LIGHTDISTRIBUTION AND PHOTOMETRICAL EFFECT

Die lichttechnische Wirkung einer Leuchte in einem leeren Raum ist abhängig von ihrer Abstrahlungscharakteristik und der Reflexion an den Wänden und der Decke des Raumes (siehe Abbildung 3.152). Die Reflexion an Wänden und Decke ist ihrerseits abhängig von dem Reflexionsgrad dieser Flächen sowie deren Abstand zur Leuchte, also der Raumgeometrie. Befinden sich Gegenstände in dem Raum, so sind deren optische Eigenschaften und ihre  geometrische Lage zur Leuchte ebenfalls zu berücksichtigen.

Modern design programs today (see chapter "Photometric design software DIALux and Relux") can determine the photometric effects of luminaires very precisely. This way, e.g. illuminance or luminance can be calculated for any surface in a room with great precision. Correspondingly, illuminance can be determined on any given measuring surface or measuring plane anywhere in the room.

The distribution characteristic of the luminaire is usually specified using a luminous intensity distribution. To this end, the luminaire is treated like a point light source. This so-called distant field observation leads to sound calculation results in software programs if the exact spatial location and extent of the light emission from the luminaire has only little influence on the result in the measuring plane. In case of large luminaires with elongated or planar light emission, photometric programs will divide them up into several light points located at regular intervals (see also chapter ).

To describe a luminaire, the luminous intensity distribution can also be divided into solid angle ranges where portions of the luminaire's total luminous flux are distributed (see figure). This is referred to as luminous flux distribution. An important measuring plane is the working plane, where the visual task is located in many applications.

Classifications of luminaires    Luminous intensity distribution curve