around the disclination we used interferometric technique. The theoretical predictions were confirmed by the detection of the phase π-step occurring between the Mauguin lines.