Techniques for fabrication of large-size graded reflectivity mirrors

According to the parameter requirements of a graded reflectivity mirror with a Gaussian profile, the layer structure and the mask pattern are designed using a graded-thickness middle layer. The mask and the automatic mask-switchover equipment are designed considering the actual requirement of the thin films and the specific deposit facility. The uniformity of the layer thickness is analyzed. The measurement results indicate that samples prepared with this technique are basically in accordance with the design parameter. The scattering effect between the material molecules and the mask, thickness errors, and the alignment error between the mask and the substrate are the main factors that influence the deposit result. (c) 2008 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3027595]