A spectroscopy system separates the diffuse reflectance component of a reflectance spectrum from the specular reflectance component using a remote field stop filter. The surface of the sample is placed at a focal plane of an optical system. The optical system forms an image on the surface of the sample that includes an image of the remote field stop filter. The optical system images the surface of the sample onto either the same or another remote field stop. Energy reflected from the surface of the sample which is in focus at the remote field stop retains the image information about the image of the filter, whereas energy reflected from below the surface of the sample does not necessarily retain image information about the image of the filter. Since the energy from the surface of the sample is specularly reflected and the energy from below the surface is diffusely reflected, the specular component of the reflectance spectrum is spatially separate from some of the diffuse reflection component at the remote image stop and is filtered out. The now filtered reflection spectrum contains diffusely reflected energy, which is directed to the detector of a spectrometer.
