Method and apparatus for reading or measuring magneto-optical storage media using pinhole aperture
US4847823A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 19, 1987 |
| Grant date | Jul 11, 1989 |
| Priority date | — |
| Expiry date | Jun 19, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B11/10543
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A scanning confocal optical imaging system is utilized to read or measure data magnetically recorded on a magneto-optic disk. The system includes a laser for producing a linearly polarized beam and a beam splitter for directing the transmitted beam to the disk and for deflecting a portion of the reflected return beam from the disk to a photodetector. A pinhole plate is placed between the beam splitter and the disk for restricting the size of the transmitted and reflected beams, and a polarizer is positioned between the beam splitter and the photodetector to receive the deflected return beam and provide an output that discriminates between the differing directions of rotation of the polarization plane of the transmitted beam by the magnetized area on the disk so that the direction of magnetization of the magnetized area can be read by the photodetector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.