Both rigid and flexible optical endoscopes require an external source of light to illuminate the area that needs to be examined. In the case of surgical procedures the areas in question are usually located in cavities and, therefore, are devoid of natural illumination. The external light sources can either be small and portable, or larger standalone devices. Portable light sources, also commonly known as light handles, are connected to an endoscope body through adapters or couplers. In spite of their compact size, some light handles are able to provide high intensity light, sufficient even for demanding applications.
Larger standalone light sources are sometimes required for longer endoscopes and for such procedures as examinations of the gastrointestinal tract. This type of light sources usually involves a connection to a power outlet. The light travels from the light source to the endoscope through specially designed fiberoptic light guides of different lengths. Standalone light sources, of course, have a much higher light intensity.