Apparatus for differentiating between heterogeneous surface features and unique surface features

摘要

Provided herein is an apparatus, including a photon detector array; and a processing means configured for processing photon-detector-array signals corresponding to a first set of photons scattered from surface features of an article focused in a first focal plane and a second set of photons scattered from surface features of an article focused in a second focal plane, wherein the processing means is further configured for distinguishing foreign surface features of the article from foreign native features of the article.