Durable silver coating for Kepler Space Telescope primary mirror

摘要

A durable silver coating was developed and applied to the Kepler Space Telescope primary mirror. The coating was manufactured by an ion-assisted evaporation process and coating uniformity was better than 30-nm PTV over the 1.4-m mirror aperture. The protection scheme for silver was devised and patented twelve years ago by Lawrence Livermore National Laboratory (LLNL) in the United States. An interference coating was added to the basic protected silver design, to enhance the reflectance from 400-nm to the near infrared.