Novel method of measuring surface torsional anchoring strength of nematic liquid crystals
Novel method of measuring surface torsional anchoring strength of nematic liquid crystals
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DOI：
10.1143/jjap.35.4434
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发表时间：
1996-08-01
期刊：
影响因子：
--
通讯作者：
Kimura, M
中科院分区：
文献类型：
--
作者：
Akahane, T;Kaneko, H;Kimura, M
提出了一种简单、准确的测量向列型液晶表面扭锚强度的方法。该方法是基于同时确定一个扭曲向列型电池的实际扭转角和电池间隙（光学延迟），其中上下基板的易轴处于特定角度（例如，90度）。TN电池被放置在两个偏振片之间。TN单元和分析仪安装在可旋转的台上。测量过程包括以下步骤。(1)使用单色光，我们通过旋转TN电池和分析仪来最小化光的透射量(我们分别用Psi(p)（(1)）和Psi(0)（(1)表示分析仪和TN电池与偏振片的最小角度）。(2)我们将TN电池从Psi(0)（(1)）设置为特定角度，并通过仅旋转分析仪来最小化透射光量(我们将分析仪的最小角度表示为Psi(p)（(2)）。根据Psi(p)（(1)）和Psi(p)（(2)）的值，我们可以利用基于琼斯矩阵法的透光率解析表达式来确定实际的扭转角和光延迟。我们讨论了这种方法的准确性。并给出了实验实例。
A simple and accurate method of measuring the surface torsional anchoring strength of nematic liquid crystals is proposed. This method is based on the simultaneous determination of the actual twist angle and the cell gap (optical retardation) of a twisted nematic cell in which the easy axes of the upper and lower substrates are at a particular angle (e.g., 90 degrees). The TN cell is placed between two polarizers. The TN cell and the analyzer are mounted on rotatable stages. The measurement procedure consists of the following steps. (1) Using monochromatic light, we minimize the amount of light transmitted by rotating both the TN cell and the analyzer (we denote these minimizing angles of the analyzer and the TN cell from the polarizer as Psi(p)((1)) and Psi(0)((1)) respectively. (2) We set the TN cell at a particular angle from Psi(0)((1)), and minimize the amount of light transmitted by rotating only the analyzer (we denote this minimizing angle of the analyzer as Psi(p)((2)). From the values of Psi(p)((1)) and Psi(p)((2)), we can determine both the actual twist angle and the optical retardation using the analytical expression for optical transmissivity based on the Jones matrix method. We discuss the accuracy of this method. Experimental examples are also shown.