Projection lamp unit

In a projection lamp unit including a glass reflector having a concave reflecting surface and an incandescent lamp positioned within said glass reflector and having an envelope located within the concavity of said reflector and including a coiled filament positioned within said envelope and substantiallly centered at the focal point of said reflector, the improvement wherein said concave reflecting suface comprises a plurality of alternately disposed, radially extending surface regions each including a plurality of individual diffusing facets occupying a plurality of radial rows each of a substantially tapered configuration having a maximum width at the periphery of said reflector, said surface regions of diffusing facets alternating respectively with a plurality of substantially equally spaced specular stripes each having a highly polished, mirrorlike finish and also being of a substantially tapered configuration having a maximum width at said periphery of said reflector, the combination of said regions of said diffusing facets and said specular stripes providing optimization of total optical output and beam pattern uniformity regardless of the placement of said coiled filament structure relative to the orientation of said regions of said facets and said stripes.