Storage Ring FELs are used as one of the main sources for circular polarized γ-radiation in various experiments. The achievable energy of this γ-radiation is strongly related to the central wavelength of the UV-wavelengths in the FEL. This lasing wavelength in-turn determined by the VUV-resonator mirrors, which face a unique set of requirements including high reflectivity and low losses at wavelength of 155 nm and below, as well as resistance to intense UV-and γ-radiation. The contribution will show the manufacturing, laser damage caused in the FEL as well damage mitigation strategies.