| Liquid crystal(LC) is a kind of instar matter between completeness inerratic crastal and isotropic liquid . Its characters are between the solid crystal and the isotropic 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 electrical light effect, magnetooptical effect or thermal light effect in outside field.LC is a kind of anisotropic matter. It is like odd axis crystal in optics. Under commonly circs, its optic axis and molecule long axis is accordant. When we applied magnetism(electric) out field, under the differ magnetic (electric) field intension action, the differ obliquity of molecule long axis is rotated. So in this state, the optic axis of LC box is changed, the birefringence will affect . This is the magneto-dependent (Voltage-dependent) birefringence of LC. By using this character, light deflexion implement and light modulator are made. But in china and other country, the study of this character is mostly the application. The study of magneto-dependent birefringence is short. Therefore , the study of magneto-dependent birefringence domino offect is very important.The nematic LC molecule is rodlike with big slenderness 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 mostimportant character of nematic LC is that the orientation of the molecules leans to the same direction when LC is affected by magnetic field, electric field, surface force, and mechanical force. The process of the spontaneous orientation of the long axis, cause LC produce the high birefringence. This thesis studied the magneto-dependent polarization characteristic (birefringence) of nematic LC BL-009.The thesis includes six chapters. LC discover , develop history and the function and general situation in present of LC magneto-dependent birefringence are introduced in the first part. At the same time, the significance of study polarization characteristic of LC magneto- dependent birefringence is recited.The basic knowledge of LC is introduced in the second chapter. The refractive index anisotropistiu positive negative of optics and optic basic of LC are discussed.The polarization and birefringence of light are recited in the third chapter. And the Faraday domino offect, magnetism line polarization birefringence of magneto-optical material in theory are detailed analysed.The magnetism domino offect of LC is introduced in the fourth chapter. The magnetization ratio anisotropism , Fredericks changing and magnetically induced twiste effect in planar nematic LC are introduced.The birefringence of LC is introduced in the fifth chapter. And the origin and diversified factors of LC birefringence in theory is detailed analysed. In addition,jones matrix of linearity TN nematic LC can be found in this chapter.The sixth chapter detailed expatiate the experiment of magneto-dependent polarization characteristic. This experimentadopts polarization-interference technique to study polarization characteristic of LC. The testing system is erected by Using continued tunable magnetic field apparatus , measure angle apparatus , photoelectricity detector and tunable laser (or else laser) , ect. At first, by using 1350nm infrared laser , nematic LC BL-009, under temperature of 20 centigrade, the testing is done. The disciplinarian of transmission light intension , molecule axis rotation angle of LC with magnetic field and azimuth angle between magnetic field and LC box are gaven. Secondly, the magneto-cause deflexion effect of LC is detailed studied in area of visible light. It is divided three aspects:the transmission light intension of LC; the changing of minimum of transmission light intension of LC; molecule axis rotation... |
PDF Full Text Request