Light distribution curve is a visual representation of the light diffused by a luminaire.
Types of light distribution:

  • Symmetrical light distribution

In the figure below, you can see two lines radiate from the centre, a solid line and a dotted line. These lines indicate the light distribution and intensity from various angles. The solid line indicate the frontal view and the dotted line the side view. In the example below the two curves overlap. The light distribution is the same in the frontal view and in the side view. The two curves overlap on the right side of the chart, which is why dotted line is invisible.

  • Asymmetrical light distribution

If you look straight at the luminaire, meaning if you position yourself along the 0-180 degree axis, you can find that the upward beam is spherical and the downward beam is split into two spherical planes, because of the inbuilt reflector. If you look at the luminaire from the side, you can find a spherical plane upwards and downwards. This means that the luminaire distributes the light evenly. The light distribution is measured from the centre of the luminaire.