Further studies on MgF(2)-overcoated aluminum mirrors with highest reflectance in the vacuum ultraviolet.

MgF(2)-overcoated aluminum films with high-vacuum ultraviolet reflectance have been the subject of further investigations of the preparation parameters affecting their reflectance, and of the effect of aging and exposure to conditions likely to be encountered in their applications. Techniques for monitoring the thickness of MgF(2) by reflectance measurements with ultraviolet light and by complete evaporation of weighed quantities of MgF(2) are described. It is shown that MgF(2)-protected aluminum mirrors retain their high-vacuum ultraviolet reflectance during extended exposure to air, ultraviolet irradiation, and bombardment with 1-MeV electrons and 5-MeV protons, and that such mirrors can be easily cleaned if contaminated with oil.