Optics of Liquid Crystals and Liquid Crystal Displays

Abstract

The basic elements of a liquid crystal device or display incorporate a switchable anisotropic material that is sandwiched between two glass plates coated with transparent electrodes (e.g., Indium Tin Oxide) on their surfaces. The optical characteristics of the device are dependent on the polarizing optics that sandwich it and the director structure of the liquid crystal within the bulk of the device. Usually, the glass plates have polarizers attached whose axes are appropriately orientated depending on the geometry of the display. In order to model the optical properties of a liquid crystal device, we present a variety of optical methods. We introduce the basic concepts of optical anisotropy and describe the advantages/disadvantages of different device geometries (TN, VAN, and IPS). The conventional Jones 2 × 2 matrix method and the extended Jones Method are discussed in the context of modeling TN devices. We show how the Jones matrix methods can be applied to the calculation of the optical transmission characteristics of TN devices at normal incidence. A schematic for implementing the extended Jones method within software is presented and we show how this can be applied to model biaxial and uniaxial devices to obtain isocontrast and isotransmission characteristics for typical device structures.