Optical information medium and recording method therefor
US6728198B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 4, 2002 |
| Grant date | Apr 27, 2004 |
| Priority date | — |
| Expiry date | Jun 4, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/24076
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical information medium made up of a transparent substrate capable of allowing a recording laser beam to penetrate therethrough; a recording layer formed on the transparent substrate; and a reflective layer formed on the recording layer and reflecting a reproducing laser beam thereupon. A numerical aperture of an objective lens of an optical pickup for irradiating the recording laser beam on the recording layer is approximately 0.65, and the numerical aperture of an objective lens of the optical pickup for irradiating the recording laser beam on the reflection layer is approximately 0.60. An inclination angle &thgr; at both edges of the groove for tracking, being formed spirally on the surface of the transparent substrate on which the recording layer is formed, with respect to the main surface of the transparent substrate, is selected to be from 55° to 75°. An index ∝, expressed by 1−Dr/Ds when assuming that the depth of the groove on the transparent substrate is Ds and the depth of the recording layer at the position of said groove is Dr, is selected to be from 0.2 to 0.4. Further, the full width at half maximum of the groove on the transparent substrate …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.