Photodetector for hologram-type optical head including means for detecting return light spot deviation
US5001334A · kind A · utility
4Cited by
4References
3Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Aug 30, 1988 |
| Grant date | Mar 19, 1991 |
| Priority date | — |
| Expiry date | Aug 30, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0916
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A photodetector for a hologram-type optical head comprises, as a basic constitution, 6-piece-divided photodiodes. In order to prevent the photodetector from receiving the influence of wavelength variation of a laser diode, that is, spot deviations, one photodiode is divided into two small elements and the spot deviation is detected by utilizing the difference between outputs of the two small elements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.