A Novel Glass Mirror Design for Imaging Atmospheric Cherenkov Telescopes

The large dimensions of Imaging Atmospheric Cherenkov Telescopes (IACTs) make it practically unfeasible to protect them from environmental influences. Due to this, the mirrors which are installed on the telescopes are affected by corrosion from wind, dust, and rain. In current mirror technologies the reflective material is covered by a thin quartz layer for protection. However, still a significant decrease in reflectivity can be observed over the timescale of a few years. Additionally, current mirrors are impossible to clean from deposited dust and dirt without damaging their delicate surface, leading to an unstable reflectivity over short timescales. I present a novel glass mirror design which is easily cleaned and very resistant to degradation due to environmental influences. This new technology could provide a stable performance over a period comparable to the lifetime of an IACT. Results of tests which were performed on first prototypes in terms of reflectivity, focusing and stability under exposure to the environment are presented.