How to read Luminous intensity diagram?


Intensity, I, is the flux per unit solid angle. It is the amount of flux from a point source contained in a small angular volume. A source can be considered a point source for this application if the irradiance falls off as the inverse square of the distance from the source. Intensity, for a given source, can vary with direction.

To obtain the absolute value, the value read on the curve for the lamp flush should be multiplied Divided by 1000.

Example reading intensity associated with each direction:

(1) Identify the angle of interest (Ex: 45 °)

(2) The intersection point between the outgoing radius and the graph of the photometric curve is located;

(3) Measure the distance between this point and the source (Ex: 240 cd / klm).


Lamp flow used = 3600 lm

Value on curve = 240 cd / klm

Absolute Real Value = 240 * (3600/1000) = 864 cd

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Post time: Sep-26-2017
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