CIE recommends four measuring geometries for colorimetry, including the 0°/d and d/0° geometries.
|Standard Geometries 0°/d, d/0° and d/8°|
In this context, d stands for observation of the light that is diffusely scattered by the sample by means of the wall of an integrating sphere or diffuse illumination of the sample by means of an integrating sphere.
0°/d Measuring geometry
Illumination of the sample under 0°, measurement on the sphere
d/0° Measuring geometry
Diffuse illumination of the sample, measurement under 0°
Standard Geometry 0°/d and d/0°
According to CIE definition, the axis of the beam of rays must be tilted by no more than 10° with respect to the surface normal upon perpendicular illumination or observation of the sample.
This is made possible by the d/8° measuring geometry, which offers particular advantages in the measurement of glossy or structured samples. Observation of the diffusely illuminated sample under an angle of 8° allows the influence of the mirror-reflected component of glossy samples to be eliminated by inserting a beam trap in the integrating sphere.
d/8° Measuring geometry
Diffuse illumination of the sample, measurement under 8°