Calcite Crystals Thermal Properties

Since 1960s,polarized technology has gained a rapid development and it has been applied to different fields related with optical technology.As the basis of polarized technology's development,the number of polarization-devices has developed from just several kinds to dozens of different kinds.Moreover,many special polarization-devices have been invented, among which crystal polarized prism,with the advantages of good performance has become a major development.During the process of employing,temperature field can't be escaped,the refractive indices of the crystal and shape of face should be changed because of the change of temperature.Although the change is very small,but enough to affect the light propagation in crystals,thus influence the optical performance of the devices.This thesis mainly takes Calcite crystal as an example,temperature characteristic have been studied,that have offered the theory and experiment basis for use of prism at different temperature.The full text includes the following contents briefly:In the first chapter,we mainly introduce the general development of polarizing devices and temperature effect of crystal,and explain the work of this thesis.In chapter two,firstly,the materials properties of the iceland crystal are described;secondly, the temperature expansion nature of iceland crystal are described,with wich we gain the expression in any direction of iceland crystal's index of temperature expansion,and the zero-expansion direction.Last,we deduce the effects from temperature to the optical path difference of iceland crystal,against the effects from temperature to the linear expansion and refractive indices of the iceland crystal.Chapter three,fistly,the the ideas and methods of finite element analytical calculations are introduced,and its decelopment.Secondly,thermal analysis function of ANSYS application software is directed systematicly;last,we generate the thermal analysis process.Chapter four,first,we build thermal deformation mathematics model of material,which give the relation between displacement,stress and strain.second,The ANSYS was employed to make a simulation study of the Iceland crystal's thermal deformation.Which analyzes and calculates its thermal deformation,and a pictorial diagram was drawn to show that its coefficient of thermal expansion should be both positive and negative.What was more,based on theoretical analysis and calculation,the finite element model was proved to be proper and that a zero-expansion direction existed in the Iceland crystal.In addition the Iceland crystal's thermal stress distributing regular pattern in the direction both parallel and vertical to the axis was drawn, which explained the mechanism that the cataclysm of temperature would damage the crystal's structure.In the foundation of finite element model proposed in this article,we analyze the influence that response time,the temperature difference and the air transport speed to the Iceland crystal's temperature and the thermal stress.The results show that:Iceland crystal on heating or cooling,temperature gradient should be controled as well as the air transport speed,if the gradient of temperature oversized,the Iceland crystal instantaneous can destroy.Innovate this article:first,we theoretically infer the zero-expansion direction of iceland crystal,in view of the temperature to the Iceland spar crystal linear expansion and the refractive index two aspect influence,infers the temperature to the Iceland spar crystal light path difference influence;Secondly,the finite element method and ANSYS instrument are introduced to build the thermal detormation model of iceland crystal,which opened new way for the microscopic deformation;Finally,ANSYS tool is applyed to model analysis the three factors which affect iceland crystal's thermotics nature.The significance of this topic:On the one hand,the study of Iceland crystal thermotics properties supply theory reference data for the rational use and optimum design of crystal polarizing device;On the other hand,in the view of about the microscopic deformation experimental technique and the equipment insufficient consummation have the limitation to the microscopic stress strain survey,the introduction of finite element method and the ANSYS tool to research crystal infinitesimal deformation,will have the profound significance.