STUDIES ON MOLECULAR ALIGNMENT MODEL IN NEMATIC LIQUID CRYSTALS EMPLOYING DYNAMICAL IMAGE-PROCESSING TECHNOLOGY

利用图像处理技术和单、双块脉冲法，测量了扭转角为90 °的双折射液晶（LC）膜中锥光图形和干涉强度的动态变化，分析了由少量交变脉冲组成的电场去除后LC分子取向的动态变化。详细的实验结果进行了研究。发现了一些新的物理现象。在电场去除后，液晶分子的变化在fes毫秒内继续排列。这被称为LC分子排列的滞后变化。2.在施加电场后，无论施加方式如何，锥光图形出现最大强度所需的时间几乎相同。根据粘弹性理论中的修正Voigt模型，结合交变电流电路理论，通过数值计算，认为LC分子的悬浮容量、粘滞电阻和电变形对滞后变化有影响。3.的LC排列的变形的变化率估计的Voigt模型与改变的粘度系数的弹性模量的比率作为从膜表面的距离的函数，而不是考虑的锚固力的影响。我们可以用指数形式表示变化率的方程。4.在晶体光学的基础上，发展了计算机模拟锥光图形的方法。

The dynamical changes of the conoscopic figures and the interference intensities in the twisted nematic liquid crystal (LC) film with twisted angle of 90 degrees were measured to analyze the dynamical changes of the LC molecular alignments after the electric field composed of a small number of altemating pulsed were removed with the use of an image-processing technology and the single or double block pulse method. The details of the experimental results were studied. Some new physical phenomena were found. 1. The changes of the LC molecules continue aligning for a fes milliseconds after the electric field is removed. This is called the lagging changes of the LC molecular alignments. 2. The time required to show the maximum intensities of the conoscopic figures after the electric field is applied is almost the same regardless of the applied manners. It is considered by the numerical calculation derived from a modified Voigt model in the viscoelastic theory combining the theory of an altemating current circuit that the floating capacity, the viscosity resistance and electric deformations of the LC molecules have effects upon the lagging changes. 3. The changing rate of deformations of the LC alignments is estimated by the Voigt model with changing the ratio of the coefficient of viscisity to the elastic modulus as a function of the distance from the film surfaces instead of considering the effect of the anchoring force. We can represent the equation of the changing rate exponentially. 4. The method of computer simulations to obtain the conoscopic figures was developed on the basis of crystal optics.