Jewell S A, Sambles J R
Thin Film Photonics Group, School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, United Kingdom.
Phys Rev E Stat Nonlin Soft Matter Phys. 2006 Jan;73(1 Pt 1):011706. doi: 10.1103/PhysRevE.73.011706. Epub 2006 Jan 17.
The dynamic response of a chiral dual-frequency hybrid aligned nematic liquid-crystal cell to a multiple frequency pulse has been characterized using a time-resolved fully leaky guided-mode optical characterization technique. On application of a low-frequency voltage the cell is found to switch to homeotropic alignment, effectively destroying the inherent twist in the cell. When this voltage is immediately followed by a high-frequency voltage the structure is driven into a homogeneously aligned twisted structure. Analysis of the response of the director to this change in effective dielectric anisotropy of the material reveals a form of backflow. This arises due to the combination of the coupling between the rotation and flow of the director, the constraining effect of the pitch on the twist in the cell, and the driving of the director into homogeneous alignment. The measured director profiles have been compared to model profiles generated using the Leslie-Eriksen-Parodi nematodynamics theory, and the viscosity coefficients for the material have been determined.
利用时间分辨全漏导模光学表征技术，对一种手性双频混合排列向列型液晶盒对多频脉冲的动态响应进行了表征。施加低频电压时，发现液晶盒切换到垂面排列，有效地破坏了液晶盒固有的扭曲。当此电压紧接着施加高频电压时，结构被驱动到均匀排列的扭曲结构。对指向矢对材料有效介电各向异性变化的响应分析揭示了一种回流形式。这是由于指向矢的旋转与流动之间的耦合、节距对液晶盒扭曲的约束作用以及指向矢被驱动到均匀排列这三者共同作用的结果。已将测得的指向矢分布与使用莱斯利 - 埃里克森 - 帕罗迪向列动力学理论生成的模型分布进行了比较，并确定了该材料的粘度系数。
