Transient structures in the Fréedericksz transition

An alternating electric field is applied to a planarly aligned nematic liquid crystal with a positive dielectric anisotropy sandwiched between two electrodes. This leads to a reorientation of the director when the critical threshold for the Fr\'eedericksz transition is exceeded. Triggered by this reorientation process, patterns arise. In the experiments presented, a transient periodic structure showing up as a system of fairly regular stripes parallel to the initial orientation of the director is observed. This pattern seems to be caused by a secondary instability of the homogenous reorientation process.