Phase change optical disk and a method for recording and playbacking optical information on or from an optical disk
US5862122A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 23, 1997 |
| Grant date | Jan 19, 1999 |
| Priority date | — |
| Expiry date | Oct 23, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/24316
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The optical phase difference between reflected laser light from the crystalline and the amorphous part of a phase change recording layer is established as 180 degrees .+-.5 degrees. The ratio between the light absorption factor when the phase change recording film is in the crystalline condition to that when it is in the amorphous condition is set to within the range 0.9 to 1.1. With the wavelength of the laser light used as .lambda., the optical depth of a guide groove formed on the substrate is set to within the range .lambda./9 to .lambda./6. With the wavelength of the laser light used in the range 635 nm to 650 nm, the depth of the guide groove is in the range 40 to 70 nm. In an optical disk such as this, when seen from reflected light, the groove region of a groove during playback and land region of the groove during playback are optically equivalent. For this reason, it is substantially the same as the case in which the optical phase difference between the reflected laser light from the crystalline part of the recording film and the reflected laser light from the amorphous part of the recording film is zero, this making it possible to achieve consistency in the signal levels …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.