Laser pick-up
US5018804A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 29, 1989 |
| Grant date | May 28, 1991 |
| Priority date | — |
| Expiry date | Dec 29, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/13
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A laser pick-up device for an optical disk receives three laser beams to irradiate the optical disk and uses a six-division optical detector to detect the laser beams reflected from the optical disk and to track exactly the optical disk. A reflection type diffraction grating is positioned at a front position in order to divide and reflect the laser beam generated by a laser diode. A holographic element having the function of a toric lens is used as a diffracting device for the reflected beams. The six-division optical detector is positioned to one side and/or behind the diffraction grating. The grid gaps of the holographic element can be larger using the present invention which simplifies the manufacturing the holographic element and thereby provides a laser pick-up device that is suitable for mass production.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.