An inspection system and method uses a first illumination apparatus, such as a ring illumination apparatus to illuminate one or more reflective elements, such as solder balls on an electronic component or other protruding surfaces or objects. The ring illumination apparatus includes a substantially ring-shaped...http://www.google.com/patents/US6236747?utm_source=gb-gplus-sharePatent US6236747 - System and method for image subtraction for ball and bumped grid array inspection
