Positive unit magnification reflective optics for holographic storage
US6147782A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 1, 1998 |
| Grant date | Nov 14, 2000 |
| Priority date | — |
| Expiry date | May 1, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03H2230/10
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A positive unit magnification reflective head is used to back-reflect a primary light beam, for storing reflection microholograms at the coincident foci of the primary and reflected beams. Imaging the primary beam focus onto itself at positive unit magnification allows increasing system tolerance to tilts and transverse misalignments between the primary and reflective heads. Holograms are stored at multiple depths in a holographic storage medium. Tunable-focus primary and reflective heads are positioned on opposite sides of the storage medium. The reflective head images each storage location onto itself at positive unit magnification. Suitable reflective heads include: two lenses in an f-2f-f configuration and a planar mirror; a lens and a corner cube; a thin lens and a thick lens with a coated reflective back surface; and a thin lens and a back-coated gradient-index (GRIN) lens. To control the polarization of the reflected beam, the corner cube may include a plastic filler bonded on the back of the reflective surface. The filler index of refraction is chosen such that the primary beam is incident on the reflective surface of the corner cube at the critical angle.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.