Scanning apparatus with integrated beam separating and beam-splitting element for scanning a magneto-optical record carrier
US5095476A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 13, 1991 |
| Grant date | Mar 10, 1992 |
| Priority date | — |
| Expiry date | Feb 13, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1395
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Scanning apparatus for a magneto-optical record carrier includes an integrated beam separating and beam splitting element consisting of a supporting body (30) on the surfaces of which are a semi-transparent mirror (22) and a polarization-sensitive beam-splitting layer (26). The semi-transparent mirror separates the scanning beam from the beam reflected from the record carrier. The beam-splitting layer splits the reflected beam into orthogonally polarized sub-beams (27 and 28) which are incident on respective photodiodes or on different regions of a single multiple photodiode. The supporting body may be of a birefringent material which provides orthogonally polarized beam-splitting, in which case the beam splitting layer may be omitted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.