Jewell S, Sambles J R
Opt Express. 2005 Apr 4;13(7):2627-33. doi: 10.1364/opex.13.002627.
The dielectric anisotropy of a highly dispersive dual-frequency nematic liquid crystal (MDA-00-3969 (Merck KGa)) has been determined using the optical fully-leaky guided-mode technique. A 4Vrms sinusoidal voltage was applied across a 5microm hybrid aligned nematic (HAN) cell at various frequencies in both the positive and negative dielectric anisotropy regime. Optical data was collected at each frequency enabling the director profile in each case to be determined using a multi-layer optics model in combination with a liquid crystal free-energy minimization routine. The thresholdless response of the HAN cell combined with the extreme sensitivity of the optical characterization technique has allowed subtle changes in dielectric permittivity with frequency to be observed. The resulting measured dispersion shows excellent agreement with a single Debye-type relaxation model.
采用光学全漏导模技术测定了高分散双频向列型液晶（MDA - 00 - 3969，默克公司）的介电各向异性。在正、负介电各向异性区域的不同频率下，向一个5微米的混合排列向列型（HAN）液晶盒施加4Vrms的正弦电压。在每个频率下收集光学数据，从而能够结合多层光学模型和液晶自由能最小化程序来确定每种情况下的指向矢分布。HAN液晶盒的无阈值响应与光学表征技术的极高灵敏度相结合，使得能够观察到介电常数随频率的细微变化。所得的测量色散与单一德拜型弛豫模型表现出极佳的一致性。
