STRAY-LIGHT CORRECTIONS IN INTEGRATING-SPHERE MEASUREMENTS ON LOW-SCATTERING SAMPLES

A method for correcting integrating-sphere signals that considers diff erences in the angular distribution of scattered light is extended to sources of errors that are due to stray light from imperfect optical c omponents. We show that it is possible to measure low levels of scatti ng, below 1%, by using a standard integrating sphere, provided that th e various contributions to stray light are taken into account properly . For low-scattering samples these corrections are more important than those from the angular distribution of the scattering. A procedure fo r the experimental determination of stray-light components is suggeste d. Simple, easy to use, compact equations for the diffuse and specular reflectance and transmittance values of the sample as functions of th e recorded signals are presented.