| Polarizing prisms are the optical devices to generate polarized light. A kind of birefringent polarizing prism is widely used in the modem laser technology, which has many prominent merits such as the high extinction ratio and the big anti-light injury threshold in contrast with other kinds of prisms. Polarizers, beam splitters, phase retarders and depolarizers are the most commonly used polarizing prisms. Temperature affects the performance of the instrument, equipment and devices. Much attention has been paid to this problem for a long time. One example is the thermal effects on the polarizing devices that are made up with Iceland crystal or other birefringent materials. With the rapid developments of the laser technology in our country, polarizing prisms are used in more and more areas. So researches on thermal effects of the polarizing devices are becoming very important. Not only the thermal properties but also the optical properties of these birefringent crystals (materials) are anisotropic. So how the temperature affects the properties of these devices is very complicated, and shouldn't be neglected. The effects on the macroscopical optical property of the crystal with the variation of the temperature mainly behave as the variation of the refractive index. Although the changes are small, they are big enough to alter a great deal of characteristics when the ray propagates in the crystal. The thermo-optical effect is harmful to a majority of the optical devices. The transmittance, the extinction ratio and the transmitted intensity are all changed due to the alteration of the refractive index, hi addition, optical waves will be distorted or the intensity of the transmitted waves will be non-homogeneously distributed because of the change of the crystal's temperature as well as the uneven temperature distribution.The dissertation puts emphasis on the Iceland crystal and theair-spaced Glan-type polarizing prisms made of the Iceland crystal. Thermal effects on the devices are also presented.The first chapter mainly introduces the general development of the polarizing devices and the importance of the researches on this subject. The second chapter firstly presents the basic conception of the polarizing principles of the prisms, and introduces the Snell theorem and the total reflection formula. The reflectivity formula of the s vibration as well as the p vibration is given. Structures and polarization principles of the polarizing prisms such as the Glan-Thompson prism or the Glan-Taylor prism, beam splitter prisms such as the Wollaston prism or the Rochon prism and their beam splitting principles, the operating principle and features of the phase delay plate, the operating principle and the classification of the achromatic phase delay devices, along with the depolarization devices are all presented.Chapter 3 is arranged in the following sequence to acquire the refractive index of the Iceland crystal for different values of the wavelength and the temperature. Firstly, the properties of the Iceland crystal are described. The notion of the dispersion and the Sellmeier equation are presented. Secondly, constants in the Sellmeier equation are analytically calculated out and expressed as the function of four different groups of values of the wavelength and the refractive index. The optimal constants are obtained using the iterative method in the visible range of the light. Thirdly, we calculate out the refractive index as a function of the temperature for different values of the wavelength with the interpolation method, by which we obtain the constants of the Sellmeier equation for different values of the temperature. Then we can easily obtain the values of the refractive index for different values of the wavelength and the temperature.When the temperature changes, several device parameters such as the transmittance, the extinction ratio and the curve of the transmittedintensity will change accordingly for devices made of the Iceland crystal. At the beginning of chapter 4 we cons... |
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