Comparison of luminous intensity distributions measured on luminaire turning and mirror goniophotometer

A goniophotometer is needed to measure the luminous intensity distribution of luminaires. Goniophotometer types differ basically how their axes relate to the optical axes of the luminaire under test and in which order they apply the turnings. As the result one gets luminous intensity distributions in different coordinate systems, but those can be transferred into each other's system. Some light source types like gas discharge types based on their operation principle are not allowed to measure them other then in their operation position. There are some light source types which operate independent from their operating positions. Such light sources are for example the semiconductor based light sources, like the LEDs. Some specially designed high power luminaires (like luminaires for sport lighting) can have forbidden operating positions which also are not allowed to measure with luminaire turning goniophotometers.