Anti-atomic oxygen properties of MgF optical coating for JEM-EUSO mission

Tagawa, Masahito*; Yokota, Kumiko*; Tachiuchi, Hiroto*; Teraoka, Yuden; Takizawa, Yoshiyuki*

no journal, , 

Effect of atomic oxygen on the candidate of lens materials for the first objective lens of JEM-EUSO telescope was evaluated by the laser detonation ground-based atomic oxygen exposure facility at Kobe University. It was confirmed that transparency of PMMA was gradually lost by the atomic oxygen exposure. MgF anti-reflection coating was also oxidized by the reaction with hyperthermal atomic oxygen exposure. Due to its imperfection of the coating, oxidation of material may be continued with increasing the fluence. It was not recommended to use the combination of PMMA and MgF on the first objective lens of LEM-EUSO telescope.