An optical element for causing a visible spotter beam emitted by a hand-held scanning bar code reader provides visible indications of the area of a surface which is being scanned by an invisible scanning beam. The optical element transforms the visible spotter beam, at its extreme of travel, into two...http://www.google.com.mx/patents/US5550364?utm_source=gb-gplus-sharePatent US5550364 - Method and apparatus for spotter beam formation using a partitioned optical element
