osed on a first portion of said medium, detecting at least a portion of the light of variable intensity reflected...http://www.google.com/patents/US5825402?utm_source=gb-gplus-sharePatent US5825402 - Method and appratus for reading and writing indicia such as bar codes using a scanned laser beamAdvanced Patent SearchPublication numberUS5825402 APublication typeGrantApplication numberUS 08/037,749P