Iodine lamps; Quartz halogen lamps

Lamps that produce light as a result of electrical current through a metal wire, contained in a small transparent bulb that heats the metal to incandescence. The bulb also contains halogen that reacts with the vaporized metal, so that bulb blackening by vaporized metal is minimized.

During the operation of an incandescent lamp, tungsten evaporates from the filament and settles on the coldest place inside the lamp (the bulb wall), causing lamp blackening, which leads to a considerable depreciation of the light output during lamp life. In order to keep lamp blackening, and the corresponding light loss, within acceptable limits, bulbs of regular incandescent lamps are relatively large. But in order to be able to operate small-bulb high-light-output incandescent lamps, special measures have to be taken to prevent bulb blackening, which in these small bulbs would quickly lead to unacceptable light losses. The solution to...