Spherical parts such as ball bearings are inspected by rolling the parts down sizing rails so that they rotate rapidly with minimal translational motion at a point where they drop through the sizing rails. In a region of rapid rotation the part is inspected by an array of optical systems covering the...http://www.google.com.au/patents/US4259013?utm_source=gb-gplus-sharePatent US4259013 - Optical method for inspecting spherical parts
