Projection lamps utilize an internal (or proximity) reflector within the lamp's envelope. A projection lamp generally includes a preformed glass reflector and projection lamp. The reflector generally has an elliptical surface of revolution with the lamp filament at or near the focal point for concentrating a beam of light through the system's various elements. A hermetically sealed internal reflector is protected against oxidation, dirt, and other adverse conditions typically found in the lamp's environment. Projection lamps are used as decoration in the residential sector or for entertainment such as in discos. A projection lamp can produce colored light patterns constantly changing in an unpredictable manner. These colored patterns are produced by an emulsion, and is filled into a transparent container, which is disposed in the beam path of the light source of the projection lamp.
