Optical scanning device
US7184387B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 18, 2003 |
| Grant date | Feb 27, 2007 |
| Priority date | — |
| Expiry date | Sep 18, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1367
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical scanning device for scanning an optical record carrier comprising an information layer. Crosstalk cancellation is provided using a phase modulating element (40, 140) for generating a non-rotationally-symmetric phase profile in a subsidiary radiation beam. The phase profile varies with an azimuthal angle measured about the optical axis of the beam portion, the phase profile varying such that successively different phases are introduced in at least five locations which are each at successive azimuthal angles (φ1, φ2, φN) and each at a given radial distance from the optical axis, wherein the phase profile is such that the phases introduced, when taken in modulo 2π form, successively cycle through 0 to 2π at least twice, whereby the subsidiary beam spot is provided with an intensity distribution on the information layer which overlaps that of the side-lobe of the main beam spot.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.