Multilayer reflection microhologram storage in tape media
US6020985A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 13, 1998 |
| Grant date | Feb 1, 2000 |
| Priority date | — |
| Expiry date | Nov 13, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0013
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Digital data bits are stored as discrete-level reflection microholograms in a multi-depth digital optical data storage system. Reference and signal beams are incident in a counterpropagating geometry on opposite faces of a tape. The reflection microholograms are stored at the coinciding focus of the reference and signal beams. The holograms are stored at the diffraction limit of high-N.A. optics, and have relatively high grating frequencies and small sizes. Dynamic aberration compensators correct for the depth-varying spherical aberration imparted to the beams by the medium. Multiple mutually-incoherent lasers are used for parallel storage and retrieval to increase data transfer rates. Achievable densities and signal-to-noise ratios are substantially higher than for index-perturbation or transmission hologram storage methods.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.