Opto-magnetic head apparatus
US5684762A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 6, 1995 |
| Grant date | Nov 4, 1997 |
| Priority date | — |
| Expiry date | Apr 6, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B11/10576
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An opto-magnetic head apparatus including a beam splitter for splitting laser light reflected from a photomagnetic recording medium into three bundles of light having different polarization directions in a specific plane. One of the three bundles of light is used as a servo-signal and the remaining two bundles of light are used as a data-signal. A diffracting element, which splits at least the bundle of light used as a servo signal into two bundles of light in a direction perpendicular to the direction in which the splitting of the laser light by the beam splitter occurs, provides a predetermined amount of positive or negative defocus to the bundles of light split by the diffracting element. The opto-magnetic head apparatus also includes a pair of servo-signal light receiving elements which receive the bundles of servo-signal light split by the diffracting element and which are located in a plane normal to the optical axis. Two data-signal light receiving elements, which receive the bundles of the data-signal light, are located in the same plane as the servo-signal light receiving elements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.