Abstract: Bulk material formed by a multiplicity of individual moving particles is heat-treated by directing a light beam into an observation volume of the material and generating light reflections off at least one particle in the observation volume. A characteristic of the light reflections which is indicative of a desired extent to which the material is to be heat-treated is identified and the material is subjected to a heated environment and thereby heat-treated. The light reflections are monitored for the characteristic, and subjecting the material to the heated environment is ended in response to detecting the characteristic of the light reflections.

Abstract: A reflectometer for use with a roasting system includes a laser diode, a lens and a photodetector. The laser diode emits a laser beam having a wavelength corresponding to the maximum actinic response of the items being roasted. The laser beam is reflected off a mirror into a collecting volume of the items being roasted. The items being roasted then reflect light through the lens and to the photodetector. The system also includes a cross polarizer and a narrow-band filter between the lens and photodetector in order to filter undesirable reflected light. The collecting volume and the detector are within the searchlight cone defined by the lens and its focal point such that the reflected light from the collecting volume has a constant illumination.