Instrument Geometry – Directional 45°/0° or Diffuse d/8° Sphere? Follow

Directional or Diffuse?… just look in the port.

The geometry of an instrument is the relative position of the light source, sample plane and detector, and is one of the 6 key parameters that define a color measurement. There are two general categories of instrument geometries – directional 45°/0°(or 45°/0°) and diffuse d/8° sphere.

To tell the difference between directional and diffuse instrument geometries, look in the port. If the inside is black, when the lights are on, the instrument has a CIE directional 45°/0°(or 45°/0°) geometry. If the inside is white, then it is a CIE diffuse  d/8° sphere geometry instrument.

While both geometries can be used for color measurement, it is best to measure some samples with a directional 45°/0° geometry instrument and others with diffuse d/8° sphere. More information in our Application Notes at AN 1033.00 Color versus Appearance.