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Guide Lighting technology | Luminaire technology | Reflectors Reflectors – general
Reflectance
Reflectance of reflectors: mirror-finish
Reflectors can be divided into different reflectance groups: mirrorfinish, specular and satin matt. Mirror-finish reflectors with good material quality are free of interference. The high reflectance and the highest specular quality make the luminaire appear as a “dark hole” in the ceiling. Reflections of items such as bright room furnishings are possible in the reflector. A further characteristic is high luminance contrasts in the reflector. The lower specular quality of specular reflectors reduces the disadvantages associated with highly specular reflectors. Satin-matt reflectors are also interference free if the anodising thickness is sufficient. The high reflectance and the low specular quality lead to low contrast within the reflector. This means that disturbing reflections from room furnishings are prevented and it also produces a calm room ambiance. Diffuse surface reflection can cause luminances of >200cd/m2 in the area beyond the cut-off angle. There is usually no disturbance on VDU screens.
Specular
Satin matt
Geometry 3
3
4
2 1
2
4
3 2
Light distribution is determined to a large extent by the form of the reflector. Almost all reflector shapes can be attributed to the parabola, the circle or the ellipse.
1
Path of beam from point light sources when reflected by:
Circle
Ellipse
Edition: 03/01/2010 | Updated version at www.erco.com
Parabola
Hyperbola
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