Definitions for "integrating sphere"
a hollow body having an interior of highly light reflecting but also diffusing material, and having relatively small openings in the shell of the hollow body to admit light
a hollow, spherical optical chamber coated internally with a high reflectance material that exhibits lambertian (ie diffuse) reflectance
an optical device for various purposes such as measuring the optical flux from a laser diode , light-emitting diode (LED) or bulb, or measuring scattering losses from a surface