A sphere whose interior is coated with a highly reflective, matte white material, so light from a source inside bounces many times and spreads evenly over the wall. A detector or spectroradiometer port, shielded from direct light by a baffle, then reads a signal proportional to total flux. Spheres measure lumens, CCT, CRI and SPD quickly; corrections for the sample's own absorption use an auxiliary lamp. Large luminaires need large spheres or a goniophotometer.
Put the sample in the 2 meter integrating sphere and run the auxiliary lamp correction, it's a dark housing.
Also heard as
- sphere
- Ulbricht sphere
- photometric sphere
Related terms
Spectroradiometer
An instrument that measures light's power at each wavelength, from which color and photometric values are calculated.
Luminous flux
The total amount of visible light a source emits in all directions, weighted for the eye's sensitivity and measured in lumens.
LM-79
The standard method for measuring a complete LED luminaire's light output, power, efficacy, color and distribution.
Goniophotometer
An instrument that measures a luminaire's light intensity in every direction by turning the luminaire, or a mirror around it, relative to a detector.