Prism Polarizer Extinction Ratio Of The Spectral Effects

Since the advent of lasers in 1960s, it is widely used in the area of science and technology with its unique performance. At the same time, polarization technology and polarizing devices have also been developing rapidly. The technology has become a specialized method in the area of optical inspection, optical metrology, optical information processing etc and has been widely used in various fields related to optical application. Polarizer is the key to the polarization technology. And since 1960, new polarizing devices, especially laser polarizers develop rapidly. The kind of laser polarizer home and abroad has increased from several to dozens in just a few years. What's more, many special laser polarizers come out.With the continual development of laser technology and polarization technology, prism-type polarizer is widely used and has gradually become essential optical components of modern optical technology, such as laser modulation, optical transmission, polarization information processing and main method for gaining polarized light and changing polarization currently. Most of the prism-type polarizers are made of birefringent crystal. At present, the most commonly used material is natural Iceland spar crystal. Due to the dispersion of light, parameters of polarizing prism, such as the transmission ratio, extinction ratio, vary with wavelength of the incident light. Extinction ratio is one of important parameters which are characterization of optical properties of polarizing prism. It has a close relationship with the transmittance of the prism. Research is mostly on how to obtain a high extinction ratio and little study of its changes with the wavelength has been known in the past.Based on the work of predecessors, with extinction ratio of polarizing prism key object, the extinction ratio with different wavelength in visible region has been theoretically analyzed. The extinction ratio of Glan-Taylor prism is experimentally studied with high extinction ratio of experimental system. Main points are as follows:The first chapter is an introduction. It offers a summary of background and purpose of the dissertation, as well as innovation and main work that has been done.The second chapter firstly introduces how to get different polarized light and laws related to propagation of light in transparent media, which is also theoretical basis of designing polarizing prism. Main parameters of polarizing prism are introduced, too. Then typical design of polarizing prism and beam-splitter prism is briefly given. And also several common polarizing prisms and beam-splitter prisms are shown in detail.In the third chapter, Iceland spar crystal is introduced. Sellmeier equation of extraordinary ray in iceland crystal is given taking the dispersion of light into account. And according to Fresnel formula, transmission ratio of the polarizing prism is discussed in detail and multi-beam interference between two inclined planes is analyzed. Formulas for transmission ratio under different circumstances are achieved, so are the corresponding curves.In chapter four, principles of measuring transmittance and extinction ratio as well as method of measuring the extinction ratio are given. At the same time, the extinction ratio measurement system was established based on the intelligent high extinction test system. The extinction ratio of Glan-Taylor prism is tested with the system. And experimental curve of extinction ratio in visible region with wavelength is got. Considering various error factors, the experimental results can reflect the theoretical trends of transmittance and extinction ratio with wavelength.For a more comprehensive study about extinction ratio of polarizing prism, other factors that effect transmittance and extinction ratio are given apart form wavelength in chapter four. They are the absorption and scattering of materials and the glued medium, processing techniques, external field etc.The innovations of this thesis lie in:based on the theory of transmission ratio, extinction ratio of polarizing prism is theoretically analyzed. Continuous measurement for extinction ratio with all wavelengths in visible region is done with improved high extinction ratio measuring system. At the same time, curve of transmission ratio with wavelength is also achieved with the testing system.