The optical instrument includes a body mounted for X-Y movement above a generally planar object and carries a wide-angle lens, and a plurality of collecting mirrors disposed at angular locations about and spaced from the axis of the lens. A reversing mirror is located above the lens and sensors are disposed...http://www.google.com/patents/US5245411?utm_source=gb-gplus-sharePatent US5245411 - Optical instrument and conveyor for automated optical inspection machine and methods of operation
