Abstract: Incandescent light bulb efficiency is improved by: (1) modifying the surface micro-structure of a lamp filament in such a way as to increase the emissivity in the visible region of the spectrum without significantly increasing this quantity outside this spectral region, or suppressing the emission of energy outside the visible portion of the spectrum by modifying the surface structure; (2) application of refractory coatings on the lamp filament that are highly emissive in the visible region of the spectrum; and (3) coating the filament with an "optically thin" refractory material to suppress filament evaporation, permitting higher operating temperature.