Figure 8
From: Uncovering different states of topological defects in schlieren textures of a nematic liquid crystal
Ray-tracing around the ideal escaped structure. Schematics of the relationship between the nematic director, n, and the transition dipole moment of the dye, t, on a radial 2D plane with the escaped structure in the system with (a) PMN and (b) CNX. The horizontal axis indicates radial axis in the unit of r/r 0, where r 0 is the radius of the escaped region. The cases of the down-state are shown. In the system with PMN, only the extraordinary component of the excitation light and the fluorescence light is associated with the image formation. The extraordinary rays entering from the bottom side of the computational cell are shown for (c) the up-state and (d) the down-state in the r/r 0 (horizontal axis)- z/r 0 (vertical axis) space. Their representative n along the r axis are shown by double headed arrows. By considering the numerical aperture of the objective lens, the results with different incidence angles of rays, −20, 0, and + 20 degrees, are shown to qualitatively capture the bending characteristics. The light from the point X seems to originate at the point Y due to the LC lensing effect (Incident rays entering at r = 0.3 are highlighted by arrows as examples), suggesting that the original fluorescence distribution shrinks toward the centre of the defect in the resulting images. This lensing effect is more remarkable for the down-state as shown in (d).
