Optical assembly and apparatus employing same using an aspherical lens and an aperture stop
US5291008A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 10, 1992 |
| Grant date | Mar 1, 1994 |
| Priority date | — |
| Expiry date | Jan 10, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K2007/10485
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
There is disclosed an simplified apparatus that enables optical scanners to achieve minimum field curvature and at the same time provide uniformly distributed light on an image sensor. A single element lens, preferably an aspherical lens made of a plastic material is combined with an aperture stop. The combination is capable of reducing lens aberrations and minimizing image field curvature for an object plane that contains indicia to be scanned or read. A suitably demagnified image of the indicia is focused onto an image sensor such as a CCD array. The spatial light distribution function in the image plane can be equalized by an attenuator, such as a neutral density filter or a slit, suitably configured to compensate for the reduced optical efficiency at large field angles. An aspherical lens containing a dye or a cold mirror can be used for limiting light transmission to a range of wavelengths.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.