Evaporated Films for Large Mirrors

Abstract

An apparatus and technique for depositing metallic films upon large mirrors is described. Chromium and aluminum have been found to possess valuable properties of reflectivity and permanence, and to exhibit no tarnish after several months' use in the laboratory. The reflectivity of aluminum has been observed to decrease from 90 per cent at 6ooo A to 8o per cent at 3000 A. Some astronomical advantages of these films are discussed