Thin Al and Ag coatings (20 nm-100 nm) have been deposited on Be substrates using an ion beam enhanced deposition (IBED) process. Optical characterization was carried out by measuring the total hemispherical reflectance (THR) of these films over a wavelength range of 400-1000 nm and renorrnalizing the THR values to the solar spectrum (AM0). Al and Ag films laid down on polished sintered Be substrates had THR values below calculated theoretical values of 5-8% while Ag films laid down on sputtered Be substrates had THR values of only 1-3% below the calculated values. High coating adherency was demonstrated through the use of pulsed (65 ns) electron beam irradiations up to 0.45 cal/cm2. At this fluence, the Ag coatings melted and the Al coatings were unaffected.