Optical anti-reflective information record
US4216501A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 11, 1978 |
| Grant date | Aug 5, 1980 |
| Priority date | — |
| Expiry date | Dec 11, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/252
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A flat major surface of a disc-shaped substrate (e.g., of glass) is coated with a light-reflective layer (e.g., of aluminum) which is coated with a dielectric material (e.g., silicon dioxide) highly transparent for light of a frequency supplied by a recording laser, which dielectric material is coated with a thin layer of a material absorptive for light of the frequency supplied by the recording laser (e.g., titanium). The coating parameters are chosen to establish an anti-reflection condition for the coated record blank at the recording light frequency. The light output of the laser, which is intensity modulated in accordance with a signal to be recorded, is focused upon the coated surface of the disc as the disc is rotated. With the peak intensity of the focused light sufficient to at least cause melting of the absorptive layer, an information track is formed as a succession of spaced pits in which the reflective layer is effectively exposed through the layer of dielectric material. For playback, light of a constant intensity is focused on the information track as the disc is rotated. The focused light is of insufficient intensity to effect melting of the remaining absorptive lay…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.