Utilizing wasted laser light in optical systems
US5115420A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 16, 1990 |
| Grant date | May 19, 1992 |
| Priority date | — |
| Expiry date | Jan 16, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B11/10576
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A laser in a magneto optical recorder supplies a laser light beam to be used in processing signals to and from a magneto optical record member. The laser beam is split into two portions. A first portion is the data beam which is directed to impinge upon a magnetooptic storage member. A second portion is so-called wasted light which is directed away from the storage member. The wasted light is intercepted by a mirror and reflected into a beam splitter to phase-coherently combine with light reflected from the storage member for improving signal-to-noise ratio of the reflected storage member light beam. This action improves signal-to-noise ratio and enhances servo operation in the focusing position control of the optical head with respect to an optical storage medium. The focus control signal derived from the reflected light is not only used to control the focus of an objective lens in the system but also for positioning the mirror in synchronism with the movement of the storage member along the axis of the objective lens so that the phase-coherence of the wasted light beam and the data beam is maintained.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.