Optical reproducing apparatus
US5029154A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 21, 1989 |
| Grant date | Jul 2, 1991 |
| Priority date | — |
| Expiry date | Nov 21, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1353
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical reproducing apparatus has a dual grating provided with a substrate, a first diffraction grating and a second diffraction grating. The first grating receives an incident light reflected from an optical recording medium and separates the reflected light into a first transmitted light and a first diffracted light. The second grating receives the first transmitted light and the first diffracted light through the substrate and discharges a second diffracted light and a second transmitted light. A tracking error signal detector detects a tracking error signal by receiving one of the second transmitted light and the second diffracted light. A focusing error signal detector detects a focusing error signal be receiving the other of the second transmitted light and the second diffracted light.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.