Abstract: An improved mercury vapor lamp construction as described which includes an ultraviolet reflecting underlayer of alumina particles for the phosphor coating to enable reduction in the phosphor coating weight without accompanying reduction in the lamp lumen output. The alumina underlayer comprises spherical alumina particles that have been vapor-deposited in a certain particle size range to provide selective reflection of the ultraviolet radiation being emitted from the overlying phosphor coating. The alumina underlayer is deposited upon the interior surface of the lamp glass envelope and has been found generally useful in otherwise conventional high-pressure and low-pressure mercury vapor lamps.

Abstract: A light diffusion coating for an electric lamp is described which comprises a thin layer of spherical alumina particles that have been vapor-deposited in a certain particle size range to provide more effective light scattering. The coatings are deposited upon the interior surface of the sealed glass envelope and have been found especially useful for incandescent lamps as well as for such other lamps as electric discharge lamps.