To obtain spectral information of diffuse, or specular materials, reflection probes are used. The light from a light source is sent through six illumination fibres to the sample and the reflection is measured by a 7th fibre that's mounted in the centre of the reflection probe tip. The 7th fibre is coupled to a spectrometer.
Versions with a greater number of fibres are available if extra energy is required to increase the reflectance signal.
Full details on the this probe and the extended range of fibre optic probes can be found by clicking here.