Based upon the principle of multiple diffuse reflection (resulting from the Lambertian coating), the integrating
sphere is used to spatially integrate radiant flux, either from an external or an internal source of radiation.
The efficiency of an integrating sphere is determined by a number of factors, including the size and number of
ports, the size and location of baffles or screens, the number of inclusions in the sphere, and most importantly,
the reflectance and diffuse nature of the sphere coating that has to be ideally diffuse reflecting.
The oldest application for the integrating sphere is the measurement of total geometric luminous flux from
electric lamps. The technique originated at the turn of the 20th century (by Richard Ulbricht in Germany,
which is why it is also called an Ulbricht sphere) as a simple and fast method of comparing the
lumen output of different lamp types. It is still widely used in the lamp industry for quality
control during manufacture.
We installed a 2.5m integrating sphere at the PTB (Physikalisch-Technische Bundesanstalt) in Braunschweig, Germany.
Take part in the installation process