Cold light source
A cold light source (engl. Cold light source, cls) transmits light with greatly reduced infrared portion of. It is widely used in microscopy , endoscopes , surgical microscopes and various other medical and optical devices , i.e. wherever light of very high intensity in the visible spectral range is required, but the heat generated by an ordinary light source would be disruptive or even harmful.
The actual light source is usually a halogen - or xenon - lamp with a rotationally elliptical reflector . It often focuses the light on a bundle of light guides. The light is generated in a glass bulb called a burner , which is located in the second focal point of the reflector. The light guide (fiber optic bundle) transports the light to the place that is to be illuminated.
Even the reflector often has a cold light mirror coating , that is a dichroic mirror layer that only reflects visible light, but allows infrared to pass through. Additional filters between the lamp and the input of the optical fiber ensure that no infrared light or (important for some applications) also no ultraviolet light gets into the optical fiber. More complex cold light sources are provided with automatically changeable filters and diaphragms with variable light transmission to control the brightness of the cold light source.
However, light sources for curing photosensitive resins in dentistry specifically transmit the blue portion of the radiation.
A quick automatic or manual exchange of the lamp for an already installed replacement lamp is necessary for safety reasons with surgical microscopes.
The heat produced by the lamp must be removed from the lamp housing by convection or a fan. The ventilation openings required for this should not expose any scattered light. A cold light source that meets all of these requirements is an expensive and complex fine mechanical-optical device.
Cold light sources are often designed as free-standing tabletop devices. But there are also versions that are attached to other devices as accessories. Complete integration into other devices is also common.
See also
- Cold light mirror lamp: use of this principle for general lighting.
literature
- Wilhelm Gerster: Modern lighting systems for indoors and outdoors. 1st edition, Compact Verlag, Munich, 1997, ISBN 3-8174-2395-0
- Hans R. Ris: Lighting technology for practitioners. 2nd edition, VDE-Verlag GmbH, Berlin-Offenbach, 1997, ISBN 3-8007-2163-5