液晶材料参数及盒厚测试方法的研究

THE Study of Measuring Method of Liquid Crystal Parameter and Cell Thickness

本文利用表面等离于体技术和导模技术测定了银膜、SiO膜的介电常数和厚度,从而确定了液晶的介电常数和液晶盒厚度。首次将集成光学的漏模技术(m线方法)应用到测量液晶参数上,测定了液晶的折射率和液晶盒厚。

As we know, An is an important parameter in liquid crystal physics and their applica-tions .There are several methods determining the refractive indices of the liquid crystal, such as Abbe refractometer method, the optical rotatory dispersion (ORD) method, and the circular dichroism (CD) method. Each method has its advantages and disadvantages.In this paper,the technique of leaky modes (m-line method) is used to determine the refractive indices of the liquid crystal and the cell thickness. In the experiment,mlines formed by leaky modes are observed and the corresponding coupling angles are obtained. Through calculation, the refractive indices of the liquid crystal and the cell thickness are obtained. The accuracy is about 10- 4. The technique of leaky modes makes use of the substrate radiation modes of a leaky wave guides. This provides a technique for measuring liquid crystal parameters without a prism coupling to the waveguide and its in-herent disadvantages. In addition to unwanted pressure, the prism coupler may distort the propagation constants within the waveguide through its evanescem field and requires careful adjustment to obtain effective coupling. By contrast, the technique of leaky modes is distortion-free, pressure-free, convenient and easy to use. The accuracy obtainable is comparable to that obtained with prism coupling to real waveguides.In my work, the techniques of surface plasma and guided modes are used to determine the parameters of Ag film , SiO film and liquid crystal materials, such as the dielectric con-stants and the thickness of Ag film and SiO film, the thickness of the cell and the dielectric constants of liquid crystal.