A hand held, omnidirectional symbology or bar code reader for imaging linear and two dimensional (matrix, maxi-code) bar codes over relatively long working distances. The reader includes an imaging system including a focusing objective taking lens and a two-dimensional photodetector that operate to form...http://www.google.fr/patents/US6098887?utm_source=gb-gplus-shareBrevet US6098887 - Optical focusing device and method
