High-density information recording/reproducing method
US5886969A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 21, 1997 |
| Grant date | Mar 23, 1999 |
| Priority date | — |
| Expiry date | Nov 21, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2220/2537
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical recording/reproducing method employs a recording laser beam having a first output and a first wavelength, and a reproducing laser beam having a second output lower than the first output and a second wavelength shorter than the first wavelength. A disk-like recording medium is irradiated with the recording and reproducing laser beams by use of an objective lens having an NA of about 0.55 so that a small mark equal to or smaller than about one fourth of a spot size optically defined from the wavelength of the recording laser beam and the NA of the objective lens is formed on the recording medium by a recording characteristic of the recording medium and a shielding plate provided in an optical system for irradiation with the laser beam. Two-dimensional recording is performed as a recording system to arrange marks at lattice points of a two-dimensional lattice which extend in a track direction and a track radius direction. The reproducing system detects a reproduction signal from the mark on the two-dimensional lattice point, and the reproduction signal from each mark is used to perform a signal processing, thereby detecting information.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.