Compressive Stress Effect On Optical Properties Of Iceland Spar Crystals

Polarizing Prism is one of the most important optical devices in polarized optics, and it alsoplays an important role in the development of polarization technology. But during the installationand use of polarizing prisms, external stress can’t be escaped. These effects are mainlymanifested by the refractive index and the shape of crystals. Although the changes brought aboutby the stress field is very small, but it is sufficient to affect the propagation of light in crystalswhich will affect the optical properties of the device.This thesis mainly takes Calcite crystal as an example, designing an experiment to measurethe elastic modulus of Calcite crystal in the direction of optical axis and perpendicular to theoptical axis. And then the elastic modulus of Calcite crystal has anisotropic is confirmed. Anoptical path was built to make preliminary research on whether external press have effect onCrystal’s axis direction, extinction ratio and phase delay. The study of this subject provides atheoretical basis for the design of polarizing prisms and its application in stress field, and it alsoprovides a basis for future study of other optical properties of polarizing Prism in stress field.The full text includes the following aspects briefly:In the first chapter, we mainly introduce the development situation of polarizing andpolarizing device technology. And then crystal’s mechanical effects, contents and significance ofthe study was described.In chapter two, chemical composition structure and physical properties of Calcite crystalwas introduced firstly. And then we describe the optical axis direction and the application ofCalcite crystal briefly.In chapter three, we first explicate the elastic theory and elastic anisotropy of the crystal andthe nature of elastic deformation. Then we describe the methods of measuring the extinction ratioof crystal with and without stress, and the relationship between extinction ratio and phase delayof crystal was derivated. Finally, we analyze the relationship between optical axis and extinctionposition of the crystal under stress theoretically.In the fourth part of this article we design experiments to measure elastic modulus ofCalcite crystal using electronic universal testing machine. First we use elastic modulus of K9glass which is known to us to do an experiment, and then compare the experimental results withactual values to calculate the ratio k. In order to verify the correctness of it,we use this methodto measure the elastic modulus of anisotropic Crystal both in optical axis direction and thedirection perpendicular to the optical axis. Results show that actual numerical difference issmaller. At last we measured the elastic modulus of Calcite crystal both in optical axis directionand direction perpendicular to the optical axis with this method.Finally,we confirmed that the elastic modulus of Calcite crystal crystals are anisotropic.In the fifth chapter, we measured optical axis under compressive stress, and gave aqualitative analysis. And concluded that the change of extinction ratio and phase delay of Calcitecrystal, when it was under different stress in the same direction.Significance: Provide a theory of reference for future research on the optical property ofCalcite crystal under stress field, and also provide some reference for the optimum design andrational use of Crystal polarizing device.This article’s main work and innovation: K9glass was used as a baseline to measure theelastic modulus of Calcite crystal in the direction of optical axis and perpendicular to the opticalaxis. And then the elastic modulus of Calcite crystal has anisotropic was confirmed. Secondly,we found out the relationship between the extinction location and optical axis, and then designedexperiments to explore whether the optical axis direction of Calcite crystal is changed undercompressive stress. A Crystal model was designed to probe the change of optical axis direction,extinction ratio and phase delay of the Calcite crystal, when Calcite crystal was under differentstress in the same direction.