Abstract: A diffuse reflectance probe is disclosed which employs in an exemplary embodiment, fiberoptic light transmitting elements and a light pipe for collecting light. The fiberoptic light transmitting elements surround the light pipe and a window having a beveled surface communicates with the light transmitting fiberoptics to direct illuminating radiation in a relatively large field of view in a close working distance with the probe.

Abstract: A fiber optic mixer is disclosed. A large diameter fiber has a curved radiation input end portion and a straight radiation output end portion. The length of the curved input end portion of the fiber is long enough to cause all entering radiation to hit the reflecting core boundary while the length of the straight output end portion is long enough to provide sufficient internal reflections to mix the radiation entering at the input end to produce a nearly zero correlation between an enterirg ray position and its position as an exiting ray. The fiber optic mixer can be used to efficiently couple radiation from the source or interferometer of a Fourier Transform Infrared Spectrometer (FT-IR) to a multiplicity of optical fibers so that each fiber receives substantially identical spectral, angular and intensity distributions of radiation.