Method and device for measuring by means of photometric spheres

摘要

The aim is to eliminate an integration error which is caused by functionally induced sphere apertures and deviations of the diffuse reflection or transmission of the sample from the Lambert cosine law. Provided relative to the sphere aperture is a surface, e.g. an additional aperture, which appears at substantially the same angle seen from the sample. This surface is made to be white-reflective, on the one hand, and non-reflective, on the other hand, a measured value of the reflectivity or transmittance being formed in each case. A corrected reflectivity or transmittance can be determined from the two measured values obtained for the reflectivity or transmittance and from the area ratios of the sphere apertures or the additional area to the entire inner surface of the sphere.