Holographic optical element, position shift detecting apparatus, optical pickup apparatus, optical recording medium drive and method of fabricating holographic optical element
US6917454B2 · kind B2 · utility
2Cited by
4References
7Claims
0Family size
Assignee
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Key dates
| Filing date | Sep 9, 2002 |
| Grant date | Jul 12, 2005 |
| Priority date | — |
| Expiry date | Sep 9, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0916
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a holographic pattern provided in a holographic optical element, a pattern 1a twists a diffracted light beam in a clockwise direction, to form a semi-circular light spot Sa on photodetection parts A and B so as to extend over a dividing line LX in a four-segment photodetection part. A pattern 1b similarly twists the diffracted light beam in a clockwise direction, to form a semi-circular light spot Sb on photodetection parts C and D so as to extend over a dividing line LX in the four-segment photodetection part.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.