| Abstract [eng] |
Investigation of Multilayer Dielectric Mirrors after Extraneous UV Exposure Nowadays laser sources are widely used in material processing and military market as a tool for precision cutting application or ultrahigh resolution measurements. At this moment high price of laser sources are still limiting range of commercial application. Reducing cost of laser sources and components are the main task of global manufactures. Meanwhile it is obvious that dielectric coated optics are key components limiting performance of final system. These components have to handle wide range of temperatures, physical pressure and various extraneous exposures. The aim of this work is to determinate which commercially available metal oxide based dielectric mirror are sensitive to UV exposure and to understand mechanism of losses. Some deeper investigation results of Nb2O5, HfO2 ,TiO2,are presented in this work. Commercially available dielectric mirrors optimized for use in NIR spectral range were investigated with spectrophotometer and custom laser based reflectivity measurement set-us. These measurements were held in dark and under UV exposure in order to determinate changes in reflectivity. To understand changes in thin films which resulted in degradation of reflectivity additional X-ray diffraction, IR spectroscopy and impedance spectroscopy measurements were done. It is clear that TiO2 based laser mirrors are sensitive to UV exposure and final reflectivity decrease after exposure. Impedance spectroscopy, X-ray diffraction and IR spectroscopy results suggests that generated photoelectrones are participating in chemisorbtion which results OH- ions, OH- ions in the structure might be the source of absorption and scattering losses, but refractive index of TiO2 layer is not changing. |
