Molecular orientation depth profiling of LC thin film under shear flow by near-field birefringence response

In this paper, homogenous alignment LC film and homeotropic alignment LC film which are mainly used in LC display devices were detected, and their molecular orientation distribution in depth direction were profiled layer by layer by using a novel method which can also be used to observe anchoring effect (anchoring extrapolation length) caused by alignment layer. Instead of the traditional method detecting LC bulk sandwiched by two alignment substrates with electrodes, here we used mechanical shear flow by vibrating fiber probe to reorientate the nematic LC molecules and measured their birefringence response to the reorientation in optical near-field. From the birefringence response, the director of molecules under fiber probe is observed, from which molecular orientation of LC thin film in depth direction can be modeled.