Scanning apparatus
US4904034A · kind A · utility
Inventors
Key dates
| Filing date | Jan 29, 1988 |
| Grant date | Feb 27, 1990 |
| Priority date | — |
| Expiry date | Jan 29, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/12
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A scanner including a source of coherent light, a radial hologon, a f.theta. lens and a target. Between the light source and the hologon there are means for forming light from the source into a collimated beam having an oblong cross-sectional shape and for directing the beam onto the hologon at a predetermined incident angle and with the long axis of the oblong cross-sectional shape of the beam radial of the axis of rotation of the hologon. Prismatic means are provided between the hologon and the lens means for so modifying the cross-sectional shape of the beam that the spot at the target station has a selected shape and orientation. This allows the shape, orientation and size of the beam on the hologon to be optimum for duty cycle of the hologon and for spot size on the target. The prismatic means allows the spot shape and orientation on target to be optimized. The prismatic means tends to introduce undesirable bow into the scan line, therefore the wavelength of the light and the grating factor (n .lambda.)/d of the hologon are selected to produce an approximately equivalent opposite bow.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.