Optical head with astigmatic reflecting element
US4870632A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 17, 1988 |
| Grant date | Sep 26, 1989 |
| Priority date | — |
| Expiry date | Mar 17, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1381
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical head for reproducing optical recording medium (6) has reflection optical means, such as, a reflection type astigmatic optical Fresnel lens (7A, 7B) or reflection type light-beam dividing (into at least two beams) Fresnel lens (13), grating (18) or prism (19), on or above a surface of a beam splitter (4), so that reflect return light from the optical recording medium (6) travels in the beam splitter 4 to photo-detector means (8, 15) having at least two divided parts (8A, 8B, 8C, 8D or 15A, 15B, 15C, 15D); thereby size of the optical head is reduced by setting the optical path from the reflection optical means to the photo-detector inside the beam splitter (4).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.