Critical illumination generally has problems with evenness of illumination as an image of the illumination source (for example a halogen lamp filament) is visible in the resulting image.
The compact size of the halogen lamp permits a reasonable size for portable projectors, although heat-absorbing filters must be placed between the lamp and the film to prevent melting.
Some high-power incandescent flashlights use a halogen lamp where the bulb contains a halogen gas such as iodine or bromine to improve the life and efficacy of the bulb.
Within the heating assembly are the circular halogen lamp, a fan, and the controls for the oven which frequently include an automatic shut-off timer and a temperature control interface.
