Concentric photodetector arrangement for focusing and tracking
US4843603A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 11, 1988 |
| Grant date | Jun 27, 1989 |
| Priority date | — |
| Expiry date | Mar 11, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/09
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical data storage system includes a laser which is focused on an optical disk by an objective lens. A tracking actuator and a focus actuator move the objective lens about a tracking axis and focus axis respectively. The tracking and focus actuators respond to signals provided by a focus and tracking detector. The focus and tracking detector is formed by four photodetectors which are electrically isolated from one another. The third and fourth photodetectors are disposed about the outer peripheries of the first and second photodetectors, respectively, about an axis. Each photodetector emits an electrical signal representative of the radiation detected thereon.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.