Optical pickup with conversion of diffusion angle of outgoing light relative to diffusion angle of incident light
US5790502A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 26, 1995 |
| Grant date | Aug 4, 1998 |
| Priority date | — |
| Expiry date | Sep 26, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B11/10576
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In an optical pickup, light, emitted from a light-emitting element, is transmitted through a first beam splitter film with polarization selectivity, and a zero-order diffraction beam and two (.+-.) first order diffraction beams are produced. These beams are applied in a condensed manner to an optical disk through a condensing element, and the return light beam from the optical disk is fed to a photodetector through a second beam splitter film with polarization selectivity, thereby effecting the recording and reproduction of information, the tracking and the focusing. A diffusion angle conversion hologram is provided between the light-emitting element and the first beam splitter film, and with respect to the diffusion angle conversion hologram, the relation between the diffusion angle of the incident beam and the diffusion angle of the outgoing beam is specified. With this arrangement, the light to be incident on the condensing element can have an ideal spherical wave free from a wave aberration, so that an image spot on the optical disk can be condensed into a diffraction limit, and besides by correcting the phase of the beam, a RF signal with a high C/N ratio, a stable focus error…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.