Abstract: A method of determining the nuclear radiation dosage to which a thermoluminescent crystal, such as a diamond or cubic boron nitride crystal, has previously been subjected, involves the steps of heating the cyrstal up while supporting it against gravity on an upwardly flowing stream of gas. The light which the crystal emits is collected and analyzed to give a radiation dosage measure in accordance with a know relationship between amount of collected light and radiation dosage. The gas stream may be a hot gas stream in which case the hot gas also serves to heat up the crystal. In one embodiment of the invention, the crystal is supported and heated up inside an integrating sphere which collects the emitted light.

Abstract: The invention relates to the measurement of the shade of a particle. The particle is illuminated with light of variable intensity and viewed against a background level of illumination. A measurement is made of the ratio of time for which the intensity of light from the particle exceeds the intensity of the background to obtain a measurement of the shade of the particle.

Abstract: The colors or surface conditions of small articles are determined by passing the articles through an integrating sphere and separately illuminating the articles before they enter the sphere, during their passage through the sphere and after they leave the sphere. The light transmitted through or reflected by each article is collected by the sphere and passed to analyzing apparatus. The articles are sorted according to the measurements.