Method and apparatus for spotter beam formation using a partitioned optical element
US5550364A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 21, 1994 |
| Grant date | Aug 27, 1996 |
| Priority date | — |
| Expiry date | Mar 21, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K2207/1011
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
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 pairs of cursor beams which are directed along predetermined trajectories relative to the trajectory followed by the scanning beam. The predetermined trajectories can be above and below, or to the left and right of the center of travel of the invisible scanning beam. In one embodiment, a method of identifying the proper focusing distance of the scanning reader is presented. The method identifies the focusing distance by making the pairs of cursor beams formed from the visible beam at its two angular extreme of travel to form a predetermined pattern indicating the proper focusing distance. The optical element can be made from segmented or gradient surfaces, such as Fresnel surfaces, or from a holographic optical element.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.