High density optical disc configuration
US5883879A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | May 19, 1997 |
| Grant date | Mar 16, 1999 |
| Priority date | — |
| Expiry date | May 19, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/24085
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical disc includes two transparent substrate layers each having a recording surface with a plurality of pits arranged concentrically or spirally. The plurality of pits represents information stored on the recording surface. Each transparent substrate layer has a thickness of 0.6.+-.0.03 mm. A reflecting layer is formed on each of the recording surfaces of the two transparent substrate layers. An inclining angle formed between a pit inner wall and a normal line of each transparent substrate layer is 20.degree.-55.degree., and pit depth is set to be .lambda./3.5N-.lambda./2.7N. .lambda. is defined as the wavelength of a laser beam incident the optical disc for reading the information recorded on the optical disc, and N is the index of refraction of each transparent substrate layer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.