Multi-beam optical recording-reproduction device with independent error detection for each beam
US5367512A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 8, 1993 |
| Grant date | Nov 22, 1994 |
| Priority date | — |
| Expiry date | Jun 8, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/094
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A multi-beam optical recording-reproducing device is capable of detecting the focusing and tracking errors of respective beams independently of each other by means of a simple optical system. The optical system for independent tracking error detection may include a wedge prism 39 and a four-partitioned photosensor 42, and that for the independent focusing error detection may include a half prism 33 for dividing the beams into reflected and transmitted portions, first and second knife-edges 34 and 19 for the reflected and transmitted beams, respectively, and a first and second two-partitioned photosensors 35 and 20 for receiving the beams via the first and the second knife-edge, respectively (FIG. 7). Alternatively, the optical system for independent focusing error detection may include a single knife-edge plate 61 having two knife-edges, and a four-partitioned photosensor 64 (FIG. 10), or a wedge prism 71 and an eight-partitioned photosensor 74 (FIG. 12). Further, the optical system for independent tracking error detection may include a concave cylindrical lens 83 (FIG. 14) forming a far field pattern perpendicular to the tracks on the information storage optical medium 9.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.