Since the discovery of the first liquid crystal in 1888 by the Austrian biologist Friedrich Reinitzer with the considerable assistance of the German physicist Otto Lehman, who in that time had been universally recognised authority in the field of microscope technique, thousands and thousands of liquid crystals have been synthesised among them nematics, short-pitch cholesterics and various kinds of smectics such as smectic-A and smectic-C. The smectic-A or smectic-C phases grow from a nematic or unwinded large-pitch cholesteric oriented in the middle part of the cells and from strongly-deformed nematic or unwinded large-pitch cholesteric layer in the boundary regions of the liquid crystal cells.
This is a monograph/text devoted to a detailed treatment of the optical, electro-optical and nonlinear optical properties of all the mesophases of liquid crystals and related processes, phenomena and application principles. Quantitative data on material and optical parameters spanning the ultraviolet, visible, infrared as well as the microwave regimes are presented along with detailed theoretical treatments of basic liquid crystal physics, material properties and nonlinear optics.Starting with a discussion on the basic building blocks of liquid crystalline molecules, the authors proceed to present in a pedagogical manner current theories, experiments, and applications of these unique and important optical properties of liquid crystals. Numerous tables of hard-to-find liquid crystalline parameters, a self-contained chapter on general nonlinear optics, and comprehensive literature review are also included.
The special feature of the book is the in depth treatment of both the electro-optic effects and the addressing schemes of liquid crystal displays elucidating their interdependence. After basic explanations readily understandable for students and stimulating for engineers, physicists and chemists, the reader is gradually led to the latest developments such as vertically aligned and mixed mode TN-displays, compensation foils, multiple line and low power addressing, transistor driven LCOS-devices with DRAM and SRAM addressing and TFT-addressing of transmissive displays with a 92% aperture ratio. The results are analytically derived and not merely stated to enhance insight and the capability to tailor displays to individual needs or to perform novel designs. Towards this aim the propagation of light with the help of Jones vectors, four different characterizations of the state of polarization and the operation as well as the passive and active matrix addressing of all LCDs, like nematic, polymer dispersed, guest host and bistable devices is explained. Besides the mainstream twisted and supertwisted nematic LCDs attention is drawn to bistable ferroelectric, chiral nematic and modified nematic LCDs as they are most promising for future portable low power systems. Tables on display formats and units for the measurement of displays finally render the book suitable as a reference for experts working in the field and as a textbook for universities or display courses. The forefront of research is reached by the treatment of plastic substrates, the replacement of vacuum processes by less expensive printing and low temperature fabrication of a-Si- and poly-Si-TFTS.
This volume is based on lectures and contributed papers presented at the Eleventh Course of the International School of Materials Science and Tech nology that was held in Erice, Sicily, Italy at the Ettore Majorana Center for Scientific Culture during the period 6-17 July 1986. The subject of the course was "Electro-optic and Photorefractive Materials: Applications in Sig nal Processing and Phase Conjugation" . The fields of electro-optics and photorefraction have developed rapidly since the invention of lasers just over twenty-five years ago. The possibil of altering the optical properties of a material by electric fields or by ity optical waves is of great importance for both pure science and for practical applications such as optical signal processing, telecommunications and opti cal display devices. These effects allow us to manipulate (modulate, deflect) and process a given light wave. Modulation, deflection and processing of light waves by means of the electro-optic effect is of fundamental importance in fiber optic telecommuniC1. tions and sensor systems w here the light signals can be processed prior or subsequent to transmission through the fibers. Thin film electro-optic materials with suitable electrode arrays on· the surface of the wave-guiding structures result in a technology often referred to as inte grated optics. In principle, integrated optics devices allow miniaturization and integration of many operations onto a single chip. The photorefractive effect, defined as a photo-induced change of the in dices of refraction, was the other topic treated in this course.
In 1988 physicists and chemists commemorated the centenary of the discovery of the first liquid crystals. Fora long period after this discovery, although many significant results were found, liquid crystal research remained a marginal topic of condensed matter physics. The situation changed in the sixties. At that time the remarkable electro-optical properties of liquid crystals were recognized and found soon widespread application in numeric displays. From a more fundamental point of view, the interest in disordered systems. increased in general at the same time. Liquid crystals represented an important dass of such systems. Among others, phase transitions, hydrodynamics and topological defects occurring in them attracted considerable attention. The connection between the liquid-crystalline state and the structure of biological membranes stimulated a Iot of works also. In the present volume we discuss a relatively new and rapidly developing branch of the fi. eld, namely nonlinear optical effects in liquid crystals. Optical studies have always played a signifi. cant role in liquid crystal science. Research of optical nonlinearities in liquid crystals began at the end of the sixties. Since then it became a powerful tool in the investigation of symmetry properties, interfacial phenomena or dynamic behaviour. Furthermore, several new aspects of nonlinear processes were demonstrated and studied extensively in liquid crystals. The subject covered in this book is therefore of importance both for liquid crystal research and for nonlinear optics itself. The term "nonlinear optics" is used here in a broad sense.
