An optical scanner unit for scanning a document includes a laser unit for emitting a laser beam used for scanning the document, an optical system in which the laser beam emitted from the laser unit travels to the document and a reflection light beam obtained by reflection of the laser beam on the document...http://www.google.co.uk/patents/US5457550?utm_source=gb-gplus-sharePatent US5457550 - Optical scanner unit having recursive optical system
