21 / 10 / 2026
When we look at a luminaire switched on, we immediately perceive how much light it produces and how that light is distributed in space.
But designing a lighting system correctly requires more than perception. We need to know how much light is emitted, in which directions and at what intensity.
This information is obtained with a goniophotometer, one of the most important instruments in photometry applied to professional lighting.
A goniophotometer is a measuring instrument used to analyse the distribution of light emitted by a luminaire in different directions in space.
During the test, the luminaire is measured at different angles, allowing its luminous emission to be reconstructed accurately.
The result is therefore not just a luminous-flux value, but a true map of the light, useful for understanding whether the distribution is wide or concentrated, symmetrical or asymmetrical.
The collected data are converted into photometric curves and files that can be used in the main lighting design software packages.
This allows the designer to place the luminaire virtually inside a space and predict how the light will behave before installation.
This is fundamental because two luminaires with the same luminous flux can produce completely different results depending on their optics and beam distribution.
The goniophotometer is not used only to generate data for software.
It is also a verification tool during product development.
A new optic, a different diffuser geometry or a change to the LED source can alter the behaviour of the light. Measurements therefore make it possible to compare what was expected during design with what the product actually produces.
The process becomes: design → prototype → measurement → analysis → optimisation.
In this way, photometry becomes an integral part of product development and helps make performance measurable, verifiable and repeatable.
In the 3F Filippi photometric laboratory, the goniophotometer is used to verify luminaire behaviour and generate the data required for lighting design.
Measuring light distribution makes it possible to verify performance, efficiency and optical quality, turning the real behaviour of the luminaire into information that designers and technicians can use.
Together with testing and inspection activities, the photometric laboratory is therefore a key step between development, verification and the finished product.
Lighting design works with something we cannot touch: light.
To use it precisely, it has to be transformed into data.
That is exactly what the goniophotometer does: it measures what the eye perceives and translates it into objective information for the project.
Because good light should not only be designed. It should be measurable, verifiable and predictable.
Discover the 3F Filippi R&D laboratory and learn more about our approach to measuring light.
