Diffraction patterns of nonoverlapping circular grains

Experimentally, it is observed that the diffraction pattern of nonoverlapping grains contains a light-depletion region near the origin. This region, which shows up as a black ring, occurs because of the enforced quasiperiodicity that results when many grains in a confined space are prohibited to overlap. A simple quantitative model that describes this observation is presented. The model, based on the pulse-jitter phenomenon in communication theory, avoids the usual complications inherent in mathematically describing nonoverlapping grains.