Optical pickup head apparatus
US6016300A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 13, 1998 |
| Grant date | Jan 18, 2000 |
| Priority date | — |
| Expiry date | Jul 13, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0943
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical pickup head apparatus for reading information signals from a recording medium having a laser beam light source, an objective lens and a photodetector, the improvement comprises a holographic optical element constructed of a pair of diffraction gratings having different diffractive conditions wherein the element is split into two by a split line near its optical axis as a border and a diffraction generation prevention device for preventing the generation of unwanted diffracted beams from a recording medium. The optical pickup head apparatus irradiates a laser beam emitted from the light source onto a recording medium via the holographic optical element and the objective lens. Beams reflected from the recording medium are guided to the photodetector via the objective lens and the holographic optical element.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.