Calculated reduction of radiation damage on thin layered interference mirrors

Thin Layered Interference Mirrors consist of a collection of m = 0,1,2, ...,N thin material layers, the m/sup th/ layer having thickness d/sub m/. The layers are separated from each other by other material such as dielectrics (possibly vacuum, although that is more difficult to realize). To simplify the calculation, here the authors treat the case where the separating layers are vacuum, the radiation is monochromatic with wavelength λ, and normally incident on the mirror. The dominant radiation damage is assumed to be caused by heating due to induced currents. The authors present design examples when d/sub m/ <<λ for all m. In each example the mirror reflectance is close to 100%, and resistance to radiation damage is calculated to increase by a factor f/sub r/. In the optical region f/sub r/ > 10/sup 2/. Because of competing damage mechanisms, the order of magnitude of f/sub r/ is probably more significant than its calculated numerical value