Optical head and optical memory device
US5436876A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 8, 1993 |
| Grant date | Jul 25, 1995 |
| Priority date | — |
| Expiry date | Dec 8, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1381
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A small and inexpensive optical head for detecting a recorded signal, a focusing error signal and a tracking error signal, and an optical memory device utilizing the optical head. A diffraction device (103) is provided having two chirped grating regions (103A, 103B) for dividing a light beam from an optical recording medium (105) and directing the divided beams toward four band-shaped photoelectric transducers (106) and an astigmatism generator formed by the diffraction device (103) and a positive lens (102). The four photoelectric transducers are positioned in a plane inclined with respect to the optical axis of zero-order diffraction light, and the longitudinal axes of each of the band-shaped photoelectric transducers are radially arranged relative to the optical axis.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.