Apparatus for optically scanning an information plane
US4829506A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 4, 1987 |
| Grant date | May 9, 1989 |
| Priority date | — |
| Expiry date | Nov 4, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1353
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An apparatus for scanning the information plane of an optical record carrier with a radiation beam from a diode laser. The reflected radiation from the information plane is separated from the scanning beam and split into two sub-beams by a composite diffraction grating which also functions to focus the respective sub-beams on respective pairs of photodetectors. The composite grating consists of two sub-gratings which adjoin along a common bounding line, the sub-gratings having varying gratings periods and curved grating strips. Movement of the composite grating in the direction of the bounding line changes the axial imaging distance of the sub-beams from the grating, permitting adjustment of such distance to compensate for changes in the axial distance between the diode laser and the photodetector. The diode laser and photodetectors can therefore be assembled together as a single integrated unit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.