A Goniophotometer is a device used for measurement of the light emitted from an object at different angles. The use of goniophotometers has been increasing in recent years with the introduction of LED-light sources, which are mostly directed light sources, where the spatial distribution of light is not homogeneous. If a light source is homogeneous in its distribution of light, it is called a Lambertian source. Due to strict regulations, the spatial distribution of light is of high importance to automotive lighting and its design.
The various types of goniophotometer are defined here which is derive from a publication from the International Commission on Illumination.
Fixed horizontal axis, with the vertical axis attached, both perpendicular to the main output direction of the light source
Fixed vertical axis, with the horizontal axis attached, both perpendicular to the main output direction of the light source
Type A and B are Double columns structure.This type is applied to fixed the grille lamp. The symmetry axis of lamp and the horizontal of rotating supporter is coaxial, in the B-βcoordinate system, and the two is vertical Cross, in the A-αcoordinate system.
Fixed vertical axis perpendicular to the line of measurement, with a horizontal axis parallel to the main output direction of the light source
type C is single column structure .The single column structure will be gotten when the assistant column is taken down from double columns structure. This type is applied to fixed tube lamp, spot lamp etc. The axis radiation of lamp and the horizontal of rotating supporter is coaxial