Design Of Vacuum Ultraviolet Reflecting Stack And Bandpass Filter In The Visible Region

With the rapid development of the national economy and various Hi-tech equipments, optical films have been found more and more applications in many fields. This paper focuses on the desige of high-reflectance vacuum ultraviolet stack and bandpass filter in the visible region.In the second chapter, a brief description to "Layer-by-Layer"(LBL) method is given, and according to the primary principle of the selection of stack materials presented, Rh and Si are chosen to be the materials of the stack. The reflectance of the stack in the range of50～200nm is calculated based on LBL method, and higher reflectance is obtained with less film layers. The average reflectance in the entire band region is67.9%. Compared with other material combinations such as C-Si、SiC-Si、 W-Si, the calculation shows that the reflectance of Rh-Si combination is more higher. In50～110nm wavelength region, the reflectance of the stack designed is53.24%quite higher than the results calculated by other methods. The influence of film thickness error on the reflectance is also analyzed. The result shows that the reduction of film thickness impacts adversely the reflectance more than its increase. This conclusion gives a direction for the control of the film thickness in later experiment.The third chapter mainly describes the design process of the bandpass filter in the visible region. The center wavelength of the filter is505nm,and the passband range from500nm to510nm. After analysis of the optical properties of many available materials such as MgF2、SiO2、 Al2O3、Sb2O3、TiO2, the combination of TiO2and SiO2is chosen to design the filter. The final designed stack structure is (HL)3H(HL)3H(LH)3(HL)4， with its passband width10nm and peak transmittance98.36%.