Fiber-optic scattering monitor for use with bulk opaque material

A method and apparatus is developed to monitor nondestructively the turbidity of colorless bulk material. The method employs illumination and measuring spots of equal and small sizes (radius r(m)) at the same site of the sample surface. The Kubelka-Munk scattering coefficient may be measured in nonabsorbing material but calibration is necessary. The range then is approximately l/(8r(m)) < S < 10/r(m). A flexibly connected miniature measuring head (r(m) approximately 0.13 mm) is connected to a lamp-detector unit by optical fibers. Polychromatic light from a xenon lamp is used. The present apparatus is especially designed for dental research, but biological tissues and also commercially available liquids, papers, and plastics can be monitored for their scattering behavior.