Three-dimensional recording and reproducing apparatus
US5614938A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 5, 1995 |
| Grant date | Mar 25, 1997 |
| Priority date | — |
| Expiry date | Jun 5, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/25716
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a three-dimensional recording and reproducing apparatus having a recording medium including a plurality of recording layers stacked on a substrate and an optical system for converging a light irradiated from the substrate side on each of the plurality of recording layers to three-dimensionally record and reproduce information, the following equation is satisfied: EQU .lambda./4.ltoreq.(1/8NB)(1/NB.sup.2 -1)NAF.sup.4 .DELTA.d where PA0 .lambda.: Wavelength of the light; PA0 NB: Refractivity of the substrate 3; PA0 NAF: Numerical aperture of a focus lens 8 for converging a light; PA0 .DELTA.d: Positional range in the optical axis direction in which exists a recording layer on which the light is to be converged. A light spot is focused on each layer of the multi-layer structured disc to record and reproduce highly reliable data in a high density.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.