| As a kind of condensed state matter ,the characteristic and structure of Liquid crystal between solid crystal and isotropic liquid .It is a ordering liquid, As the macroscopical characters are concerned, it have the flowing power and viscidity like liquid, and the anisotropy like crystal,it has birefringence, Bragg reflection, diffraction and optical rotation like crystal. Furthermore, it has thermal light effect, electrical light effect or magneto optical effect in outside field. Today, liquid crystal,a new functional material, has been applied more and more widely.On the side of display ,owing to stable frarne,absolute environmental protecting ,save electric energy and no tire for user, liquid crystal display keeps ahead among the range of display .With the developing of the technology of liquid crystsl ,LCD will must substitute for CRT and become the chief in market.In additin, liquid crystsl light filers which have been used in optic communicatins and light information handling,emply the technical of combining the birefringence of liquid crystsl and Fabry-Petrot-type cavity.They manifest a series of merit ,such as narrow band wide ,deterioration low, wide tuning domain ,simple structure and low cost ,so liquid crystal light filter draw attention of many country . Liquid cryatal also use on the public nuisance of chemical industry, the oriented polymer of macromolecular reaction, the nondestructive evaluation and microwave determination of aviational machine and metallurgic product, checking skin cancer in medicine, body temperature measurement, etc. It has showed the great superiority.the voltage-dependent birefringence is the most important character. The oritation of liquid crystal molecule axis will vary with outfield. When we applied electric field ,the the oritation of liquid crystal molecule axis reset .It induced the roate of optic axis. At last, the birefringence willchange. This is the Voltage-dependent birefringence of liquid. Today,most applications of liquid crystal are depend on Voltage-dependent birefringence effect. Voltage-dependent birefringence of liquid crystal is widely used because of many merits.(l)Its applicable spectral range is extraordinarily broad. Many nematic liquid crystals show very large birefringence and good transparency in both near-UV, visible, and IR regions(except in the vicinities of some resonant electronic and molecular vibrational absorption bands). (2)The required voltage is very small. Usually, a large birefringence change (0.2) can be achieved by a relatively small voltage(a few volts, depending on the LC used).Its wavelength tenability is determined by the controlled birefringence of the liquid crystal used. (3)Continuous variable birefringence. The Continuous variablebirefringence can be achieved by a relatively small voltage. (4)The low lost, high recurrence rate, and good stability.There are many factor affecting voltage-dependent birefringence. But the temperature effect of voltage-dependent birefringence cannot ignore in the course of liquid crystal device design and production.This thesis mostly study the regularity of voltage-dependent birefringence with charging the temperature.The thesis includes five chapters. Liquid cryatal discover and develop history are introduced in the first part.At the same time,the most study content of liquid crystal physics and the significance of study the temperature effect of voltage-dependent birefringence.The basic knowledge of liquid crystal is introduced in the second chapter, especially the nematic liquid crystal.The nematic liquid crystal molecule is rodlike with big slendemess ratio. The barycenter of molecule is not long-range order. It has fluidity like liquid. The molecules do not layered. They can slide up and down, left and right, forward and backward.They hold parallel or nearly parallel in the long axis orientation of the molecules. The most important character of nematic liquid crystal is that the orientation of the molec... |
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