ABSTRACT
This chapter describes the main kinds of light sources as they are used in optical instruments. Starting from the old tungsten filament lamp and its diverse versions, we end up with the newer kind of modern incoherent light sources. Coherent ones deserve special chapters, for this reason they are not considered here. Diverse tungsten lamps are described; arc and discharge are also described only as a part of an optical device. Later, fluorescent lamps take a place since they are still used in some apparatus. The light-emitting diode (LED) is described in a basic context since this kind of lamp is continually evolving in modern optical instruments.
