The Design And Performance Study Of The High Temperature Phase Partial Barium Borate Crystal Polarizing Prisms

With the rapid development of laser polarization technology, various polarized devices have become the indispensable pillars, in which polarizing prism is more important. At present the main production material of polarizing prism is almost natural birefringent crystal-calcite, But with its constant developing and utilizing, the appropriate quality natural calcite material is in serious shortage.Because the shortage of calcite and the high demand of high-power laser application, it's important that exploring new birefringent crystal material to make polarizing prisms. At present, the new type of birefringent crystal material-high temperature phase barium borate crystal(a-BBO) arouses our attention; on account of its width transmission band especially in the UV band, it is expected to become a new UV birefringent crystal.In this thesis, we designs a BBO polarizing prism basing on the past design experience and analysis its characteristic in theory. Some corresponding experiments are designed to validate the theoretical results. The main sections are as follows:In the introduction, we summarized the current status of polarized applications and materials of polarized prism. The properties of high temperature phase barium borate crystal are also introduced, for the research situation; give the purpose and significance of subject research.The second chapter describes the design principle of polarizing prism, focused the Glan Taylor prism, and briefly describes some common polarizing prisms, beam splitters.ChapterⅢpresented the design scheme of a-BBO, designed and made Glan-Taylor polarizing prism for broadband via theoretical calculation. The corresponding view angle range is given.In the fourth chapter, we analyze the properties of prism sample and give the light intensity transmittance ratio formulas along with wavelength and incident angle. Two kinds of circumstances whether considering multiple-beam interference between two incision inclines of polarizing prism are discussed.In final chapter, we introduce the experiment system and test the extinction ratio and transmission ratio of sample. Then obtain the related experimental results, compared with theoretical curves.The main research work in the thesis:1. Analyze the dispersion characteristic of a-BBO crystal and design the structural angle of Glan-Taylor and Lippich prism according to application band from 200-800nm above. For the first time, we give the design scheme of BBO prism for air gap-type, and the theoretical field angle range of air gap-type BBO polarizing prism. 2. Make a Glan-Taylor prism with a-BBO crystal material. Give theoretical formulas of prism transmission alonging with wavelength and incident angle and draw the corresponding theoretical curves. According to the material properties, we proposed protection scheme, and solved the problem of moistureproof film designing and its evaporation.3. Improve the system of measuring prism parameters and the measurement process.Measure the extinction coefficient of BBO polarizing prism based on the intelligent extinction ratio test system. The test results show that it has the superior extinction ratio. Using the illuminant systems composted of LHT75 xenon lamp and Onmi-λ150 monochromator, we get the changing patterns of prism transmission ratio with wavelength when normal incidence. Then transmission spectrum curve is in good agreement with the theoretical curve and the transmission ratio is quality.For the present situation, researching the new a-BBO crystal material and manufacturing corresponding polarizing prism is significance. Due to text emphasis, the thesis introduced rarely about processing technology. But the researching and perfection will be the basis of universal using for this prism.